static void FinishStrongLockAcquire(void);
static void WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner);
static void ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock);
+static void LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent);
static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
PROCLOCK *proclock, LockMethod lockMethodTable);
static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
static void
RemoveLocalLock(LOCALLOCK *locallock)
{
+ int i;
+
+ for (i = locallock->numLockOwners - 1; i >= 0; i--)
+ {
+ if (locallock->lockOwners[i].owner != NULL)
+ ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock);
+ }
pfree(locallock->lockOwners);
locallock->lockOwners = NULL;
+
if (locallock->holdsStrongLockCount)
{
uint32 fasthashcode;
locallock->holdsStrongLockCount = FALSE;
SpinLockRelease(&FastPathStrongRelationLocks->mutex);
}
+
if (!hash_search(LockMethodLocalHash,
(void *) &(locallock->tag),
HASH_REMOVE, NULL))
lockOwners[i].owner = owner;
lockOwners[i].nLocks = 1;
locallock->numLockOwners++;
+ if (owner != NULL)
+ ResourceOwnerRememberLock(owner, locallock);
}
/*
Assert(lockOwners[i].nLocks > 0);
if (--lockOwners[i].nLocks == 0)
{
+ if (owner != NULL)
+ ResourceOwnerForgetLock(owner, locallock);
/* compact out unused slot */
locallock->numLockOwners--;
if (i < locallock->numLockOwners)
{
LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
- /* If it's above array position 0, move it down to 0 */
- for (i = locallock->numLockOwners - 1; i > 0; i--)
+ /* If session lock is above array position 0, move it down to 0 */
+ for (i = 0; i < locallock->numLockOwners; i++)
{
if (lockOwners[i].owner == NULL)
- {
lockOwners[0] = lockOwners[i];
- break;
- }
+ else
+ ResourceOwnerForgetLock(lockOwners[i].owner, locallock);
}
if (locallock->numLockOwners > 0 &&
/* We aren't deleting this locallock, so done */
continue;
}
+ else
+ locallock->numLockOwners = 0;
}
/*
/*
* LockReleaseCurrentOwner
* Release all locks belonging to CurrentResourceOwner
+ *
+ * If the caller knows what those locks are, it can pass them as an array.
+ * That speeds up the call significantly, when a lot of locks are held.
+ * Otherwise, pass NULL for locallocks, and we'll traverse through our hash
+ * table to find them.
*/
void
-LockReleaseCurrentOwner(void)
+LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks)
{
- HASH_SEQ_STATUS status;
- LOCALLOCK *locallock;
+ if (locallocks == NULL)
+ {
+ HASH_SEQ_STATUS status;
+ LOCALLOCK *locallock;
- hash_seq_init(&status, LockMethodLocalHash);
+ hash_seq_init(&status, LockMethodLocalHash);
- while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
+ while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
+ ReleaseLockIfHeld(locallock, false);
+ }
+ else
{
- ReleaseLockIfHeld(locallock, false);
+ int i;
+
+ for (i = nlocks - 1; i >= 0; i--)
+ ReleaseLockIfHeld(locallocks[i], false);
}
}
locallock->nLocks -= lockOwners[i].nLocks;
/* compact out unused slot */
locallock->numLockOwners--;
+ if (owner != NULL)
+ ResourceOwnerForgetLock(owner, locallock);
if (i < locallock->numLockOwners)
lockOwners[i] = lockOwners[locallock->numLockOwners];
}
/*
* LockReassignCurrentOwner
* Reassign all locks belonging to CurrentResourceOwner to belong
- * to its parent resource owner
+ * to its parent resource owner.
+ *
+ * If the caller knows what those locks are, it can pass them as an array.
+ * That speeds up the call significantly, when a lot of locks are held
+ * (e.g pg_dump with a large schema). Otherwise, pass NULL for locallocks,
+ * and we'll traverse through our hash table to find them.
