From 56c7140ca813ba4c7ecb122a1d2b1268e705d092 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Thu, 7 Apr 2011 16:43:39 -0400 Subject: [PATCH] Tweaks for SSI out-of-shared memory behavior. If we call hash_search() with HASH_ENTER, it will bail out rather than return NULL, so it's redundant to check for NULL again in the caller. Thus, in cases where we believe it's impossible for the hash table to run out of slots anyway, we can simplify the code slightly. On the flip side, in cases where it's theoretically possible to run out of space, we don't want to rely on dynahash.c to throw an error; instead, we pass HASH_ENTER_NULL and throw the error ourselves if a NULL comes back, so that we can provide a more descriptive error message. Kevin Grittner --- src/backend/storage/lmgr/predicate.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index 5096ea0c1c..46b86546ee 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -1604,12 +1604,7 @@ RegisterPredicateLockingXid(const TransactionId xid) sxid = (SERIALIZABLEXID *) hash_search(SerializableXidHash, &sxidtag, HASH_ENTER, &found); - if (!sxid) - /* This should not be possible, based on allocation. */ - ereport(ERROR, - (errcode(ERRCODE_OUT_OF_MEMORY), - errmsg("out of shared memory"))); - + Assert(sxid != NULL); Assert(!found); /* Initialize the structure. */ @@ -2045,7 +2040,7 @@ CreatePredicateLock(const PREDICATELOCKTARGETTAG *targettag, target = (PREDICATELOCKTARGET *) hash_search_with_hash_value(PredicateLockTargetHash, targettag, targettaghash, - HASH_ENTER, &found); + HASH_ENTER_NULL, &found); if (!target) ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY), @@ -2060,7 +2055,7 @@ CreatePredicateLock(const PREDICATELOCKTARGETTAG *targettag, lock = (PREDICATELOCK *) hash_search_with_hash_value(PredicateLockHash, &locktag, PredicateLockHashCodeFromTargetHashCode(&locktag, targettaghash), - HASH_ENTER, &found); + HASH_ENTER_NULL, &found); if (!lock) ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY), @@ -3251,7 +3246,7 @@ ReleaseOneSerializableXact(SERIALIZABLEXACT *sxact, bool partial, predlock = hash_search_with_hash_value(PredicateLockHash, &tag, PredicateLockHashCodeFromTargetHashCode(&tag, targettaghash), - HASH_ENTER, &found); + HASH_ENTER_NULL, &found); if (!predlock) ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY), @@ -4301,10 +4296,7 @@ predicatelock_twophase_recover(TransactionId xid, uint16 info, sxid = (SERIALIZABLEXID *) hash_search(SerializableXidHash, &sxidtag, HASH_ENTER, &found); - if (!sxid) - ereport(ERROR, - (errcode(ERRCODE_OUT_OF_MEMORY), - errmsg("out of shared memory"))); + Assert(sxid != NULL); Assert(!found); sxid->myXact = (SERIALIZABLEXACT *) sxact;