From d624b14c9a4bd93426a5e475d4503589927ef2ae Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Fri, 13 Sep 2024 02:10:04 +0300 Subject: [PATCH v15 1/2] Update header comment for lookup_type_cache() Describe the way we handle concurrent invalidation messages. --- src/backend/utils/cache/typcache.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c index 2ec136b7d30..11382547ec0 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 in the last for + * TYPTYPE_COMPOSITE. So, it can't get invalidated during the + * lookup_type_cache() call. */ TypeCacheEntry * lookup_type_cache(Oid type_id, int flags) -- 2.39.5 (Apple Git-154)