aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--src/backend/access/transam/multixact.c6
-rw-r--r--src/backend/access/transam/twophase.c47
-rw-r--r--src/backend/storage/lmgr/lock.c6
-rw-r--r--src/include/access/twophase.h4
4 files changed, 44 insertions, 19 deletions
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 07ae7a31db5..c3998719405 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -1713,7 +1713,7 @@ PostPrepare_MultiXact(TransactionId xid)
myOldestMember = OldestMemberMXactId[MyBackendId];
if (MultiXactIdIsValid(myOldestMember))
{
- BackendId dummyBackendId = TwoPhaseGetDummyBackendId(xid);
+ BackendId dummyBackendId = TwoPhaseGetDummyBackendId(xid, false);
/*
* Even though storing MultiXactId is atomic, acquire lock to make
@@ -1755,7 +1755,7 @@ void
multixact_twophase_recover(TransactionId xid, uint16 info,
void *recdata, uint32 len)
{
- BackendId dummyBackendId = TwoPhaseGetDummyBackendId(xid);
+ BackendId dummyBackendId = TwoPhaseGetDummyBackendId(xid, false);
MultiXactId oldestMember;
/*
@@ -1776,7 +1776,7 @@ void
multixact_twophase_postcommit(TransactionId xid, uint16 info,
void *recdata, uint32 len)
{
- BackendId dummyBackendId = TwoPhaseGetDummyBackendId(xid);
+ BackendId dummyBackendId = TwoPhaseGetDummyBackendId(xid, true);
Assert(len == sizeof(MultiXactId));
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index add979bf0b2..64679dd2de9 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -801,9 +801,12 @@ pg_prepared_xact(PG_FUNCTION_ARGS)
* TwoPhaseGetGXact
* Get the GlobalTransaction struct for a prepared transaction
* specified by XID
+ *
+ * If lock_held is set to true, TwoPhaseStateLock will not be taken, so the
+ * caller had better hold it.
*/
static GlobalTransaction
-TwoPhaseGetGXact(TransactionId xid)
+TwoPhaseGetGXact(TransactionId xid, bool lock_held)
{
GlobalTransaction result = NULL;
int i;
@@ -811,6 +814,8 @@ TwoPhaseGetGXact(TransactionId xid)
static TransactionId cached_xid = InvalidTransactionId;
static GlobalTransaction cached_gxact = NULL;
+ Assert(!lock_held || LWLockHeldByMe(TwoPhaseStateLock));
+
/*
* During a recovery, COMMIT PREPARED, or ABORT PREPARED, we'll be called
* repeatedly for the same XID. We can save work with a simple cache.
@@ -818,7 +823,8 @@ TwoPhaseGetGXact(TransactionId xid)
if (xid == cached_xid)
return cached_gxact;
- LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
+ if (!lock_held)
+ LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
{
@@ -832,7 +838,8 @@ TwoPhaseGetGXact(TransactionId xid)
}
}
- LWLockRelease(TwoPhaseStateLock);
+ if (!lock_held)
+ LWLockRelease(TwoPhaseStateLock);
if (result == NULL) /* should not happen */
elog(ERROR, "failed to find GlobalTransaction for xid %u", xid);
@@ -849,12 +856,13 @@ TwoPhaseGetGXact(TransactionId xid)
*
* Dummy backend IDs are similar to real backend IDs of real backends.
* They start at MaxBackends + 1, and are unique across all currently active
- * real backends and prepared transactions.
+ * real backends and prepared transactions. If lock_held is set to true,
+ * TwoPhaseStateLock will not be taken, so the caller had better hold it.
*/
BackendId
-TwoPhaseGetDummyBackendId(TransactionId xid)
+TwoPhaseGetDummyBackendId(TransactionId xid, bool lock_held)
{
- GlobalTransaction gxact = TwoPhaseGetGXact(xid);
+ GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
return gxact->dummyBackendId;
}
@@ -862,11 +870,14 @@ TwoPhaseGetDummyBackendId(TransactionId xid)
/*
* TwoPhaseGetDummyProc
* Get the PGPROC that represents a prepared transaction specified by XID
+ *
+ * If lock_held is set to true, TwoPhaseStateLock will not be taken, so the
+ * caller had better hold it.
