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postgres/src/backend/postmaster/postmaster.c
Peter Eisentraut df8b8968d4 Order getopt arguments 
Order the letters in the arguments of getopt() and getopt_long(), as
well as in the subsequent switch statements.  In most cases, I used
alphabetical with lower case first.  In a few cases, existing
different orders (e.g., upper case first) was kept to reduce the diff
size.

Discussion: https://www.postgresql.org/message-id/flat/3efd0fe8-351b-f836-9122-886002602357%40enterprisedb.com
2022-12-12 15:20:00 +01:00

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/*-------------------------------------------------------------------------
*
* postmaster.c
* This program acts as a clearing house for requests to the
* POSTGRES system. Frontend programs send a startup message
* to the Postmaster and the postmaster uses the info in the
* message to setup a backend process.
*
* The postmaster also manages system-wide operations such as
* startup and shutdown. The postmaster itself doesn't do those
* operations, mind you --- it just forks off a subprocess to do them
* at the right times. It also takes care of resetting the system
* if a backend crashes.
*
* The postmaster process creates the shared memory and semaphore
* pools during startup, but as a rule does not touch them itself.
* In particular, it is not a member of the PGPROC array of backends
* and so it cannot participate in lock-manager operations. Keeping
* the postmaster away from shared memory operations makes it simpler
* and more reliable. The postmaster is almost always able to recover
* from crashes of individual backends by resetting shared memory;
* if it did much with shared memory then it would be prone to crashing
* along with the backends.
*
* When a request message is received, we now fork() immediately.
* The child process performs authentication of the request, and
* then becomes a backend if successful. This allows the auth code
* to be written in a simple single-threaded style (as opposed to the
* crufty "poor man's multitasking" code that used to be needed).
* More importantly, it ensures that blockages in non-multithreaded
* libraries like SSL or PAM cannot cause denial of service to other
* clients.
*
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/postmaster/postmaster.c
*
* NOTES
*
* Initialization:
* The Postmaster sets up shared memory data structures
* for the backends.
*
* Synchronization:
* The Postmaster shares memory with the backends but should avoid
* touching shared memory, so as not to become stuck if a crashing
* backend screws up locks or shared memory. Likewise, the Postmaster
* should never block on messages from frontend clients.
*
* Garbage Collection:
* The Postmaster cleans up after backends if they have an emergency
* exit and/or core dump.
*
* Error Reporting:
* Use write_stderr() only for reporting "interactive" errors
* (essentially, bogus arguments on the command line). Once the
* postmaster is launched, use ereport().
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include <signal.h>
#include <time.h>
#include <sys/wait.h>
#include <ctype.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <sys/param.h>
#include <netdb.h>
#include <limits.h>
#ifdef USE_BONJOUR
#include <dns_sd.h>
#endif
#ifdef USE_SYSTEMD
#include <systemd/sd-daemon.h>
#endif
#ifdef HAVE_PTHREAD_IS_THREADED_NP
#include <pthread.h>
#endif
#include "access/transam.h"
#include "access/xlog.h"
#include "access/xlogrecovery.h"
#include "catalog/pg_control.h"
#include "common/file_perm.h"
#include "common/ip.h"
#include "common/pg_prng.h"
#include "common/string.h"
#include "lib/ilist.h"
#include "libpq/auth.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "libpq/pqsignal.h"
#include "pg_getopt.h"
#include "pgstat.h"
#include "port/pg_bswap.h"
#include "postmaster/autovacuum.h"
#include "postmaster/auxprocess.h"
#include "postmaster/bgworker_internals.h"
#include "postmaster/fork_process.h"
#include "postmaster/interrupt.h"
#include "postmaster/pgarch.h"
#include "postmaster/postmaster.h"
#include "postmaster/syslogger.h"
#include "replication/logicallauncher.h"
#include "replication/walsender.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/datetime.h"
#include "utils/memutils.h"
#include "utils/pidfile.h"
#include "utils/ps_status.h"
#include "utils/queryjumble.h"
#include "utils/timeout.h"
#include "utils/timestamp.h"
#include "utils/varlena.h"
#ifdef EXEC_BACKEND
#include "storage/spin.h"
#endif
/*
* Possible types of a backend. Beyond being the possible bkend_type values in
* struct bkend, these are OR-able request flag bits for SignalSomeChildren()
* and CountChildren().
*/
#define BACKEND_TYPE_NORMAL 0x0001 /* normal backend */
#define BACKEND_TYPE_AUTOVAC 0x0002 /* autovacuum worker process */
#define BACKEND_TYPE_WALSND 0x0004 /* walsender process */
#define BACKEND_TYPE_BGWORKER 0x0008 /* bgworker process */
#define BACKEND_TYPE_ALL 0x000F /* OR of all the above */
/*
* List of active backends (or child processes anyway; we don't actually
* know whether a given child has become a backend or is still in the
* authorization phase). This is used mainly to keep track of how many
* children we have and send them appropriate signals when necessary.
*
* As shown in the above set of backend types, this list includes not only
* "normal" client sessions, but also autovacuum workers, walsenders, and
* background workers. (Note that at the time of launch, walsenders are
* labeled BACKEND_TYPE_NORMAL; we relabel them to BACKEND_TYPE_WALSND
* upon noticing they've changed their PMChildFlags entry. Hence that check
* must be done before any operation that needs to distinguish walsenders
* from normal backends.)
*
* Also, "dead_end" children are in it: these are children launched just for
* the purpose of sending a friendly rejection message to a would-be client.
* We must track them because they are attached to shared memory, but we know
* they will never become live backends. dead_end children are not assigned a
* PMChildSlot. dead_end children have bkend_type NORMAL.
*
* "Special" children such as the startup, bgwriter and autovacuum launcher
* tasks are not in this list. They are tracked via StartupPID and other
* pid_t variables below. (Thus, there can't be more than one of any given
* "special" child process type. We use BackendList entries for any child
* process there can be more than one of.)
*/
typedef struct bkend
{
pid_t pid; /* process id of backend */
int32 cancel_key; /* cancel key for cancels for this backend */
int child_slot; /* PMChildSlot for this backend, if any */
int bkend_type; /* child process flavor, see above */
bool dead_end; /* is it going to send an error and quit? */
bool bgworker_notify; /* gets bgworker start/stop notifications */
dlist_node elem; /* list link in BackendList */
} Backend;
static dlist_head BackendList = DLIST_STATIC_INIT(BackendList);
#ifdef EXEC_BACKEND
static Backend *ShmemBackendArray;
#endif
BackgroundWorker *MyBgworkerEntry = NULL;
/* The socket number we are listening for connections on */
int PostPortNumber = DEF_PGPORT;
/* The directory names for Unix socket(s) */
char *Unix_socket_directories;
/* The TCP listen address(es) */
char *ListenAddresses;
/*
* ReservedBackends is the number of backends reserved for superuser use.
* This number is taken out of the pool size given by MaxConnections so
* number of backend slots available to non-superusers is
* (MaxConnections - ReservedBackends). Note what this really means is
* "if there are <= ReservedBackends connections available, only superusers
* can make new connections" --- pre-existing superuser connections don't
* count against the limit.
*/
int ReservedBackends;
/* The socket(s) we're listening to. */
#define MAXLISTEN 64
static pgsocket ListenSocket[MAXLISTEN];
/* still more option variables */
bool EnableSSL = false;
int PreAuthDelay = 0;
int AuthenticationTimeout = 60;
bool log_hostname; /* for ps display and logging */
bool Log_connections = false;
bool Db_user_namespace = false;
bool enable_bonjour = false;
char *bonjour_name;
bool restart_after_crash = true;
bool remove_temp_files_after_crash = true;
bool send_abort_for_crash = false;
bool send_abort_for_kill = false;
/* PIDs of special child processes; 0 when not running */
static pid_t StartupPID = 0,
BgWriterPID = 0,
CheckpointerPID = 0,
WalWriterPID = 0,
WalReceiverPID = 0,
AutoVacPID = 0,
PgArchPID = 0,
SysLoggerPID = 0;
/* Startup process's status */
typedef enum
{
STARTUP_NOT_RUNNING,
STARTUP_RUNNING,
STARTUP_SIGNALED, /* we sent it a SIGQUIT or SIGKILL */
STARTUP_CRASHED
} StartupStatusEnum;
static StartupStatusEnum StartupStatus = STARTUP_NOT_RUNNING;
/* Startup/shutdown state */
#define NoShutdown 0
#define SmartShutdown 1
#define FastShutdown 2
#define ImmediateShutdown 3
static int Shutdown = NoShutdown;
static bool FatalError = false; /* T if recovering from backend crash */
/*
* We use a simple state machine to control startup, shutdown, and
* crash recovery (which is rather like shutdown followed by startup).
*
* After doing all the postmaster initialization work, we enter PM_STARTUP
* state and the startup process is launched. The startup process begins by
* reading the control file and other preliminary initialization steps.
* In a normal startup, or after crash recovery, the startup process exits
* with exit code 0 and we switch to PM_RUN state. However, archive recovery
* is handled specially since it takes much longer and we would like to support
* hot standby during archive recovery.
*
* When the startup process is ready to start archive recovery, it signals the
* postmaster, and we switch to PM_RECOVERY state. The background writer and
* checkpointer are launched, while the startup process continues applying WAL.
* If Hot Standby is enabled, then, after reaching a consistent point in WAL
* redo, startup process signals us again, and we switch to PM_HOT_STANDBY
* state and begin accepting connections to perform read-only queries. When
* archive recovery is finished, the startup process exits with exit code 0
* and we switch to PM_RUN state.
*
* Normal child backends can only be launched when we are in PM_RUN or
* PM_HOT_STANDBY state. (connsAllowed can also restrict launching.)
* In other states we handle connection requests by launching "dead_end"
* child processes, which will simply send the client an error message and
* quit. (We track these in the BackendList so that we can know when they
* are all gone; this is important because they're still connected to shared
* memory, and would interfere with an attempt to destroy the shmem segment,
* possibly leading to SHMALL failure when we try to make a new one.)
* In PM_WAIT_DEAD_END state we are waiting for all the dead_end children
* to drain out of the system, and therefore stop accepting connection
* requests at all until the last existing child has quit (which hopefully
* will not be very long).
*
* Notice that this state variable does not distinguish *why* we entered
* states later than PM_RUN --- Shutdown and FatalError must be consulted
* to find that out. FatalError is never true in PM_RECOVERY, PM_HOT_STANDBY,
* or PM_RUN states, nor in PM_SHUTDOWN states (because we don't enter those
* states when trying to recover from a crash). It can be true in PM_STARTUP
* state, because we don't clear it until we've successfully started WAL redo.
*/
typedef enum
{
PM_INIT, /* postmaster starting */
PM_STARTUP, /* waiting for startup subprocess */
PM_RECOVERY, /* in archive recovery mode */
PM_HOT_STANDBY, /* in hot standby mode */
PM_RUN, /* normal "database is alive" state */
PM_STOP_BACKENDS, /* need to stop remaining backends */
PM_WAIT_BACKENDS, /* waiting for live backends to exit */
PM_SHUTDOWN, /* waiting for checkpointer to do shutdown
* ckpt */
PM_SHUTDOWN_2, /* waiting for archiver and walsenders to
* finish */
PM_WAIT_DEAD_END, /* waiting for dead_end children to exit */
PM_NO_CHILDREN /* all important children have exited */
} PMState;
static PMState pmState = PM_INIT;
/*
* While performing a "smart shutdown", we restrict new connections but stay
* in PM_RUN or PM_HOT_STANDBY state until all the client backends are gone.
* connsAllowed is a sub-state indicator showing the active restriction.
* It is of no interest unless pmState is PM_RUN or PM_HOT_STANDBY.
*/
static bool connsAllowed = true;
/* Start time of SIGKILL timeout during immediate shutdown or child crash */
/* Zero means timeout is not running */
static time_t AbortStartTime = 0;
/* Length of said timeout */
#define SIGKILL_CHILDREN_AFTER_SECS 5
static bool ReachedNormalRunning = false; /* T if we've reached PM_RUN */
bool ClientAuthInProgress = false; /* T during new-client
* authentication */
bool redirection_done = false; /* stderr redirected for syslogger? */
/* received START_AUTOVAC_LAUNCHER signal */
static volatile sig_atomic_t start_autovac_launcher = false;
/* the launcher needs to be signaled to communicate some condition */
static volatile bool avlauncher_needs_signal = false;
/* received START_WALRECEIVER signal */
static volatile sig_atomic_t WalReceiverRequested = false;
/* set when there's a worker that needs to be started up */
static volatile bool StartWorkerNeeded = true;
static volatile bool HaveCrashedWorker = false;
#ifdef USE_SSL
/* Set when and if SSL has been initialized properly */
static bool LoadedSSL = false;
#endif
#ifdef USE_BONJOUR
static DNSServiceRef bonjour_sdref = NULL;
#endif
/*
* postmaster.c - function prototypes
*/
static void CloseServerPorts(int status, Datum arg);
static void unlink_external_pid_file(int status, Datum arg);
static void getInstallationPaths(const char *argv0);
static void checkControlFile(void);
static Port *ConnCreate(int serverFd);
static void ConnFree(Port *port);
static void SIGHUP_handler(SIGNAL_ARGS);
static void pmdie(SIGNAL_ARGS);
static void reaper(SIGNAL_ARGS);
static void sigusr1_handler(SIGNAL_ARGS);
static void process_startup_packet_die(SIGNAL_ARGS);
static void dummy_handler(SIGNAL_ARGS);
static void StartupPacketTimeoutHandler(void);
static void CleanupBackend(int pid, int exitstatus);
static bool CleanupBackgroundWorker(int pid, int exitstatus);
static void HandleChildCrash(int pid, int exitstatus, const char *procname);
static void LogChildExit(int lev, const char *procname,
int pid, int exitstatus);
static void PostmasterStateMachine(void);
static void BackendInitialize(Port *port);
static void BackendRun(Port *port) pg_attribute_noreturn();
static void ExitPostmaster(int status) pg_attribute_noreturn();
static int ServerLoop(void);
static int BackendStartup(Port *port);
static int ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done);
static void SendNegotiateProtocolVersion(List *unrecognized_protocol_options);
static void processCancelRequest(Port *port, void *pkt);
static int initMasks(fd_set *rmask);
static void report_fork_failure_to_client(Port *port, int errnum);
static CAC_state canAcceptConnections(int backend_type);
static bool RandomCancelKey(int32 *cancel_key);
static void signal_child(pid_t pid, int signal);
static void sigquit_child(pid_t pid);
static bool SignalSomeChildren(int signal, int target);
static void TerminateChildren(int signal);
#define SignalChildren(sig) SignalSomeChildren(sig, BACKEND_TYPE_ALL)
static int CountChildren(int target);
static bool assign_backendlist_entry(RegisteredBgWorker *rw);
static void maybe_start_bgworkers(void);
static bool CreateOptsFile(int argc, char *argv[], char *fullprogname);
static pid_t StartChildProcess(AuxProcType type);
static void StartAutovacuumWorker(void);
static void MaybeStartWalReceiver(void);
static void InitPostmasterDeathWatchHandle(void);
/*
* Archiver is allowed to start up at the current postmaster state?
*
* If WAL archiving is enabled always, we are allowed to start archiver
* even during recovery.
*/
#define PgArchStartupAllowed() \
(((XLogArchivingActive() && pmState == PM_RUN) || \
(XLogArchivingAlways() && \
(pmState == PM_RECOVERY || pmState == PM_HOT_STANDBY))) && \
PgArchCanRestart())
#ifdef EXEC_BACKEND
#ifdef WIN32
#define WNOHANG 0 /* ignored, so any integer value will do */
static pid_t waitpid(pid_t pid, int *exitstatus, int options);
static void WINAPI pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired);
static HANDLE win32ChildQueue;
typedef struct
{
HANDLE waitHandle;
HANDLE procHandle;
DWORD procId;
} win32_deadchild_waitinfo;
#endif /* WIN32 */
static pid_t backend_forkexec(Port *port);
static pid_t internal_forkexec(int argc, char *argv[], Port *port);
/* Type for a socket that can be inherited to a client process */
#ifdef WIN32
typedef struct
{
SOCKET origsocket; /* Original socket value, or PGINVALID_SOCKET
* if not a socket */
WSAPROTOCOL_INFO wsainfo;
} InheritableSocket;
#else
typedef int InheritableSocket;
#endif
/*
* Structure contains all variables passed to exec:ed backends
*/
typedef struct
{
Port port;
InheritableSocket portsocket;
char DataDir[MAXPGPATH];
pgsocket ListenSocket[MAXLISTEN];
int32 MyCancelKey;
int MyPMChildSlot;
#ifndef WIN32
unsigned long UsedShmemSegID;
#else
void *ShmemProtectiveRegion;
HANDLE UsedShmemSegID;
#endif
void *UsedShmemSegAddr;
slock_t *ShmemLock;
VariableCache ShmemVariableCache;
Backend *ShmemBackendArray;
#ifndef HAVE_SPINLOCKS
PGSemaphore *SpinlockSemaArray;
#endif
int NamedLWLockTrancheRequests;
NamedLWLockTranche *NamedLWLockTrancheArray;
LWLockPadded *MainLWLockArray;
slock_t *ProcStructLock;
PROC_HDR *ProcGlobal;
PGPROC *AuxiliaryProcs;
PGPROC *PreparedXactProcs;
PMSignalData *PMSignalState;
pid_t PostmasterPid;
TimestampTz PgStartTime;
TimestampTz PgReloadTime;
pg_time_t first_syslogger_file_time;
bool redirection_done;
bool IsBinaryUpgrade;
bool query_id_enabled;
int max_safe_fds;
int MaxBackends;
#ifdef WIN32
HANDLE PostmasterHandle;
HANDLE initial_signal_pipe;
HANDLE syslogPipe[2];
#else
int postmaster_alive_fds[2];
int syslogPipe[2];
#endif
char my_exec_path[MAXPGPATH];
char pkglib_path[MAXPGPATH];
} BackendParameters;
static void read_backend_variables(char *id, Port *port);
static void restore_backend_variables(BackendParameters *param, Port *port);
#ifndef WIN32
static bool save_backend_variables(BackendParameters *param, Port *port);
#else
static bool save_backend_variables(BackendParameters *param, Port *port,
HANDLE childProcess, pid_t childPid);
#endif
static void ShmemBackendArrayAdd(Backend *bn);
static void ShmemBackendArrayRemove(Backend *bn);
#endif /* EXEC_BACKEND */
#define StartupDataBase() StartChildProcess(StartupProcess)
#define StartArchiver() StartChildProcess(ArchiverProcess)
#define StartBackgroundWriter() StartChildProcess(BgWriterProcess)
#define StartCheckpointer() StartChildProcess(CheckpointerProcess)
#define StartWalWriter() StartChildProcess(WalWriterProcess)
#define StartWalReceiver() StartChildProcess(WalReceiverProcess)
/* Macros to check exit status of a child process */
#define EXIT_STATUS_0(st) ((st) == 0)
#define EXIT_STATUS_1(st) (WIFEXITED(st) && WEXITSTATUS(st) == 1)
#define EXIT_STATUS_3(st) (WIFEXITED(st) && WEXITSTATUS(st) == 3)
#ifndef WIN32
/*
* File descriptors for pipe used to monitor if postmaster is alive.
* First is POSTMASTER_FD_WATCH, second is POSTMASTER_FD_OWN.
*/
int postmaster_alive_fds[2] = {-1, -1};
#else
/* Process handle of postmaster used for the same purpose on Windows */
HANDLE PostmasterHandle;
#endif
/*
* Postmaster main entry point
*/
void
PostmasterMain(int argc, char *argv[])
{
int opt;
int status;
char *userDoption = NULL;
bool listen_addr_saved = false;
int i;
char *output_config_variable = NULL;
InitProcessGlobals();
PostmasterPid = MyProcPid;
IsPostmasterEnvironment = true;
/*
* Start our win32 signal implementation
*/
#ifdef WIN32
pgwin32_signal_initialize();
#endif
/*
* We should not be creating any files or directories before we check the
* data directory (see checkDataDir()), but just in case set the umask to
* the most restrictive (owner-only) permissions.
*
* checkDataDir() will reset the umask based on the data directory
* permissions.
*/
umask(PG_MODE_MASK_OWNER);
/*
* By default, palloc() requests in the postmaster will be allocated in
* the PostmasterContext, which is space that can be recycled by backends.
* Allocated data that needs to be available to backends should be
* allocated in TopMemoryContext.
*/
PostmasterContext = AllocSetContextCreate(TopMemoryContext,
"Postmaster",
ALLOCSET_DEFAULT_SIZES);
MemoryContextSwitchTo(PostmasterContext);
/* Initialize paths to installation files */
getInstallationPaths(argv[0]);
/*
* Set up signal handlers for the postmaster process.
*
* In the postmaster, we use pqsignal_pm() rather than pqsignal() (which
* is used by all child processes and client processes). That has a
* couple of special behaviors:
*
* 1. We tell sigaction() to block all signals for the duration of the
* signal handler. This is faster than our old approach of
* blocking/unblocking explicitly in the signal handler, and it should also
* prevent excessive stack consumption if signals arrive quickly.
*
* 2. We do not set the SA_RESTART flag. This is because signals will be
* blocked at all times except when ServerLoop is waiting for something to
* happen, and during that window, we want signals to exit the select(2)
* wait so that ServerLoop can respond if anything interesting happened.
* On some platforms, signals marked SA_RESTART would not cause the
* select() wait to end.
*
* Child processes will generally want SA_RESTART, so pqsignal() sets that
* flag. We expect children to set up their own handlers before
* unblocking signals.
*
* CAUTION: when changing this list, check for side-effects on the signal
* handling setup of child processes. See tcop/postgres.c,
* bootstrap/bootstrap.c, postmaster/bgwriter.c, postmaster/walwriter.c,
* postmaster/autovacuum.c, postmaster/pgarch.c, postmaster/syslogger.c,
* postmaster/bgworker.c and postmaster/checkpointer.c.
