diff options
Diffstat (limited to 'src/backend/storage/lmgr/lock.c')
| -rw-r--r-- | src/backend/storage/lmgr/lock.c | 177 |
1 files changed, 101 insertions, 76 deletions
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c index 23a2dcf1e24..14325e53183 100644 --- a/src/backend/storage/lmgr/lock.c +++ b/src/backend/storage/lmgr/lock.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.71 2000/07/17 03:05:08 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.72 2000/11/08 22:10:00 tgl Exp $ * * NOTES * Outside modules can create a lock table and acquire/release @@ -453,7 +453,7 @@ LockMethodTableRename(LOCKMETHOD lockmethod) bool LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) { - XIDLookupEnt *result, + XIDLookupEnt *xident, item; HTAB *xidTable; bool found; @@ -559,9 +559,9 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) /* * Find or create an xid entry with this tag */ - result = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &item, + xident = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &item, HASH_ENTER, &found); - if (!result) + if (!xident) { SpinRelease(masterLock); elog(NOTICE, "LockAcquire: xid table corrupted"); @@ -573,16 +573,41 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) */ if (!found) { - result->nHolding = 0; - MemSet((char *) result->holders, 0, sizeof(int) * MAX_LOCKMODES); - ProcAddLock(&result->queue); - XID_PRINT("LockAcquire: new", result); + xident->nHolding = 0; + MemSet((char *) xident->holders, 0, sizeof(int) * MAX_LOCKMODES); + ProcAddLock(&xident->queue); + XID_PRINT("LockAcquire: new", xident); } else { - XID_PRINT("LockAcquire: found", result); - Assert((result->nHolding > 0) && (result->holders[lockmode] >= 0)); - Assert(result->nHolding <= lock->nActive); + int i; + + XID_PRINT("LockAcquire: found", xident); + Assert((xident->nHolding > 0) && (xident->holders[lockmode] >= 0)); + Assert(xident->nHolding <= lock->nActive); + /* + * Issue warning if we already hold a lower-level lock on this + * object and do not hold a lock of the requested level or higher. + * This indicates a deadlock-prone coding practice (eg, we'd have + * a deadlock if another backend were following the same code path + * at about the same time). + * + * XXX Doing numeric comparison on the lockmodes is a hack; + * it'd be better to use a table. For now, though, this works. + */ + for (i = lockMethodTable->ctl->numLockModes; i > 0; i--) + { + if (xident->holders[i] > 0) + { + if (i >= (int) lockmode) + break; /* safe: we have a lock >= req level */ + elog(DEBUG, "Deadlock risk: raising lock level" + " from %s to %s on object %u/%u/%u", + lock_types[i], lock_types[lockmode], + lock->tag.relId, lock->tag.dbId, lock->tag.objId.blkno); + break; + } + } } /* ---------------- @@ -601,12 +626,12 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) * hold this lock. * -------------------- */ - if (result->nHolding == lock->nActive || result->holders[lockmode] != 0) + if (xident->nHolding == lock->nActive || xident->holders[lockmode] != 0) { - result->holders[lockmode]++; - result->nHolding++; - XID_PRINT("LockAcquire: owning", result); - Assert((result->nHolding > 0) && (result->holders[lockmode] > 0)); + xident->holders[lockmode]++; + xident->nHolding++; + XID_PRINT("LockAcquire: owning", xident); + Assert((xident->nHolding > 0) && (xident->holders[lockmode] > 0)); GrantLock(lock, lockmode); SpinRelease(masterLock); return TRUE; @@ -623,27 +648,27 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) * If I don't hold locks or my locks don't conflict with waiters * then force to sleep. */ - if (result->nHolding > 0) + if (xident->nHolding > 0) { for (; i <= lockMethodTable->ctl->numLockModes; i++) { - if (result->holders[i] > 0 && + if (xident->holders[i] > 0 && lockMethodTable->ctl->conflictTab[i] & lock->waitMask) break; /* conflict */ } } - if (result->nHolding == 0 || i > lockMethodTable->ctl->numLockModes) + if (xident->nHolding == 0 || i > lockMethodTable->ctl->numLockModes) { XID_PRINT("LockAcquire: higher priority proc waiting", - result); + xident); status = STATUS_FOUND; } else - status = LockResolveConflicts(lockmethod, lock, lockmode, xid, result); + status = LockResolveConflicts(lockmethod, lock, lockmode, xid, xident); } else - status = LockResolveConflicts(lockmethod, lock, lockmode, xid, result); + status = LockResolveConflicts(lockmethod, lock, lockmode, xid, xident); if (status == STATUS_OK) GrantLock(lock, lockmode); @@ -657,17 +682,17 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) */ if (lockmethod == USER_LOCKMETHOD) { - if (!result->nHolding) + if (!xident->nHolding) { - SHMQueueDelete(&result->queue); - result = (XIDLookupEnt *) hash_search(xidTable, - (Pointer) result, + SHMQueueDelete(&xident->queue); + xident = (XIDLookupEnt *) hash_search(xidTable, + (Pointer) xident, HASH_REMOVE, &found); - if (!result || !found) + if (!xident || !found) elog(NOTICE, "LockAcquire: remove xid, table corrupted"); } else - XID_PRINT("LockAcquire: NHOLDING", result); + XID_PRINT("LockAcquire: NHOLDING", xident); lock->nHolding--; lock->holders[lockmode]--; LOCK_PRINT("LockAcquire: user lock failed", lock, lockmode); @@ -682,7 +707,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) * Construct bitmask of locks we hold before going to sleep. */ MyProc->holdLock = 0; - if (result->nHolding > 0) + if (xident->nHolding > 0) { int i, tmpMask = 2; @@ -690,7 +715,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) for (i = 1; i <= lockMethodTable->ctl->numLockModes; i++, tmpMask <<= 1) { - if (result->holders[i] > 0) + if (xident->holders[i] > 0) MyProc->holdLock |= tmpMask; } Assert(MyProc->holdLock != 0); @@ -702,15 +727,15 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) * Check the xid entry status, in case something in the ipc * communication doesn't work correctly. */ - if (!((result->nHolding > 0) && (result->holders[lockmode] > 0))) + if (!((xident->nHolding > 0) && (xident->holders[lockmode] > 0))) { - XID_PRINT("LockAcquire: INCONSISTENT", result); + XID_PRINT("LockAcquire: INCONSISTENT", xident); LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode); /* Should we retry ? */ SpinRelease(masterLock); return FALSE; } - XID_PRINT("LockAcquire: granted", result); + XID_PRINT("LockAcquire: granted", xident); LOCK_PRINT("LockAcquire: granted", lock, lockmode); } @@ -738,7 +763,7 @@ LockResolveConflicts(LOCKMETHOD lockmethod, TransactionId xid, XIDLookupEnt *xidentP) /* xident ptr or NULL */ { - XIDLookupEnt *result, + XIDLookupEnt *xident, item; int *myHolders; int numLockModes; @@ -758,7 +783,7 @@ LockResolveConflicts(LOCKMETHOD lockmethod, * A pointer to the xid entry was supplied from the caller. * Actually only LockAcquire can do it. */ - result = xidentP; + xident = xidentP; } else { @@ -788,9 +813,9 @@ LockResolveConflicts(LOCKMETHOD lockmethod, /* * Find or create an xid entry with this tag */ - result = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &item, + xident = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &item, HASH_ENTER, &found); - if (!result) + if (!xident) { elog(NOTICE, "LockResolveConflicts: xid table corrupted"); return STATUS_ERROR; @@ -808,14 +833,14 @@ LockResolveConflicts(LOCKMETHOD lockmethod, * the lock stats. * --------------- */ - MemSet(result->holders, 0, numLockModes * sizeof(*(lock->holders))); - result->nHolding = 0; - XID_PRINT("LockResolveConflicts: NOT FOUND", result); + MemSet(xident->holders, 0, numLockModes * sizeof(*(lock->holders))); + xident->nHolding = 0; + XID_PRINT("LockResolveConflicts: NOT FOUND", xident); } else - XID_PRINT("LockResolveConflicts: found", result); + XID_PRINT("LockResolveConflicts: found", xident); } - Assert((result->nHolding >= 0) && (result->holders[lockmode] >= 0)); + Assert((xident->nHolding >= 0) && (xident->holders[lockmode] >= 0)); /* ---------------------------- * first check for global conflicts: If no locks conflict @@ -829,10 +854,10 @@ LockResolveConflicts(LOCKMETHOD lockmethod, */ if (!(LockMethodTable[lockmethod]->ctl->conflictTab[lockmode] & lock->mask)) { - result->holders[lockmode]++; - result->nHolding++; - XID_PRINT("LockResolveConflicts: no conflict", result); - Assert((result->nHolding > 0) && (result->holders[lockmode] > 0)); + xident->holders[lockmode]++; + xident->nHolding++; + XID_PRINT("LockResolveConflicts: no conflict", xident); + Assert((xident->nHolding > 0) && (xident->holders[lockmode] > 0)); return STATUS_OK; } @@ -842,7 +867,7 @@ LockResolveConflicts(LOCKMETHOD lockmethod, * that does not reflect our own locks. * ------------------------ */ - myHolders = result->holders; + myHolders = xident->holders; bitmask = 0; tmpMask = 2; for (i = 1; i <= numLockModes; i++, tmpMask <<= 1) @@ -861,14 +886,14 @@ LockResolveConflicts(LOCKMETHOD lockmethod, if (!