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Add a new option to RestoreBkpBlocks() to indicate if a cleanup lock should

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be used instead of the normal exclusive lock, and make WAL redo functions
responsible for calling RestoreBkpBlocks(). They know better what kind of a
lock they need.

At the moment, this just moves things around with no functional change, but
makes the hot standby patch that's under review cleaner.
This commit is contained in:
Heikki Linnakangas
2009-01-20 18:59:37 +00:00
parent b287f0a39e
commit b2a667b9ee
15 changed files with 95 additions and 36 deletions
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45
src/backend/access/transam/xlogutils.c
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@ -11,7 +11,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.66 2009/01/01 17:23:36 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.67 2009/01/20 18:59:37 heikki Exp $
*
*-------------------------------------------------------------------------
*/
@ -217,8 +217,19 @@ XLogCheckInvalidPages(void)
/*
* XLogReadBuffer
* A shorthand of XLogReadBufferExtended(), for reading from the main
* fork.
* Read a page during XLOG replay.
*
* This is a shorthand of XLogReadBufferExtended() followed by
* LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE), for reading from the main
* fork.
*
* (Getting the lock is not really necessary, since we expect that this is
* only used during single-process XLOG replay, but some subroutines such
* as MarkBufferDirty will complain if we don't. And hopefully we'll get
* hot standby support in the future, where there will be backends running
* read-only queries during XLOG replay.)
*
* The returned buffer is exclusively-locked.
*
* For historical reasons, instead of a ReadBufferMode argument, this only
* supports RBM_ZERO (init == true) and RBM_NORMAL (init == false) modes.
@ -226,22 +237,21 @@ XLogCheckInvalidPages(void)
Buffer
XLogReadBuffer(RelFileNode rnode, BlockNumber blkno, bool init)
{
return XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno,
init ? RBM_ZERO : RBM_NORMAL);
Buffer buf;
buf = XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno,
init ? RBM_ZERO : RBM_NORMAL);
if (BufferIsValid(buf))
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
return buf;
}
/*
* XLogReadBufferExtended
* Read a page during XLOG replay
*
* This is functionally comparable to ReadBuffer followed by
* LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE): you get back a pinned
* and locked buffer. (Getting the lock is not really necessary, since we
* expect that this is only used during single-process XLOG replay, but
* some subroutines such as MarkBufferDirty will complain if we don't.)
*
* There's some differences in the behavior wrt. the "mode" argument,
* compared to ReadBufferExtended:
* This is functionally comparable to ReadBufferExtended. There's some
* differences in the behavior wrt. the "mode" argument:
*
* In RBM_NORMAL mode, if the page doesn't exist, or contains all-zeroes, we
* return InvalidBuffer. In this case the caller should silently skip the
@ -306,16 +316,19 @@ XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
Assert(BufferGetBlockNumber(buffer) == blkno);
}
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
if (mode == RBM_NORMAL)
{
/* check that page has been initialized */
Page page = (Page) BufferGetPage(buffer);
/*
* We assume that PageIsNew is safe without a lock. During recovery,
* there should be no other backends that could modify the buffer at
* the same time.
*/
if (PageIsNew(page))
{
UnlockReleaseBuffer(buffer);
ReleaseBuffer(buffer);
log_invalid_page(rnode, forknum, blkno, true);
return InvalidBuffer;
}