Add new pgstats routine to split pending data setup This commit adds pgstat_prep_pending_from_entry_ref(), a new pgstats routine that is able to prepare an existing PgStat_EntryRef to receive pending stats. This split gives a way for callers to obtain first a reference via pgstat_get_entry_ref(), then set up pending data as two separate, distinctive, steps.
Previously, the only way to get an entry reference with pending data ready was pgstat_prep_pending_entry(), which bundles lookup, creation, and pending setup in a single call. Callers that need finer control over the entry creation had no way to attach pending data to an already-obtained entry reference. One case where this has shown to matter for a stats kind is where one wants to check some capacity (for example where a GUC bounds the maximum numer of entries allowed) before deciding if a new entry should be created. So this split can help in reducing calls to pgstat_get_entry_ref(), meaning less shmem hash table lookups. The only logical ordering change is that pgStatPendingContext is initialized after calling pgstat_get_entry_ref() in pgstat_prep_pending_entry(). This does not matter in practice. pgstat_prep_pending_entry() is refactored to use the new function internally. All the existing callers are unchanged. Existing out-of-core custom stats kinds should see no impact. Author: Sami Imseih <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Reviewed-by: Michael Paquier <[email protected]> Discussion: https://postgr.es/m/CAA5RZ0sV+TsLejUMhAM=PJoOm8u-t8ru7B67KvyLCy=19sm...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/e65c331b8fbf8c9632b62c5a9dcb589cbd3046a8 Modified Files -------------- src/backend/utils/activity/pgstat.c | 55 +++++++++++++++++++++++-------------- src/include/utils/pgstat_internal.h | 1 + 2 files changed, 36 insertions(+), 20 deletions(-)
