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Code Activity

bufmgr: Introduce FlushUnlockedBuffer

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There were several copies of code locking a buffer, flushing its contents, and
unlocking the buffer. It seems worth centralizing that into a helper function.

Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com>
Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
This commit is contained in:
Andres Freund
2025-10-08 14:34:30 -04:00
parent 819dc118c0
commit 3c2b97b29e
1 changed files with 20 additions and 16 deletions
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36
src/backend/storage/buffer/bufmgr.c
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@@ -534,6 +534,8 @@ static inline BufferDesc *BufferAlloc(SMgrRelation smgr,
static bool AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress);
static void CheckReadBuffersOperation(ReadBuffersOperation *operation, bool is_complete);
static Buffer GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context);
static void FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln,
IOObject io_object, IOContext io_context);
static void FlushBuffer(BufferDesc *buf, SMgrRelation reln,
IOObject io_object, IOContext io_context);
static void FindAndDropRelationBuffers(RelFileLocator rlocator,
@@ -3927,11 +3929,8 @@ SyncOneBuffer(int buf_id, bool skip_recently_used, WritebackContext *wb_context)
* buffer is clean by the time we've locked it.)
*/
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
FlushBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
tag = bufHdr->tag;
@@ -4378,6 +4377,19 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
error_context_stack = errcallback.previous;
}
/*
* Convenience wrapper around FlushBuffer() that locks/unlocks the buffer
* before/after calling FlushBuffer().
*/
static void
FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln,
IOObject io_object, IOContext io_context)
{
LWLockAcquire(BufferDescriptorGetContentLock(buf), LW_SHARED);
FlushBuffer(buf, reln, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
LWLockRelease(BufferDescriptorGetContentLock(buf));
}
/*
* RelationGetNumberOfBlocksInFork
* Determines the current number of pages in the specified relation fork.
@@ -4967,9 +4979,7 @@ FlushRelationBuffers(Relation rel)
(buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
FlushBuffer(bufHdr, srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
FlushUnlockedBuffer(bufHdr, srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
UnpinBuffer(bufHdr);
}
else
@@ -5064,9 +5074,7 @@ FlushRelationsAllBuffers(SMgrRelation *smgrs, int nrels)
(buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
FlushBuffer(bufHdr, srelent->srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
FlushUnlockedBuffer(bufHdr, srelent->srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
UnpinBuffer(bufHdr);
}
else
@@ -5292,9 +5300,7 @@ FlushDatabaseBuffers(Oid dbid)
(buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
FlushBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
UnpinBuffer(bufHdr);
}
else
@@ -6569,10 +6575,8 @@ EvictUnpinnedBufferInternal(BufferDesc *desc, bool *buffer_flushed)
/* If it was dirty, try to clean it once. */
if (buf_state & BM_DIRTY)
{
LWLockAcquire(BufferDescriptorGetContentLock(desc), LW_SHARED);
FlushBuffer(desc, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
FlushUnlockedBuffer(desc, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
*buffer_flushed = true;
LWLockRelease(BufferDescriptorGetContentLock(desc));
}
/* This will return false if it becomes dirty or someone else pins it. */