*/
void
-LockReassignCurrentOwner(void)
+LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks)
{
ResourceOwner parent = ResourceOwnerGetParent(CurrentResourceOwner);
- HASH_SEQ_STATUS status;
- LOCALLOCK *locallock;
- LOCALLOCKOWNER *lockOwners;
Assert(parent != NULL);
- hash_seq_init(&status, LockMethodLocalHash);
+ if (locallocks == NULL)
+ {
+ HASH_SEQ_STATUS status;
+ LOCALLOCK *locallock;
- while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
+ hash_seq_init(&status, LockMethodLocalHash);
+
+ while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
+ LockReassignOwner(locallock, parent);
+ }
+ else
{
int i;
- int ic = -1;
- int ip = -1;
- /*
- * Scan to see if there are any locks belonging to current owner or
- * its parent
- */
- lockOwners = locallock->lockOwners;
- for (i = locallock->numLockOwners - 1; i >= 0; i--)
- {
- if (lockOwners[i].owner == CurrentResourceOwner)
- ic = i;
- else if (lockOwners[i].owner == parent)
- ip = i;
- }
+ for (i = nlocks - 1; i >= 0; i--)
+ LockReassignOwner(locallocks[i], parent);
+ }
+}
- if (ic < 0)
- continue; /* no current locks */
+/*
+ * Subroutine of LockReassignCurrentOwner. Reassigns a given lock belonging to
+ * CurrentResourceOwner to its parent.
+ */
+static void
+LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent)
+{
+ LOCALLOCKOWNER *lockOwners;
+ int i;
+ int ic = -1;
+ int ip = -1;
- if (ip < 0)
- {
- /* Parent has no slot, so just give it child's slot */
- lockOwners[ic].owner = parent;
- }
- else
- {
- /* Merge child's count with parent's */
- lockOwners[ip].nLocks += lockOwners[ic].nLocks;
- /* compact out unused slot */
- locallock->numLockOwners--;
- if (ic < locallock->numLockOwners)
- lockOwners[ic] = lockOwners[locallock->numLockOwners];
- }
+ /*
+ * Scan to see if there are any locks belonging to current owner or its
+ * parent
+ */
+ lockOwners = locallock->lockOwners;
+ for (i = locallock->numLockOwners - 1; i >= 0; i--)
+ {
+ if (lockOwners[i].owner == CurrentResourceOwner)
+ ic = i;
+ else if (lockOwners[i].owner == parent)
+ ip = i;
+ }
+
+ if (ic < 0)
+ return; /* no current locks */
+
+ if (ip < 0)
+ {
+ /* Parent has no slot, so just give it the child's slot */
+ lockOwners[ic].owner = parent;
+ ResourceOwnerRememberLock(parent, locallock);
+ }
+ else
+ {
+ /* Merge child's count with parent's */
+ lockOwners[ip].nLocks += lockOwners[ic].nLocks;
+ /* compact out unused slot */
+ locallock->numLockOwners--;
+ if (ic < locallock->numLockOwners)
+ lockOwners[ic] = lockOwners[locallock->numLockOwners];
}
+ ResourceOwnerForgetLock(CurrentResourceOwner, locallock);
}
/*
#include "utils/rel.h"
#include "utils/snapmgr.h"
+/*
+ * To speed up bulk releasing or reassigning locks from a resource owner to
+ * its parent, each resource owner has a small cache of locks it owns. The
+ * lock manager has the same information in its local lock hash table, and
+ * we fall back on that if cache overflows, but traversing the hash table
+ * is slower when there are a lot of locks belonging to other resource owners.
+ *
+ * MAX_RESOWNER_LOCKS is the size of the per-resource owner cache. It's
+ * chosen based on some testing with pg_dump with a large schema. When the
+ * tests were done (on 9.2), resource owners in a pg_dump run contained up
+ * to 9 locks, regardless of the schema size, except for the top resource
+ * owner which contained much more (overflowing the cache). 15 seems like a
+ * nice round number that's somewhat higher than what pg_dump needs. Note that
+ * making this number larger is not free - the bigger the cache, the slower
+ * it is to release locks (in retail), when a resource owner holds many locks.
