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Restructure backend SIGINT/SIGTERM handling so that 'die' interrupts

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are treated more like 'cancel' interrupts: the signal handler sets a
flag that is examined at well-defined spots, rather than trying to cope
with an interrupt that might happen anywhere.  See pghackers discussion
of 1/12/01.
This commit is contained in:
Tom Lane
2001-01-14 05:08:17 +00:00
parent 027f144e39
commit 36839c1927
24 changed files with 614 additions and 479 deletions
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73
src/backend/storage/buffer/bufmgr.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.103 2001/01/12 21:53:57 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.104 2001/01/14 05:08:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -92,6 +92,7 @@ static Buffer ReadBufferWithBufferLock(Relation relation, BlockNumber blockNum,
bool bufferLockHeld);
static BufferDesc *BufferAlloc(Relation reln, BlockNumber blockNum,
bool *foundPtr, bool bufferLockHeld);
static int ReleaseBufferWithBufferLock(Buffer buffer);
static int BufferReplace(BufferDesc *bufHdr);
void PrintBufferDescs(void);
@ -687,10 +688,14 @@ ReleaseAndReadBuffer(Buffer buffer,
{
bufHdr = &BufferDescriptors[buffer - 1];
Assert(PrivateRefCount[buffer - 1] > 0);
PrivateRefCount[buffer - 1]--;
if (PrivateRefCount[buffer - 1] == 0)
if (PrivateRefCount[buffer - 1] > 1)
{
PrivateRefCount[buffer - 1]--;
}
else
{
SpinAcquire(BufMgrLock);
PrivateRefCount[buffer - 1] = 0;
Assert(bufHdr->refcount > 0);
bufHdr->refcount--;
if (bufHdr->refcount == 0)
@ -1185,10 +1190,7 @@ recheck:
/* Assert checks that buffer will actually get freed! */
Assert(PrivateRefCount[i - 1] == 1 &&
bufHdr->refcount == 1);
/* ReleaseBuffer expects we do not hold the lock at entry */
SpinRelease(BufMgrLock);
ReleaseBuffer(i);
SpinAcquire(BufMgrLock);
ReleaseBufferWithBufferLock(i);
}
/*
* And mark the buffer as no longer occupied by this rel.
@ -1270,10 +1272,7 @@ recheck:
/* Assert checks that buffer will actually get freed! */
Assert(PrivateRefCount[i - 1] == 1 &&
bufHdr->refcount == 1);
/* ReleaseBuffer expects we do not hold the lock at entry */
SpinRelease(BufMgrLock);
ReleaseBuffer(i);
SpinAcquire(BufMgrLock);
ReleaseBufferWithBufferLock(i);
}
/*
* And mark the buffer as no longer occupied by this rel.
@ -1624,10 +1623,14 @@ ReleaseBuffer(Buffer buffer)
bufHdr = &BufferDescriptors[buffer - 1];
Assert(PrivateRefCount[buffer - 1] > 0);
PrivateRefCount[buffer - 1]--;
if (PrivateRefCount[buffer - 1] == 0)
if (PrivateRefCount[buffer - 1] > 1)
{
PrivateRefCount[buffer - 1]--;
}
else
{
SpinAcquire(BufMgrLock);
PrivateRefCount[buffer - 1] = 0;
Assert(bufHdr->refcount > 0);
bufHdr->refcount--;
if (bufHdr->refcount == 0)
@ -1641,6 +1644,48 @@ ReleaseBuffer(Buffer buffer)
return STATUS_OK;
}
/*
* ReleaseBufferWithBufferLock
* Same as ReleaseBuffer except we hold the lock
*/
static int
ReleaseBufferWithBufferLock(Buffer buffer)
{
BufferDesc *bufHdr;
if (BufferIsLocal(buffer))
{
Assert(LocalRefCount[-buffer - 1] > 0);
LocalRefCount[-buffer - 1]--;
return STATUS_OK;
}
if (BAD_BUFFER_ID(buffer))
return STATUS_ERROR;
bufHdr = &BufferDescriptors[buffer - 1];
Assert(PrivateRefCount[buffer - 1] > 0);
if (PrivateRefCount[buffer - 1] > 1)
{
PrivateRefCount[buffer - 1]--;
}
else
{
PrivateRefCount[buffer - 1] = 0;
Assert(bufHdr->refcount > 0);
bufHdr->refcount--;
if (bufHdr->refcount == 0)
{
AddBufferToFreelist(bufHdr);
bufHdr->flags |= BM_FREE;
}
}
return STATUS_OK;
}
#ifdef NOT_USED
void
IncrBufferRefCount_Debug(char *file, int line, Buffer buffer)
@ -2217,9 +2262,9 @@ MarkBufferForCleanup(Buffer buffer, void (*CleanupFunc)(Buffer))
SpinRelease(BufMgrLock);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
PrivateRefCount[buffer - 1]--;
SpinAcquire(BufMgrLock);
PrivateRefCount[buffer - 1] = 0;
Assert(bufHdr->refcount > 0);
bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED);
bufHdr->CleanupFunc = CleanupFunc;