*/
pqinitmask();
PG_SETMASK(&BlockSig);
pqsignal_pm(SIGHUP, SIGHUP_handler); /* reread config file and have
* children do same */
pqsignal_pm(SIGINT, pmdie); /* send SIGTERM and shut down */
pqsignal_pm(SIGQUIT, pmdie); /* send SIGQUIT and die */
pqsignal_pm(SIGTERM, pmdie); /* wait for children and shut down */
pqsignal_pm(SIGALRM, SIG_IGN); /* ignored */
pqsignal_pm(SIGPIPE, SIG_IGN); /* ignored */
pqsignal_pm(SIGUSR1, sigusr1_handler); /* message from child process */
pqsignal_pm(SIGUSR2, dummy_handler); /* unused, reserve for children */
pqsignal_pm(SIGCHLD, reaper); /* handle child termination */
#ifdef SIGURG
/*
* Ignore SIGURG for now. Child processes may change this (see
* InitializeLatchSupport), but they will not receive any such signals
* until they wait on a latch.
*/
pqsignal_pm(SIGURG, SIG_IGN); /* ignored */
#endif
/*
* No other place in Postgres should touch SIGTTIN/SIGTTOU handling. We
* ignore those signals in a postmaster environment, so that there is no
* risk of a child process freezing up due to writing to stderr. But for
* a standalone backend, their default handling is reasonable. Hence, all
* child processes should just allow the inherited settings to stand.
*/
#ifdef SIGTTIN
pqsignal_pm(SIGTTIN, SIG_IGN); /* ignored */
#endif
#ifdef SIGTTOU
pqsignal_pm(SIGTTOU, SIG_IGN); /* ignored */
#endif
/* ignore SIGXFSZ, so that ulimit violations work like disk full */
#ifdef SIGXFSZ
pqsignal_pm(SIGXFSZ, SIG_IGN); /* ignored */
#endif
/*
* Options setup
*/
InitializeGUCOptions();
opterr = 1;
/*
* Parse command-line options. CAUTION: keep this in sync with
* tcop/postgres.c (the option sets should not conflict) and with the
* common help() function in main/main.c.
*/
while ((opt = getopt(argc, argv, "B:bC:c:D:d:EeFf:h:ijk:lN:OPp:r:S:sTt:W:-:")) != -1)
{
switch (opt)
{
case 'B':
SetConfigOption("shared_buffers", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'b':
/* Undocumented flag used for binary upgrades */
IsBinaryUpgrade = true;
break;
case 'C':
output_config_variable = strdup(optarg);
break;
case 'c':
case '-':
{
char *name,
*value;
ParseLongOption(optarg, &name, &value);
if (!value)
{
if (opt == '-')
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("--%s requires a value",
optarg)));
else
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("-c %s requires a value",
optarg)));
}
SetConfigOption(name, value, PGC_POSTMASTER, PGC_S_ARGV);
pfree(name);
pfree(value);
break;
}
case 'D':
userDoption = strdup(optarg);
break;
case 'd':
set_debug_options(atoi(optarg), PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'E':
SetConfigOption("log_statement", "all", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'e':
SetConfigOption("datestyle", "euro", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'F':
SetConfigOption("fsync", "false", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'f':
if (!set_plan_disabling_options(optarg, PGC_POSTMASTER, PGC_S_ARGV))
{
write_stderr("%s: invalid argument for option -f: \"%s\"\n",
progname, optarg);
ExitPostmaster(1);
}
break;
case 'h':
SetConfigOption("listen_addresses", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'i':
SetConfigOption("listen_addresses", "*", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'j':
/* only used by interactive backend */
break;
case 'k':
SetConfigOption("unix_socket_directories", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'l':
SetConfigOption("ssl", "true", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'N':
SetConfigOption("max_connections", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'O':
SetConfigOption("allow_system_table_mods", "true", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'P':
SetConfigOption("ignore_system_indexes", "true", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'p':
SetConfigOption("port", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'r':
/* only used by single-user backend */
break;
case 'S':
SetConfigOption("work_mem", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
case 's':
SetConfigOption("log_statement_stats", "true", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 'T':
/*
* This option used to be defined as sending SIGSTOP after a
* backend crash, but sending SIGABRT seems more useful.
*/
SetConfigOption("send_abort_for_crash", "true", PGC_POSTMASTER, PGC_S_ARGV);
break;
case 't':
{
const char *tmp = get_stats_option_name(optarg);
if (tmp)
{
SetConfigOption(tmp, "true", PGC_POSTMASTER, PGC_S_ARGV);
}
else
{
write_stderr("%s: invalid argument for option -t: \"%s\"\n",
progname, optarg);
ExitPostmaster(1);
}
break;
}
case 'W':
SetConfigOption("post_auth_delay", optarg, PGC_POSTMASTER, PGC_S_ARGV);
break;
default:
write_stderr("Try \"%s --help\" for more information.\n",
progname);
ExitPostmaster(1);
}
}
/*
* Postmaster accepts no non-option switch arguments.
*/
if (optind < argc)
{
write_stderr("%s: invalid argument: \"%s\"\n",
progname, argv[optind]);
write_stderr("Try \"%s --help\" for more information.\n",
progname);
ExitPostmaster(1);
}
/*
* Locate the proper configuration files and data directory, and read
* postgresql.conf for the first time.
*/
if (!SelectConfigFiles(userDoption, progname))
ExitPostmaster(2);
if (output_config_variable != NULL)
{
/*
* If this is a runtime-computed GUC, it hasn't yet been initialized,
* and the present value is not useful. However, this is a convenient
* place to print the value for most GUCs because it is safe to run
* postmaster startup to this point even if the server is already
* running. For the handful of runtime-computed GUCs that we cannot
* provide meaningful values for yet, we wait until later in
* postmaster startup to print the value. We won't be able to use -C
* on running servers for those GUCs, but using this option now would
* lead to incorrect results for them.
*/
int flags = GetConfigOptionFlags(output_config_variable, true);
if ((flags & GUC_RUNTIME_COMPUTED) == 0)
{
/*
* "-C guc" was specified, so print GUC's value and exit. No
* extra permission check is needed because the user is reading
* inside the data dir.
*/
const char *config_val = GetConfigOption(output_config_variable,
false, false);
puts(config_val ? config_val : "");
ExitPostmaster(0);
}
/*
* A runtime-computed GUC will be printed later on. As we initialize
* a server startup sequence, silence any log messages that may show
* up in the output generated. FATAL and more severe messages are
* useful to show, even if one would only expect at least PANIC. LOG
* entries are hidden.
*/
SetConfigOption("log_min_messages", "FATAL", PGC_SUSET,
PGC_S_OVERRIDE);
}
/* Verify that DataDir looks reasonable */
checkDataDir();
/* Check that pg_control exists */
checkControlFile();
/* And switch working directory into it */
ChangeToDataDir();
/*
* Check for invalid combinations of GUC settings.
*/
if (ReservedBackends >= MaxConnections)
{
write_stderr("%s: superuser_reserved_connections (%d) must be less than max_connections (%d)\n",
progname,
ReservedBackends, MaxConnections);
ExitPostmaster(1);
}
if (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL)
ereport(ERROR,
(errmsg("WAL archival cannot be enabled when wal_level is \"minimal\"")));
if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL)
ereport(ERROR,
(errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"replica\" or \"logical\"")));
/*
* Other one-time internal sanity checks can go here, if they are fast.
* (Put any slow processing further down, after postmaster.pid creation.)
*/
if (!CheckDateTokenTables())
{
write_stderr("%s: invalid datetoken tables, please fix\n", progname);
ExitPostmaster(1);
}
/*
* Now that we are done processing the postmaster arguments, reset
* getopt(3) library so that it will work correctly in subprocesses.
*/
optind = 1;
#ifdef HAVE_INT_OPTRESET
optreset = 1; /* some systems need this too */
#endif
/* For debugging: display postmaster environment */
{
extern char **environ;
char **p;
ereport(DEBUG3,
(errmsg_internal("%s: PostmasterMain: initial environment dump:",
progname)));
ereport(DEBUG3,
(errmsg_internal("-----------------------------------------")));
for (p = environ; *p; ++p)
ereport(DEBUG3,
(errmsg_internal("\t%s", *p)));
ereport(DEBUG3,
(errmsg_internal("-----------------------------------------")));
}
/*
* Create lockfile for data directory.
*
* We want to do this before we try to grab the input sockets, because the
* data directory interlock is more reliable than the socket-file
* interlock (thanks to whoever decided to put socket files in /tmp :-().
* For the same reason, it's best to grab the TCP socket(s) before the
* Unix socket(s).
*
* Also note that this internally sets up the on_proc_exit function that
* is responsible for removing both data directory and socket lockfiles;
* so it must happen before opening sockets so that at exit, the socket
* lockfiles go away after CloseServerPorts runs.
*/
CreateDataDirLockFile(true);
/*
* Read the control file (for error checking and config info).
*
* Since we verify the control file's CRC, this has a useful side effect
* on machines where we need a run-time test for CRC support instructions.
* The postmaster will do the test once at startup, and then its child
* processes will inherit the correct function pointer and not need to
* repeat the test.
*/
LocalProcessControlFile(false);
/*
* Register the apply launcher. It's probably a good idea to call this
* before any modules had a chance to take the background worker slots.
*/
ApplyLauncherRegister();
/*
* process any libraries that should be preloaded at postmaster start
*/
process_shared_preload_libraries();
/*
* Initialize SSL library, if specified.
*/
#ifdef USE_SSL
if (EnableSSL)
{
(void) secure_initialize(true);
LoadedSSL = true;
}
#endif
/*
* Now that loadable modules have had their chance to alter any GUCs,
* calculate MaxBackends.
*/
InitializeMaxBackends();
/*
* Give preloaded libraries a chance to request additional shared memory.
*/
process_shmem_requests();
/*
* Now that loadable modules have had their chance to request additional
* shared memory, determine the value of any runtime-computed GUCs that
* depend on the amount of shared memory required.
*/
InitializeShmemGUCs();
/*
* Now that modules have been loaded, we can process any custom resource
* managers specified in the wal_consistency_checking GUC.
*/
InitializeWalConsistencyChecking();
/*
* If -C was specified with a runtime-computed GUC, we held off printing
* the value earlier, as the GUC was not yet initialized. We handle -C
* for most GUCs before we lock the data directory so that the option may
* be used on a running server. However, a handful of GUCs are runtime-
* computed and do not have meaningful values until after locking the data
* directory, and we cannot safely calculate their values earlier on a
* running server. At this point, such GUCs should be properly
* initialized, and we haven't yet set up shared memory, so this is a good
* time to handle the -C option for these special GUCs.
*/
if (output_config_variable != NULL)
{
const char *config_val = GetConfigOption(output_config_variable,
false, false);
puts(config_val ? config_val : "");
ExitPostmaster(0);
}
/*
* Set up shared memory and semaphores.
*
* Note: if using SysV shmem and/or semas, each postmaster startup will
* normally choose the same IPC keys. This helps ensure that we will
* clean up dead IPC objects if the postmaster crashes and is restarted.
*/
CreateSharedMemoryAndSemaphores();
/*
* Estimate number of openable files. This must happen after setting up
* semaphores, because on some platforms semaphores count as open files.
*/
set_max_safe_fds();
/*
* Set reference point for stack-depth checking.
*/
(void) set_stack_base();
/*
* Initialize pipe (or process handle on Windows) that allows children to
* wake up from sleep on postmaster death.
*/
InitPostmasterDeathWatchHandle();
#ifdef WIN32
/*
* Initialize I/O completion port used to deliver list of dead children.
*/
win32ChildQueue = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1);
if (win32ChildQueue == NULL)
ereport(FATAL,
(errmsg("could not create I/O completion port for child queue")));
#endif
#ifdef EXEC_BACKEND
/* Write out nondefault GUC settings for child processes to use */
write_nondefault_variables(PGC_POSTMASTER);
/*
* Clean out the temp directory used to transmit parameters to child
* processes (see internal_forkexec, below). We must do this before
* launching any child processes, else we have a race condition: we could
* remove a parameter file before the child can read it. It should be
* safe to do so now, because we verified earlier that there are no
* conflicting Postgres processes in this data directory.
*/
RemovePgTempFilesInDir(PG_TEMP_FILES_DIR, true, false);
#endif
/*
* Forcibly remove the files signaling a standby promotion request.
* Otherwise, the existence of those files triggers a promotion too early,
* whether a user wants that or not.
*
* This removal of files is usually unnecessary because they can exist
* only during a few moments during a standby promotion. However there is
* a race condition: if pg_ctl promote is executed and creates the files
* during a promotion, the files can stay around even after the server is
* brought up to be the primary. Then, if a new standby starts by using
* the backup taken from the new primary, the files can exist at server
* startup and must be removed in order to avoid an unexpected promotion.
*
* Note that promotion signal files need to be removed before the startup
* process is invoked. Because, after that, they can be used by
* postmaster's SIGUSR1 signal handler.
*/
RemovePromoteSignalFiles();
/* Do the same for logrotate signal file */
RemoveLogrotateSignalFiles();
/* Remove any outdated file holding the current log filenames. */
if (unlink(LOG_METAINFO_DATAFILE) < 0 && errno != ENOENT)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
LOG_METAINFO_DATAFILE)));
/*
* If enabled, start up syslogger collection subprocess
*/
SysLoggerPID = SysLogger_Start();
/*
* Reset whereToSendOutput from DestDebug (its starting state) to
* DestNone. This stops ereport from sending log messages to stderr unless
* Log_destination permits. We don't do this until the postmaster is
* fully launched, since startup failures may as well be reported to
* stderr.
*
* If we are in fact disabling logging to stderr, first emit a log message
* saying so, to provide a breadcrumb trail for users who may not remember
* that their logging is configured to go somewhere else.
*/
if (!(Log_destination & LOG_DESTINATION_STDERR))
ereport(LOG,
(errmsg("ending log output to stderr"),
errhint("Future log output will go to log destination \"%s\".",
Log_destination_string)));
whereToSendOutput = DestNone;
/*
* Report server startup in log. While we could emit this much earlier,
* it seems best to do so after starting the log collector, if we intend
* to use one.
*/
ereport(LOG,
(errmsg("starting %s", PG_VERSION_STR)));
/*
* Establish input sockets.
*
* First, mark them all closed, and set up an on_proc_exit function that's
* charged with closing the sockets again at postmaster shutdown.
*/
for (i = 0; i < MAXLISTEN; i++)
ListenSocket[i] = PGINVALID_SOCKET;
on_proc_exit(CloseServerPorts, 0);
if (ListenAddresses)
{
char *rawstring;
List *elemlist;
ListCell *l;
int success = 0;
/* Need a modifiable copy of ListenAddresses */
rawstring = pstrdup(ListenAddresses);
/* Parse string into list of hostnames */
if (!SplitGUCList(rawstring, ',', &elemlist))
{
/* syntax error in list */
ereport(FATAL,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid list syntax in parameter \"%s\"",
"listen_addresses")));
}
foreach(l, elemlist)
{
char *curhost = (char *) lfirst(l);
if (strcmp(curhost, "*") == 0)
status = StreamServerPort(AF_UNSPEC, NULL,
(unsigned short) PostPortNumber,
NULL,
ListenSocket, MAXLISTEN);
else
status = StreamServerPort(AF_UNSPEC, curhost,
(unsigned short) PostPortNumber,
NULL,
ListenSocket, MAXLISTEN);
if (status == STATUS_OK)
{
success++;
/* record the first successful host addr in lockfile */
if (!listen_addr_saved)
{
AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, curhost);
listen_addr_saved = true;
}
}
else
ereport(WARNING,
(errmsg("could not create listen socket for \"%s\"",
curhost)));
}
if (!success && elemlist != NIL)
ereport(FATAL,
(errmsg("could not create any TCP/IP sockets")));
list_free(elemlist);
pfree(rawstring);
}
#ifdef USE_BONJOUR
/* Register for Bonjour only if we opened TCP socket(s) */
if (enable_bonjour && ListenSocket[0] != PGINVALID_SOCKET)
{
DNSServiceErrorType err;
/*
* We pass 0 for interface_index, which will result in registering on
* all "applicable" interfaces. It's not entirely clear from the
* DNS-SD docs whether this would be appropriate if we have bound to
* just a subset of the available network interfaces.
*/
err = DNSServiceRegister(&bonjour_sdref,
0,
0,
bonjour_name,
"_postgresql._tcp.",
NULL,
NULL,
pg_hton16(PostPortNumber),
0,
NULL,
NULL,
NULL);
if (err != kDNSServiceErr_NoError)
ereport(LOG,
(errmsg("DNSServiceRegister() failed: error code %ld",
(long) err)));
/*
* We don't bother to read the mDNS daemon's reply, and we expect that
* it will automatically terminate our registration when the socket is
* closed at postmaster termination. So there's nothing more to be
* done here. However, the bonjour_sdref is kept around so that
* forked children can close their copies of the socket.
*/
}
#endif
if (Unix_socket_directories)
{
char *rawstring;
List *elemlist;
ListCell *l;
int success = 0;
/* Need a modifiable copy of Unix_socket_directories */
rawstring = pstrdup(Unix_socket_directories);
/* Parse string into list of directories */
if (!SplitDirectoriesString(rawstring, ',', &elemlist))
{
/* syntax error in list */
ereport(FATAL,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid list syntax in parameter \"%s\"",
"unix_socket_directories")));
}
foreach(l, elemlist)
{
char *socketdir = (char *) lfirst(l);
status = StreamServerPort(AF_UNIX, NULL,
(unsigned short) PostPortNumber,
socketdir,
ListenSocket, MAXLISTEN);
if (status == STATUS_OK)
{
success++;
/* record the first successful Unix socket in lockfile */
if (success == 1)
AddToDataDirLockFile(LOCK_FILE_LINE_SOCKET_DIR, socketdir);
}
else
ereport(WARNING,
(errmsg("could not create Unix-domain socket in directory \"%s\"",
socketdir)));
}
if (!success && elemlist != NIL)
ereport(FATAL,
(errmsg("could not create any Unix-domain sockets")));
list_free_deep(elemlist);
pfree(rawstring);
}
/*
* check that we have some socket to listen on
*/
if (ListenSocket[0] == PGINVALID_SOCKET)
ereport(FATAL,
(errmsg("no socket created for listening")));
/*
* If no valid TCP ports, write an empty line for listen address,
* indicating the Unix socket must be used. Note that this line is not
* added to the lock file until there is a socket backing it.
*/
if (!listen_addr_saved)
AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, "");
/*
* Record postmaster options. We delay this till now to avoid recording
* bogus options (eg, unusable port number).
*/
if (!CreateOptsFile(argc, argv, my_exec_path))
ExitPostmaster(1);
/*
* Write the external PID file if requested
*/
if (external_pid_file)
{
FILE *fpidfile = fopen(external_pid_file, "w");
if (fpidfile)
{
fprintf(fpidfile, "%d\n", MyProcPid);
fclose(fpidfile);
/* Make PID file world readable */
if (chmod(external_pid_file, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) != 0)
write_stderr("%s: could not change permissions of external PID file \"%s\": %s\n",
progname, external_pid_file, strerror(errno));
}
else
write_stderr("%s: could not write external PID file \"%s\": %s\n",
progname, external_pid_file, strerror(errno));
on_proc_exit(unlink_external_pid_file, 0);
}
/*
* Remove old temporary files. At this point there can be no other
* Postgres processes running in this directory, so this should be safe.
*/
RemovePgTempFiles();
/*
* Initialize the autovacuum subsystem (again, no process start yet)
*/
autovac_init();
/*
* Load configuration files for client authentication.
*/
if (!load_hba())
{
/*
* It makes no sense to continue if we fail to load the HBA file,
* since there is no way to connect to the database in this case.
*/
ereport(FATAL,
/* translator: %s is a configuration file */
(errmsg("could not load %s", HbaFileName)));
}
if (!load_ident())
{
/*
* We can start up without the IDENT file, although it means that you
* cannot log in using any of the authentication methods that need a
* user name mapping. load_ident() already logged the details of error
* to the log.
*/
}
#ifdef HAVE_PTHREAD_IS_THREADED_NP
/*
* On macOS, libintl replaces setlocale() with a version that calls
* CFLocaleCopyCurrent() when its second argument is "" and every relevant
* environment variable is unset or empty. CFLocaleCopyCurrent() makes
* the process multithreaded. The postmaster calls sigprocmask() and
* calls fork() without an immediate exec(), both of which have undefined
* behavior in a multithreaded program. A multithreaded postmaster is the
* normal case on Windows, which offers neither fork() nor sigprocmask().
*/
if (pthread_is_threaded_np() != 0)
ereport(FATAL,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("postmaster became multithreaded during startup"),
errhint("Set the LC_ALL environment variable to a valid locale.")));
#endif
/*
* Remember postmaster startup time
*/
PgStartTime = GetCurrentTimestamp();
/*
* Report postmaster status in the postmaster.pid file, to allow pg_ctl to
* see what's happening.
*/
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STARTING);
/* Start bgwriter and checkpointer so they can help with recovery */
if (CheckpointerPID == 0)
CheckpointerPID = StartCheckpointer();
if (BgWriterPID == 0)
BgWriterPID = StartBackgroundWriter();
/*
* We're ready to rock and roll...
*/
StartupPID = StartupDataBase();
Assert(StartupPID != 0);
StartupStatus = STARTUP_RUNNING;
pmState = PM_STARTUP;
/* Some workers may be scheduled to start now */
maybe_start_bgworkers();
status = ServerLoop();
/*
* ServerLoop probably shouldn't ever return, but if it does, close down.
*/
ExitPostmaster(status != STATUS_OK);
abort(); /* not reached */
}
/*
* on_proc_exit callback to close server's listen sockets
*/
static void
CloseServerPorts(int status, Datum arg)
{
int i;
/*
* First, explicitly close all the socket FDs. We used to just let this
* happen implicitly at postmaster exit, but it's better to close them
* before we remove the postmaster.pid lockfile; otherwise there's a race
* condition if a new postmaster wants to re-use the TCP port number.
*/
for (i = 0; i < MAXLISTEN; i++)
{
if (ListenSocket[i] != PGINVALID_SOCKET)
{
StreamClose(ListenSocket[i]);
ListenSocket[i] = PGINVALID_SOCKET;
}
}
/*
* Next, remove any filesystem entries for Unix sockets. To avoid race
* conditions against incoming postmasters, this must happen after closing
* the sockets and before removing lock files.
*/
RemoveSocketFiles();
/*
* We don't do anything about socket lock files here; those will be
* removed in a later on_proc_exit callback.