(LockMethodTable[lockmethod]->ctl->conflictTab[lockmode] & bitmask)) { /* no conflict. Get the lock and go on */ - result->holders[lockmode]++; - result->nHolding++; - XID_PRINT("LockResolveConflicts: resolved", result); - Assert((result->nHolding > 0) && (result->holders[lockmode] > 0)); + xident->holders[lockmode]++; + xident->nHolding++; + XID_PRINT("LockResolveConflicts: resolved", xident); + Assert((xident->nHolding > 0) && (xident->holders[lockmode] > 0)); return STATUS_OK; } - XID_PRINT("LockResolveConflicts: conflicting", result); + XID_PRINT("LockResolveConflicts: conflicting", xident); return STATUS_FOUND; } @@ -965,7 +990,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) SPINLOCK masterLock; bool found; LOCKMETHODTABLE *lockMethodTable; - XIDLookupEnt *result, + XIDLookupEnt *xident, item; HTAB *xidTable; TransactionId xid; @@ -1053,9 +1078,9 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) * Find an xid entry with this tag */ xidTable = lockMethodTable->xidHash; - result = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &item, + xident = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &item, HASH_FIND_SAVE, &found); - if (!result || !found) + if (!xident || !found) { SpinRelease(masterLock); #ifdef USER_LOCKS @@ -1066,23 +1091,23 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) elog(NOTICE, "LockRelease: xid table corrupted"); return FALSE; } - XID_PRINT("LockRelease: found", result); - Assert(result->tag.lock == MAKE_OFFSET(lock)); + XID_PRINT("LockRelease: found", xident); + Assert(xident->tag.lock == MAKE_OFFSET(lock)); /* * Check that we are actually holding a lock of the type we want to * release. */ - if (!(result->holders[lockmode] > 0)) + if (!(xident->holders[lockmode] > 0)) { SpinRelease(masterLock); - XID_PRINT("LockAcquire: WRONGTYPE", result); + XID_PRINT("LockAcquire: WRONGTYPE", xident); elog(NOTICE, "LockRelease: you don't own a lock of type %s", lock_types[lockmode]); - Assert(result->holders[lockmode] >= 0); + Assert(xident->holders[lockmode] >= 0); return FALSE; } - Assert(result->nHolding > 0); + Assert(xident->nHolding > 0); /* * fix the general lock stats @@ -1147,27 +1172,27 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode) * now check to see if I have any private locks. If I do, decrement * the counts associated with them. */ - result->holders[lockmode]--; - result->nHolding--; - XID_PRINT("LockRelease: updated", result); - Assert((result->nHolding >= 0) && (result->holders[lockmode] >= 0)); + xident->holders[lockmode]--; + xident->nHolding--; + XID_PRINT("LockRelease: updated", xident); + Assert((xident->nHolding >= 0) && (xident->holders[lockmode] >= 0)); /* * If this was my last hold on this lock, delete my entry in the XID * table. */ - if (!result->nHolding) + if (!xident->nHolding) { - if (result->queue.prev == INVALID_OFFSET) + if (xident->queue.prev == INVALID_OFFSET) elog(NOTICE, "LockRelease: xid.prev == INVALID_OFFSET"); - if (result->queue.next == INVALID_OFFSET) + if (xident->queue.next == INVALID_OFFSET) elog(NOTICE, "LockRelease: xid.next == INVALID_OFFSET"); - if (result->queue.next != INVALID_OFFSET) - SHMQueueDelete(&result->queue); - XID_PRINT("LockRelease: deleting", result); - result = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &result, + if (xident->queue.next != INVALID_OFFSET) + SHMQueueDelete(&xident->queue); + XID_PRINT("LockRelease: deleting", xident); + xident = (XIDLookupEnt *) hash_search(xidTable, (Pointer) &xident, HASH_REMOVE_SAVED, &found); - if (!result || !found) + if (!xident || !found) { SpinRelease(masterLock); elog(NOTICE, "LockRelease: remove xid, table corrupted"); @@ -1196,7 +1221,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue) int done; XIDLookupEnt *xidLook = NULL; XIDLookupEnt *tmp = NULL; - XIDLookupEnt *result; + XIDLookupEnt *xident; SHMEM_OFFSET end = MAKE_OFFSET(lockQueue); SPINLOCK masterLock; LOCKMETHODTABLE *lockMethodTable; @@ -1371,11 +1396,11 @@ LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue) */ XID_PRINT("LockReleaseAll: deleting", xidLook); - result = (XIDLookupEnt *) hash_search(lockMethodTable->xidHash, + xident = (XIDLookupEnt *) hash_search(lockMethodTable->xidHash, (Pointer) xidLook, HASH_REMOVE, &found); - if (!result || !found) + if (!xident || !found) { SpinRelease(masterLock); elog(NOTICE, "LockReleaseAll: xid table corrupted"); |