Use Snapshot in heap access methods.

src/backend/storage/ipc/shmem.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.28 1998/07/21 06:17:35 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.29 1998/07/27 19:38:10 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -585,7 +585,6 @@ ShmemInitStruct(char *name, unsigned long size, bool *foundPtr)
 	return (structPtr);
 }
 
-
 /*
  * TransactionIdIsInProgress -- is given transaction running by some backend
  *
@@ -625,3 +624,75 @@ TransactionIdIsInProgress(TransactionId xid)
 	elog(ERROR, "TransactionIdIsInProgress: ShmemIndex corrupted");
 	return (false);
 }
+
+#ifdef LowLevelLocking
+/*
+ * GetSnapshotData -- returns information about running transactions.
+ *
+ * InvalidTransactionId is used as terminator in snapshot->xip array.
+ * If serialized is true then XID >= current xact ID will not be
+ * placed in array. Current xact ID are never placed there (just
+ * to reduce its length, xmin/xmax may be equal to cid).
+ * MyProc->xmin will be setted if equal to InvalidTransactionId.
+ * 
+ * Yet another strange func for this place...	- vadim 07/21/98
+ */
+Snapshot
+GetSnapshotData(bool serialized)
+{
+	Snapshot		snapshot = (Snapshot) malloc(sizeof(SnapshotData));
+	TransactionId	snapshot->xip = (TransactionId*) 
+									malloc(32 * sizeof(TransactionId));
+	ShmemIndexEnt  *result;
+	PROC		   *proc;
+	TransactionId	cid = GetCurrentTransactionId();
+	uint			count = 0;
+	unit			free = 31;
+
+	Assert(ShmemIndex);
+	
+	snapshot->xmax = cid;
+	snapshot->xmin = cid;
+
+	SpinAcquire(ShmemIndexLock);
+
+	hash_seq((HTAB *) NULL);
+	while ((result = (ShmemIndexEnt *) hash_seq(ShmemIndex)) != NULL)
+	{
+		if (result == (ShmemIndexEnt *) TRUE)
+		{
+			if (MyProc->xmin == InvalidTransactionId)
+				MyProc->xmin = snapshot->xmin;
+			SpinRelease(ShmemIndexLock);
+			snapshot->xip[count] = InvalidTransactionId;
+			return (snapshot);
+		}
+		if (result->location == INVALID_OFFSET ||
+			strncmp(result->key, "PID ", 4) != 0)
+			continue;
+		proc = (PROC *) MAKE_PTR(result->location);
+		if (proc == MyProc || proc->xid < FirstTransactionId ||
+				serialized && proc->xid >= cid)
+			continue;
+		if (proc->xid < snapshot->xmin)
+			snapshot->xmin = proc->xid;
+		else if (proc->xid > snapshot->xmax)
+			snapshot->xmax = proc->xid;
+		if (free == 0)
+		{
+			snapshot->xip = (TransactionId*) realloc(snapshot->xip, 
+								(count + 33) * sizeof(TransactionId));
+			free = 32;
+		}
+		snapshot->xip[count] = proc->xid;
+		free--;
+		count++;
+	}
+
+	SpinRelease(ShmemIndexLock);
+	free(snapshot->xip);
+	free(snapshot);
+	elog(ERROR, "GetSnapshotData: ShmemIndex corrupted");
+	return (NULL);
+}
+#endif

src/backend/storage/large_object/inv_api.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.31 1998/07/21 04:17:24 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.32 1998/07/27 19:38:11 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -656,9 +656,13 @@ inv_fetchtup(LargeObjectDesc *obj_desc, Buffer *bufP)
 			 * For time travel, we need to use the actual time qual here,
 			 * rather that NowTimeQual.  We currently have no way to pass
 			 * a time qual in.
+			 *
+			 * This is now valid for snapshot !!!
+			 * And should be fixed in some way...	- vadim 07/28/98
+			 * 
 			 */
 
-			htup = heap_fetch(obj_desc->heap_r, false,
+			htup = heap_fetch(obj_desc->heap_r, SnapshotNow,
 							  &(res->heap_iptr), bufP);
 
 		} while (htup == (HeapTuple) NULL);
@@ -669,7 +673,7 @@ inv_fetchtup(LargeObjectDesc *obj_desc, Buffer *bufP)
 	}
 	else
 	{
-		htup = heap_fetch(obj_desc->heap_r, false,
+		htup = heap_fetch(obj_desc->heap_r, SnapshotNow,
 						  &(obj_desc->htid), bufP);
 	}
 
@@ -1235,7 +1239,7 @@ _inv_getsize(Relation hreln, TupleDesc hdesc, Relation ireln)
 		if (buf != InvalidBuffer)
 			ReleaseBuffer(buf);
 
-		htup = heap_fetch(hreln, false, &(res->heap_iptr), &buf);
+		htup = heap_fetch(hreln, SnapshotNow, &(res->heap_iptr), &buf);
 		pfree(res);
 
 	} while (!HeapTupleIsValid(htup));

src/backend/storage/lmgr/proc.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.39 1998/06/30 02:33:32 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.40 1998/07/27 19:38:15 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -46,7 +46,7 @@
  *		This is so that we can support more backends. (system-wide semaphore
  *		sets run out pretty fast.)				  -ay 4/95
  *
- * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.39 1998/06/30 02:33:32 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.40 1998/07/27 19:38:15 vadim Exp $
  */
 #include <sys/time.h>
 #include <unistd.h>
@@ -252,6 +252,9 @@ InitProcess(IPCKey key)
 	MyProc->pid = MyProcPid;
 #endif
 	MyProc->xid = InvalidTransactionId;
+#ifdef LowLevelLocking
+	MyProc->xmin = InvalidTransactionId;
+#endif
 
 	/* ----------------
 	 * Start keeping spin lock stats from here on.	Any botch before
@@ -479,11 +482,13 @@ ProcSleep(PROC_QUEUE *waitQueue,
 	MyProc->token = token;
 	MyProc->waitLock = lock;
 
+#ifndef LowLevelLocking
 	/* -------------------
 	 * currently, we only need this for the ProcWakeup routines
 	 * -------------------
 	 */
 	TransactionIdStore((TransactionId) GetCurrentTransactionId(), &MyProc->xid);
+#endif
 
 	/* -------------------
 	 * assume that these two operations are atomic (because