*/
}
/*
* on_proc_exit callback to delete external_pid_file
*/
static void
unlink_external_pid_file(int status, Datum arg)
{
if (external_pid_file)
unlink(external_pid_file);
}
/*
* Compute and check the directory paths to files that are part of the
* installation (as deduced from the postgres executable's own location)
*/
static void
getInstallationPaths(const char *argv0)
{
DIR *pdir;
/* Locate the postgres executable itself */
if (find_my_exec(argv0, my_exec_path) < 0)
ereport(FATAL,
(errmsg("%s: could not locate my own executable path", argv0)));
#ifdef EXEC_BACKEND
/* Locate executable backend before we change working directory */
if (find_other_exec(argv0, "postgres", PG_BACKEND_VERSIONSTR,
postgres_exec_path) < 0)
ereport(FATAL,
(errmsg("%s: could not locate matching postgres executable",
argv0)));
#endif
/*
* Locate the pkglib directory --- this has to be set early in case we try
* to load any modules from it in response to postgresql.conf entries.
*/
get_pkglib_path(my_exec_path, pkglib_path);
/*
* Verify that there's a readable directory there; otherwise the Postgres
* installation is incomplete or corrupt. (A typical cause of this
* failure is that the postgres executable has been moved or hardlinked to
* some directory that's not a sibling of the installation lib/
* directory.)
*/
pdir = AllocateDir(pkglib_path);
if (pdir == NULL)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open directory \"%s\": %m",
pkglib_path),
errhint("This may indicate an incomplete PostgreSQL installation, or that the file \"%s\" has been moved away from its proper location.",
my_exec_path)));
FreeDir(pdir);
/*
* XXX is it worth similarly checking the share/ directory? If the lib/
* directory is there, then share/ probably is too.
*/
}
/*
* Check that pg_control exists in the correct location in the data directory.
*
* No attempt is made to validate the contents of pg_control here. This is
* just a sanity check to see if we are looking at a real data directory.
*/
static void
checkControlFile(void)
{
char path[MAXPGPATH];
FILE *fp;
snprintf(path, sizeof(path), "%s/global/pg_control", DataDir);
fp = AllocateFile(path, PG_BINARY_R);
if (fp == NULL)
{
write_stderr("%s: could not find the database system\n"
"Expected to find it in the directory \"%s\",\n"
"but could not open file \"%s\": %s\n",
progname, DataDir, path, strerror(errno));
ExitPostmaster(2);
}
FreeFile(fp);
}
/*
* Determine how long should we let ServerLoop sleep.
*
* In normal conditions we wait at most one minute, to ensure that the other
* background tasks handled by ServerLoop get done even when no requests are
* arriving. However, if there are background workers waiting to be started,
* we don't actually sleep so that they are quickly serviced. Other exception
* cases are as shown in the code.
*/
static void
DetermineSleepTime(struct timeval *timeout)
{
TimestampTz next_wakeup = 0;
/*
* Normal case: either there are no background workers at all, or we're in
* a shutdown sequence (during which we ignore bgworkers altogether).
*/
if (Shutdown > NoShutdown ||
(!StartWorkerNeeded && !HaveCrashedWorker))
{
if (AbortStartTime != 0)
{
/* time left to abort; clamp to 0 in case it already expired */
timeout->tv_sec = SIGKILL_CHILDREN_AFTER_SECS -
(time(NULL) - AbortStartTime);
timeout->tv_sec = Max(timeout->tv_sec, 0);
timeout->tv_usec = 0;
}
else
{
timeout->tv_sec = 60;
timeout->tv_usec = 0;
}
return;
}
if (StartWorkerNeeded)
{
timeout->tv_sec = 0;
timeout->tv_usec = 0;
return;
}
if (HaveCrashedWorker)
{
slist_mutable_iter siter;
/*
* When there are crashed bgworkers, we sleep just long enough that
* they are restarted when they request to be. Scan the list to
* determine the minimum of all wakeup times according to most recent
* crash time and requested restart interval.
*/
slist_foreach_modify(siter, &BackgroundWorkerList)
{
RegisteredBgWorker *rw;
TimestampTz this_wakeup;
rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
if (rw->rw_crashed_at == 0)
continue;
if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART
|| rw->rw_terminate)
{
ForgetBackgroundWorker(&siter);
continue;
}
this_wakeup = TimestampTzPlusMilliseconds(rw->rw_crashed_at,
1000L * rw->rw_worker.bgw_restart_time);
if (next_wakeup == 0 || this_wakeup < next_wakeup)
next_wakeup = this_wakeup;
}
}
if (next_wakeup != 0)
{
long secs;
int microsecs;
TimestampDifference(GetCurrentTimestamp(), next_wakeup,
&secs, &microsecs);
timeout->tv_sec = secs;
timeout->tv_usec = microsecs;
/* Ensure we don't exceed one minute */
if (timeout->tv_sec > 60)
{
timeout->tv_sec = 60;
timeout->tv_usec = 0;
}
}
else
{
timeout->tv_sec = 60;
timeout->tv_usec = 0;
}
}
/*
* Main idle loop of postmaster
*
* NB: Needs to be called with signals blocked
*/
static int
ServerLoop(void)
{
fd_set readmask;
int nSockets;
time_t last_lockfile_recheck_time,
last_touch_time;
last_lockfile_recheck_time = last_touch_time = time(NULL);
nSockets = initMasks(&readmask);
for (;;)
{
fd_set rmask;
int selres;
time_t now;
/*
* Wait for a connection request to arrive.
*
* We block all signals except while sleeping. That makes it safe for
* signal handlers, which again block all signals while executing, to
* do nontrivial work.
*
* If we are in PM_WAIT_DEAD_END state, then we don't want to accept
* any new connections, so we don't call select(), and just sleep.
*/
memcpy((char *) &rmask, (char *) &readmask, sizeof(fd_set));
if (pmState == PM_WAIT_DEAD_END)
{
PG_SETMASK(&UnBlockSig);
pg_usleep(100000L); /* 100 msec seems reasonable */
selres = 0;
PG_SETMASK(&BlockSig);
}
else
{
/* must set timeout each time; some OSes change it! */
struct timeval timeout;
/* Needs to run with blocked signals! */
DetermineSleepTime(&timeout);
PG_SETMASK(&UnBlockSig);
selres = select(nSockets, &rmask, NULL, NULL, &timeout);
PG_SETMASK(&BlockSig);
}
/* Now check the select() result */
if (selres < 0)
{
if (errno != EINTR && errno != EWOULDBLOCK)
{
ereport(LOG,
(errcode_for_socket_access(),
errmsg("select() failed in postmaster: %m")));
return STATUS_ERROR;
}
}
/*
* New connection pending on any of our sockets? If so, fork a child
* process to deal with it.
*/
if (selres > 0)
{
int i;
for (i = 0; i < MAXLISTEN; i++)
{
if (ListenSocket[i] == PGINVALID_SOCKET)
break;
if (FD_ISSET(ListenSocket[i], &rmask))
{
Port *port;
port = ConnCreate(ListenSocket[i]);
if (port)
{
BackendStartup(port);
/*
* We no longer need the open socket or port structure
* in this process
*/
StreamClose(port->sock);
ConnFree(port);
}
}
}
}
/* If we have lost the log collector, try to start a new one */
if (SysLoggerPID == 0 && Logging_collector)
SysLoggerPID = SysLogger_Start();
/*
* If no background writer process is running, and we are not in a
* state that prevents it, start one. It doesn't matter if this
* fails, we'll just try again later. Likewise for the checkpointer.
*/
if (pmState == PM_RUN || pmState == PM_RECOVERY ||
pmState == PM_HOT_STANDBY || pmState == PM_STARTUP)
{
if (CheckpointerPID == 0)
CheckpointerPID = StartCheckpointer();
if (BgWriterPID == 0)
BgWriterPID = StartBackgroundWriter();
}
/*
* Likewise, if we have lost the walwriter process, try to start a new
* one. But this is needed only in normal operation (else we cannot
* be writing any new WAL).
*/
if (WalWriterPID == 0 && pmState == PM_RUN)
WalWriterPID = StartWalWriter();
/*
* If we have lost the autovacuum launcher, try to start a new one. We
* don't want autovacuum to run in binary upgrade mode because
* autovacuum might update relfrozenxid for empty tables before the
* physical files are put in place.
*/
if (!IsBinaryUpgrade && AutoVacPID == 0 &&
(AutoVacuumingActive() || start_autovac_launcher) &&
pmState == PM_RUN)
{
AutoVacPID = StartAutoVacLauncher();
if (AutoVacPID != 0)
start_autovac_launcher = false; /* signal processed */
}
/* If we have lost the archiver, try to start a new one. */
if (PgArchPID == 0 && PgArchStartupAllowed())
PgArchPID = StartArchiver();
/* If we need to signal the autovacuum launcher, do so now */
if (avlauncher_needs_signal)
{
avlauncher_needs_signal = false;
if (AutoVacPID != 0)
kill(AutoVacPID, SIGUSR2);
}
/* If we need to start a WAL receiver, try to do that now */
if (WalReceiverRequested)
MaybeStartWalReceiver();
/* Get other worker processes running, if needed */
if (StartWorkerNeeded || HaveCrashedWorker)
maybe_start_bgworkers();
#ifdef HAVE_PTHREAD_IS_THREADED_NP
/*
* With assertions enabled, check regularly for appearance of
* additional threads. All builds check at start and exit.
*/
Assert(pthread_is_threaded_np() == 0);
#endif
/*
* Lastly, check to see if it's time to do some things that we don't
* want to do every single time through the loop, because they're a
* bit expensive. Note that there's up to a minute of slop in when
* these tasks will be performed, since DetermineSleepTime() will let
* us sleep at most that long; except for SIGKILL timeout which has
* special-case logic there.
*/
now = time(NULL);
/*
* If we already sent SIGQUIT to children and they are slow to shut
* down, it's time to send them SIGKILL (or SIGABRT if requested).
* This doesn't happen normally, but under certain conditions backends
* can get stuck while shutting down. This is a last measure to get
* them unwedged.
*
* Note we also do this during recovery from a process crash.
*/
if ((Shutdown >= ImmediateShutdown || FatalError) &&
AbortStartTime != 0 &&
(now - AbortStartTime) >= SIGKILL_CHILDREN_AFTER_SECS)
{
/* We were gentle with them before. Not anymore */
ereport(LOG,
/* translator: %s is SIGKILL or SIGABRT */
(errmsg("issuing %s to recalcitrant children",
send_abort_for_kill ? "SIGABRT" : "SIGKILL")));
TerminateChildren(send_abort_for_kill ? SIGABRT : SIGKILL);
/* reset flag so we don't SIGKILL again */
AbortStartTime = 0;
}
/*
* Once a minute, verify that postmaster.pid hasn't been removed or
* overwritten. If it has, we force a shutdown. This avoids having
* postmasters and child processes hanging around after their database
* is gone, and maybe causing problems if a new database cluster is
* created in the same place. It also provides some protection
* against a DBA foolishly removing postmaster.pid and manually
* starting a new postmaster. Data corruption is likely to ensue from
* that anyway, but we can minimize the damage by aborting ASAP.
*/
if (now - last_lockfile_recheck_time >= 1 * SECS_PER_MINUTE)
{
if (!RecheckDataDirLockFile())
{
ereport(LOG,
(errmsg("performing immediate shutdown because data directory lock file is invalid")));
kill(MyProcPid, SIGQUIT);
}
last_lockfile_recheck_time = now;
}
/*
* Touch Unix socket and lock files every 58 minutes, to ensure that
* they are not removed by overzealous /tmp-cleaning tasks. We assume
* no one runs cleaners with cutoff times of less than an hour ...
*/
if (now - last_touch_time >= 58 * SECS_PER_MINUTE)
{
TouchSocketFiles();
TouchSocketLockFiles();
last_touch_time = now;
}
}
}
/*
* Initialise the masks for select() for the ports we are listening on.
* Return the number of sockets to listen on.
*/
static int
initMasks(fd_set *rmask)
{
int maxsock = -1;
int i;
FD_ZERO(rmask);
for (i = 0; i < MAXLISTEN; i++)
{
int fd = ListenSocket[i];
if (fd == PGINVALID_SOCKET)
break;
FD_SET(fd, rmask);
if (fd > maxsock)
maxsock = fd;
}
return maxsock + 1;
}
/*
* Read a client's startup packet and do something according to it.
*
* Returns STATUS_OK or STATUS_ERROR, or might call ereport(FATAL) and
* not return at all.
*
* (Note that ereport(FATAL) stuff is sent to the client, so only use it
* if that's what you want. Return STATUS_ERROR if you don't want to
* send anything to the client, which would typically be appropriate
* if we detect a communications failure.)
*
* Set ssl_done and/or gss_done when negotiation of an encrypted layer
* (currently, TLS or GSSAPI) is completed. A successful negotiation of either
* encryption layer sets both flags, but a rejected negotiation sets only the
* flag for that layer, since the client may wish to try the other one. We
* should make no assumption here about the order in which the client may make
* requests.
*/
static int
ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
{
int32 len;
char *buf;
ProtocolVersion proto;
MemoryContext oldcontext;
pq_startmsgread();
/*
* Grab the first byte of the length word separately, so that we can tell
* whether we have no data at all or an incomplete packet. (This might
* sound inefficient, but it's not really, because of buffering in
* pqcomm.c.)
*/
if (pq_getbytes((char *) &len, 1) == EOF)
{
/*
* If we get no data at all, don't clutter the log with a complaint;
* such cases often occur for legitimate reasons. An example is that
* we might be here after responding to NEGOTIATE_SSL_CODE, and if the
* client didn't like our response, it'll probably just drop the
* connection. Service-monitoring software also often just opens and
* closes a connection without sending anything. (So do port
* scanners, which may be less benign, but it's not really our job to
* notice those.)
*/
return STATUS_ERROR;
}
if (pq_getbytes(((char *) &len) + 1, 3) == EOF)
{
/* Got a partial length word, so bleat about that */
if (!ssl_done && !gss_done)
ereport(COMMERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("incomplete startup packet")));
return STATUS_ERROR;
}
len = pg_ntoh32(len);
len -= 4;
if (len < (int32) sizeof(ProtocolVersion) ||
len > MAX_STARTUP_PACKET_LENGTH)
{
ereport(COMMERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("invalid length of startup packet")));
return STATUS_ERROR;
}
/*
* Allocate space to hold the startup packet, plus one extra byte that's
* initialized to be zero. This ensures we will have null termination of
* all strings inside the packet.
*/
buf = palloc(len + 1);
buf[len] = '\0';
if (pq_getbytes(buf, len) == EOF)
{
ereport(COMMERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("incomplete startup packet")));
return STATUS_ERROR;
}
pq_endmsgread();
/*
* The first field is either a protocol version number or a special
* request code.
*/
port->proto = proto = pg_ntoh32(*((ProtocolVersion *) buf));
if (proto == CANCEL_REQUEST_CODE)
{
processCancelRequest(port, buf);
/* Not really an error, but we don't want to proceed further */
return STATUS_ERROR;
}
if (proto == NEGOTIATE_SSL_CODE && !ssl_done)
{
char SSLok;
#ifdef USE_SSL
/* No SSL when disabled or on Unix sockets */
if (!LoadedSSL || port->laddr.addr.ss_family == AF_UNIX)
SSLok = 'N';
else
SSLok = 'S'; /* Support for SSL */
#else
SSLok = 'N'; /* No support for SSL */
#endif
retry1:
if (send(port->sock, &SSLok, 1, 0) != 1)
{
if (errno == EINTR)
goto retry1; /* if interrupted, just retry */
ereport(COMMERROR,
(errcode_for_socket_access(),
errmsg("failed to send SSL negotiation response: %m")));
return STATUS_ERROR; /* close the connection */
}
#ifdef USE_SSL
if (SSLok == 'S' && secure_open_server(port) == -1)
return STATUS_ERROR;
#endif
/*
* At this point we should have no data already buffered. If we do,
* it was received before we performed the SSL handshake, so it wasn't
* encrypted and indeed may have been injected by a man-in-the-middle.
* We report this case to the client.
*/
if (pq_buffer_has_data())
ereport(FATAL,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("received unencrypted data after SSL request"),
errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack.")));
/*
* regular startup packet, cancel, etc packet should follow, but not
* another SSL negotiation request, and a GSS request should only
* follow if SSL was rejected (client may negotiate in either order)
*/
return ProcessStartupPacket(port, true, SSLok == 'S');
}
else if (proto == NEGOTIATE_GSS_CODE && !gss_done)
{
char GSSok = 'N';
#ifdef ENABLE_GSS
/* No GSSAPI encryption when on Unix socket */
if (port->laddr.addr.ss_family != AF_UNIX)
GSSok = 'G';
#endif
while (send(port->sock, &GSSok, 1, 0) != 1)
{
if (errno == EINTR)
continue;
ereport(COMMERROR,
(errcode_for_socket_access(),
errmsg("failed to send GSSAPI negotiation response: %m")));
return STATUS_ERROR; /* close the connection */
}
#ifdef ENABLE_GSS
if (GSSok == 'G' && secure_open_gssapi(port) == -1)
return STATUS_ERROR;
#endif
/*
* At this point we should have no data already buffered. If we do,
* it was received before we performed the GSS handshake, so it wasn't
* encrypted and indeed may have been injected by a man-in-the-middle.
* We report this case to the client.
*/
if (pq_buffer_has_data())
ereport(FATAL,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("received unencrypted data after GSSAPI encryption request"),
errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack.")));
/*
* regular startup packet, cancel, etc packet should follow, but not
* another GSS negotiation request, and an SSL request should only
* follow if GSS was rejected (client may negotiate in either order)
*/
return ProcessStartupPacket(port, GSSok == 'G', true);
}
/* Could add additional special packet types here */
/*
* Set FrontendProtocol now so that ereport() knows what format to send if
* we fail during startup.
*/
FrontendProtocol = proto;
/* Check that the major protocol version is in range. */
if (PG_PROTOCOL_MAJOR(proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) ||
PG_PROTOCOL_MAJOR(proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST))
ereport(FATAL,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("unsupported frontend protocol %u.%u: server supports %u.0 to %u.%u",
PG_PROTOCOL_MAJOR(proto), PG_PROTOCOL_MINOR(proto),
PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST),
PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST),
PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST))));
/*
* Now fetch parameters out of startup packet and save them into the Port
* structure. All data structures attached to the Port struct must be
* allocated in TopMemoryContext so that they will remain available in a
* running backend (even after PostmasterContext is destroyed). We need
* not worry about leaking this storage on failure, since we aren't in the
* postmaster process anymore.
*/
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
/* Handle protocol version 3 startup packet */
{
int32 offset = sizeof(ProtocolVersion);
List *unrecognized_protocol_options = NIL;
/*
* Scan packet body for name/option pairs. We can assume any string
* beginning within the packet body is null-terminated, thanks to
* zeroing extra byte above.
*/
port->guc_options = NIL;
while (offset < len)
{
char *nameptr = buf + offset;
int32 valoffset;
char *valptr;
if (*nameptr == '\0')
break; /* found packet terminator */
valoffset = offset + strlen(nameptr) + 1;
if (valoffset >= len)
break; /* missing value, will complain below */
valptr = buf + valoffset;
if (strcmp(nameptr, "database") == 0)
port->database_name = pstrdup(valptr);
else if (strcmp(nameptr, "user") == 0)
port->user_name = pstrdup(valptr);
else if (strcmp(nameptr, "options") == 0)
port->cmdline_options = pstrdup(valptr);
else if (strcmp(nameptr, "replication") == 0)
{
/*
* Due to backward compatibility concerns the replication
* parameter is a hybrid beast which allows the value to be
* either boolean or the string 'database'. The latter
* connects to a specific database which is e.g. required for
* logical decoding while.
*/
if (strcmp(valptr, "database") == 0)
{
am_walsender = true;
am_db_walsender = true;
}
else if (!parse_bool(valptr, &am_walsender))
ereport(FATAL,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid value for parameter \"%s\": \"%s\"",
"replication",
valptr),
errhint("Valid values are: \"false\", 0, \"true\", 1, \"database\".")));
}
else if (strncmp(nameptr, "_pq_.", 5) == 0)
{
/*
* Any option beginning with _pq_. is reserved for use as a
* protocol-level option, but at present no such options are
* defined.
*/
unrecognized_protocol_options =
lappend(unrecognized_protocol_options, pstrdup(nameptr));
}
else
{
/* Assume it's a generic GUC option */
port->guc_options = lappend(port->guc_options,
pstrdup(nameptr));
port->guc_options = lappend(port->guc_options,
pstrdup(valptr));
/*
* Copy application_name to port if we come across it. This
* is done so we can log the application_name in the
* connection authorization message. Note that the GUC would
* be used but we haven't gone through GUC setup yet.
*/
if (strcmp(nameptr, "application_name") == 0)
{
port->application_name = pg_clean_ascii(valptr, 0);
}
}
offset = valoffset + strlen(valptr) + 1;
}
/*
* If we didn't find a packet terminator exactly at the end of the
* given packet length, complain.
*/
if (offset != len - 1)
ereport(FATAL,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("invalid startup packet layout: expected terminator as last byte")));
/*
* If the client requested a newer protocol version or if the client
* requested any protocol options we didn't recognize, let them know
* the newest minor protocol version we do support and the names of
* any unrecognized options.
*/
if (PG_PROTOCOL_MINOR(proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST) ||
unrecognized_protocol_options != NIL)
SendNegotiateProtocolVersion(unrecognized_protocol_options);
}
/* Check a user name was given. */
if (port->user_name == NULL || port->user_name[0] == '\0')
ereport(FATAL,
(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
errmsg("no PostgreSQL user name specified in startup packet")));
/* The database defaults to the user name. */
if (port->database_name == NULL || port->database_name[0] == '\0')
port->database_name = pstrdup(port->user_name);
if (Db_user_namespace)
{
/*
* If user@, it is a global user, remove '@'. We only want to do this
* if there is an '@' at the end and no earlier in the user string or
* they may fake as a local user of another database attaching to this
* database.
*/
if (strchr(port->user_name, '@') ==
port->user_name + strlen(port->user_name) - 1)
*strchr(port->user_name, '@') = '\0';
else
{
/* Append '@' and dbname */
port->user_name = psprintf("%s@%s", port->user_name, port->database_name);
}
}
/*
* Truncate given database and user names to length of a Postgres name.
* This avoids lookup failures when overlength names are given.
