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| author | Alexander Korotkov <akorotkov@postgresql.org> | 2024-10-24 14:34:16 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2024-10-24 14:34:16 +0300 |
| commit | c1500a1ba7e16ac9e98c6baf792f0be64a48e839 (patch) | |
| tree | 82e95739b1eb530a3ade7b7b8479987418e9fc74 | |
| parent | 499edb09741b8fad2de038361fb342aae6e6007f (diff) | |
| download | postgresql-c1500a1ba7e16ac9e98c6baf792f0be64a48e839.tar.gz postgresql-c1500a1ba7e16ac9e98c6baf792f0be64a48e839.zip | |
Update header comment for lookup_type_cache()
Describe the way we handle concurrent invalidation messages.
Discussion: https://postgr.es/m/CAPpHfdsQhwUrnB3of862j9RgHoJM--eRbifvBMvtQxpC57dxCA%40mail.gmail.com
Reviewed-by: Andrei Lepikhov, Artur Zakirov, Pavel Borisov
| -rw-r--r-- | src/backend/utils/cache/typcache.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c index 2ec136b7d30..f142624ad2e 100644 --- a/src/backend/utils/cache/typcache.c +++ b/src/backend/utils/cache/typcache.c @@ -351,6 +351,15 @@ type_cache_syshash(const void *key, Size keysize) * invalid. Note however that we may fail to find one or more of the * values requested by 'flags'; the caller needs to check whether the fields * are InvalidOid or not. + * + * Note that while filling TypeCacheEntry we might process concurrent + * invalidation messages, causing our not-yet-filled TypeCacheEntry to be + * invalidated. In this case, we typically only clear flags while values are + * still available for the caller. It's expected that the caller holds + * enough locks on type-depending objects that the values are still relevant. + * It's also important that the tupdesc is filled after all other + * TypeCacheEntry items for TYPTYPE_COMPOSITE. So, tupdesc can't get + * invalidated during the lookup_type_cache() call. */ TypeCacheEntry * lookup_type_cache(Oid type_id, int flags) |