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Rename some pgstats callbacks related to flush of entries

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The two callbacks have_fixed_pending_cb and flush_fixed_cb have been
introduced in fc415edf8ca8 to provide a way for fixed-numbered
statistics to control the flush of their data.  These are renamed to
respectively have_static_pending_cb and flush_static_cb.  The
restriction that these only apply to fixed-numbered stats is removed.

A follow-up patch will make use of them for backend statistics.  This
stats kind is variable-numbered, and patches are under discussion to
track WAL data for IO and backend stats which cannot use
PgStat_EntryRef->pending as pending data would be touched in critical
sections, where no memory allocation can happen.

Per discussion with Andres Freund.

Author: Bertrand Drouvot
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/66efowskppsns35v5u2m7k4sdnl7yoz5bo64tdjwq7r5lhplrz@y7dme5xwh2r5
This commit is contained in:
Michael Paquier 2025-01-21 10:12:39 +09:00
parent 60c513f8fa
commit 28de66cee5
2 changed files with 30 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
src/backend/utils/activity/pgstat.c
View File

@ -437,8 +437,8 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
.shared_data_off = offsetof(PgStatShared_IO, stats),
.shared_data_len = sizeof(((PgStatShared_IO *) 0)->stats),
.flush_fixed_cb = pgstat_io_flush_cb,
.have_fixed_pending_cb = pgstat_io_have_pending_cb,
.flush_static_cb = pgstat_io_flush_cb,
.have_static_pending_cb = pgstat_io_have_pending_cb,
.init_shmem_cb = pgstat_io_init_shmem_cb,
.reset_all_cb = pgstat_io_reset_all_cb,
.snapshot_cb = pgstat_io_snapshot_cb,
@ -455,8 +455,8 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
.shared_data_off = offsetof(PgStatShared_SLRU, stats),
.shared_data_len = sizeof(((PgStatShared_SLRU *) 0)->stats),
.flush_fixed_cb = pgstat_slru_flush_cb,
.have_fixed_pending_cb = pgstat_slru_have_pending_cb,
.flush_static_cb = pgstat_slru_flush_cb,
.have_static_pending_cb = pgstat_slru_have_pending_cb,
.init_shmem_cb = pgstat_slru_init_shmem_cb,
.reset_all_cb = pgstat_slru_reset_all_cb,
.snapshot_cb = pgstat_slru_snapshot_cb,
@ -474,8 +474,8 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
.shared_data_len = sizeof(((PgStatShared_Wal *) 0)->stats),
.init_backend_cb = pgstat_wal_init_backend_cb,
.flush_fixed_cb = pgstat_wal_flush_cb,
.have_fixed_pending_cb = pgstat_wal_have_pending_cb,
.flush_static_cb = pgstat_wal_flush_cb,
.have_static_pending_cb = pgstat_wal_have_pending_cb,
.init_shmem_cb = pgstat_wal_init_shmem_cb,
.reset_all_cb = pgstat_wal_reset_all_cb,
.snapshot_cb = pgstat_wal_snapshot_cb,
@ -713,22 +713,17 @@ pgstat_report_stat(bool force)
{
bool do_flush = false;
/* Check for pending fixed-numbered stats */
/* Check for pending stats */
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)
continue;
if (!kind_info->fixed_amount)
{
Assert(kind_info->have_fixed_pending_cb == NULL);
continue;
}
if (!kind_info->have_fixed_pending_cb)
if (!kind_info->have_static_pending_cb)
continue;
if (kind_info->have_fixed_pending_cb())
if (kind_info->have_static_pending_cb())
{
do_flush = true;
break;
@ -789,25 +784,20 @@ pgstat_report_stat(bool force)
partial_flush = false;
/* flush of variable-numbered stats */
/* flush of variable-numbered stats tracked in pending entries list */
partial_flush |= pgstat_flush_pending_entries(nowait);
/* flush of fixed-numbered stats */
/* flush of other stats kinds */
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)
continue;
if (!kind_info->fixed_amount)
{
Assert(kind_info->flush_fixed_cb == NULL);
continue;
}
if (!kind_info->flush_fixed_cb)
if (!kind_info->flush_static_cb)
continue;
partial_flush |= kind_info->flush_fixed_cb(nowait);
partial_flush |= kind_info->flush_static_cb(nowait);
}
last_flush = now;

27
src/include/utils/pgstat_internal.h
View File

@ -156,8 +156,8 @@ typedef struct PgStat_EntryRef
* Pending statistics data that will need to be flushed to shared memory
* stats eventually. Each stats kind utilizing pending data defines what
* format its pending data has and needs to provide a
* PgStat_KindInfo->flush_pending_cb callback to merge pending into shared
* stats.
* PgStat_KindInfo->flush_pending_cb callback to merge pending entries
* into the shared stats hash table.
*/
void *pending;
dlist_node pending_node; /* membership in pgStatPending list */
@ -260,7 +260,8 @@ typedef struct PgStat_KindInfo
/*
* For variable-numbered stats: flush pending stats. Required if pending
* data is used. See flush_fixed_cb for fixed-numbered stats.
* data is used. See flush_static_cb when dealing with stats data that
* that cannot use PgStat_EntryRef->pending.
*/
bool (*flush_pending_cb) (PgStat_EntryRef *sr, bool nowait);
@ -289,17 +290,23 @@ typedef struct PgStat_KindInfo
void (*init_shmem_cb) (void *stats);
/*
* For fixed-numbered statistics: Flush pending stats. Returns true if
* some of the stats could not be flushed, due to lock contention for
* example. Optional.
* For fixed-numbered or variable-numbered statistics: Flush pending stats
* entries, for stats kinds that do not use PgStat_EntryRef->pending.
*
* Returns true if some of the stats could not be flushed, due to lock
* contention for example. Optional.
*/
bool (*flush_fixed_cb) (bool nowait);
bool (*flush_static_cb) (bool nowait);
/*
* For fixed-numbered statistics: Check for pending stats in need of
* flush. Returns true if there are any stats pending for flush. Optional.
* For fixed-numbered or variable-numbered statistics: Check for pending
* stats in need of flush with flush_static_cb, when these do not use
* PgStat_EntryRef->pending.
*
* Returns true if there are any stats pending for flush, triggering
* flush_static_cb. Optional.
*/
bool (*have_fixed_pending_cb) (void);
bool (*have_static_pending_cb) (void);
/*
* For fixed-numbered statistics: Reset All.