*/
PGPROC *
-TwoPhaseGetDummyProc(TransactionId xid)
+TwoPhaseGetDummyProc(TransactionId xid, bool lock_held)
{
- GlobalTransaction gxact = TwoPhaseGetGXact(xid);
+ GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
return &ProcGlobal->allProcs[gxact->pgprocno];
}
@@ -1560,6 +1571,14 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
if (hdr->initfileinval)
RelationCacheInitFilePostInvalidate();
+ /*
+ * Acquire the two-phase lock. We want to work on the two-phase callbacks
+ * while holding it to avoid potential conflicts with other transactions
+ * attempting to use the same GID, so the lock is released once the shared
+ * memory state is cleared.
+ */
+ LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
+
/* And now do the callbacks */
if (isCommit)
ProcessRecords(bufptr, xid, twophase_postcommit_callbacks);
@@ -1568,6 +1587,15 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
PredicateLockTwoPhaseFinish(xid, isCommit);
+ /* Clear shared memory state */
+ RemoveGXact(gxact);
+
+ /*
+ * Release the lock as all callbacks are called and shared memory cleanup
+ * is done.
+ */
+ LWLockRelease(TwoPhaseStateLock);
+
/* Count the prepared xact as committed or aborted */
AtEOXact_PgStat(isCommit);
@@ -1577,9 +1605,6 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
if (gxact->ondisk)
RemoveTwoPhaseFile(xid, true);
- LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
- RemoveGXact(gxact);
- LWLockRelease(TwoPhaseStateLock);
MyLockedGxact = NULL;
RESUME_INTERRUPTS();
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 3bb5ce350aa..78fdbd6ff88 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -3243,7 +3243,7 @@ AtPrepare_Locks(void)
void
PostPrepare_Locks(TransactionId xid)
{
- PGPROC *newproc = TwoPhaseGetDummyProc(xid);
+ PGPROC *newproc = TwoPhaseGetDummyProc(xid, false);
HASH_SEQ_STATUS status;
LOCALLOCK *locallock;
LOCK *lock;
@@ -4034,7 +4034,7 @@ lock_twophase_recover(TransactionId xid, uint16 info,
void *recdata, uint32 len)
{
TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
- PGPROC *proc = TwoPhaseGetDummyProc(xid);
+ PGPROC *proc = TwoPhaseGetDummyProc(xid, false);
LOCKTAG *locktag;
LOCKMODE lockmode;
LOCKMETHODID lockmethodid;
@@ -4247,7 +4247,7 @@ lock_twophase_postcommit(TransactionId xid, uint16 info,
void *recdata, uint32 len)
{
TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
- PGPROC *proc = TwoPhaseGetDummyProc(xid);
+ PGPROC *proc = TwoPhaseGetDummyProc(xid, true);
LOCKTAG *locktag;
LOCKMETHODID lockmethodid;
LockMethod lockMethodTable;
diff --git a/src/include/access/twophase.h b/src/include/access/twophase.h
index 6228b091d89..fcd1913c43a 100644
--- a/src/include/access/twophase.h
+++ b/src/include/access/twophase.h
@@ -34,8 +34,8 @@ extern void TwoPhaseShmemInit(void);
extern void AtAbort_Twophase(void);
extern void PostPrepare_Twophase(void);
-extern PGPROC *TwoPhaseGetDummyProc(TransactionId xid);
-extern BackendId TwoPhaseGetDummyBackendId(TransactionId xid);
+extern PGPROC *TwoPhaseGetDummyProc(TransactionId xid, bool lock_held);
+extern BackendId TwoPhaseGetDummyBackendId(TransactionId xid, bool lock_held);
extern GlobalTransaction MarkAsPreparing(TransactionId xid, const char *gid,
TimestampTz prepared_at,
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-24 15:06:30 +0000