*/
if (strlen(port->database_name) >= NAMEDATALEN)
port->database_name[NAMEDATALEN - 1] = '\0';
if (strlen(port->user_name) >= NAMEDATALEN)
port->user_name[NAMEDATALEN - 1] = '\0';
if (am_walsender)
MyBackendType = B_WAL_SENDER;
else
MyBackendType = B_BACKEND;
/*
* Normal walsender backends, e.g. for streaming replication, are not
* connected to a particular database. But walsenders used for logical
* replication need to connect to a specific database. We allow streaming
* replication commands to be issued even if connected to a database as it
* can make sense to first make a basebackup and then stream changes
* starting from that.
*/
if (am_walsender && !am_db_walsender)
port->database_name[0] = '\0';
/*
* Done putting stuff in TopMemoryContext.
*/
MemoryContextSwitchTo(oldcontext);
/*
* If we're going to reject the connection due to database state, say so
* now instead of wasting cycles on an authentication exchange. (This also
* allows a pg_ping utility to be written.)
*/
switch (port->canAcceptConnections)
{
case CAC_STARTUP:
ereport(FATAL,
(errcode(ERRCODE_CANNOT_CONNECT_NOW),
errmsg("the database system is starting up")));
break;
case CAC_NOTCONSISTENT:
if (EnableHotStandby)
ereport(FATAL,
(errcode(ERRCODE_CANNOT_CONNECT_NOW),
errmsg("the database system is not yet accepting connections"),
errdetail("Consistent recovery state has not been yet reached.")));
else
ereport(FATAL,
(errcode(ERRCODE_CANNOT_CONNECT_NOW),
errmsg("the database system is not accepting connections"),
errdetail("Hot standby mode is disabled.")));
break;
case CAC_SHUTDOWN:
ereport(FATAL,
(errcode(ERRCODE_CANNOT_CONNECT_NOW),
errmsg("the database system is shutting down")));
break;
case CAC_RECOVERY:
ereport(FATAL,
(errcode(ERRCODE_CANNOT_CONNECT_NOW),
errmsg("the database system is in recovery mode")));
break;
case CAC_TOOMANY:
ereport(FATAL,
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("sorry, too many clients already")));
break;
case CAC_OK:
break;
}
return STATUS_OK;
}
/*
* Send a NegotiateProtocolVersion to the client. This lets the client know
* that they have requested a newer minor protocol version than we are able
* to speak. We'll speak the highest version we know about; the client can,
* of course, abandon the connection if that's a problem.
*
* We also include in the response a list of protocol options we didn't
* understand. This allows clients to include optional parameters that might
* be present either in newer protocol versions or third-party protocol
* extensions without fear of having to reconnect if those options are not
* understood, while at the same time making certain that the client is aware
* of which options were actually accepted.
*/
static void
SendNegotiateProtocolVersion(List *unrecognized_protocol_options)
{
StringInfoData buf;
ListCell *lc;
pq_beginmessage(&buf, 'v'); /* NegotiateProtocolVersion */
pq_sendint32(&buf, PG_PROTOCOL_LATEST);
pq_sendint32(&buf, list_length(unrecognized_protocol_options));
foreach(lc, unrecognized_protocol_options)
pq_sendstring(&buf, lfirst(lc));
pq_endmessage(&buf);
/* no need to flush, some other message will follow */
}
/*
* The client has sent a cancel request packet, not a normal
* start-a-new-connection packet. Perform the necessary processing.
* Nothing is sent back to the client.
*/
static void
processCancelRequest(Port *port, void *pkt)
{
CancelRequestPacket *canc = (CancelRequestPacket *) pkt;
int backendPID;
int32 cancelAuthCode;
Backend *bp;
#ifndef EXEC_BACKEND
dlist_iter iter;
#else
int i;
#endif
backendPID = (int) pg_ntoh32(canc->backendPID);
cancelAuthCode = (int32) pg_ntoh32(canc->cancelAuthCode);
/*
* See if we have a matching backend. In the EXEC_BACKEND case, we can no
* longer access the postmaster's own backend list, and must rely on the
* duplicate array in shared memory.
*/
#ifndef EXEC_BACKEND
dlist_foreach(iter, &BackendList)
{
bp = dlist_container(Backend, elem, iter.cur);
#else
for (i = MaxLivePostmasterChildren() - 1; i >= 0; i--)
{
bp = (Backend *) &ShmemBackendArray[i];
#endif
if (bp->pid == backendPID)
{
if (bp->cancel_key == cancelAuthCode)
{
/* Found a match; signal that backend to cancel current op */
ereport(DEBUG2,
(errmsg_internal("processing cancel request: sending SIGINT to process %d",
backendPID)));
signal_child(bp->pid, SIGINT);
}
else
/* Right PID, wrong key: no way, Jose */
ereport(LOG,
(errmsg("wrong key in cancel request for process %d",
backendPID)));
return;
}
#ifndef EXEC_BACKEND /* make GNU Emacs 26.1 see brace balance */
}
#else
}
#endif
/* No matching backend */
ereport(LOG,
(errmsg("PID %d in cancel request did not match any process",
backendPID)));
}
/*
* canAcceptConnections --- check to see if database state allows connections
* of the specified type. backend_type can be BACKEND_TYPE_NORMAL,
* BACKEND_TYPE_AUTOVAC, or BACKEND_TYPE_BGWORKER. (Note that we don't yet
* know whether a NORMAL connection might turn into a walsender.)
*/
static CAC_state
canAcceptConnections(int backend_type)
{
CAC_state result = CAC_OK;
/*
* Can't start backends when in startup/shutdown/inconsistent recovery
* state. We treat autovac workers the same as user backends for this
* purpose. However, bgworkers are excluded from this test; we expect
* bgworker_should_start_now() decided whether the DB state allows them.
*/
if (pmState != PM_RUN && pmState != PM_HOT_STANDBY &&
backend_type != BACKEND_TYPE_BGWORKER)
{
if (Shutdown > NoShutdown)
return CAC_SHUTDOWN; /* shutdown is pending */
else if (!FatalError && pmState == PM_STARTUP)
return CAC_STARTUP; /* normal startup */
else if (!FatalError && pmState == PM_RECOVERY)
return CAC_NOTCONSISTENT; /* not yet at consistent recovery
* state */
else
return CAC_RECOVERY; /* else must be crash recovery */
}
/*
* "Smart shutdown" restrictions are applied only to normal connections,
* not to autovac workers or bgworkers.
*/
if (!connsAllowed && backend_type == BACKEND_TYPE_NORMAL)
return CAC_SHUTDOWN; /* shutdown is pending */
/*
* Don't start too many children.
*
* We allow more connections here than we can have backends because some
* might still be authenticating; they might fail auth, or some existing
* backend might exit before the auth cycle is completed. The exact
* MaxBackends limit is enforced when a new backend tries to join the
* shared-inval backend array.
*
* The limit here must match the sizes of the per-child-process arrays;
* see comments for MaxLivePostmasterChildren().
*/
if (CountChildren(BACKEND_TYPE_ALL) >= MaxLivePostmasterChildren())
result = CAC_TOOMANY;
return result;
}
/*
* ConnCreate -- create a local connection data structure
*
* Returns NULL on failure, other than out-of-memory which is fatal.
*/
static Port *
ConnCreate(int serverFd)
{
Port *port;
if (!(port = (Port *) calloc(1, sizeof(Port))))
{
ereport(LOG,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
ExitPostmaster(1);
}
if (StreamConnection(serverFd, port) != STATUS_OK)
{
if (port->sock != PGINVALID_SOCKET)
StreamClose(port->sock);
ConnFree(port);
return NULL;
}
return port;
}
/*
* ConnFree -- free a local connection data structure
*
* Caller has already closed the socket if any, so there's not much
* to do here.
*/
static void
ConnFree(Port *port)
{
free(port);
}
/*
* ClosePostmasterPorts -- close all the postmaster's open sockets
*
* This is called during child process startup to release file descriptors
* that are not needed by that child process. The postmaster still has
* them open, of course.
*
* Note: we pass am_syslogger as a boolean because we don't want to set
* the global variable yet when this is called.
*/
void
ClosePostmasterPorts(bool am_syslogger)
{
int i;
#ifndef WIN32
/*
* Close the write end of postmaster death watch pipe. It's important to
* do this as early as possible, so that if postmaster dies, others won't
* think that it's still running because we're holding the pipe open.
*/
if (close(postmaster_alive_fds[POSTMASTER_FD_OWN]) != 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg_internal("could not close postmaster death monitoring pipe in child process: %m")));
postmaster_alive_fds[POSTMASTER_FD_OWN] = -1;
/* Notify fd.c that we released one pipe FD. */
ReleaseExternalFD();
#endif
/*
* Close the postmaster's listen sockets. These aren't tracked by fd.c,
* so we don't call ReleaseExternalFD() here.
*/
for (i = 0; i < MAXLISTEN; i++)
{
if (ListenSocket[i] != PGINVALID_SOCKET)
{
StreamClose(ListenSocket[i]);
ListenSocket[i] = PGINVALID_SOCKET;
}
}
/*
* If using syslogger, close the read side of the pipe. We don't bother
* tracking this in fd.c, either.
*/
if (!am_syslogger)
{
#ifndef WIN32
if (syslogPipe[0] >= 0)
close(syslogPipe[0]);
syslogPipe[0] = -1;
#else
if (syslogPipe[0])
CloseHandle(syslogPipe[0]);
syslogPipe[0] = 0;
#endif
}
#ifdef USE_BONJOUR
/* If using Bonjour, close the connection to the mDNS daemon */
if (bonjour_sdref)
close(DNSServiceRefSockFD(bonjour_sdref));
#endif
}
/*
* InitProcessGlobals -- set MyProcPid, MyStartTime[stamp], random seeds
*
* Called early in the postmaster and every backend.
*/
void
InitProcessGlobals(void)
{
MyProcPid = getpid();
MyStartTimestamp = GetCurrentTimestamp();
MyStartTime = timestamptz_to_time_t(MyStartTimestamp);
/*
* Set a different global seed in every process. We want something
* unpredictable, so if possible, use high-quality random bits for the
* seed. Otherwise, fall back to a seed based on timestamp and PID.
*/
if (unlikely(!pg_prng_strong_seed(&pg_global_prng_state)))
{
uint64 rseed;
/*
* Since PIDs and timestamps tend to change more frequently in their
* least significant bits, shift the timestamp left to allow a larger
* total number of seeds in a given time period. Since that would
* leave only 20 bits of the timestamp that cycle every ~1 second,
* also mix in some higher bits.
*/
rseed = ((uint64) MyProcPid) ^
((uint64) MyStartTimestamp << 12) ^
((uint64) MyStartTimestamp >> 20);
pg_prng_seed(&pg_global_prng_state, rseed);
}
/*
* Also make sure that we've set a good seed for random(3). Use of that
* is deprecated in core Postgres, but extensions might use it.
*/
#ifndef WIN32
srandom(pg_prng_uint32(&pg_global_prng_state));
#endif
}
/*
* SIGHUP -- reread config files, and tell children to do same
*/
static void
SIGHUP_handler(SIGNAL_ARGS)
{
int save_errno = errno;
if (Shutdown <= SmartShutdown)
{
ereport(LOG,
(errmsg("received SIGHUP, reloading configuration files")));
ProcessConfigFile(PGC_SIGHUP);
SignalChildren(SIGHUP);
if (StartupPID != 0)
signal_child(StartupPID, SIGHUP);
if (BgWriterPID != 0)
signal_child(BgWriterPID, SIGHUP);
if (CheckpointerPID != 0)
signal_child(CheckpointerPID, SIGHUP);
if (WalWriterPID != 0)
signal_child(WalWriterPID, SIGHUP);
if (WalReceiverPID != 0)
signal_child(WalReceiverPID, SIGHUP);
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGHUP);
if (PgArchPID != 0)
signal_child(PgArchPID, SIGHUP);
if (SysLoggerPID != 0)
signal_child(SysLoggerPID, SIGHUP);
/* Reload authentication config files too */
if (!load_hba())
ereport(LOG,
/* translator: %s is a configuration file */
(errmsg("%s was not reloaded", HbaFileName)));
if (!load_ident())
ereport(LOG,
(errmsg("%s was not reloaded", IdentFileName)));
#ifdef USE_SSL
/* Reload SSL configuration as well */
if (EnableSSL)
{
if (secure_initialize(false) == 0)
LoadedSSL = true;
else
ereport(LOG,
(errmsg("SSL configuration was not reloaded")));
}
else
{
secure_destroy();
LoadedSSL = false;
}
#endif
#ifdef EXEC_BACKEND
/* Update the starting-point file for future children */
write_nondefault_variables(PGC_SIGHUP);
#endif
}
errno = save_errno;
}
/*
* pmdie -- signal handler for processing various postmaster signals.
*/
static void
pmdie(SIGNAL_ARGS)
{
int save_errno = errno;
ereport(DEBUG2,
(errmsg_internal("postmaster received signal %d",
postgres_signal_arg)));
switch (postgres_signal_arg)
{
case SIGTERM:
/*
* Smart Shutdown:
*
* Wait for children to end their work, then shut down.
*/
if (Shutdown >= SmartShutdown)
break;
Shutdown = SmartShutdown;
ereport(LOG,
(errmsg("received smart shutdown request")));
/* Report status */
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING);
#ifdef USE_SYSTEMD
sd_notify(0, "STOPPING=1");
#endif
/*
* If we reached normal running, we go straight to waiting for
* client backends to exit. If already in PM_STOP_BACKENDS or a
* later state, do not change it.
*/
if (pmState == PM_RUN || pmState == PM_HOT_STANDBY)
connsAllowed = false;
else if (pmState == PM_STARTUP || pmState == PM_RECOVERY)
{
/* There should be no clients, so proceed to stop children */
pmState = PM_STOP_BACKENDS;
}
/*
* Now wait for online backup mode to end and backends to exit. If
* that is already the case, PostmasterStateMachine will take the
* next step.
*/
PostmasterStateMachine();
break;
case SIGINT:
/*
* Fast Shutdown:
*
* Abort all children with SIGTERM (rollback active transactions
* and exit) and shut down when they are gone.
*/
if (Shutdown >= FastShutdown)
break;
Shutdown = FastShutdown;
ereport(LOG,
(errmsg("received fast shutdown request")));
/* Report status */
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING);
#ifdef USE_SYSTEMD
sd_notify(0, "STOPPING=1");
#endif
if (pmState == PM_STARTUP || pmState == PM_RECOVERY)
{
/* Just shut down background processes silently */
pmState = PM_STOP_BACKENDS;
}
else if (pmState == PM_RUN ||
pmState == PM_HOT_STANDBY)
{
/* Report that we're about to zap live client sessions */
ereport(LOG,
(errmsg("aborting any active transactions")));
pmState = PM_STOP_BACKENDS;
}
/*
* PostmasterStateMachine will issue any necessary signals, or
* take the next step if no child processes need to be killed.
*/
PostmasterStateMachine();
break;
case SIGQUIT:
/*
* Immediate Shutdown:
*
* abort all children with SIGQUIT, wait for them to exit,
* terminate remaining ones with SIGKILL, then exit without
* attempt to properly shut down the data base system.
*/
if (Shutdown >= ImmediateShutdown)
break;
Shutdown = ImmediateShutdown;
ereport(LOG,
(errmsg("received immediate shutdown request")));
/* Report status */
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING);
#ifdef USE_SYSTEMD
sd_notify(0, "STOPPING=1");
#endif
/* tell children to shut down ASAP */
/* (note we don't apply send_abort_for_crash here) */
SetQuitSignalReason(PMQUIT_FOR_STOP);
TerminateChildren(SIGQUIT);
pmState = PM_WAIT_BACKENDS;
/* set stopwatch for them to die */
AbortStartTime = time(NULL);
/*
* Now wait for backends to exit. If there are none,
* PostmasterStateMachine will take the next step.
*/
PostmasterStateMachine();
break;
}
errno = save_errno;
}
/*
* Reaper -- signal handler to cleanup after a child process dies.
*/
static void
reaper(SIGNAL_ARGS)
{
int save_errno = errno;
int pid; /* process id of dead child process */
int exitstatus; /* its exit status */
ereport(DEBUG4,
(errmsg_internal("reaping dead processes")));
while ((pid = waitpid(-1, &exitstatus, WNOHANG)) > 0)
{
/*
* Check if this child was a startup process.
*/
if (pid == StartupPID)
{
StartupPID = 0;
/*
* Startup process exited in response to a shutdown request (or it
* completed normally regardless of the shutdown request).
*/
if (Shutdown > NoShutdown &&
(EXIT_STATUS_0(exitstatus) || EXIT_STATUS_1(exitstatus)))
{
StartupStatus = STARTUP_NOT_RUNNING;
pmState = PM_WAIT_BACKENDS;
/* PostmasterStateMachine logic does the rest */
continue;
}
if (EXIT_STATUS_3(exitstatus))
{
ereport(LOG,
(errmsg("shutdown at recovery target")));
StartupStatus = STARTUP_NOT_RUNNING;
Shutdown = Max(Shutdown, SmartShutdown);
TerminateChildren(SIGTERM);
pmState = PM_WAIT_BACKENDS;
/* PostmasterStateMachine logic does the rest */
continue;
}
/*
* Unexpected exit of startup process (including FATAL exit)
* during PM_STARTUP is treated as catastrophic. There are no
* other processes running yet, so we can just exit.
*/
if (pmState == PM_STARTUP &&
StartupStatus != STARTUP_SIGNALED &&
!EXIT_STATUS_0(exitstatus))
{
LogChildExit(LOG, _("startup process"),
pid, exitstatus);
ereport(LOG,
(errmsg("aborting startup due to startup process failure")));
ExitPostmaster(1);
}
/*
* After PM_STARTUP, any unexpected exit (including FATAL exit) of
* the startup process is catastrophic, so kill other children,
* and set StartupStatus so we don't try to reinitialize after
* they're gone. Exception: if StartupStatus is STARTUP_SIGNALED,
* then we previously sent the startup process a SIGQUIT; so
* that's probably the reason it died, and we do want to try to
* restart in that case.
*
* This stanza also handles the case where we sent a SIGQUIT
* during PM_STARTUP due to some dead_end child crashing: in that
* situation, if the startup process dies on the SIGQUIT, we need
* to transition to PM_WAIT_BACKENDS state which will allow
* PostmasterStateMachine to restart the startup process. (On the
* other hand, the startup process might complete normally, if we
* were too late with the SIGQUIT. In that case we'll fall
* through and commence normal operations.)
*/
if (!EXIT_STATUS_0(exitstatus))
{
if (StartupStatus == STARTUP_SIGNALED)
{
StartupStatus = STARTUP_NOT_RUNNING;
if (pmState == PM_STARTUP)
pmState = PM_WAIT_BACKENDS;
}
else
StartupStatus = STARTUP_CRASHED;
HandleChildCrash(pid, exitstatus,
_("startup process"));
continue;
}
/*
* Startup succeeded, commence normal operations
*/
StartupStatus = STARTUP_NOT_RUNNING;
FatalError = false;
AbortStartTime = 0;
ReachedNormalRunning = true;
pmState = PM_RUN;
connsAllowed = true;
/*
* Crank up the background tasks, if we didn't do that already
* when we entered consistent recovery state. It doesn't matter
* if this fails, we'll just try again later.
*/
if (CheckpointerPID == 0)
CheckpointerPID = StartCheckpointer();
if (BgWriterPID == 0)
BgWriterPID = StartBackgroundWriter();
if (WalWriterPID == 0)
WalWriterPID = StartWalWriter();
/*
* Likewise, start other special children as needed. In a restart
* situation, some of them may be alive already.
*/
if (!IsBinaryUpgrade && AutoVacuumingActive() && AutoVacPID == 0)
AutoVacPID = StartAutoVacLauncher();
if (PgArchStartupAllowed() && PgArchPID == 0)
PgArchPID = StartArchiver();
/* workers may be scheduled to start now */
maybe_start_bgworkers();
/* at this point we are really open for business */
ereport(LOG,
(errmsg("database system is ready to accept connections")));
/* Report status */
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY);
#ifdef USE_SYSTEMD
sd_notify(0, "READY=1");
#endif
continue;
}
/*
* Was it the bgwriter? Normal exit can be ignored; we'll start a new
* one at the next iteration of the postmaster's main loop, if
* necessary. Any other exit condition is treated as a crash.
*/
if (pid == BgWriterPID)
{
BgWriterPID = 0;
if (!EXIT_STATUS_0(exitstatus))
HandleChildCrash(pid, exitstatus,
_("background writer process"));
continue;
}
/*
* Was it the checkpointer?
*/
if (pid == CheckpointerPID)
{
CheckpointerPID = 0;
if (EXIT_STATUS_0(exitstatus) && pmState == PM_SHUTDOWN)
{
/*
* OK, we saw normal exit of the checkpointer after it's been
* told to shut down. We expect that it wrote a shutdown
* checkpoint. (If for some reason it didn't, recovery will
* occur on next postmaster start.)
*
* At this point we should have no normal backend children
* left (else we'd not be in PM_SHUTDOWN state) but we might
* have dead_end children to wait for.
*
* If we have an archiver subprocess, tell it to do a last
* archive cycle and quit. Likewise, if we have walsender
* processes, tell them to send any remaining WAL and quit.
*/
Assert(Shutdown > NoShutdown);
/* Waken archiver for the last time */
if (PgArchPID != 0)
signal_child(PgArchPID, SIGUSR2);
/*
* Waken walsenders for the last time. No regular backends
* should be around anymore.
*/
SignalChildren(SIGUSR2);
pmState = PM_SHUTDOWN_2;
}
else
{
/*
* Any unexpected exit of the checkpointer (including FATAL
* exit) is treated as a crash.
*/
HandleChildCrash(pid, exitstatus,
_("checkpointer process"));
}
continue;
}
/*
* Was it the wal writer? Normal exit can be ignored; we'll start a
* new one at the next iteration of the postmaster's main loop, if
* necessary. Any other exit condition is treated as a crash.
*/
if (pid == WalWriterPID)
{
WalWriterPID = 0;
if (!EXIT_STATUS_0(exitstatus))
HandleChildCrash(pid, exitstatus,
_("WAL writer process"));
continue;
}
/*
* Was it the wal receiver? If exit status is zero (normal) or one
* (FATAL exit), we assume everything is all right just like normal
* backends. (If we need a new wal receiver, we'll start one at the
* next iteration of the postmaster's main loop.)
