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Add callback for backend initialization in pgstats

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pgstat_initialize() is currently used by the WAL stats as a code path to
take some custom actions when a backend starts.  A callback is added to
generalize the concept so as all stats kinds can do the same, for
builtin and custom kinds, if set.

Reviewed-by: Bertrand Drouvot, Kyotaro Horiguchi
Discussion: https://postgr.es/m/ZtZr1K4PLdeWclXY@paquier.xyz
This commit is contained in:
Michael Paquier 2024-09-05 16:05:21 +09:00
parent 341e9a05e7
commit 1b373aed20
3 changed files with 20 additions and 4 deletions
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14
src/backend/utils/activity/pgstat.c
View File

@ -441,6 +441,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
.shared_data_off = offsetof(PgStatShared_Wal, stats), .shared_data_off = offsetof(PgStatShared_Wal, stats),
.shared_data_len = sizeof(((PgStatShared_Wal *) 0)->stats), .shared_data_len = sizeof(((PgStatShared_Wal *) 0)->stats),
.init_backend_cb = pgstat_wal_init_backend_cb,
.init_shmem_cb = pgstat_wal_init_shmem_cb, .init_shmem_cb = pgstat_wal_init_shmem_cb,
.reset_all_cb = pgstat_wal_reset_all_cb, .reset_all_cb = pgstat_wal_reset_all_cb,
.snapshot_cb = pgstat_wal_snapshot_cb, .snapshot_cb = pgstat_wal_snapshot_cb,
@ -604,10 +605,19 @@ pgstat_initialize(void)
pgstat_attach_shmem(); pgstat_attach_shmem();
pgstat_init_wal();
pgstat_init_snapshot_fixed(); pgstat_init_snapshot_fixed();
/* Backend initialization callbacks */
for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
{
const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
if (kind_info == NULL || kind_info->init_backend_cb == NULL)
continue;
kind_info->init_backend_cb();
}
/* Set up a process-exit hook to clean up */ /* Set up a process-exit hook to clean up */
before_shmem_exit(pgstat_shutdown_hook, 0); before_shmem_exit(pgstat_shutdown_hook, 0);

2
src/backend/utils/activity/pgstat_wal.c
View File

@ -138,7 +138,7 @@ pgstat_flush_wal(bool nowait)
} }
void void
pgstat_init_wal(void) pgstat_wal_init_backend_cb(void)
{ {
/* /*
* Initialize prevWalUsage with pgWalUsage so that pgstat_flush_wal() can * Initialize prevWalUsage with pgWalUsage so that pgstat_flush_wal() can

8
src/include/utils/pgstat_internal.h
View File

@ -229,6 +229,12 @@ typedef struct PgStat_KindInfo
*/ */
uint32 pending_size; uint32 pending_size;
/*
* Perform custom actions when initializing a backend (standalone or under
* postmaster). Optional.
*/
void (*init_backend_cb) (void);
/* /*
* For variable-numbered stats: flush pending stats. Required if pending * For variable-numbered stats: flush pending stats. Required if pending
* data is used. * data is used.
@ -673,9 +679,9 @@ extern void pgstat_slru_snapshot_cb(void);
*/ */
extern bool pgstat_flush_wal(bool nowait); extern bool pgstat_flush_wal(bool nowait);
extern void pgstat_init_wal(void);
extern bool pgstat_have_pending_wal(void); extern bool pgstat_have_pending_wal(void);
extern void pgstat_wal_init_backend_cb(void);
extern void pgstat_wal_init_shmem_cb(void *stats); extern void pgstat_wal_init_shmem_cb(void *stats);
extern void pgstat_wal_reset_all_cb(TimestampTz ts); extern void pgstat_wal_reset_all_cb(TimestampTz ts);
extern void pgstat_wal_snapshot_cb(void); extern void pgstat_wal_snapshot_cb(void);