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Split backend status and progress related functionality out of pgstat.c.
Backend status (supporting pg_stat_activity) and command
progress (supporting pg_stat_progress*) related code is largely
independent from the rest of pgstat.[ch] (supporting views like
pg_stat_all_tables that accumulate data over time). See also
a333476b92.
This commit doesn't rename the function names to make the distinction
from the rest of pgstat_ clearer - that'd be more invasive and not
clearly beneficial. If we were to decide to do such a rename at some
point, it's better done separately from moving the code as well.
Robert's review was of an earlier version.
Reviewed-By: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/20210316195440.twxmlov24rr2nxrg@alap3.anarazel.de
This commit is contained in:
Andres Freund
316
src/include/utils/backend_status.h
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316
src/include/utils/backend_status.h
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/* ----------
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* backend_status.h
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* Definitions related to backend status reporting
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*
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* Copyright (c) 2001-2021, PostgreSQL Global Development Group
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*
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* src/include/utils/backend_status.h
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* ----------
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*/
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#ifndef BACKEND_STATUS_H
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#define BACKEND_STATUS_H
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#include "datatype/timestamp.h"
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#include "libpq/pqcomm.h"
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#include "miscadmin.h" /* for BackendType */
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#include "utils/backend_progress.h"
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/* ----------
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* Backend states
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* ----------
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*/
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typedef enum BackendState
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{
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STATE_UNDEFINED,
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STATE_IDLE,
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STATE_RUNNING,
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STATE_IDLEINTRANSACTION,
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STATE_FASTPATH,
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STATE_IDLEINTRANSACTION_ABORTED,
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STATE_DISABLED
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} BackendState;
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/* ----------
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* Shared-memory data structures
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* ----------
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*/
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/*
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* PgBackendSSLStatus
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*
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* For each backend, we keep the SSL status in a separate struct, that
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* is only filled in if SSL is enabled.
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*
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* All char arrays must be null-terminated.
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*/
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typedef struct PgBackendSSLStatus
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{
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/* Information about SSL connection */
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int ssl_bits;
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char ssl_version[NAMEDATALEN];
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char ssl_cipher[NAMEDATALEN];
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char ssl_client_dn[NAMEDATALEN];
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/*
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* serial number is max "20 octets" per RFC 5280, so this size should be
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* fine
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*/
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char ssl_client_serial[NAMEDATALEN];
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char ssl_issuer_dn[NAMEDATALEN];
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} PgBackendSSLStatus;
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/*
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* PgBackendGSSStatus
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*
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* For each backend, we keep the GSS status in a separate struct, that
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* is only filled in if GSS is enabled.
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*
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* All char arrays must be null-terminated.
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*/
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typedef struct PgBackendGSSStatus
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{
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/* Information about GSSAPI connection */
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char gss_princ[NAMEDATALEN]; /* GSSAPI Principal used to auth */
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bool gss_auth; /* If GSSAPI authentication was used */
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bool gss_enc; /* If encryption is being used */
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} PgBackendGSSStatus;
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/* ----------
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* PgBackendStatus
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*
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* Each live backend maintains a PgBackendStatus struct in shared memory
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* showing its current activity. (The structs are allocated according to
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* BackendId, but that is not critical.) Note that the collector process
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* has no involvement in, or even access to, these structs.
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*
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* Each auxiliary process also maintains a PgBackendStatus struct in shared
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* memory.
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* ----------
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*/
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typedef struct PgBackendStatus
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{
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/*
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* To avoid locking overhead, we use the following protocol: a backend
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* increments st_changecount before modifying its entry, and again after
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* finishing a modification. A would-be reader should note the value of
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* st_changecount, copy the entry into private memory, then check
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* st_changecount again. If the value hasn't changed, and if it's even,
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* the copy is valid; otherwise start over. This makes updates cheap
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* while reads are potentially expensive, but that's the tradeoff we want.
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*
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* The above protocol needs memory barriers to ensure that the apparent
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* order of execution is as it desires. Otherwise, for example, the CPU
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* might rearrange the code so that st_changecount is incremented twice
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* before the modification on a machine with weak memory ordering. Hence,
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* use the macros defined below for manipulating st_changecount, rather
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* than touching it directly.
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*/
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int st_changecount;
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/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
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int st_procpid;
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/* Type of backends */
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BackendType st_backendType;
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/* Times when current backend, transaction, and activity started */
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TimestampTz st_proc_start_timestamp;
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TimestampTz st_xact_start_timestamp;
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TimestampTz st_activity_start_timestamp;
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TimestampTz st_state_start_timestamp;
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/* Database OID, owning user's OID, connection client address */
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Oid st_databaseid;
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Oid st_userid;
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SockAddr st_clientaddr;
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char *st_clienthostname; /* MUST be null-terminated */
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/* Information about SSL connection */
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bool st_ssl;
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PgBackendSSLStatus *st_sslstatus;
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/* Information about GSSAPI connection */
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bool st_gss;
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PgBackendGSSStatus *st_gssstatus;
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/* current state */
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BackendState st_state;
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/* application name; MUST be null-terminated */
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char *st_appname;
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/*
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* Current command string; MUST be null-terminated. Note that this string
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* possibly is truncated in the middle of a multi-byte character. As
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* activity strings are stored more frequently than read, that allows to
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* move the cost of correct truncation to the display side. Use
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* pgstat_clip_activity() to truncate correctly.