*/
if (pid == WalReceiverPID)
{
WalReceiverPID = 0;
if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
HandleChildCrash(pid, exitstatus,
_("WAL receiver process"));
continue;
}
/*
* Was it the autovacuum launcher? Normal exit can be ignored; we'll
* start a new one at the next iteration of the postmaster's main
* loop, if necessary. Any other exit condition is treated as a
* crash.
*/
if (pid == AutoVacPID)
{
AutoVacPID = 0;
if (!EXIT_STATUS_0(exitstatus))
HandleChildCrash(pid, exitstatus,
_("autovacuum launcher process"));
continue;
}
/*
* Was it the archiver? If exit status is zero (normal) or one (FATAL
* exit), we assume everything is all right just like normal backends
* and just try to restart a new one so that we immediately retry
* archiving remaining files. (If fail, we'll try again in future
* cycles of the postmaster's main loop.) Unless we were waiting for
* it to shut down; don't restart it in that case, and
* PostmasterStateMachine() will advance to the next shutdown step.
*/
if (pid == PgArchPID)
{
PgArchPID = 0;
if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
HandleChildCrash(pid, exitstatus,
_("archiver process"));
if (PgArchStartupAllowed())
PgArchPID = StartArchiver();
continue;
}
/* Was it the system logger? If so, try to start a new one */
if (pid == SysLoggerPID)
{
SysLoggerPID = 0;
/* for safety's sake, launch new logger *first* */
SysLoggerPID = SysLogger_Start();
if (!EXIT_STATUS_0(exitstatus))
LogChildExit(LOG, _("system logger process"),
pid, exitstatus);
continue;
}
/* Was it one of our background workers? */
if (CleanupBackgroundWorker(pid, exitstatus))
{
/* have it be restarted */
HaveCrashedWorker = true;
continue;
}
/*
* Else do standard backend child cleanup.
*/
CleanupBackend(pid, exitstatus);
} /* loop over pending child-death reports */
/*
* After cleaning out the SIGCHLD queue, see if we have any state changes
* or actions to make.
*/
PostmasterStateMachine();
errno = save_errno;
}
/*
* Scan the bgworkers list and see if the given PID (which has just stopped
* or crashed) is in it. Handle its shutdown if so, and return true. If not a
* bgworker, return false.
*
* This is heavily based on CleanupBackend. One important difference is that
* we don't know yet that the dying process is a bgworker, so we must be silent
* until we're sure it is.
*/
static bool
CleanupBackgroundWorker(int pid,
int exitstatus) /* child's exit status */
{
char namebuf[MAXPGPATH];
slist_mutable_iter iter;
slist_foreach_modify(iter, &BackgroundWorkerList)
{
RegisteredBgWorker *rw;
rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
if (rw->rw_pid != pid)
continue;
#ifdef WIN32
/* see CleanupBackend */
if (exitstatus == ERROR_WAIT_NO_CHILDREN)
exitstatus = 0;
#endif
snprintf(namebuf, MAXPGPATH, _("background worker \"%s\""),
rw->rw_worker.bgw_type);
if (!EXIT_STATUS_0(exitstatus))
{
/* Record timestamp, so we know when to restart the worker. */
rw->rw_crashed_at = GetCurrentTimestamp();
}
else
{
/* Zero exit status means terminate */
rw->rw_crashed_at = 0;
rw->rw_terminate = true;
}
/*
* Additionally, just like a backend, any exit status other than 0 or
* 1 is considered a crash and causes a system-wide restart.
*/
if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
{
HandleChildCrash(pid, exitstatus, namebuf);
return true;
}
/*
* We must release the postmaster child slot. If the worker failed to
* do so, it did not clean up after itself, requiring a crash-restart
* cycle.
*/
if (!ReleasePostmasterChildSlot(rw->rw_child_slot))
{
HandleChildCrash(pid, exitstatus, namebuf);
return true;
}
/* Get it out of the BackendList and clear out remaining data */
dlist_delete(&rw->rw_backend->elem);
#ifdef EXEC_BACKEND
ShmemBackendArrayRemove(rw->rw_backend);
#endif
/*
* It's possible that this background worker started some OTHER
* background worker and asked to be notified when that worker started
* or stopped. If so, cancel any notifications destined for the
* now-dead backend.
*/
if (rw->rw_backend->bgworker_notify)
BackgroundWorkerStopNotifications(rw->rw_pid);
free(rw->rw_backend);
rw->rw_backend = NULL;
rw->rw_pid = 0;
rw->rw_child_slot = 0;
ReportBackgroundWorkerExit(&iter); /* report child death */
LogChildExit(EXIT_STATUS_0(exitstatus) ? DEBUG1 : LOG,
namebuf, pid, exitstatus);
return true;
}
return false;
}
/*
* CleanupBackend -- cleanup after terminated backend.
*
* Remove all local state associated with backend.
*
* If you change this, see also CleanupBackgroundWorker.
*/
static void
CleanupBackend(int pid,
int exitstatus) /* child's exit status. */
{
dlist_mutable_iter iter;
LogChildExit(DEBUG2, _("server process"), pid, exitstatus);
/*
* If a backend dies in an ugly way then we must signal all other backends
* to quickdie. If exit status is zero (normal) or one (FATAL exit), we
* assume everything is all right and proceed to remove the backend from
* the active backend list.
*/
#ifdef WIN32
/*
* On win32, also treat ERROR_WAIT_NO_CHILDREN (128) as nonfatal case,
* since that sometimes happens under load when the process fails to start
* properly (long before it starts using shared memory). Microsoft reports
* it is related to mutex failure:
* http://archives.postgresql.org/pgsql-hackers/2010-09/msg00790.php
*/
if (exitstatus == ERROR_WAIT_NO_CHILDREN)
{
LogChildExit(LOG, _("server process"), pid, exitstatus);
exitstatus = 0;
}
#endif
if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
{
HandleChildCrash(pid, exitstatus, _("server process"));
return;
}
dlist_foreach_modify(iter, &BackendList)
{
Backend *bp = dlist_container(Backend, elem, iter.cur);
if (bp->pid == pid)
{
if (!bp->dead_end)
{
if (!ReleasePostmasterChildSlot(bp->child_slot))
{
/*
* Uh-oh, the child failed to clean itself up. Treat as a
* crash after all.
*/
HandleChildCrash(pid, exitstatus, _("server process"));
return;
}
#ifdef EXEC_BACKEND
ShmemBackendArrayRemove(bp);
#endif
}
if (bp->bgworker_notify)
{
/*
* This backend may have been slated to receive SIGUSR1 when
* some background worker started or stopped. Cancel those
* notifications, as we don't want to signal PIDs that are not
* PostgreSQL backends. This gets skipped in the (probably
* very common) case where the backend has never requested any
* such notifications.
*/
BackgroundWorkerStopNotifications(bp->pid);
}
dlist_delete(iter.cur);
free(bp);
break;
}
}
}
/*
* HandleChildCrash -- cleanup after failed backend, bgwriter, checkpointer,
* walwriter, autovacuum, archiver or background worker.
*
* The objectives here are to clean up our local state about the child
* process, and to signal all other remaining children to quickdie.
*/
static void
HandleChildCrash(int pid, int exitstatus, const char *procname)
{
dlist_mutable_iter iter;
slist_iter siter;
Backend *bp;
bool take_action;
/*
* We only log messages and send signals if this is the first process
* crash and we're not doing an immediate shutdown; otherwise, we're only
* here to update postmaster's idea of live processes. If we have already
* signaled children, nonzero exit status is to be expected, so don't
* clutter log.
*/
take_action = !FatalError && Shutdown != ImmediateShutdown;
if (take_action)
{
LogChildExit(LOG, procname, pid, exitstatus);
ereport(LOG,
(errmsg("terminating any other active server processes")));
SetQuitSignalReason(PMQUIT_FOR_CRASH);
}
/* Process background workers. */
slist_foreach(siter, &BackgroundWorkerList)
{
RegisteredBgWorker *rw;
rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
if (rw->rw_pid == 0)
continue; /* not running */
if (rw->rw_pid == pid)
{
/*
* Found entry for freshly-dead worker, so remove it.
*/
(void) ReleasePostmasterChildSlot(rw->rw_child_slot);
dlist_delete(&rw->rw_backend->elem);
#ifdef EXEC_BACKEND
ShmemBackendArrayRemove(rw->rw_backend);
#endif
free(rw->rw_backend);
rw->rw_backend = NULL;
rw->rw_pid = 0;
rw->rw_child_slot = 0;
/* don't reset crashed_at */
/* don't report child stop, either */
/* Keep looping so we can signal remaining workers */
}
else
{
/*
* This worker is still alive. Unless we did so already, tell it
* to commit hara-kiri.
*/
if (take_action)
sigquit_child(rw->rw_pid);
}
}
/* Process regular backends */
dlist_foreach_modify(iter, &BackendList)
{
bp = dlist_container(Backend, elem, iter.cur);
if (bp->pid == pid)
{
/*
* Found entry for freshly-dead backend, so remove it.
*/
if (!bp->dead_end)
{
(void) ReleasePostmasterChildSlot(bp->child_slot);
#ifdef EXEC_BACKEND
ShmemBackendArrayRemove(bp);
#endif
}
dlist_delete(iter.cur);
free(bp);
/* Keep looping so we can signal remaining backends */
}
else
{
/*
* This backend is still alive. Unless we did so already, tell it
* to commit hara-kiri.
*
* We could exclude dead_end children here, but at least when
* sending SIGABRT it seems better to include them.
*
* Background workers were already processed above; ignore them
* here.
*/
if (bp->bkend_type == BACKEND_TYPE_BGWORKER)
continue;
if (take_action)
sigquit_child(bp->pid);
}
}
/* Take care of the startup process too */
if (pid == StartupPID)
{
StartupPID = 0;
/* Caller adjusts StartupStatus, so don't touch it here */
}
else if (StartupPID != 0 && take_action)
{
sigquit_child(StartupPID);
StartupStatus = STARTUP_SIGNALED;
}
/* Take care of the bgwriter too */
if (pid == BgWriterPID)
BgWriterPID = 0;
else if (BgWriterPID != 0 && take_action)
sigquit_child(BgWriterPID);
/* Take care of the checkpointer too */
if (pid == CheckpointerPID)
CheckpointerPID = 0;
else if (CheckpointerPID != 0 && take_action)
sigquit_child(CheckpointerPID);
/* Take care of the walwriter too */
if (pid == WalWriterPID)
WalWriterPID = 0;
else if (WalWriterPID != 0 && take_action)
sigquit_child(WalWriterPID);
/* Take care of the walreceiver too */
if (pid == WalReceiverPID)
WalReceiverPID = 0;
else if (WalReceiverPID != 0 && take_action)
sigquit_child(WalReceiverPID);
/* Take care of the autovacuum launcher too */
if (pid == AutoVacPID)
AutoVacPID = 0;
else if (AutoVacPID != 0 && take_action)
sigquit_child(AutoVacPID);
/* Take care of the archiver too */
if (pid == PgArchPID)
PgArchPID = 0;
else if (PgArchPID != 0 && take_action)
sigquit_child(PgArchPID);
/* We do NOT restart the syslogger */
if (Shutdown != ImmediateShutdown)
FatalError = true;
/* We now transit into a state of waiting for children to die */
if (pmState == PM_RECOVERY ||
pmState == PM_HOT_STANDBY ||
pmState == PM_RUN ||
pmState == PM_STOP_BACKENDS ||
pmState == PM_SHUTDOWN)
pmState = PM_WAIT_BACKENDS;
/*
* .. and if this doesn't happen quickly enough, now the clock is ticking
* for us to kill them without mercy.
*/
if (AbortStartTime == 0)
AbortStartTime = time(NULL);
}
/*
* Log the death of a child process.
*/
static void
LogChildExit(int lev, const char *procname, int pid, int exitstatus)
{
/*
* size of activity_buffer is arbitrary, but set equal to default
* track_activity_query_size
*/
char activity_buffer[1024];
const char *activity = NULL;
if (!EXIT_STATUS_0(exitstatus))
activity = pgstat_get_crashed_backend_activity(pid,
activity_buffer,
sizeof(activity_buffer));
if (WIFEXITED(exitstatus))
ereport(lev,
/*------
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) exited with exit code %d",
procname, pid, WEXITSTATUS(exitstatus)),
activity ? errdetail("Failed process was running: %s", activity) : 0));
else if (WIFSIGNALED(exitstatus))
{
#if defined(WIN32)
ereport(lev,
/*------
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) was terminated by exception 0x%X",
procname, pid, WTERMSIG(exitstatus)),
errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."),
activity ? errdetail("Failed process was running: %s", activity) : 0));
#else
ereport(lev,
/*------
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) was terminated by signal %d: %s",
procname, pid, WTERMSIG(exitstatus),
pg_strsignal(WTERMSIG(exitstatus))),
activity ? errdetail("Failed process was running: %s", activity) : 0));
#endif
}
else
ereport(lev,
/*------
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) exited with unrecognized status %d",
procname, pid, exitstatus),
activity ? errdetail("Failed process was running: %s", activity) : 0));
}
/*
* Advance the postmaster's state machine and take actions as appropriate
*
* This is common code for pmdie(), reaper() and sigusr1_handler(), which
* receive the signals that might mean we need to change state.
*/
static void
PostmasterStateMachine(void)
{
/* If we're doing a smart shutdown, try to advance that state. */
if (pmState == PM_RUN || pmState == PM_HOT_STANDBY)
{
if (!connsAllowed)
{
/*
* This state ends when we have no normal client backends running.
* Then we're ready to stop other children.
*/
if (CountChildren(BACKEND_TYPE_NORMAL) == 0)
pmState = PM_STOP_BACKENDS;
}
}
/*
* If we're ready to do so, signal child processes to shut down. (This
* isn't a persistent state, but treating it as a distinct pmState allows
* us to share this code across multiple shutdown code paths.)
*/
if (pmState == PM_STOP_BACKENDS)
{
/*
* Forget any pending requests for background workers, since we're no
* longer willing to launch any new workers. (If additional requests
* arrive, BackgroundWorkerStateChange will reject them.)
*/
ForgetUnstartedBackgroundWorkers();
/* Signal all backend children except walsenders */
SignalSomeChildren(SIGTERM,
BACKEND_TYPE_ALL - BACKEND_TYPE_WALSND);
/* and the autovac launcher too */
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGTERM);
/* and the bgwriter too */
if (BgWriterPID != 0)
signal_child(BgWriterPID, SIGTERM);
/* and the walwriter too */
if (WalWriterPID != 0)
signal_child(WalWriterPID, SIGTERM);
/* If we're in recovery, also stop startup and walreceiver procs */
if (StartupPID != 0)
signal_child(StartupPID, SIGTERM);
if (WalReceiverPID != 0)
signal_child(WalReceiverPID, SIGTERM);
/* checkpointer, archiver, stats, and syslogger may continue for now */
/* Now transition to PM_WAIT_BACKENDS state to wait for them to die */
pmState = PM_WAIT_BACKENDS;
}
/*
* If we are in a state-machine state that implies waiting for backends to
* exit, see if they're all gone, and change state if so.
*/
if (pmState == PM_WAIT_BACKENDS)
{
/*
* PM_WAIT_BACKENDS state ends when we have no regular backends
* (including autovac workers), no bgworkers (including unconnected
* ones), and no walwriter, autovac launcher or bgwriter. If we are
* doing crash recovery or an immediate shutdown then we expect the
* checkpointer to exit as well, otherwise not. The stats and
* syslogger processes are disregarded since they are not connected to
* shared memory; we also disregard dead_end children here. Walsenders
* and archiver are also disregarded, they will be terminated later
* after writing the checkpoint record.
*/
if (CountChildren(BACKEND_TYPE_ALL - BACKEND_TYPE_WALSND) == 0 &&
StartupPID == 0 &&
WalReceiverPID == 0 &&
BgWriterPID == 0 &&
(CheckpointerPID == 0 ||
(!FatalError && Shutdown < ImmediateShutdown)) &&
WalWriterPID == 0 &&
AutoVacPID == 0)
{
if (Shutdown >= ImmediateShutdown || FatalError)
{
/*
* Start waiting for dead_end children to die. This state
* change causes ServerLoop to stop creating new ones.
*/
pmState = PM_WAIT_DEAD_END;
/*
* We already SIGQUIT'd the archiver and stats processes, if
* any, when we started immediate shutdown or entered
* FatalError state.
*/
}
else
{
/*
* If we get here, we are proceeding with normal shutdown. All
* the regular children are gone, and it's time to tell the
* checkpointer to do a shutdown checkpoint.
*/
Assert(Shutdown > NoShutdown);
/* Start the checkpointer if not running */
if (CheckpointerPID == 0)
CheckpointerPID = StartCheckpointer();
/* And tell it to shut down */
if (CheckpointerPID != 0)
{
signal_child(CheckpointerPID, SIGUSR2);
pmState = PM_SHUTDOWN;
}
else
{
/*
* If we failed to fork a checkpointer, just shut down.
* Any required cleanup will happen at next restart. We
* set FatalError so that an "abnormal shutdown" message
* gets logged when we exit.
*
* We don't consult send_abort_for_crash here, as it's
* unlikely that dumping cores would illuminate the reason
* for checkpointer fork failure.
*/
FatalError = true;
pmState = PM_WAIT_DEAD_END;
/* Kill the walsenders and archiver too */
SignalChildren(SIGQUIT);
if (PgArchPID != 0)
signal_child(PgArchPID, SIGQUIT);
}
}
}
}
if (pmState == PM_SHUTDOWN_2)
{
/*
* PM_SHUTDOWN_2 state ends when there's no other children than
* dead_end children left. There shouldn't be any regular backends
* left by now anyway; what we're really waiting for is walsenders and
* archiver.
*/
if (PgArchPID == 0 && CountChildren(BACKEND_TYPE_ALL) == 0)
{
pmState = PM_WAIT_DEAD_END;
}
}
if (pmState == PM_WAIT_DEAD_END)
{
/*
* PM_WAIT_DEAD_END state ends when the BackendList is entirely empty
* (ie, no dead_end children remain), and the archiver is gone too.
*
* The reason we wait for those two is to protect them against a new
* postmaster starting conflicting subprocesses; this isn't an
* ironclad protection, but it at least helps in the
* shutdown-and-immediately-restart scenario. Note that they have
* already been sent appropriate shutdown signals, either during a
* normal state transition leading up to PM_WAIT_DEAD_END, or during
* FatalError processing.
*/
if (dlist_is_empty(&BackendList) && PgArchPID == 0)
{
/* These other guys should be dead already */
Assert(StartupPID == 0);
Assert(WalReceiverPID == 0);
Assert(BgWriterPID == 0);
Assert(CheckpointerPID == 0);
Assert(WalWriterPID == 0);
Assert(AutoVacPID == 0);
/* syslogger is not considered here */
pmState = PM_NO_CHILDREN;
}
}
/*
* If we've been told to shut down, we exit as soon as there are no
* remaining children. If there was a crash, cleanup will occur at the
* next startup. (Before PostgreSQL 8.3, we tried to recover from the
* crash before exiting, but that seems unwise if we are quitting because
* we got SIGTERM from init --- there may well not be time for recovery
* before init decides to SIGKILL us.)
*
* Note that the syslogger continues to run. It will exit when it sees
* EOF on its input pipe, which happens when there are no more upstream
* processes.
*/
if (Shutdown > NoShutdown && pmState == PM_NO_CHILDREN)
{
if (FatalError)
{
ereport(LOG, (errmsg("abnormal database system shutdown")));
ExitPostmaster(1);
}
else
{
/*
* Normal exit from the postmaster is here. We don't need to log
* anything here, since the UnlinkLockFiles proc_exit callback
* will do so, and that should be the last user-visible action.
*/
ExitPostmaster(0);
}
}
/*
* If the startup process failed, or the user does not want an automatic
* restart after backend crashes, wait for all non-syslogger children to
* exit, and then exit postmaster. We don't try to reinitialize when the
* startup process fails, because more than likely it will just fail again
* and we will keep trying forever.
*/
if (pmState == PM_NO_CHILDREN)
{
if (StartupStatus == STARTUP_CRASHED)
{
ereport(LOG,
(errmsg("shutting down due to startup process failure")));
ExitPostmaster(1);
}
if (!restart_after_crash)
{
ereport(LOG,
(errmsg("shutting down because restart_after_crash is off")));
ExitPostmaster(1);
}
}
/*
* If we need to recover from a crash, wait for all non-syslogger children
* to exit, then reset shmem and StartupDataBase.
*/
if (FatalError && pmState == PM_NO_CHILDREN)
{
ereport(LOG,
(errmsg("all server processes terminated; reinitializing")));
/* remove leftover temporary files after a crash */
if (remove_temp_files_after_crash)
RemovePgTempFiles();
/* allow background workers to immediately restart */
ResetBackgroundWorkerCrashTimes();
shmem_exit(1);
/* re-read control file into local memory */
LocalProcessControlFile(true);
/* re-create shared memory and semaphores */
CreateSharedMemoryAndSemaphores();
StartupPID = StartupDataBase();
Assert(StartupPID != 0);
StartupStatus = STARTUP_RUNNING;
pmState = PM_STARTUP;
/* crash recovery started, reset SIGKILL flag */
AbortStartTime = 0;
}
}
/*
* Send a signal to a postmaster child process
*
* On systems that have setsid(), each child process sets itself up as a
* process group leader. For signals that are generally interpreted in the
* appropriate fashion, we signal the entire process group not just the
* direct child process. This allows us to, for example, SIGQUIT a blocked
* archive_recovery script, or SIGINT a script being run by a backend via
* system().
*
* There is a race condition for recently-forked children: they might not
* have executed setsid() yet. So we signal the child directly as well as
* the group. We assume such a child will handle the signal before trying
* to spawn any grandchild processes. We also assume that signaling the
* child twice will not cause any problems.
*/
static void
signal_child(pid_t pid, int signal)
{
if (kill(pid, signal) < 0)
elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) pid, signal);
#ifdef HAVE_SETSID
switch (signal)
{
case SIGINT:
case SIGTERM:
case SIGQUIT:
case SIGKILL:
case SIGABRT:
if (kill(-pid, signal) < 0)
elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) (-pid), signal);
break;
default:
break;
}
#endif
}
/*
* Convenience function for killing a child process after a crash of some
* other child process. We log the action at a higher level than we would
* otherwise do, and we apply send_abort_for_crash to decide which signal
* to send. Normally it's SIGQUIT -- and most other comments in this file
* are written on the assumption that it is -- but developers might prefer
* to use SIGABRT to collect per-child core dumps.
