diff options
Diffstat (limited to 'src/backend/storage/buffer/localbuf.c')
| -rw-r--r-- | src/backend/storage/buffer/localbuf.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c index bcbedc9c651..17f86ce44e4 100644 --- a/src/backend/storage/buffer/localbuf.c +++ b/src/backend/storage/buffer/localbuf.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.52 2004/02/10 01:55:25 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.53 2004/04/21 18:06:30 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -36,19 +36,25 @@ static int nextFreeLocalBuf = 0; /* * LocalBufferAlloc - * allocate a local buffer. We do round robin allocation for now. + * + * API is similar to bufmgr.c's BufferAlloc, except that we do not need + * to have the BufMgrLock since this is all local. Also, IO_IN_PROGRESS + * does not get set. */ BufferDesc * LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) { + BufferTag newTag; /* identity of requested block */ int i; - BufferDesc *bufHdr = NULL; + BufferDesc *bufHdr; + + INIT_BUFFERTAG(newTag, reln, blockNum); /* a low tech search for now -- not optimized for scans */ for (i = 0; i < NLocBuffer; i++) { - if (LocalBufferDescriptors[i].tag.rnode.relNode == - reln->rd_node.relNode && - LocalBufferDescriptors[i].tag.blockNum == blockNum) + bufHdr = &LocalBufferDescriptors[i]; + if (BUFFERTAGS_EQUAL(bufHdr->tag, newTag)) { #ifdef LBDEBUG fprintf(stderr, "LB ALLOC (%u,%d) %d\n", @@ -56,8 +62,14 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) #endif LocalRefCount[i]++; - *foundPtr = TRUE; - return &LocalBufferDescriptors[i]; + if (bufHdr->flags & BM_VALID) + *foundPtr = TRUE; + else + { + /* Previous read attempt must have failed; try again */ + *foundPtr = FALSE; + } + return bufHdr; } } @@ -67,6 +79,7 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) #endif /* need to get a new buffer (round robin for now) */ + bufHdr = NULL; for (i = 0; i < NLocBuffer; i++) { int b = (nextFreeLocalBuf + i) % NLocBuffer; @@ -108,7 +121,7 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) * * Note this path cannot be taken for a buffer that was previously in * use, so it's okay to do it (and possibly error out) before marking - * the buffer as valid. + * the buffer as not dirty. */ if (bufHdr->data == (SHMEM_OFFSET) 0) { @@ -135,9 +148,8 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) /* * it's all ours now. */ - bufHdr->tag.rnode = reln->rd_node; - bufHdr->tag.blockNum = blockNum; - bufHdr->flags &= ~BM_DIRTY; + bufHdr->tag = newTag; + bufHdr->flags &= ~(BM_VALID | BM_DIRTY | BM_JUST_DIRTIED | BM_IO_ERROR); bufHdr->cntxDirty = false; *foundPtr = FALSE; |