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Implement LockBufferForCleanup(), which will allow concurrent VACUUM

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to wait until it's safe to remove tuples and compact free space in a
shared buffer page.  Miscellaneous small code cleanups in bufmgr, too.
This commit is contained in:
Tom Lane
2001-07-06 21:04:26 +00:00
parent 1e9e5defc2
commit 55432fedd2
11 changed files with 418 additions and 254 deletions
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63
src/backend/storage/buffer/freelist.c
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@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/freelist.c,v 1.23 2001/01/24 19:43:06 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/freelist.c,v 1.24 2001/07/06 21:04:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -29,14 +29,14 @@
#include "storage/buf_internals.h"
#include "storage/bufmgr.h"
#include "storage/proc.h"
static BufferDesc *SharedFreeList;
/* only actually used in debugging. The lock
* should be acquired before calling the freelist manager.
/*
* State-checking macros
*/
extern SPINLOCK BufMgrLock;
#define IsInQueue(bf) \
( \
@@ -45,7 +45,7 @@ extern SPINLOCK BufMgrLock;
AssertMacro((bf->flags & BM_FREE)) \
)
#define NotInQueue(bf) \
#define IsNotInQueue(bf) \
( \
AssertMacro((bf->freeNext == INVALID_DESCRIPTOR)), \
AssertMacro((bf->freePrev == INVALID_DESCRIPTOR)), \
@@ -61,14 +61,14 @@ extern SPINLOCK BufMgrLock;
* the manner in which buffers are added to the freelist queue.
* Currently, they are added on an LRU basis.
*/
void
static void
AddBufferToFreelist(BufferDesc *bf)
{
#ifdef BMTRACE
_bm_trace(bf->tag.relId.dbId, bf->tag.relId.relId, bf->tag.blockNum,
BufferDescriptorGetBuffer(bf), BMT_DEALLOC);
#endif /* BMTRACE */
NotInQueue(bf);
IsNotInQueue(bf);
/* change bf so it points to inFrontOfNew and its successor */
bf->freePrev = SharedFreeList->freePrev;
@@ -83,13 +83,14 @@ AddBufferToFreelist(BufferDesc *bf)
/*
* PinBuffer -- make buffer unavailable for replacement.
*
* This should be applied only to shared buffers, never local ones.
* Bufmgr lock must be held by caller.
*/
void
PinBuffer(BufferDesc *buf)
{
long b;
/* Assert (buf->refcount < 25); */
int b = BufferDescriptorGetBuffer(buf) - 1;
if (buf->refcount == 0)
{
@@ -104,13 +105,12 @@ PinBuffer(BufferDesc *buf)
buf->flags &= ~BM_FREE;
}
else
NotInQueue(buf);
IsNotInQueue(buf);
b = BufferDescriptorGetBuffer(buf) - 1;
Assert(PrivateRefCount[b] >= 0);
if (PrivateRefCount[b] == 0)
buf->refcount++;
PrivateRefCount[b]++;
Assert(PrivateRefCount[b] > 0);
}
#ifdef NOT_USED
@@ -135,24 +135,35 @@ refcount = %ld, file: %s, line: %d\n",
/*
* UnpinBuffer -- make buffer available for replacement.
*
* This should be applied only to shared buffers, never local ones.
* Bufmgr lock must be held by caller.
*/
void
UnpinBuffer(BufferDesc *buf)
{
long b = BufferDescriptorGetBuffer(buf) - 1;
int b = BufferDescriptorGetBuffer(buf) - 1;
IsNotInQueue(buf);
Assert(buf->refcount > 0);
Assert(PrivateRefCount[b] > 0);
PrivateRefCount[b]--;
if (PrivateRefCount[b] == 0)
buf->refcount--;
NotInQueue(buf);
if (buf->refcount == 0)
{
/* buffer is now unpinned */
AddBufferToFreelist(buf);
buf->flags |= BM_FREE;
}
else if ((buf->flags & BM_PIN_COUNT_WAITER) != 0 &&
buf->refcount == 1)
{
/* we just released the last pin other than the waiter's */
buf->flags &= ~BM_PIN_COUNT_WAITER;
ProcSendSignal(buf->wait_backend_id);
}
else
{
/* do nothing */
@@ -179,18 +190,16 @@ refcount = %ld, file: %s, line: %d\n",
/*
* GetFreeBuffer() -- get the 'next' buffer from the freelist.
*
*/
BufferDesc *
GetFreeBuffer()
GetFreeBuffer(void)
{
BufferDesc *buf;
if (Free_List_Descriptor == SharedFreeList->freeNext)
{
/* queue is empty. All buffers in the buffer pool are pinned. */
elog(ERROR, "out of free buffers: time to abort !\n");
elog(ERROR, "out of free buffers: time to abort!");
return NULL;
}
buf = &(BufferDescriptors[SharedFreeList->freeNext]);
@@ -220,7 +229,7 @@ InitFreeList(bool init)
if (init)
{
/* we only do this once, normally the postmaster */
/* we only do this once, normally in the postmaster */
SharedFreeList->data = INVALID_OFFSET;
SharedFreeList->flags = 0;
SharedFreeList->flags &= ~(BM_VALID | BM_DELETED | BM_FREE);
@@ -249,37 +258,23 @@ DBG_FreeListCheck(int nfree)
buf = &(BufferDescriptors[SharedFreeList->freeNext]);
for (i = 0; i < nfree; i++, buf = &(BufferDescriptors[buf->freeNext]))
{
if (!(buf->flags & (BM_FREE)))
{
if (buf != SharedFreeList)
{
printf("\tfree list corrupted: %d flags %x\n",
buf->buf_id, buf->flags);
}
else
{
printf("\tfree list corrupted: too short -- %d not %d\n",
i, nfree);
}
}
if ((BufferDescriptors[buf->freeNext].freePrev != buf->buf_id) ||
(BufferDescriptors[buf->freePrev].freeNext != buf->buf_id))
{
printf("\tfree list links corrupted: %d %ld %ld\n",
buf->buf_id, buf->freePrev, buf->freeNext);
}
}
if (buf != SharedFreeList)
{
printf("\tfree list corrupted: %d-th buffer is %d\n",
nfree, buf->buf_id);
}
}
#endif