*/
static void
sigquit_child(pid_t pid)
{
ereport(DEBUG2,
(errmsg_internal("sending %s to process %d",
(send_abort_for_crash ? "SIGABRT" : "SIGQUIT"),
(int) pid)));
signal_child(pid, (send_abort_for_crash ? SIGABRT : SIGQUIT));
}
/*
* Send a signal to the targeted children (but NOT special children;
* dead_end children are never signaled, either).
*/
static bool
SignalSomeChildren(int signal, int target)
{
dlist_iter iter;
bool signaled = false;
dlist_foreach(iter, &BackendList)
{
Backend *bp = dlist_container(Backend, elem, iter.cur);
if (bp->dead_end)
continue;
/*
* Since target == BACKEND_TYPE_ALL is the most common case, we test
* it first and avoid touching shared memory for every child.
*/
if (target != BACKEND_TYPE_ALL)
{
/*
* Assign bkend_type for any recently announced WAL Sender
* processes.
*/
if (bp->bkend_type == BACKEND_TYPE_NORMAL &&
IsPostmasterChildWalSender(bp->child_slot))
bp->bkend_type = BACKEND_TYPE_WALSND;
if (!(target & bp->bkend_type))
continue;
}
ereport(DEBUG4,
(errmsg_internal("sending signal %d to process %d",
signal, (int) bp->pid)));
signal_child(bp->pid, signal);
signaled = true;
}
return signaled;
}
/*
* Send a termination signal to children. This considers all of our children
* processes, except syslogger and dead_end backends.
*/
static void
TerminateChildren(int signal)
{
SignalChildren(signal);
if (StartupPID != 0)
{
signal_child(StartupPID, signal);
if (signal == SIGQUIT || signal == SIGKILL || signal == SIGABRT)
StartupStatus = STARTUP_SIGNALED;
}
if (BgWriterPID != 0)
signal_child(BgWriterPID, signal);
if (CheckpointerPID != 0)
signal_child(CheckpointerPID, signal);
if (WalWriterPID != 0)
signal_child(WalWriterPID, signal);
if (WalReceiverPID != 0)
signal_child(WalReceiverPID, signal);
if (AutoVacPID != 0)
signal_child(AutoVacPID, signal);
if (PgArchPID != 0)
signal_child(PgArchPID, signal);
}
/*
* BackendStartup -- start backend process
*
* returns: STATUS_ERROR if the fork failed, STATUS_OK otherwise.
*
* Note: if you change this code, also consider StartAutovacuumWorker.
*/
static int
BackendStartup(Port *port)
{
Backend *bn; /* for backend cleanup */
pid_t pid;
/*
* Create backend data structure. Better before the fork() so we can
* handle failure cleanly.
*/
bn = (Backend *) malloc(sizeof(Backend));
if (!bn)
{
ereport(LOG,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
return STATUS_ERROR;
}
/*
* Compute the cancel key that will be assigned to this backend. The
* backend will have its own copy in the forked-off process' value of
* MyCancelKey, so that it can transmit the key to the frontend.
*/
if (!RandomCancelKey(&MyCancelKey))
{
free(bn);
ereport(LOG,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("could not generate random cancel key")));
return STATUS_ERROR;
}
bn->cancel_key = MyCancelKey;
/* Pass down canAcceptConnections state */
port->canAcceptConnections = canAcceptConnections(BACKEND_TYPE_NORMAL);
bn->dead_end = (port->canAcceptConnections != CAC_OK);
/*
* Unless it's a dead_end child, assign it a child slot number
*/
if (!bn->dead_end)
bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
else
bn->child_slot = 0;
/* Hasn't asked to be notified about any bgworkers yet */
bn->bgworker_notify = false;
#ifdef EXEC_BACKEND
pid = backend_forkexec(port);
#else /* !EXEC_BACKEND */
pid = fork_process();
if (pid == 0) /* child */
{
free(bn);
/* Detangle from postmaster */
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/* Perform additional initialization and collect startup packet */
BackendInitialize(port);
/*
* Create a per-backend PGPROC struct in shared memory. We must do
* this before we can use LWLocks. In the !EXEC_BACKEND case (here)
* this could be delayed a bit further, but EXEC_BACKEND needs to do
* stuff with LWLocks before PostgresMain(), so we do it here as well
* for symmetry.
*/
InitProcess();
/* And run the backend */
BackendRun(port);
}
#endif /* EXEC_BACKEND */
if (pid < 0)
{
/* in parent, fork failed */
int save_errno = errno;
if (!bn->dead_end)
(void) ReleasePostmasterChildSlot(bn->child_slot);
free(bn);
errno = save_errno;
ereport(LOG,
(errmsg("could not fork new process for connection: %m")));
report_fork_failure_to_client(port, save_errno);
return STATUS_ERROR;
}
/* in parent, successful fork */
ereport(DEBUG2,
(errmsg_internal("forked new backend, pid=%d socket=%d",
(int) pid, (int) port->sock)));
/*
* Everything's been successful, it's safe to add this backend to our list
* of backends.
*/
bn->pid = pid;
bn->bkend_type = BACKEND_TYPE_NORMAL; /* Can change later to WALSND */
dlist_push_head(&BackendList, &bn->elem);
#ifdef EXEC_BACKEND
if (!bn->dead_end)
ShmemBackendArrayAdd(bn);
#endif
return STATUS_OK;
}
/*
* Try to report backend fork() failure to client before we close the
* connection. Since we do not care to risk blocking the postmaster on
* this connection, we set the connection to non-blocking and try only once.
*
* This is grungy special-purpose code; we cannot use backend libpq since
* it's not up and running.
*/
static void
report_fork_failure_to_client(Port *port, int errnum)
{
char buffer[1000];
int rc;
/* Format the error message packet (always V2 protocol) */
snprintf(buffer, sizeof(buffer), "E%s%s\n",
_("could not fork new process for connection: "),
strerror(errnum));
/* Set port to non-blocking. Don't do send() if this fails */
if (!pg_set_noblock(port->sock))
return;
/* We'll retry after EINTR, but ignore all other failures */
do
{
rc = send(port->sock, buffer, strlen(buffer) + 1, 0);
} while (rc < 0 && errno == EINTR);
}
/*
* BackendInitialize -- initialize an interactive (postmaster-child)
* backend process, and collect the client's startup packet.
*
* returns: nothing. Will not return at all if there's any failure.
*
* Note: this code does not depend on having any access to shared memory.
* Indeed, our approach to SIGTERM/timeout handling *requires* that
* shared memory not have been touched yet; see comments within.
* In the EXEC_BACKEND case, we are physically attached to shared memory
* but have not yet set up most of our local pointers to shmem structures.
*/
static void
BackendInitialize(Port *port)
{
int status;
int ret;
char remote_host[NI_MAXHOST];
char remote_port[NI_MAXSERV];
StringInfoData ps_data;
/* Save port etc. for ps status */
MyProcPort = port;
/* Tell fd.c about the long-lived FD associated with the port */
ReserveExternalFD();
/*
* PreAuthDelay is a debugging aid for investigating problems in the
* authentication cycle: it can be set in postgresql.conf to allow time to
* attach to the newly-forked backend with a debugger. (See also
* PostAuthDelay, which we allow clients to pass through PGOPTIONS, but it
* is not honored until after authentication.)
*/
if (PreAuthDelay > 0)
pg_usleep(PreAuthDelay * 1000000L);
/* This flag will remain set until InitPostgres finishes authentication */
ClientAuthInProgress = true; /* limit visibility of log messages */
/* set these to empty in case they are needed before we set them up */
port->remote_host = "";
port->remote_port = "";
/*
* Initialize libpq and enable reporting of ereport errors to the client.
* Must do this now because authentication uses libpq to send messages.
*/
pq_init(); /* initialize libpq to talk to client */
whereToSendOutput = DestRemote; /* now safe to ereport to client */
/*
* We arrange to do _exit(1) if we receive SIGTERM or timeout while trying
* to collect the startup packet; while SIGQUIT results in _exit(2).
* Otherwise the postmaster cannot shutdown the database FAST or IMMED
* cleanly if a buggy client fails to send the packet promptly.
*
* Exiting with _exit(1) is only possible because we have not yet touched
* shared memory; therefore no outside-the-process state needs to get
* cleaned up.
*/
pqsignal(SIGTERM, process_startup_packet_die);
/* SIGQUIT handler was already set up by InitPostmasterChild */
InitializeTimeouts(); /* establishes SIGALRM handler */
PG_SETMASK(&StartupBlockSig);
/*
* Get the remote host name and port for logging and status display.
*/
remote_host[0] = '\0';
remote_port[0] = '\0';
if ((ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
remote_host, sizeof(remote_host),
remote_port, sizeof(remote_port),
(log_hostname ? 0 : NI_NUMERICHOST) | NI_NUMERICSERV)) != 0)
ereport(WARNING,
(errmsg_internal("pg_getnameinfo_all() failed: %s",
gai_strerror(ret))));
/*
* Save remote_host and remote_port in port structure (after this, they
* will appear in log_line_prefix data for log messages).
*/
port->remote_host = strdup(remote_host);
port->remote_port = strdup(remote_port);
/* And now we can issue the Log_connections message, if wanted */
if (Log_connections)
{
if (remote_port[0])
ereport(LOG,
(errmsg("connection received: host=%s port=%s",
remote_host,
remote_port)));
else
ereport(LOG,
(errmsg("connection received: host=%s",
remote_host)));
}
/*
* If we did a reverse lookup to name, we might as well save the results
* rather than possibly repeating the lookup during authentication.
*
* Note that we don't want to specify NI_NAMEREQD above, because then we'd
* get nothing useful for a client without an rDNS entry. Therefore, we
* must check whether we got a numeric IPv4 or IPv6 address, and not save
* it into remote_hostname if so. (This test is conservative and might
* sometimes classify a hostname as numeric, but an error in that
* direction is safe; it only results in a possible extra lookup.)
*/
if (log_hostname &&
ret == 0 &&
strspn(remote_host, "0123456789.") < strlen(remote_host) &&
strspn(remote_host, "0123456789ABCDEFabcdef:") < strlen(remote_host))
port->remote_hostname = strdup(remote_host);
/*
* Ready to begin client interaction. We will give up and _exit(1) after
* a time delay, so that a broken client can't hog a connection
* indefinitely. PreAuthDelay and any DNS interactions above don't count
* against the time limit.
*
* Note: AuthenticationTimeout is applied here while waiting for the
* startup packet, and then again in InitPostgres for the duration of any
* authentication operations. So a hostile client could tie up the
* process for nearly twice AuthenticationTimeout before we kick him off.
*
* Note: because PostgresMain will call InitializeTimeouts again, the
* registration of STARTUP_PACKET_TIMEOUT will be lost. This is okay
* since we never use it again after this function.
*/
RegisterTimeout(STARTUP_PACKET_TIMEOUT, StartupPacketTimeoutHandler);
enable_timeout_after(STARTUP_PACKET_TIMEOUT, AuthenticationTimeout * 1000);
/*
* Receive the startup packet (which might turn out to be a cancel request
* packet).
*/
status = ProcessStartupPacket(port, false, false);
/*
* Disable the timeout, and prevent SIGTERM again.
*/
disable_timeout(STARTUP_PACKET_TIMEOUT, false);
PG_SETMASK(&BlockSig);
/*
* As a safety check that nothing in startup has yet performed
* shared-memory modifications that would need to be undone if we had
* exited through SIGTERM or timeout above, check that no on_shmem_exit
* handlers have been registered yet. (This isn't terribly bulletproof,
* since someone might misuse an on_proc_exit handler for shmem cleanup,
* but it's a cheap and helpful check. We cannot disallow on_proc_exit
* handlers unfortunately, since pq_init() already registered one.)
*/
check_on_shmem_exit_lists_are_empty();
/*
* Stop here if it was bad or a cancel packet. ProcessStartupPacket
* already did any appropriate error reporting.
*/
if (status != STATUS_OK)
proc_exit(0);
/*
* Now that we have the user and database name, we can set the process
* title for ps. It's good to do this as early as possible in startup.
*/
initStringInfo(&ps_data);
if (am_walsender)
appendStringInfo(&ps_data, "%s ", GetBackendTypeDesc(B_WAL_SENDER));
appendStringInfo(&ps_data, "%s ", port->user_name);
if (port->database_name[0] != '\0')
appendStringInfo(&ps_data, "%s ", port->database_name);
appendStringInfoString(&ps_data, port->remote_host);
if (port->remote_port[0] != '\0')
appendStringInfo(&ps_data, "(%s)", port->remote_port);
init_ps_display(ps_data.data);
pfree(ps_data.data);
set_ps_display("initializing");
}
/*
* BackendRun -- set up the backend's argument list and invoke PostgresMain()
*
* returns:
* Doesn't return at all.
*/
static void
BackendRun(Port *port)
{
/*
* Make sure we aren't in PostmasterContext anymore. (We can't delete it
* just yet, though, because InitPostgres will need the HBA data.)
*/
MemoryContextSwitchTo(TopMemoryContext);
PostgresMain(port->database_name, port->user_name);
}
#ifdef EXEC_BACKEND
/*
* postmaster_forkexec -- fork and exec a postmaster subprocess
*
* The caller must have set up the argv array already, except for argv[2]
* which will be filled with the name of the temp variable file.
*
* Returns the child process PID, or -1 on fork failure (a suitable error
* message has been logged on failure).
*
* All uses of this routine will dispatch to SubPostmasterMain in the
* child process.
*/
pid_t
postmaster_forkexec(int argc, char *argv[])
{
Port port;
/* This entry point passes dummy values for the Port variables */
memset(&port, 0, sizeof(port));
return internal_forkexec(argc, argv, &port);
}
/*
* backend_forkexec -- fork/exec off a backend process
*
* Some operating systems (WIN32) don't have fork() so we have to simulate
* it by storing parameters that need to be passed to the child and
* then create a new child process.
*
* returns the pid of the fork/exec'd process, or -1 on failure
*/
static pid_t
backend_forkexec(Port *port)
{
char *av[4];
int ac = 0;
av[ac++] = "postgres";
av[ac++] = "--forkbackend";
av[ac++] = NULL; /* filled in by internal_forkexec */
av[ac] = NULL;
Assert(ac < lengthof(av));
return internal_forkexec(ac, av, port);
}
#ifndef WIN32
/*
* internal_forkexec non-win32 implementation
*
* - writes out backend variables to the parameter file
* - fork():s, and then exec():s the child process
*/
static pid_t
internal_forkexec(int argc, char *argv[], Port *port)
{
static unsigned long tmpBackendFileNum = 0;
pid_t pid;
char tmpfilename[MAXPGPATH];
BackendParameters param;
FILE *fp;
if (!save_backend_variables(&param, port))
return -1; /* log made by save_backend_variables */
/* Calculate name for temp file */
snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu",
PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX,
MyProcPid, ++tmpBackendFileNum);
/* Open file */
fp = AllocateFile(tmpfilename, PG_BINARY_W);
if (!fp)
{
/*
* As in OpenTemporaryFileInTablespace, try to make the temp-file
* directory, ignoring errors.
*/
(void) MakePGDirectory(PG_TEMP_FILES_DIR);
fp = AllocateFile(tmpfilename, PG_BINARY_W);
if (!fp)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m",
tmpfilename)));
return -1;
}
}
if (fwrite(&param, sizeof(param), 1, fp) != 1)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m", tmpfilename)));
FreeFile(fp);
return -1;
}
/* Release file */
if (FreeFile(fp))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m", tmpfilename)));
return -1;
}
/* Make sure caller set up argv properly */
Assert(argc >= 3);
Assert(argv[argc] == NULL);
Assert(strncmp(argv[1], "--fork", 6) == 0);
Assert(argv[2] == NULL);
/* Insert temp file name after --fork argument */
argv[2] = tmpfilename;
/* Fire off execv in child */
if ((pid = fork_process()) == 0)
{
if (execv(postgres_exec_path, argv) < 0)
{
ereport(LOG,
(errmsg("could not execute server process \"%s\": %m",
postgres_exec_path)));
/* We're already in the child process here, can't return */
exit(1);
}
}
return pid; /* Parent returns pid, or -1 on fork failure */
}
#else /* WIN32 */
/*
* internal_forkexec win32 implementation
*
* - starts backend using CreateProcess(), in suspended state
* - writes out backend variables to the parameter file
* - during this, duplicates handles and sockets required for
* inheritance into the new process
* - resumes execution of the new process once the backend parameter
* file is complete.
*/
static pid_t
internal_forkexec(int argc, char *argv[], Port *port)
{
int retry_count = 0;
STARTUPINFO si;
PROCESS_INFORMATION pi;
int i;
int j;
char cmdLine[MAXPGPATH * 2];
HANDLE paramHandle;
BackendParameters *param;
SECURITY_ATTRIBUTES sa;
char paramHandleStr[32];
win32_deadchild_waitinfo *childinfo;
/* Make sure caller set up argv properly */
Assert(argc >= 3);
Assert(argv[argc] == NULL);
Assert(strncmp(argv[1], "--fork", 6) == 0);
Assert(argv[2] == NULL);
/* Resume here if we need to retry */
retry:
/* Set up shared memory for parameter passing */
ZeroMemory(&sa, sizeof(sa));
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
paramHandle = CreateFileMapping(INVALID_HANDLE_VALUE,
&sa,
PAGE_READWRITE,
0,
sizeof(BackendParameters),
NULL);
if (paramHandle == INVALID_HANDLE_VALUE)
{
ereport(LOG,
(errmsg("could not create backend parameter file mapping: error code %lu",
GetLastError())));
return -1;
}
param = MapViewOfFile(paramHandle, FILE_MAP_WRITE, 0, 0, sizeof(BackendParameters));
if (!param)
{
ereport(LOG,
(errmsg("could not map backend parameter memory: error code %lu",
GetLastError())));
CloseHandle(paramHandle);
return -1;
}
/* Insert temp file name after --fork argument */
#ifdef _WIN64
sprintf(paramHandleStr, "%llu", (LONG_PTR) paramHandle);
#else
sprintf(paramHandleStr, "%lu", (DWORD) paramHandle);
#endif
argv[2] = paramHandleStr;
/* Format the cmd line */
cmdLine[sizeof(cmdLine) - 1] = '\0';
cmdLine[sizeof(cmdLine) - 2] = '\0';
snprintf(cmdLine, sizeof(cmdLine) - 1, "\"%s\"", postgres_exec_path);
i = 0;
while (argv[++i] != NULL)
{
j = strlen(cmdLine);
snprintf(cmdLine + j, sizeof(cmdLine) - 1 - j, " \"%s\"", argv[i]);
}
if (cmdLine[sizeof(cmdLine) - 2] != '\0')
{
ereport(LOG,
(errmsg("subprocess command line too long")));
UnmapViewOfFile(param);
CloseHandle(paramHandle);
return -1;
}
memset(&pi, 0, sizeof(pi));
memset(&si, 0, sizeof(si));
si.cb = sizeof(si);
/*
* Create the subprocess in a suspended state. This will be resumed later,
* once we have written out the parameter file.
*/
if (!CreateProcess(NULL, cmdLine, NULL, NULL, TRUE, CREATE_SUSPENDED,
NULL, NULL, &si, &pi))
{
ereport(LOG,
(errmsg("CreateProcess() call failed: %m (error code %lu)",
GetLastError())));
UnmapViewOfFile(param);
CloseHandle(paramHandle);
return -1;
}
if (!save_backend_variables(param, port, pi.hProcess, pi.dwProcessId))
{
/*
* log made by save_backend_variables, but we have to clean up the
* mess with the half-started process
*/
if (!TerminateProcess(pi.hProcess, 255))
ereport(LOG,
(errmsg_internal("could not terminate unstarted process: error code %lu",
GetLastError())));
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
UnmapViewOfFile(param);
CloseHandle(paramHandle);
return -1; /* log made by save_backend_variables */
}
/* Drop the parameter shared memory that is now inherited to the backend */
if (!UnmapViewOfFile(param))
ereport(LOG,
(errmsg("could not unmap view of backend parameter file: error code %lu",
GetLastError())));
if (!CloseHandle(paramHandle))
ereport(LOG,
(errmsg("could not close handle to backend parameter file: error code %lu",
GetLastError())));
/*
* Reserve the memory region used by our main shared memory segment before
* we resume the child process. Normally this should succeed, but if ASLR
* is active then it might sometimes fail due to the stack or heap having
* gotten mapped into that range. In that case, just terminate the
* process and retry.
*/
if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess))
{
/* pgwin32_ReserveSharedMemoryRegion already made a log entry */
if (!TerminateProcess(pi.hProcess, 255))
ereport(LOG,
(errmsg_internal("could not terminate process that failed to reserve memory: error code %lu",
GetLastError())));
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
if (++retry_count < 100)
goto retry;
ereport(LOG,
(errmsg("giving up after too many tries to reserve shared memory"),
errhint("This might be caused by ASLR or antivirus software.")));
return -1;
}
/*
* Now that the backend variables are written out, we start the child
* thread so it can start initializing while we set up the rest of the
* parent state.
*/
if (ResumeThread(pi.hThread) == -1)
{
if (!TerminateProcess(pi.hProcess, 255))
{
ereport(LOG,
(errmsg_internal("could not terminate unstartable process: error code %lu",
GetLastError())));
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
return -1;
}
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
ereport(LOG,
(errmsg_internal("could not resume thread of unstarted process: error code %lu",
GetLastError())));
return -1;
}
/*
* Queue a waiter to signal when this child dies. The wait will be handled
* automatically by an operating system thread pool.
*
* Note: use malloc instead of palloc, since it needs to be thread-safe.
* Struct will be free():d from the callback function that runs on a
* different thread.
*/
childinfo = malloc(sizeof(win32_deadchild_waitinfo));
if (!childinfo)
ereport(FATAL,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
childinfo->procHandle = pi.hProcess;
childinfo->procId = pi.dwProcessId;
if (!RegisterWaitForSingleObject(&childinfo->waitHandle,
pi.hProcess,
pgwin32_deadchild_callback,
childinfo,
INFINITE,
WT_EXECUTEONLYONCE | WT_EXECUTEINWAITTHREAD))
ereport(FATAL,
(errmsg_internal("could not register process for wait: error code %lu",
GetLastError())));
/* Don't close pi.hProcess here - the wait thread needs access to it */
CloseHandle(pi.hThread);
return pi.dwProcessId;
}
#endif /* WIN32 */
/*
* SubPostmasterMain -- Get the fork/exec'd process into a state equivalent
* to what it would be if we'd simply forked on Unix, and then
* dispatch to the appropriate place.
