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Restructure backend SIGINT/SIGTERM handling so that 'die' interrupts
are treated more like 'cancel' interrupts: the signal handler sets a flag that is examined at well-defined spots, rather than trying to cope with an interrupt that might happen anywhere. See pghackers discussion of 1/12/01.
This commit is contained in:
Tom Lane
@ -12,10 +12,10 @@
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: miscadmin.h,v 1.76 2001/01/07 04:17:28 tgl Exp $
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* $Id: miscadmin.h,v 1.77 2001/01/14 05:08:16 tgl Exp $
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*
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* NOTES
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* some of the information in this file will be moved to
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* some of the information in this file should be moved to
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* other files.
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*
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*-------------------------------------------------------------------------
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@ -23,11 +23,63 @@
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#ifndef MISCADMIN_H
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#define MISCADMIN_H
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#include <sys/types.h> /* For pid_t */
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#include "postgres.h"
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#include "storage/ipc.h"
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/*****************************************************************************
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* System interrupt handling
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*
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* There are two types of interrupts that a running backend needs to accept
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* without messing up its state: QueryCancel (SIGINT) and ProcDie (SIGTERM).
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* In both cases, we need to be able to clean up the current transaction
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* gracefully, so we can't respond to the interrupt instantaneously ---
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* there's no guarantee that internal data structures would be self-consistent
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* if the code is interrupted at an arbitrary instant. Instead, the signal
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* handlers set flags that are checked periodically during execution.
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*
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* The CHECK_FOR_INTERRUPTS() macro is called at strategically located spots
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* where it is normally safe to accept a cancel or die interrupt. In some
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* cases, we invoke CHECK_FOR_INTERRUPTS() inside low-level subroutines that
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* might sometimes be called in contexts that do *not* want to allow a cancel
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* or die interrupt. The CRIT_SECTION mechanism allows code to ensure that
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* no cancel or die interrupt will be accepted, even if CHECK_FOR_INTERRUPTS
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* gets called in a subroutine.
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*
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* Special mechanisms are used to let an interrupt be accepted when we are
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* waiting for a lock or spinlock, and when we are waiting for command input
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* (but, of course, only if the critical section counter is zero). See the
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* related code for details.
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*
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*****************************************************************************/
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/* in globals.c */
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/* these are marked volatile because they are set by signal handlers: */
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extern volatile bool InterruptPending;
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extern volatile bool QueryCancelPending;
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extern volatile bool ProcDiePending;
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/* these are marked volatile because they are examined by signal handlers: */
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extern volatile bool ImmediateInterruptOK;
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extern volatile uint32 CritSectionCount;
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/* in postgres.c */
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extern void ProcessInterrupts(void);
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#define CHECK_FOR_INTERRUPTS() \
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do { \
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if (InterruptPending) \
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ProcessInterrupts(); \
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} while(0)
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#define START_CRIT_SECTION() (CritSectionCount++)
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#define END_CRIT_SECTION() \
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do { \
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Assert(CritSectionCount > 0); \
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CritSectionCount--; \
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if (CritSectionCount == 0 && InterruptPending) \
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ProcessInterrupts(); \
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} while(0)
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/*****************************************************************************
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* globals.h -- *
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*****************************************************************************/
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@ -42,7 +94,6 @@ extern int PostmasterMain(int argc, char *argv[]);
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*/
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extern bool Noversion;
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extern bool Quiet;
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extern volatile bool QueryCancel;
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extern char *DataDir;
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extern int MyProcPid;
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@ -56,9 +107,7 @@ extern char OutputFileName[];
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*
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* extern BackendId MyBackendId;
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*/
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extern bool MyDatabaseIdIsInitialized;
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extern Oid MyDatabaseId;
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extern bool TransactionInitWasProcessed;
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extern bool IsUnderPostmaster;
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@ -143,7 +192,8 @@ extern void SetSessionUserIdFromUserName(const char *username);
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extern void SetDataDir(const char *dir);
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extern int FindExec(char *full_path, const char *argv0, const char *binary_name);
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extern int FindExec(char *full_path, const char *argv0,
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const char *binary_name);
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extern int CheckPathAccess(char *path, char *name, int open_mode);
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#ifdef CYR_RECODE
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@ -157,17 +207,17 @@ extern char *convertstr(unsigned char *buff, int len, int dest);
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/*
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* Description:
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* There are three processing modes in POSTGRES. They are
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* "BootstrapProcessing or "bootstrap," InitProcessing or
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* BootstrapProcessing or "bootstrap," InitProcessing or
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* "initialization," and NormalProcessing or "normal."
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*
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* The first two processing modes are used during special times. When the
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* system state indicates bootstrap processing, transactions are all given
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* transaction id "one" and are consequently guarenteed to commit. This mode
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* transaction id "one" and are consequently guaranteed to commit. This mode
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* is used during the initial generation of template databases.
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*
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* Initialization mode until all normal initialization is complete.
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* Some code behaves differently when executed in this mode to enable
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* system bootstrapping.
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* Initialization mode: used while starting a backend, until all normal
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* initialization is complete. Some code behaves differently when executed
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* in this mode to enable system bootstrapping.
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*
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* If a POSTGRES binary is in normal mode, then all code may be executed
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* normally.
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@ -185,27 +235,13 @@ typedef enum ProcessingMode
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* pinit.h -- *
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* POSTGRES initialization and cleanup definitions. *
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*****************************************************************************/
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/*
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* Note:
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* XXX AddExitHandler not defined yet.
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*/
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typedef int16 ExitStatus;
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#define NormalExitStatus (0)
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#define FatalExitStatus (127)
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/* XXX are there any other meaningful exit codes? */
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/* in utils/init/postinit.c */
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extern int lockingOff;
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extern void InitPostgres(const char *dbname, const char *username);
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extern void BaseInit(void);
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/* one of the ways to get out of here */
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#define ExitPostgres(status) proc_exec(status)
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/* processing mode support stuff */
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extern ProcessingMode Mode;
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@ -215,21 +251,22 @@ extern ProcessingMode Mode;
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#define SetProcessingMode(mode) \
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do { \
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AssertArg(mode == BootstrapProcessing || mode == InitProcessing || \
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mode == NormalProcessing); \
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Mode = mode; \
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AssertArg((mode) == BootstrapProcessing || \
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(mode) == InitProcessing || \
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(mode) == NormalProcessing); \
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Mode = (mode); \
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} while(0)
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#define GetProcessingMode() Mode
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extern void IgnoreSystemIndexes(bool mode);
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extern bool IsIgnoringSystemIndexes(void);
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extern bool IsCacheInitialized(void);
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extern void SetWaitingForLock(bool);
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extern bool CreateDataDirLockFile(const char *datadir, bool amPostmaster);
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extern bool CreateSocketLockFile(const char *socketfile, bool amPostmaster);
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extern void ValidatePgVersion(const char *path);
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/* these externs do not belong here... */
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extern void IgnoreSystemIndexes(bool mode);
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extern bool IsIgnoringSystemIndexes(void);
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extern bool IsCacheInitialized(void);
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#endif /* MISCADMIN_H */
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