pg_variable is not used in WAL version now.

src/backend/access/transam/xlog_varsup.c

@@ -0,0 +1,142 @@
+/*-------------------------------------------------------------------------
+ *
+ * varsup.c
+ *	  postgres OID & XID variables support routines
+ *
+ * Copyright (c) 2000, PostgreSQL, Inc
+ *
+ * IDENTIFICATION
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/Attic/xlog_varsup.c,v 1.1 2000/11/03 11:39:35 vadim Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/transam.h"
+#include "storage/proc.h"
+
+SPINLOCK OidGenLockId;
+
+extern SPINLOCK XidGenLockId;
+extern void XLogPutNextOid(Oid nextOid);
+
+/* pointer to "variable cache" in shared memory (set up by shmem.c) */
+VariableCache ShmemVariableCache = NULL;
+
+void
+GetNewTransactionId(TransactionId *xid)
+{
+	/*
+	 * During bootstrap initialization, we return the special
+	 * bootstrap transaction id.
+	 */
+	if (AMI_OVERRIDE)
+	{
+		*xid = AmiTransactionId;
+		return;
+	}
+
+	SpinAcquire(XidGenLockId);
+	*xid = ShmemVariableCache->nextXid;
+	(ShmemVariableCache->nextXid)++;
+
+	if (MyProc != (PROC *) NULL)
+		MyProc->xid = *xid;
+
+	SpinRelease(XidGenLockId);
+
+}
+
+/*
+ * Like GetNewTransactionId reads nextXid but don't fetch it.
+ */
+void
+ReadNewTransactionId(TransactionId *xid)
+{
+
+	/*
+	 * During bootstrap initialization, we return the special
+	 * bootstrap transaction id.
+	 */
+	if (AMI_OVERRIDE)
+	{
+		*xid = AmiTransactionId;
+		return;
+	}
+
+	SpinAcquire(XidGenLockId);
+	*xid = ShmemVariableCache->nextXid;
+	SpinRelease(XidGenLockId);
+
+}
+
+/* ----------------------------------------------------------------
+ *					object id generation support
+ * ----------------------------------------------------------------
+ */
+
+#define VAR_OID_PREFETCH		8192
+static Oid lastSeenOid = InvalidOid;
+
+void
+GetNewObjectId(Oid *oid_return)
+{
+	SpinAcquire(OidGenLockId);
+
+	/* If we run out of logged for use oids then we log more */
+	if (ShmemVariableCache->oidCount == 0)
+	{
+		XLogPutNextOid(ShmemVariableCache->nextOid + VAR_OID_PREFETCH);
+		ShmemVariableCache->oidCount = VAR_OID_PREFETCH;
+	}
+
+	if (PointerIsValid(oid_return))
+		lastSeenOid = (*oid_return) = ShmemVariableCache->nextOid;
+
+	(ShmemVariableCache->nextOid)++;
+	(ShmemVariableCache->oidCount)--;
+
+	SpinRelease(OidGenLockId);
+}
+
+void
+CheckMaxObjectId(Oid assigned_oid)
+{
+
+	if (lastSeenOid != InvalidOid && assigned_oid < lastSeenOid)
+		return;
+
+	SpinAcquire(OidGenLockId);
+	if (assigned_oid < ShmemVariableCache->nextOid)
+	{
+		lastSeenOid = ShmemVariableCache->nextOid - 1;
+		SpinRelease(OidGenLockId);
+		return;
+	}
+
+	/* If we are in the logged oid range, just bump nextOid up */
+	if (assigned_oid <= ShmemVariableCache->nextOid + 
+						ShmemVariableCache->oidCount - 1)
+	{
+		ShmemVariableCache->oidCount -= 
+			assigned_oid - ShmemVariableCache->nextOid + 1;
+		ShmemVariableCache->nextOid = assigned_oid + 1;
+		SpinRelease(OidGenLockId);
+		return;
+	}
+
+	/*
+	 * We have exceeded the logged oid range.
+	 * We should lock the database and kill all other backends
+	 * but we are loading oid's that we can not guarantee are unique
+	 * anyway, so we must rely on the user.
+	 */
+
+	XLogPutNextOid(assigned_oid + VAR_OID_PREFETCH);
+	ShmemVariableCache->oidCount = VAR_OID_PREFETCH - 1;
+	ShmemVariableCache->nextOid = assigned_oid + 1;
+
+	SpinRelease(OidGenLockId);
+
+}