*
* The first two command line arguments are expected to be "--forkFOO"
* (where FOO indicates which postmaster child we are to become), and
* the name of a variables file that we can read to load data that would
* have been inherited by fork() on Unix. Remaining arguments go to the
* subprocess FooMain() routine.
*/
void
SubPostmasterMain(int argc, char *argv[])
{
Port port;
/* In EXEC_BACKEND case we will not have inherited these settings */
IsPostmasterEnvironment = true;
whereToSendOutput = DestNone;
/* Setup essential subsystems (to ensure elog() behaves sanely) */
InitializeGUCOptions();
/* Check we got appropriate args */
if (argc < 3)
elog(FATAL, "invalid subpostmaster invocation");
/* Read in the variables file */
memset(&port, 0, sizeof(Port));
read_backend_variables(argv[2], &port);
/* Close the postmaster's sockets (as soon as we know them) */
ClosePostmasterPorts(strcmp(argv[1], "--forklog") == 0);
/* Setup as postmaster child */
InitPostmasterChild();
/*
* If appropriate, physically re-attach to shared memory segment. We want
* to do this before going any further to ensure that we can attach at the
* same address the postmaster used. On the other hand, if we choose not
* to re-attach, we may have other cleanup to do.
*
* If testing EXEC_BACKEND on Linux, you should run this as root before
* starting the postmaster:
*
* sysctl -w kernel.randomize_va_space=0
*
* This prevents using randomized stack and code addresses that cause the
* child process's memory map to be different from the parent's, making it
* sometimes impossible to attach to shared memory at the desired address.
* Return the setting to its old value (usually '1' or '2') when finished.
*/
if (strcmp(argv[1], "--forkbackend") == 0 ||
strcmp(argv[1], "--forkavlauncher") == 0 ||
strcmp(argv[1], "--forkavworker") == 0 ||
strcmp(argv[1], "--forkaux") == 0 ||
strncmp(argv[1], "--forkbgworker=", 15) == 0)
PGSharedMemoryReAttach();
else
PGSharedMemoryNoReAttach();
/* autovacuum needs this set before calling InitProcess */
if (strcmp(argv[1], "--forkavlauncher") == 0)
AutovacuumLauncherIAm();
if (strcmp(argv[1], "--forkavworker") == 0)
AutovacuumWorkerIAm();
/* Read in remaining GUC variables */
read_nondefault_variables();
/*
* Check that the data directory looks valid, which will also check the
* privileges on the data directory and update our umask and file/group
* variables for creating files later. Note: this should really be done
* before we create any files or directories.
*/
checkDataDir();
/*
* (re-)read control file, as it contains config. The postmaster will
* already have read this, but this process doesn't know about that.
*/
LocalProcessControlFile(false);
/*
* Reload any libraries that were preloaded by the postmaster. Since we
* exec'd this process, those libraries didn't come along with us; but we
* should load them into all child processes to be consistent with the
* non-EXEC_BACKEND behavior.
*/
process_shared_preload_libraries();
/* Run backend or appropriate child */
if (strcmp(argv[1], "--forkbackend") == 0)
{
Assert(argc == 3); /* shouldn't be any more args */
/*
* Need to reinitialize the SSL library in the backend, since the
* context structures contain function pointers and cannot be passed
* through the parameter file.
*
* If for some reason reload fails (maybe the user installed broken
* key files), soldier on without SSL; that's better than all
* connections becoming impossible.
*
* XXX should we do this in all child processes? For the moment it's
* enough to do it in backend children.
*/
#ifdef USE_SSL
if (EnableSSL)
{
if (secure_initialize(false) == 0)
LoadedSSL = true;
else
ereport(LOG,
(errmsg("SSL configuration could not be loaded in child process")));
}
#endif
/*
* Perform additional initialization and collect startup packet.
*
* We want to do this before InitProcess() for a couple of reasons: 1.
* so that we aren't eating up a PGPROC slot while waiting on the
* client. 2. so that if InitProcess() fails due to being out of
* PGPROC slots, we have already initialized libpq and are able to
* report the error to the client.
*/
BackendInitialize(&port);
/* Restore basic shared memory pointers */
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
InitProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores();
/* And run the backend */
BackendRun(&port); /* does not return */
}
if (strcmp(argv[1], "--forkaux") == 0)
{
AuxProcType auxtype;
Assert(argc == 4);
/* Restore basic shared memory pointers */
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
InitAuxiliaryProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores();
auxtype = atoi(argv[3]);
AuxiliaryProcessMain(auxtype); /* does not return */
}
if (strcmp(argv[1], "--forkavlauncher") == 0)
{
/* Restore basic shared memory pointers */
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
InitProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores();
AutoVacLauncherMain(argc - 2, argv + 2); /* does not return */
}
if (strcmp(argv[1], "--forkavworker") == 0)
{
/* Restore basic shared memory pointers */
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
InitProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores();
AutoVacWorkerMain(argc - 2, argv + 2); /* does not return */
}
if (strncmp(argv[1], "--forkbgworker=", 15) == 0)
{
int shmem_slot;
/* do this as early as possible; in particular, before InitProcess() */
IsBackgroundWorker = true;
/* Restore basic shared memory pointers */
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
InitProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores();
/* Fetch MyBgworkerEntry from shared memory */
shmem_slot = atoi(argv[1] + 15);
MyBgworkerEntry = BackgroundWorkerEntry(shmem_slot);
StartBackgroundWorker();
}
if (strcmp(argv[1], "--forklog") == 0)
{
/* Do not want to attach to shared memory */
SysLoggerMain(argc, argv); /* does not return */
}
abort(); /* shouldn't get here */
}
#endif /* EXEC_BACKEND */
/*
* ExitPostmaster -- cleanup
*
* Do NOT call exit() directly --- always go through here!
*/
static void
ExitPostmaster(int status)
{
#ifdef HAVE_PTHREAD_IS_THREADED_NP
/*
* There is no known cause for a postmaster to become multithreaded after
* startup. Recheck to account for the possibility of unknown causes.
* This message uses LOG level, because an unclean shutdown at this point
* would usually not look much different from a clean shutdown.
*/
if (pthread_is_threaded_np() != 0)
ereport(LOG,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg_internal("postmaster became multithreaded"),
errdetail("Please report this to <%s>.", PACKAGE_BUGREPORT)));
#endif
/* should cleanup shared memory and kill all backends */
/*
* Not sure of the semantics here. When the Postmaster dies, should the
* backends all be killed? probably not.
*
* MUST -- vadim 05-10-1999
*/
proc_exit(status);
}
/*
* sigusr1_handler - handle signal conditions from child processes
*/
static void
sigusr1_handler(SIGNAL_ARGS)
{
int save_errno = errno;
/*
* RECOVERY_STARTED and BEGIN_HOT_STANDBY signals are ignored in
* unexpected states. If the startup process quickly starts up, completes
* recovery, exits, we might process the death of the startup process
* first. We don't want to go back to recovery in that case.
*/
if (CheckPostmasterSignal(PMSIGNAL_RECOVERY_STARTED) &&
pmState == PM_STARTUP && Shutdown == NoShutdown)
{
/* WAL redo has started. We're out of reinitialization. */
FatalError = false;
AbortStartTime = 0;
/*
* Start the archiver if we're responsible for (re-)archiving received
* files.
*/
Assert(PgArchPID == 0);
if (XLogArchivingAlways())
PgArchPID = StartArchiver();
/*
* If we aren't planning to enter hot standby mode later, treat
* RECOVERY_STARTED as meaning we're out of startup, and report status
* accordingly.
*/
if (!EnableHotStandby)
{
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STANDBY);
#ifdef USE_SYSTEMD
sd_notify(0, "READY=1");
#endif
}
pmState = PM_RECOVERY;
}
if (CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) &&
pmState == PM_RECOVERY && Shutdown == NoShutdown)
{
ereport(LOG,
(errmsg("database system is ready to accept read-only connections")));
/* Report status */
AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY);
#ifdef USE_SYSTEMD
sd_notify(0, "READY=1");
#endif
pmState = PM_HOT_STANDBY;
connsAllowed = true;
/* Some workers may be scheduled to start now */
StartWorkerNeeded = true;
}
/* Process background worker state changes. */
if (CheckPostmasterSignal(PMSIGNAL_BACKGROUND_WORKER_CHANGE))
{
/* Accept new worker requests only if not stopping. */
BackgroundWorkerStateChange(pmState < PM_STOP_BACKENDS);
StartWorkerNeeded = true;
}
if (StartWorkerNeeded || HaveCrashedWorker)
maybe_start_bgworkers();
/* Tell syslogger to rotate logfile if requested */
if (SysLoggerPID != 0)
{
if (CheckLogrotateSignal())
{
signal_child(SysLoggerPID, SIGUSR1);
RemoveLogrotateSignalFiles();
}
else if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE))
{
signal_child(SysLoggerPID, SIGUSR1);
}
}
if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER) &&
Shutdown <= SmartShutdown && pmState < PM_STOP_BACKENDS)
{
/*
* Start one iteration of the autovacuum daemon, even if autovacuuming
* is nominally not enabled. This is so we can have an active defense
* against transaction ID wraparound. We set a flag for the main loop
* to do it rather than trying to do it here --- this is because the
* autovac process itself may send the signal, and we want to handle
* that by launching another iteration as soon as the current one
* completes.
*/
start_autovac_launcher = true;
}
if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER) &&
Shutdown <= SmartShutdown && pmState < PM_STOP_BACKENDS)
{
/* The autovacuum launcher wants us to start a worker process. */
StartAutovacuumWorker();
}
if (CheckPostmasterSignal(PMSIGNAL_START_WALRECEIVER))
{
/* Startup Process wants us to start the walreceiver process. */
/* Start immediately if possible, else remember request for later. */
WalReceiverRequested = true;
MaybeStartWalReceiver();
}
/*
* Try to advance postmaster's state machine, if a child requests it.
*
* Be careful about the order of this action relative to sigusr1_handler's
* other actions. Generally, this should be after other actions, in case
* they have effects PostmasterStateMachine would need to know about.
* However, we should do it before the CheckPromoteSignal step, which
* cannot have any (immediate) effect on the state machine, but does
* depend on what state we're in now.
*/
if (CheckPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE))
{
PostmasterStateMachine();
}
if (StartupPID != 0 &&
(pmState == PM_STARTUP || pmState == PM_RECOVERY ||
pmState == PM_HOT_STANDBY) &&
CheckPromoteSignal())
{
/*
* Tell startup process to finish recovery.
*
* Leave the promote signal file in place and let the Startup process
* do the unlink.
*/
signal_child(StartupPID, SIGUSR2);
}
errno = save_errno;
}
/*
* SIGTERM while processing startup packet.
*
* Running proc_exit() from a signal handler would be quite unsafe.
* However, since we have not yet touched shared memory, we can just
* pull the plug and exit without running any atexit handlers.
*
* One might be tempted to try to send a message, or log one, indicating
* why we are disconnecting. However, that would be quite unsafe in itself.
* Also, it seems undesirable to provide clues about the database's state
* to a client that has not yet completed authentication, or even sent us
* a startup packet.
*/
static void
process_startup_packet_die(SIGNAL_ARGS)
{
_exit(1);
}
/*
* Dummy signal handler
*
* We use this for signals that we don't actually use in the postmaster,
* but we do use in backends. If we were to SIG_IGN such signals in the
* postmaster, then a newly started backend might drop a signal that arrives
* before it's able to reconfigure its signal processing. (See notes in
* tcop/postgres.c.)
*/
static void
dummy_handler(SIGNAL_ARGS)
{
}
/*
* Timeout while processing startup packet.
* As for process_startup_packet_die(), we exit via _exit(1).
*/
static void
StartupPacketTimeoutHandler(void)
{
_exit(1);
}
/*
* Generate a random cancel key.
*/
static bool
RandomCancelKey(int32 *cancel_key)
{
return pg_strong_random(cancel_key, sizeof(int32));
}
/*
* Count up number of child processes of specified types (dead_end children
* are always excluded).
*/
static int
CountChildren(int target)
{
dlist_iter iter;
int cnt = 0;
dlist_foreach(iter, &BackendList)
{
Backend *bp = dlist_container(Backend, elem, iter.cur);
if (bp->dead_end)
continue;
/*
* Since target == BACKEND_TYPE_ALL is the most common case, we test
* it first and avoid touching shared memory for every child.
*/
if (target != BACKEND_TYPE_ALL)
{
/*
* Assign bkend_type for any recently announced WAL Sender
* processes.
*/
if (bp->bkend_type == BACKEND_TYPE_NORMAL &&
IsPostmasterChildWalSender(bp->child_slot))
bp->bkend_type = BACKEND_TYPE_WALSND;
if (!(target & bp->bkend_type))
continue;
}
cnt++;
}
return cnt;
}
/*
* StartChildProcess -- start an auxiliary process for the postmaster
*
* "type" determines what kind of child will be started. All child types
* initially go to AuxiliaryProcessMain, which will handle common setup.
*
* Return value of StartChildProcess is subprocess' PID, or 0 if failed
* to start subprocess.
*/
static pid_t
StartChildProcess(AuxProcType type)
{
pid_t pid;
#ifdef EXEC_BACKEND
{
char *av[10];
int ac = 0;
char typebuf[32];
/*
* Set up command-line arguments for subprocess
*/
av[ac++] = "postgres";
av[ac++] = "--forkaux";
av[ac++] = NULL; /* filled in by postmaster_forkexec */
snprintf(typebuf, sizeof(typebuf), "%d", type);
av[ac++] = typebuf;
av[ac] = NULL;
Assert(ac < lengthof(av));
pid = postmaster_forkexec(ac, av);
}
#else /* !EXEC_BACKEND */
pid = fork_process();
if (pid == 0) /* child */
{
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/* Release postmaster's working memory context */
MemoryContextSwitchTo(TopMemoryContext);
MemoryContextDelete(PostmasterContext);
PostmasterContext = NULL;
AuxiliaryProcessMain(type); /* does not return */
}
#endif /* EXEC_BACKEND */
if (pid < 0)
{
/* in parent, fork failed */
int save_errno = errno;
errno = save_errno;
switch (type)
{
case StartupProcess:
ereport(LOG,
(errmsg("could not fork startup process: %m")));
break;
case ArchiverProcess:
ereport(LOG,
(errmsg("could not fork archiver process: %m")));
break;
case BgWriterProcess:
ereport(LOG,
(errmsg("could not fork background writer process: %m")));
break;
case CheckpointerProcess:
ereport(LOG,
(errmsg("could not fork checkpointer process: %m")));
break;
case WalWriterProcess:
ereport(LOG,
(errmsg("could not fork WAL writer process: %m")));
break;
case WalReceiverProcess:
ereport(LOG,
(errmsg("could not fork WAL receiver process: %m")));
break;
default:
ereport(LOG,
(errmsg("could not fork process: %m")));
break;
}
/*
* fork failure is fatal during startup, but there's no need to choke
* immediately if starting other child types fails.
*/
if (type == StartupProcess)
ExitPostmaster(1);
return 0;
}
/*
* in parent, successful fork
*/
return pid;
}
/*
* StartAutovacuumWorker
* Start an autovac worker process.
*
* This function is here because it enters the resulting PID into the
* postmaster's private backends list.
*
* NB -- this code very roughly matches BackendStartup.
*/
static void
StartAutovacuumWorker(void)
{
Backend *bn;
/*
* If not in condition to run a process, don't try, but handle it like a
* fork failure. This does not normally happen, since the signal is only
* supposed to be sent by autovacuum launcher when it's OK to do it, but
* we have to check to avoid race-condition problems during DB state
* changes.
*/
if (canAcceptConnections(BACKEND_TYPE_AUTOVAC) == CAC_OK)
{
/*
* Compute the cancel key that will be assigned to this session. We
* probably don't need cancel keys for autovac workers, but we'd
* better have something random in the field to prevent unfriendly
* people from sending cancels to them.
*/
if (!RandomCancelKey(&MyCancelKey))
{
ereport(LOG,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("could not generate random cancel key")));
return;
}
bn = (Backend *) malloc(sizeof(Backend));
if (bn)
{
bn->cancel_key = MyCancelKey;
/* Autovac workers are not dead_end and need a child slot */
bn->dead_end = false;
bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
bn->bgworker_notify = false;
bn->pid = StartAutoVacWorker();
if (bn->pid > 0)
{
bn->bkend_type = BACKEND_TYPE_AUTOVAC;
dlist_push_head(&BackendList, &bn->elem);
#ifdef EXEC_BACKEND
ShmemBackendArrayAdd(bn);
#endif
/* all OK */
return;
}
/*
* fork failed, fall through to report -- actual error message was
* logged by StartAutoVacWorker
*/
(void) ReleasePostmasterChildSlot(bn->child_slot);
free(bn);
}
else
ereport(LOG,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
}
/*
* Report the failure to the launcher, if it's running. (If it's not, we
* might not even be connected to shared memory, so don't try to call
* AutoVacWorkerFailed.) Note that we also need to signal it so that it
* responds to the condition, but we don't do that here, instead waiting
* for ServerLoop to do it. This way we avoid a ping-pong signaling in
* quick succession between the autovac launcher and postmaster in case
* things get ugly.
*/
if (AutoVacPID != 0)
{
AutoVacWorkerFailed();
avlauncher_needs_signal = true;
}
}
/*
* MaybeStartWalReceiver
* Start the WAL receiver process, if not running and our state allows.
*
* Note: if WalReceiverPID is already nonzero, it might seem that we should
* clear WalReceiverRequested. However, there's a race condition if the
* walreceiver terminates and the startup process immediately requests a new
* one: it's quite possible to get the signal for the request before reaping
* the dead walreceiver process. Better to risk launching an extra
* walreceiver than to miss launching one we need. (The walreceiver code
* has logic to recognize that it should go away if not needed.)
*/
static void
MaybeStartWalReceiver(void)
{
if (WalReceiverPID == 0 &&
(pmState == PM_STARTUP || pmState == PM_RECOVERY ||
pmState == PM_HOT_STANDBY) &&
Shutdown <= SmartShutdown)
{
WalReceiverPID = StartWalReceiver();
if (WalReceiverPID != 0)
WalReceiverRequested = false;
/* else leave the flag set, so we'll try again later */
}
}
/*
* Create the opts file
*/
static bool
CreateOptsFile(int argc, char *argv[], char *fullprogname)
{
FILE *fp;
int i;
#define OPTS_FILE "postmaster.opts"
if ((fp = fopen(OPTS_FILE, "w")) == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m", OPTS_FILE)));
return false;
}
fprintf(fp, "%s", fullprogname);
for (i = 1; i < argc; i++)
fprintf(fp, " \"%s\"", argv[i]);
fputs("\n", fp);
if (fclose(fp))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write file \"%s\": %m", OPTS_FILE)));
return false;
}
return true;
}
/*
* MaxLivePostmasterChildren
*
* This reports the number of entries needed in per-child-process arrays
* (the PMChildFlags array, and if EXEC_BACKEND the ShmemBackendArray).
* These arrays include regular backends, autovac workers, walsenders
* and background workers, but not special children nor dead_end children.
* This allows the arrays to have a fixed maximum size, to wit the same
* too-many-children limit enforced by canAcceptConnections(). The exact value
* isn't too critical as long as it's more than MaxBackends.
*/
int
MaxLivePostmasterChildren(void)
{
return 2 * (MaxConnections + autovacuum_max_workers + 1 +
max_wal_senders + max_worker_processes);
}
/*
* Connect background worker to a database.
*/
void
BackgroundWorkerInitializeConnection(const char *dbname, const char *username, uint32 flags)
{
BackgroundWorker *worker = MyBgworkerEntry;
/* XXX is this the right errcode? */
if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION))
ereport(FATAL,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("database connection requirement not indicated during registration")));
InitPostgres(dbname, InvalidOid, /* database to connect to */
username, InvalidOid, /* role to connect as */
false, /* never honor session_preload_libraries */
(flags & BGWORKER_BYPASS_ALLOWCONN) != 0, /* ignore datallowconn? */
NULL); /* no out_dbname */
/* it had better not gotten out of "init" mode yet */
if (!IsInitProcessingMode())
ereport(ERROR,
(errmsg("invalid processing mode in background worker")));
SetProcessingMode(NormalProcessing);
}
/*
* Connect background worker to a database using OIDs.
*/
void
BackgroundWorkerInitializeConnectionByOid(Oid dboid, Oid useroid, uint32 flags)
{
BackgroundWorker *worker = MyBgworkerEntry;
/* XXX is this the right errcode? */
if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION))
ereport(FATAL,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("database connection requirement not indicated during registration")));
InitPostgres(NULL, dboid, /* database to connect to */
NULL, useroid, /* role to connect as */
false, /* never honor session_preload_libraries */
(flags & BGWORKER_BYPASS_ALLOWCONN) != 0, /* ignore datallowconn? */
NULL); /* no out_dbname */
/* it had better not gotten out of "init" mode yet */
if (!IsInitProcessingMode())
ereport(ERROR,
(errmsg("invalid processing mode in background worker")));
SetProcessingMode(NormalProcessing);
}
/*
* Block/unblock signals in a background worker
*/
void
BackgroundWorkerBlockSignals(void)
{
PG_SETMASK(&BlockSig);
}
void
BackgroundWorkerUnblockSignals(void)
{
PG_SETMASK(&UnBlockSig);
}
#ifdef EXEC_BACKEND
static pid_t
bgworker_forkexec(int shmem_slot)
{
char *av[10];
int ac = 0;
char forkav[MAXPGPATH];
snprintf(forkav, MAXPGPATH, "--forkbgworker=%d", shmem_slot);
av[ac++] = "postgres";
av[ac++] = forkav;
av[ac++] = NULL; /* filled in by postmaster_forkexec */
av[ac] = NULL;
Assert(ac < lengthof(av));
return postmaster_forkexec(ac, av);
}
#endif
/*
* Start a new bgworker.
* Starting time conditions must have been checked already.
*
* Returns true on success, false on failure.
* In either case, update the RegisteredBgWorker's state appropriately.
*
* This code is heavily based on autovacuum.c, q.v.
