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Small comment fixes and enhancements.

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This commit is contained in:
Heikki Linnakangas
2011-06-10 17:22:00 +03:00
parent bb8f0c4b48
commit c79c570bd8
3 changed files with 39 additions and 14 deletions
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48
src/backend/storage/lmgr/predicate.c
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@@ -703,8 +703,8 @@ OldSerXidInit(void)
* Set up SLRU management of the pg_serial data.
*/
OldSerXidSlruCtl->PagePrecedes = OldSerXidPagePrecedesLogically;
SimpleLruInit(OldSerXidSlruCtl, "OldSerXid SLRU Ctl", NUM_OLDSERXID_BUFFERS, 0,
OldSerXidLock, "pg_serial");
SimpleLruInit(OldSerXidSlruCtl, "OldSerXid SLRU Ctl",
NUM_OLDSERXID_BUFFERS, 0, OldSerXidLock, "pg_serial");
/* Override default assumption that writes should be fsync'd */
OldSerXidSlruCtl->do_fsync = false;
@@ -2954,7 +2954,8 @@ PredicateLockPageCombine(const Relation relation, const BlockNumber oldblkno,
}
/*
* Walk the hash table and find the new xmin.
* Walk the list of in-progress serializable transactions and find the new
* xmin.
*/
static void
SetNewSxactGlobalXmin(void)
@@ -3126,6 +3127,10 @@ ReleasePredicateLocks(const bool isCommit)
&& !SxactIsReadOnly(MySerializableXact)
&& SxactHasSummaryConflictOut(MySerializableXact))
{
/*
* we don't know which old committed transaction we conflicted with,
* so be conservative and use FirstNormalSerCommitSeqNo here
*/
MySerializableXact->SeqNo.earliestOutConflictCommit =
FirstNormalSerCommitSeqNo;
MySerializableXact->flags |= SXACT_FLAG_CONFLICT_OUT;
@@ -3320,7 +3325,8 @@ ReleasePredicateLocksIfROSafe(void)
}
/*
* Clear old predicate locks.
* Clear old predicate locks, belonging to committed transactions that are no
* longer interesting to any in-progress transaction.
*/
static void
ClearOldPredicateLocks(void)
@@ -3328,6 +3334,10 @@ ClearOldPredicateLocks(void)
SERIALIZABLEXACT *finishedSxact;
PREDICATELOCK *predlock;
/*
* Loop through finished transactions. They are in commit order, so we can
* stop as soon as we find one that's still interesting.
*/
LWLockAcquire(SerializableFinishedListLock, LW_EXCLUSIVE);
finishedSxact = (SERIALIZABLEXACT *)
SHMQueueNext(FinishedSerializableTransactions,
@@ -3346,6 +3356,10 @@ ClearOldPredicateLocks(void)
|| TransactionIdPrecedesOrEquals(finishedSxact->finishedBefore,
PredXact->SxactGlobalXmin))
{
/*
* This transaction committed before any in-progress transaction
* took its snapshot. It's no longer interesting.
*/
LWLockRelease(SerializableXactHashLock);
SHMQueueDelete(&(finishedSxact->finishedLink));
ReleaseOneSerializableXact(finishedSxact, false, false);
@@ -3362,7 +3376,10 @@ ClearOldPredicateLocks(void)
LWLockAcquire(SerializableXactHashLock, LW_SHARED);
}
else
{
/* Still interesting. */
break;
}
finishedSxact = nextSxact;
}
LWLockRelease(SerializableXactHashLock);
@@ -3391,17 +3408,19 @@ ClearOldPredicateLocks(void)
canDoPartialCleanup = (predlock->commitSeqNo <= PredXact->CanPartialClearThrough);
LWLockRelease(SerializableXactHashLock);
/*
* If this lock originally belonged to an old enough transaction, we
* can release it.
*/
if (canDoPartialCleanup)
{
PREDICATELOCKTAG tag;
SHM_QUEUE *targetLink;
PREDICATELOCKTARGET *target;
PREDICATELOCKTARGETTAG targettag;
uint32 targettaghash;
LWLockId partitionLock;
tag = predlock->tag;
targetLink = &(predlock->targetLink);
target = tag.myTarget;
targettag = target->tag;
targettaghash = PredicateLockTargetTagHashCode(&targettag);
@@ -3409,7 +3428,7 @@ ClearOldPredicateLocks(void)
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
SHMQueueDelete(targetLink);
SHMQueueDelete(&(predlock->targetLink));
SHMQueueDelete(&(predlock->xactLink));
hash_search_with_hash_value(PredicateLockHash, &tag,
@@ -3437,9 +3456,9 @@ ClearOldPredicateLocks(void)
* delete the transaction.
*
* When the partial flag is set, we can release all predicate locks and
* out-conflict information -- we've established that there are no longer
* in-conflict information -- we've established that there are no longer
* any overlapping read write transactions for which this transaction could
* matter.
* matter -- but keep the transaction entry itself and any outConflicts.
*
* When the summarize flag is set, we've run short of room for sxact data
* and must summarize to the SLRU. Predicate locks are transferred to a
@@ -3460,6 +3479,10 @@ ReleaseOneSerializableXact(SERIALIZABLEXACT *sxact, bool partial,
Assert(SxactIsRolledBack(sxact) || SxactIsCommitted(sxact));
Assert(LWLockHeldByMe(SerializableFinishedListLock));
/*
* First release all the predicate locks held by this xact (or transfer
* them to OldCommittedSxact if summarize is true)
*/
LWLockAcquire(SerializablePredicateLockListLock, LW_SHARED);
predlock = (PREDICATELOCK *)
SHMQueueNext(&(sxact->predicateLocks),
@@ -3545,9 +3568,9 @@ ReleaseOneSerializableXact(SERIALIZABLEXACT *sxact, bool partial,
sxidtag.xid = sxact->topXid;
LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
/* Release all outConflicts (unless 'partial' is true) */
if (!partial)
{
/* Release all outConflicts. */
conflict = (RWConflict)
SHMQueueNext(&sxact->outConflicts,
&sxact->outConflicts,
@@ -3582,9 +3605,9 @@ ReleaseOneSerializableXact(SERIALIZABLEXACT *sxact, bool partial,
conflict = nextConflict;
}
/* Finally, get rid of the xid and the record of the transaction itself. */
if (!partial)
{
/* Get rid of the xid and the record of the transaction itself. */
if (sxidtag.xid != InvalidTransactionId)
hash_search(SerializableXidHash, &sxidtag, HASH_REMOVE, NULL);
ReleasePredXact(sxact);
@@ -3844,7 +3867,8 @@ CheckForSerializableConflictOut(const bool visible, const Relation relation,
}
/*
* Check a particular target for rw-dependency conflict in.
* Check a particular target for rw-dependency conflict in. A subroutine of
* CheckForSerializableConflictIn().
*/
static void
CheckTargetForConflictsIn(PREDICATELOCKTARGETTAG *targettag)