143 lines
3.2 KiB
C
143 lines
3.2 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* varsup.c
|
|
* postgres OID & XID variables support routines
|
|
*
|
|
* Copyright (c) 2000, PostgreSQL Global Development Group
|
|
*
|
|
* IDENTIFICATION
|
|
* $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.35 2001/01/24 19:42:51 momjian 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);
|
|
|
|
}
|