*/
static bool
do_start_bgworker(RegisteredBgWorker *rw)
{
pid_t worker_pid;
Assert(rw->rw_pid == 0);
/*
* Allocate and assign the Backend element. Note we must do this before
* forking, so that we can handle failures (out of memory or child-process
* slots) cleanly.
*
* Treat failure as though the worker had crashed. That way, the
* postmaster will wait a bit before attempting to start it again; if we
* tried again right away, most likely we'd find ourselves hitting the
* same resource-exhaustion condition.
*/
if (!assign_backendlist_entry(rw))
{
rw->rw_crashed_at = GetCurrentTimestamp();
return false;
}
ereport(DEBUG1,
(errmsg_internal("starting background worker process \"%s\"",
rw->rw_worker.bgw_name)));
#ifdef EXEC_BACKEND
switch ((worker_pid = bgworker_forkexec(rw->rw_shmem_slot)))
#else
switch ((worker_pid = fork_process()))
#endif
{
case -1:
/* in postmaster, fork failed ... */
ereport(LOG,
(errmsg("could not fork worker process: %m")));
/* undo what assign_backendlist_entry did */
ReleasePostmasterChildSlot(rw->rw_child_slot);
rw->rw_child_slot = 0;
free(rw->rw_backend);
rw->rw_backend = NULL;
/* mark entry as crashed, so we'll try again later */
rw->rw_crashed_at = GetCurrentTimestamp();
break;
#ifndef EXEC_BACKEND
case 0:
/* in postmaster child ... */
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/*
* Before blowing away PostmasterContext, save this bgworker's
* data where it can find it.
*/
MyBgworkerEntry = (BackgroundWorker *)
MemoryContextAlloc(TopMemoryContext, sizeof(BackgroundWorker));
memcpy(MyBgworkerEntry, &rw->rw_worker, sizeof(BackgroundWorker));
/* Release postmaster's working memory context */
MemoryContextSwitchTo(TopMemoryContext);
MemoryContextDelete(PostmasterContext);
PostmasterContext = NULL;
StartBackgroundWorker();
exit(1); /* should not get here */
break;
#endif
default:
/* in postmaster, fork successful ... */
rw->rw_pid = worker_pid;
rw->rw_backend->pid = rw->rw_pid;
ReportBackgroundWorkerPID(rw);
/* add new worker to lists of backends */
dlist_push_head(&BackendList, &rw->rw_backend->elem);
#ifdef EXEC_BACKEND
ShmemBackendArrayAdd(rw->rw_backend);
#endif
return true;
}
return false;
}
/*
* Does the current postmaster state require starting a worker with the
* specified start_time?
*/
static bool
bgworker_should_start_now(BgWorkerStartTime start_time)
{
switch (pmState)
{
case PM_NO_CHILDREN:
case PM_WAIT_DEAD_END:
case PM_SHUTDOWN_2:
case PM_SHUTDOWN:
case PM_WAIT_BACKENDS:
case PM_STOP_BACKENDS:
break;
case PM_RUN:
if (start_time == BgWorkerStart_RecoveryFinished)
return true;
/* fall through */
case PM_HOT_STANDBY:
if (start_time == BgWorkerStart_ConsistentState)
return true;
/* fall through */
case PM_RECOVERY:
case PM_STARTUP:
case PM_INIT:
if (start_time == BgWorkerStart_PostmasterStart)
return true;
/* fall through */
}
return false;
}
/*
* Allocate the Backend struct for a connected background worker, but don't
* add it to the list of backends just yet.
*
* On failure, return false without changing any worker state.
*
* Some info from the Backend is copied into the passed rw.
*/
static bool
assign_backendlist_entry(RegisteredBgWorker *rw)
{
Backend *bn;
/*
* Check that database state allows another connection. Currently the
* only possible failure is CAC_TOOMANY, so we just log an error message
* based on that rather than checking the error code precisely.
*/
if (canAcceptConnections(BACKEND_TYPE_BGWORKER) != CAC_OK)
{
ereport(LOG,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("no slot available for new worker process")));
return false;
}
/*
* Compute the cancel key that will be assigned to this session. We
* probably don't need cancel keys for background workers, but we'd better
* have something random in the field to prevent unfriendly people from
* sending cancels to them.
*/
if (!RandomCancelKey(&MyCancelKey))
{
ereport(LOG,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("could not generate random cancel key")));
return false;
}
bn = malloc(sizeof(Backend));
if (bn == NULL)
{
ereport(LOG,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
return false;
}
bn->cancel_key = MyCancelKey;
bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
bn->bkend_type = BACKEND_TYPE_BGWORKER;
bn->dead_end = false;
bn->bgworker_notify = false;
rw->rw_backend = bn;
rw->rw_child_slot = bn->child_slot;
return true;
}
/*
* If the time is right, start background worker(s).
*
* As a side effect, the bgworker control variables are set or reset
* depending on whether more workers may need to be started.
*
* We limit the number of workers started per call, to avoid consuming the
* postmaster's attention for too long when many such requests are pending.
* As long as StartWorkerNeeded is true, ServerLoop will not block and will
* call this function again after dealing with any other issues.
*/
static void
maybe_start_bgworkers(void)
{
#define MAX_BGWORKERS_TO_LAUNCH 100
int num_launched = 0;
TimestampTz now = 0;
slist_mutable_iter iter;
/*
* During crash recovery, we have no need to be called until the state
* transition out of recovery.
*/
if (FatalError)
{
StartWorkerNeeded = false;
HaveCrashedWorker = false;
return;
}
/* Don't need to be called again unless we find a reason for it below */
StartWorkerNeeded = false;
HaveCrashedWorker = false;
slist_foreach_modify(iter, &BackgroundWorkerList)
{
RegisteredBgWorker *rw;
rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
/* ignore if already running */
if (rw->rw_pid != 0)
continue;
/* if marked for death, clean up and remove from list */
if (rw->rw_terminate)
{
ForgetBackgroundWorker(&iter);
continue;
}
/*
* If this worker has crashed previously, maybe it needs to be
* restarted (unless on registration it specified it doesn't want to
* be restarted at all). Check how long ago did a crash last happen.
* If the last crash is too recent, don't start it right away; let it
* be restarted once enough time has passed.
*/
if (rw->rw_crashed_at != 0)
{
if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART)
{
int notify_pid;
notify_pid = rw->rw_worker.bgw_notify_pid;
ForgetBackgroundWorker(&iter);
/* Report worker is gone now. */
if (notify_pid != 0)
kill(notify_pid, SIGUSR1);
continue;
}
/* read system time only when needed */
if (now == 0)
now = GetCurrentTimestamp();
if (!TimestampDifferenceExceeds(rw->rw_crashed_at, now,
rw->rw_worker.bgw_restart_time * 1000))
{
/* Set flag to remember that we have workers to start later */
HaveCrashedWorker = true;
continue;
}
}
if (bgworker_should_start_now(rw->rw_worker.bgw_start_time))
{
/* reset crash time before trying to start worker */
rw->rw_crashed_at = 0;
/*
* Try to start the worker.
*
* On failure, give up processing workers for now, but set
* StartWorkerNeeded so we'll come back here on the next iteration
* of ServerLoop to try again. (We don't want to wait, because
* there might be additional ready-to-run workers.) We could set
* HaveCrashedWorker as well, since this worker is now marked
* crashed, but there's no need because the next run of this
* function will do that.
*/
if (!do_start_bgworker(rw))
{
StartWorkerNeeded = true;
return;
}
/*
* If we've launched as many workers as allowed, quit, but have
* ServerLoop call us again to look for additional ready-to-run
* workers. There might not be any, but we'll find out the next
* time we run.
*/
if (++num_launched >= MAX_BGWORKERS_TO_LAUNCH)
{
StartWorkerNeeded = true;
return;
}
}
}
}
/*
* When a backend asks to be notified about worker state changes, we
* set a flag in its backend entry. The background worker machinery needs
* to know when such backends exit.
*/
bool
PostmasterMarkPIDForWorkerNotify(int pid)
{
dlist_iter iter;
Backend *bp;
dlist_foreach(iter, &BackendList)
{
bp = dlist_container(Backend, elem, iter.cur);
if (bp->pid == pid)
{
bp->bgworker_notify = true;
return true;
}
}
return false;
}
#ifdef EXEC_BACKEND
/*
* The following need to be available to the save/restore_backend_variables
* functions. They are marked NON_EXEC_STATIC in their home modules.
*/
extern slock_t *ShmemLock;
extern slock_t *ProcStructLock;
extern PGPROC *AuxiliaryProcs;
extern PMSignalData *PMSignalState;
extern pg_time_t first_syslogger_file_time;
#ifndef WIN32
#define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true)
#define read_inheritable_socket(dest, src) (*(dest) = *(src))
#else
static bool write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE child);
static bool write_inheritable_socket(InheritableSocket *dest, SOCKET src,
pid_t childPid);
static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src);
#endif
/* Save critical backend variables into the BackendParameters struct */
#ifndef WIN32
static bool
save_backend_variables(BackendParameters *param, Port *port)
#else
static bool
save_backend_variables(BackendParameters *param, Port *port,
HANDLE childProcess, pid_t childPid)
#endif
{
memcpy(&param->port, port, sizeof(Port));
if (!write_inheritable_socket(&param->portsocket, port->sock, childPid))
return false;
strlcpy(param->DataDir, DataDir, MAXPGPATH);
memcpy(&param->ListenSocket, &ListenSocket, sizeof(ListenSocket));
param->MyCancelKey = MyCancelKey;
param->MyPMChildSlot = MyPMChildSlot;
#ifdef WIN32
param->ShmemProtectiveRegion = ShmemProtectiveRegion;
#endif
param->UsedShmemSegID = UsedShmemSegID;
param->UsedShmemSegAddr = UsedShmemSegAddr;
param->ShmemLock = ShmemLock;
param->ShmemVariableCache = ShmemVariableCache;
param->ShmemBackendArray = ShmemBackendArray;
#ifndef HAVE_SPINLOCKS
param->SpinlockSemaArray = SpinlockSemaArray;
#endif
param->NamedLWLockTrancheRequests = NamedLWLockTrancheRequests;
param->NamedLWLockTrancheArray = NamedLWLockTrancheArray;
param->MainLWLockArray = MainLWLockArray;
param->ProcStructLock = ProcStructLock;
param->ProcGlobal = ProcGlobal;
param->AuxiliaryProcs = AuxiliaryProcs;
param->PreparedXactProcs = PreparedXactProcs;
param->PMSignalState = PMSignalState;
param->PostmasterPid = PostmasterPid;
param->PgStartTime = PgStartTime;
param->PgReloadTime = PgReloadTime;
param->first_syslogger_file_time = first_syslogger_file_time;
param->redirection_done = redirection_done;
param->IsBinaryUpgrade = IsBinaryUpgrade;
param->query_id_enabled = query_id_enabled;
param->max_safe_fds = max_safe_fds;
param->MaxBackends = MaxBackends;
#ifdef WIN32
param->PostmasterHandle = PostmasterHandle;
if (!write_duplicated_handle(&param->initial_signal_pipe,
pgwin32_create_signal_listener(childPid),
childProcess))
return false;
#else
memcpy(&param->postmaster_alive_fds, &postmaster_alive_fds,
sizeof(postmaster_alive_fds));
#endif
memcpy(&param->syslogPipe, &syslogPipe, sizeof(syslogPipe));
strlcpy(param->my_exec_path, my_exec_path, MAXPGPATH);
strlcpy(param->pkglib_path, pkglib_path, MAXPGPATH);
return true;
}
#ifdef WIN32
/*
* Duplicate a handle for usage in a child process, and write the child
* process instance of the handle to the parameter file.
*/
static bool
write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE childProcess)
{
HANDLE hChild = INVALID_HANDLE_VALUE;
if (!DuplicateHandle(GetCurrentProcess(),
src,
childProcess,
&hChild,
0,
TRUE,
DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS))
{
ereport(LOG,
(errmsg_internal("could not duplicate handle to be written to backend parameter file: error code %lu",
GetLastError())));
return false;
}
*dest = hChild;
return true;
}
/*
* Duplicate a socket for usage in a child process, and write the resulting
* structure to the parameter file.
* This is required because a number of LSPs (Layered Service Providers) very
* common on Windows (antivirus, firewalls, download managers etc) break
* straight socket inheritance.
*/
static bool
write_inheritable_socket(InheritableSocket *dest, SOCKET src, pid_t childpid)
{
dest->origsocket = src;
if (src != 0 && src != PGINVALID_SOCKET)
{
/* Actual socket */
if (WSADuplicateSocket(src, childpid, &dest->wsainfo) != 0)
{
ereport(LOG,
(errmsg("could not duplicate socket %d for use in backend: error code %d",
(int) src, WSAGetLastError())));
return false;
}
}
return true;
}
/*
* Read a duplicate socket structure back, and get the socket descriptor.
*/
static void
read_inheritable_socket(SOCKET *dest, InheritableSocket *src)
{
SOCKET s;
if (src->origsocket == PGINVALID_SOCKET || src->origsocket == 0)
{
/* Not a real socket! */
*dest = src->origsocket;
}
else
{
/* Actual socket, so create from structure */
s = WSASocket(FROM_PROTOCOL_INFO,
FROM_PROTOCOL_INFO,
FROM_PROTOCOL_INFO,
&src->wsainfo,
0,
0);
if (s == INVALID_SOCKET)
{
write_stderr("could not create inherited socket: error code %d\n",
WSAGetLastError());
exit(1);
}
*dest = s;
/*
* To make sure we don't get two references to the same socket, close
* the original one. (This would happen when inheritance actually
* works..
*/
closesocket(src->origsocket);
}
}
#endif
static void
read_backend_variables(char *id, Port *port)
{
BackendParameters param;
#ifndef WIN32
/* Non-win32 implementation reads from file */
FILE *fp;
/* Open file */
fp = AllocateFile(id, PG_BINARY_R);
if (!fp)
{
write_stderr("could not open backend variables file \"%s\": %s\n",
id, strerror(errno));
exit(1);
}
if (fread(&param, sizeof(param), 1, fp) != 1)
{
write_stderr("could not read from backend variables file \"%s\": %s\n",
id, strerror(errno));
exit(1);
}
/* Release file */
FreeFile(fp);
if (unlink(id) != 0)
{
write_stderr("could not remove file \"%s\": %s\n",
id, strerror(errno));
exit(1);
}
#else
/* Win32 version uses mapped file */
HANDLE paramHandle;
BackendParameters *paramp;
#ifdef _WIN64
paramHandle = (HANDLE) _atoi64(id);
#else
paramHandle = (HANDLE) atol(id);
#endif
paramp = MapViewOfFile(paramHandle, FILE_MAP_READ, 0, 0, 0);
if (!paramp)
{
write_stderr("could not map view of backend variables: error code %lu\n",
GetLastError());
exit(1);
}
memcpy(&param, paramp, sizeof(BackendParameters));
if (!UnmapViewOfFile(paramp))
{
write_stderr("could not unmap view of backend variables: error code %lu\n",
GetLastError());
exit(1);
}
if (!CloseHandle(paramHandle))
{
write_stderr("could not close handle to backend parameter variables: error code %lu\n",
GetLastError());
exit(1);
}
#endif
restore_backend_variables(&param, port);
}
/* Restore critical backend variables from the BackendParameters struct */
static void
restore_backend_variables(BackendParameters *param, Port *port)
{
memcpy(port, &param->port, sizeof(Port));
read_inheritable_socket(&port->sock, &param->portsocket);
SetDataDir(param->DataDir);
memcpy(&ListenSocket, &param->ListenSocket, sizeof(ListenSocket));
MyCancelKey = param->MyCancelKey;
MyPMChildSlot = param->MyPMChildSlot;
#ifdef WIN32
ShmemProtectiveRegion = param->ShmemProtectiveRegion;
#endif
UsedShmemSegID = param->UsedShmemSegID;
UsedShmemSegAddr = param->UsedShmemSegAddr;
ShmemLock = param->ShmemLock;
ShmemVariableCache = param->ShmemVariableCache;
ShmemBackendArray = param->ShmemBackendArray;
#ifndef HAVE_SPINLOCKS
SpinlockSemaArray = param->SpinlockSemaArray;
#endif
NamedLWLockTrancheRequests = param->NamedLWLockTrancheRequests;
NamedLWLockTrancheArray = param->NamedLWLockTrancheArray;
MainLWLockArray = param->MainLWLockArray;
ProcStructLock = param->ProcStructLock;
ProcGlobal = param->ProcGlobal;
AuxiliaryProcs = param->AuxiliaryProcs;
PreparedXactProcs = param->PreparedXactProcs;
PMSignalState = param->PMSignalState;
PostmasterPid = param->PostmasterPid;
PgStartTime = param->PgStartTime;
PgReloadTime = param->PgReloadTime;
first_syslogger_file_time = param->first_syslogger_file_time;
redirection_done = param->redirection_done;
IsBinaryUpgrade = param->IsBinaryUpgrade;
query_id_enabled = param->query_id_enabled;
max_safe_fds = param->max_safe_fds;
MaxBackends = param->MaxBackends;
#ifdef WIN32
PostmasterHandle = param->PostmasterHandle;
pgwin32_initial_signal_pipe = param->initial_signal_pipe;
#else
memcpy(&postmaster_alive_fds, &param->postmaster_alive_fds,
sizeof(postmaster_alive_fds));
#endif
memcpy(&syslogPipe, &param->syslogPipe, sizeof(syslogPipe));
strlcpy(my_exec_path, param->my_exec_path, MAXPGPATH);
strlcpy(pkglib_path, param->pkglib_path, MAXPGPATH);
/*
* We need to restore fd.c's counts of externally-opened FDs; to avoid
* confusion, be sure to do this after restoring max_safe_fds. (Note:
* BackendInitialize will handle this for port->sock.)
*/
#ifndef WIN32
if (postmaster_alive_fds[0] >= 0)
ReserveExternalFD();
if (postmaster_alive_fds[1] >= 0)
ReserveExternalFD();
#endif
}
Size
ShmemBackendArraySize(void)
{
return mul_size(MaxLivePostmasterChildren(), sizeof(Backend));
}
void
ShmemBackendArrayAllocation(void)
{
Size size = ShmemBackendArraySize();
ShmemBackendArray = (Backend *) ShmemAlloc(size);
/* Mark all slots as empty */
memset(ShmemBackendArray, 0, size);
}
static void
ShmemBackendArrayAdd(Backend *bn)
{
/* The array slot corresponding to my PMChildSlot should be free */
int i = bn->child_slot - 1;
Assert(ShmemBackendArray[i].pid == 0);
ShmemBackendArray[i] = *bn;
}
static void
ShmemBackendArrayRemove(Backend *bn)
{
int i = bn->child_slot - 1;
Assert(ShmemBackendArray[i].pid == bn->pid);
/* Mark the slot as empty */
ShmemBackendArray[i].pid = 0;
}
#endif /* EXEC_BACKEND */
#ifdef WIN32
/*
* Subset implementation of waitpid() for Windows. We assume pid is -1
* (that is, check all child processes) and options is WNOHANG (don't wait).
*/
static pid_t
waitpid(pid_t pid, int *exitstatus, int options)
{
DWORD dwd;
ULONG_PTR key;
OVERLAPPED *ovl;
/*
* Check if there are any dead children. If there are, return the pid of
* the first one that died.
*/
if (GetQueuedCompletionStatus(win32ChildQueue, &dwd, &key, &ovl, 0))
{
*exitstatus = (int) key;
return dwd;
}
return -1;
}
/*
* Note! Code below executes on a thread pool! All operations must
* be thread safe! Note that elog() and friends must *not* be used.
*/
static void WINAPI
pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
{
win32_deadchild_waitinfo *childinfo = (win32_deadchild_waitinfo *) lpParameter;
DWORD exitcode;
if (TimerOrWaitFired)
return; /* timeout. Should never happen, since we use
* INFINITE as timeout value. */
/*
* Remove handle from wait - required even though it's set to wait only
* once
*/
UnregisterWaitEx(childinfo->waitHandle, NULL);
if (!GetExitCodeProcess(childinfo->procHandle, &exitcode))
{
/*
* Should never happen. Inform user and set a fixed exitcode.
*/
write_stderr("could not read exit code for process\n");
exitcode = 255;
}
if (!PostQueuedCompletionStatus(win32ChildQueue, childinfo->procId, (ULONG_PTR) exitcode, NULL))
write_stderr("could not post child completion status\n");
/*
* Handle is per-process, so we close it here instead of in the
* originating thread
*/
CloseHandle(childinfo->procHandle);
/*
* Free struct that was allocated before the call to
* RegisterWaitForSingleObject()
*/
free(childinfo);
/* Queue SIGCHLD signal */
pg_queue_signal(SIGCHLD);
}
#endif /* WIN32 */
/*
* Initialize one and only handle for monitoring postmaster death.
*
* Called once in the postmaster, so that child processes can subsequently
* monitor if their parent is dead.
*/
static void
InitPostmasterDeathWatchHandle(void)
{
#ifndef WIN32
/*
* Create a pipe. Postmaster holds the write end of the pipe open
* (POSTMASTER_FD_OWN), and children hold the read end. Children can pass
* the read file descriptor to select() to wake up in case postmaster
* dies, or check for postmaster death with a (read() == 0). Children must
* close the write end as soon as possible after forking, because EOF
* won't be signaled in the read end until all processes have closed the
* write fd. That is taken care of in ClosePostmasterPorts().
*/
Assert(MyProcPid == PostmasterPid);
if (pipe(postmaster_alive_fds) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg_internal("could not create pipe to monitor postmaster death: %m")));
/* Notify fd.c that we've eaten two FDs for the pipe. */
ReserveExternalFD();
ReserveExternalFD();
/*
* Set O_NONBLOCK to allow testing for the fd's presence with a read()
* call.
*/
if (fcntl(postmaster_alive_fds[POSTMASTER_FD_WATCH], F_SETFL, O_NONBLOCK) == -1)
ereport(FATAL,
(errcode_for_socket_access(),
errmsg_internal("could not set postmaster death monitoring pipe to nonblocking mode: %m")));
#else
/*
* On Windows, we use a process handle for the same purpose.
*/
if (DuplicateHandle(GetCurrentProcess(),
GetCurrentProcess(),
GetCurrentProcess(),
&PostmasterHandle,
0,
TRUE,
DUPLICATE_SAME_ACCESS) == 0)
ereport(FATAL,
(errmsg_internal("could not duplicate postmaster handle: error code %lu",
GetLastError())));
#endif /* WIN32 */
}
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