From bf4a9b39e1d6ff729f9b0d4bfbbca06b306dbe18 Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot Date: Tue, 10 Sep 2024 01:22:02 +0000 Subject: [PATCH v2] define pgstat_entry_all_zeros(addr, s, r) This new macro allows to test if a memory region (representing a struct "s") starting at addr and of size sizeof(s) is full of zeroes. --- src/backend/utils/activity/pgstat_bgwriter.c | 7 +++++-- src/backend/utils/activity/pgstat_checkpointer.c | 9 +++++---- src/backend/utils/activity/pgstat_relation.c | 9 ++++----- src/include/utils/pgstat_internal.h | 10 ++++++++++ 4 files changed, 24 insertions(+), 11 deletions(-) 69.6% src/backend/utils/activity/ 30.3% src/include/utils/ diff --git a/src/backend/utils/activity/pgstat_bgwriter.c b/src/backend/utils/activity/pgstat_bgwriter.c index 364a7a2024..3f327241a2 100644 --- a/src/backend/utils/activity/pgstat_bgwriter.c +++ b/src/backend/utils/activity/pgstat_bgwriter.c @@ -30,7 +30,7 @@ void pgstat_report_bgwriter(void) { PgStatShared_BgWriter *stats_shmem = &pgStatLocal.shmem->bgwriter; - static const PgStat_BgWriterStats all_zeroes; + bool is_all_zeroes; Assert(!pgStatLocal.shmem->is_shutdown); pgstat_assert_is_up(); @@ -39,7 +39,10 @@ pgstat_report_bgwriter(void) * This function can be called even if nothing at all has happened. In * this case, avoid unnecessarily modifying the stats entry. */ - if (memcmp(&PendingBgWriterStats, &all_zeroes, sizeof(all_zeroes)) == 0) + pgstat_entry_all_zeros(&PendingBgWriterStats, PgStat_BgWriterStats, + is_all_zeroes); + + if (is_all_zeroes) return; pgstat_begin_changecount_write(&stats_shmem->changecount); diff --git a/src/backend/utils/activity/pgstat_checkpointer.c b/src/backend/utils/activity/pgstat_checkpointer.c index bbfc9c7e18..be11d09482 100644 --- a/src/backend/utils/activity/pgstat_checkpointer.c +++ b/src/backend/utils/activity/pgstat_checkpointer.c @@ -29,8 +29,7 @@ PgStat_CheckpointerStats PendingCheckpointerStats = {0}; void pgstat_report_checkpointer(void) { - /* We assume this initializes to zeroes */ - static const PgStat_CheckpointerStats all_zeroes; + bool is_all_zeroes; PgStatShared_Checkpointer *stats_shmem = &pgStatLocal.shmem->checkpointer; Assert(!pgStatLocal.shmem->is_shutdown); @@ -40,8 +39,10 @@ pgstat_report_checkpointer(void) * This function can be called even if nothing at all has happened. In * this case, avoid unnecessarily modifying the stats entry. */ - if (memcmp(&PendingCheckpointerStats, &all_zeroes, - sizeof(all_zeroes)) == 0) + pgstat_entry_all_zeros(&PendingCheckpointerStats, PgStat_CheckpointerStats, + is_all_zeroes); + + if (is_all_zeroes) return; pgstat_begin_changecount_write(&stats_shmem->changecount); diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 8a3f7d434c..a8f035dea4 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -801,7 +801,7 @@ pgstat_twophase_postabort(TransactionId xid, uint16 info, bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) { - static const PgStat_TableCounts all_zeroes; + bool is_all_zeroes; Oid dboid; PgStat_TableStatus *lstats; /* pending stats entry */ PgStatShared_Relation *shtabstats; @@ -816,11 +816,10 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) * Ignore entries that didn't accumulate any actual counts, such as * indexes that were opened by the planner but not used. */ - if (memcmp(&lstats->counts, &all_zeroes, - sizeof(PgStat_TableCounts)) == 0) - { + pgstat_entry_all_zeros(&lstats->counts, PgStat_TableCounts, is_all_zeroes); + + if (is_all_zeroes) return true; - } if (!pgstat_lock_entry(entry_ref, nowait)) return false; diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h index 61b2e1f96b..a788b65446 100644 --- a/src/include/utils/pgstat_internal.h +++ b/src/include/utils/pgstat_internal.h @@ -528,6 +528,16 @@ typedef struct PgStat_LocalState PgStat_Snapshot snapshot; } PgStat_LocalState; +/* + * Test if a memory region (representing a struct "s") starting + * at addr and of size sizeof(s) is full of zeroes. + */ +#define pgstat_entry_all_zeros(addr, s, r) \ + do { \ + /* We assume this initializes to zeroes */ \ + static const s all_zeroes; \ + r = (memcmp(addr, &all_zeroes, sizeof(all_zeroes)) == 0); \ + } while (0) /* * Inline functions defined further below. -- 2.34.1