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*/
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char *st_activity_raw;
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/*
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* Command progress reporting. Any command which wishes can advertise
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* that it is running by setting st_progress_command,
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* st_progress_command_target, and st_progress_param[].
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* st_progress_command_target should be the OID of the relation which the
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* command targets (we assume there's just one, as this is meant for
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* utility commands), but the meaning of each element in the
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* st_progress_param array is command-specific.
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*/
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ProgressCommandType st_progress_command;
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Oid st_progress_command_target;
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int64 st_progress_param[PGSTAT_NUM_PROGRESS_PARAM];
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} PgBackendStatus;
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/*
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* Macros to load and store st_changecount with appropriate memory barriers.
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*
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* Use PGSTAT_BEGIN_WRITE_ACTIVITY() before, and PGSTAT_END_WRITE_ACTIVITY()
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* after, modifying the current process's PgBackendStatus data. Note that,
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* since there is no mechanism for cleaning up st_changecount after an error,
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* THESE MACROS FORM A CRITICAL SECTION. Any error between them will be
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* promoted to PANIC, causing a database restart to clean up shared memory!
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* Hence, keep the critical section as short and straight-line as possible.
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* Aside from being safer, that minimizes the window in which readers will
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* have to loop.
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*
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* Reader logic should follow this sketch:
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*
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* for (;;)
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* {
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* int before_ct, after_ct;
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*
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* pgstat_begin_read_activity(beentry, before_ct);
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* ... copy beentry data to local memory ...
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* pgstat_end_read_activity(beentry, after_ct);
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* if (pgstat_read_activity_complete(before_ct, after_ct))
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* break;
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* CHECK_FOR_INTERRUPTS();
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* }
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*
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* For extra safety, we generally use volatile beentry pointers, although
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* the memory barriers should theoretically be sufficient.
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*/
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#define PGSTAT_BEGIN_WRITE_ACTIVITY(beentry) \
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do { \
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START_CRIT_SECTION(); \
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(beentry)->st_changecount++; \
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pg_write_barrier(); \
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} while (0)
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#define PGSTAT_END_WRITE_ACTIVITY(beentry) \
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do { \
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pg_write_barrier(); \
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(beentry)->st_changecount++; \
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Assert(((beentry)->st_changecount & 1) == 0); \
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END_CRIT_SECTION(); \
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} while (0)
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#define pgstat_begin_read_activity(beentry, before_changecount) \
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do { \
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(before_changecount) = (beentry)->st_changecount; \
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pg_read_barrier(); \
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} while (0)
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#define pgstat_end_read_activity(beentry, after_changecount) \
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do { \
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pg_read_barrier(); \
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(after_changecount) = (beentry)->st_changecount; \
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} while (0)
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#define pgstat_read_activity_complete(before_changecount, after_changecount) \
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((before_changecount) == (after_changecount) && \
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((before_changecount) & 1) == 0)
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/* ----------
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* LocalPgBackendStatus
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*
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* When we build the backend status array, we use LocalPgBackendStatus to be
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* able to add new values to the struct when needed without adding new fields
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* to the shared memory. It contains the backend status as a first member.
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* ----------
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*/
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typedef struct LocalPgBackendStatus
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{
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/*
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* Local version of the backend status entry.
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*/
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PgBackendStatus backendStatus;
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/*
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* The xid of the current transaction if available, InvalidTransactionId
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* if not.
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*/
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TransactionId backend_xid;
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/*
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* The xmin of the current session if available, InvalidTransactionId if
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* not.
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*/
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TransactionId backend_xmin;
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} LocalPgBackendStatus;
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/* ----------
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* GUC parameters
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* ----------
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*/
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extern PGDLLIMPORT bool pgstat_track_activities;
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extern PGDLLIMPORT int pgstat_track_activity_query_size;
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/* ----------
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* Other global variables
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* ----------
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*/
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extern PGDLLIMPORT PgBackendStatus *MyBEEntry;
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/* ----------
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* Functions called from postmaster
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* ----------
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*/
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extern Size BackendStatusShmemSize(void);
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extern void CreateSharedBackendStatus(void);
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/* ----------
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* Functions called from backends
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* ----------
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*/
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/* Initialization functions */
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extern void pgstat_beinit(void);
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extern void pgstat_bestart(void);
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extern void pgstat_clear_backend_activity_snapshot(void);
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/* Activity reporting functions */
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extern void pgstat_report_activity(BackendState state, const char *cmd_str);
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extern void pgstat_report_tempfile(size_t filesize);
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extern void pgstat_report_appname(const char *appname);
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extern void pgstat_report_xact_timestamp(TimestampTz tstamp);
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extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
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extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
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int buflen);
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/* ----------
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* Support functions for the SQL-callable functions to
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* generate the pgstat* views.
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* ----------
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*/
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extern int pgstat_fetch_stat_numbackends(void);
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extern PgBackendStatus *pgstat_fetch_stat_beentry(int beid);
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extern LocalPgBackendStatus *pgstat_fetch_stat_local_beentry(int beid);
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extern char *pgstat_clip_activity(const char *raw_activity);
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#endif /* BACKEND_STATUS_H */
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