+ */
+#define MAX_RESOWNER_LOCKS 15
/*
* ResourceOwner objects look like this
Buffer *buffers; /* dynamically allocated array */
int maxbuffers; /* currently allocated array size */
+ /* We can remember up to MAX_RESOWNER_LOCKS references to local locks. */
+ int nlocks; /* number of owned locks */
+ LOCALLOCK *locks[MAX_RESOWNER_LOCKS]; /* list of owned locks */
+
/* We have built-in support for remembering catcache references */
int ncatrefs; /* number of owned catcache pins */
HeapTuple *catrefs; /* dynamically allocated array */
* subtransaction, we do NOT release its locks yet, but transfer
* them to the parent.
*/
+ LOCALLOCK **locks;
+ int nlocks;
+
Assert(owner->parent != NULL);
+
+ /*
+ * Pass the list of locks owned by this resource owner to the lock
+ * manager, unless it has overflowed.
+ */
+ if (owner->nlocks > MAX_RESOWNER_LOCKS)
+ {
+ locks = NULL;
+ nlocks = 0;
+ }
+ else
+ {
+ locks = owner->locks;
+ nlocks = owner->nlocks;
+ }
+
if (isCommit)
- LockReassignCurrentOwner();
+ LockReassignCurrentOwner(locks, nlocks);
else
- LockReleaseCurrentOwner();
+ LockReleaseCurrentOwner(locks, nlocks);
}
}
else if (phase == RESOURCE_RELEASE_AFTER_LOCKS)
/* And it better not own any resources, either */
Assert(owner->nbuffers == 0);
+ Assert(owner->nlocks == 0 || owner->nlocks == MAX_RESOWNER_LOCKS + 1);
Assert(owner->ncatrefs == 0);
Assert(owner->ncatlistrefs == 0);
Assert(owner->nrelrefs == 0);
}
}
+/*
+ * Remember that a Local Lock is owned by a ResourceOwner
+ *
+ * This is different from the other Remember functions in that the list of
+ * locks is only a lossy cache. It can hold up to MAX_RESOWNER_LOCKS entries,
+ * and when it overflows, we stop tracking locks. The point of only remembering
+ * only up to MAX_RESOWNER_LOCKS entries is that if a lot of locks are held,
+ * ResourceOwnerForgetLock doesn't need to scan through a large array to find
+ * the entry.
+ */
+void
+ResourceOwnerRememberLock(ResourceOwner owner, LOCALLOCK *locallock)
+{
+ if (owner->nlocks > MAX_RESOWNER_LOCKS)
+ return; /* we have already overflowed */
+
+ if (owner->nlocks < MAX_RESOWNER_LOCKS)
+ owner->locks[owner->nlocks] = locallock;
+ else
+ {
+ /* overflowed */
+ }
+ owner->nlocks++;
+}
+
+/*
+ * Forget that a Local Lock is owned by a ResourceOwner
+ */
+void
+ResourceOwnerForgetLock(ResourceOwner owner, LOCALLOCK *locallock)
+{
+ int i;
+
+ if (owner->nlocks > MAX_RESOWNER_LOCKS)
+ return; /* we have overflowed */
+
+ Assert(owner->nlocks > 0);
+ for (i = owner->nlocks - 1; i >= 0; i--)
+ {
+ if (locallock == owner->locks[i])
+ {
+ owner->locks[i] = owner->locks[owner->nlocks - 1];
+ owner->nlocks--;
+ return;
+ }
+ }
+ elog(ERROR, "lock reference %p is not owned by resource owner %s",
+ locallock, owner->name);
+}
+
/*
* Make sure there is room for at least one more entry in a ResourceOwner's
* catcache reference array.
projects / postgresql / commitdiff