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Improve gist XLOG code to follow the coding rules needed to prevent

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torn-page problems.  This introduces some issues of its own, mainly
that there are now some critical sections of unreasonably broad scope,
but it's a step forward anyway.  Further cleanup will require some
code refactoring that I'd prefer to get Oleg and Teodor involved in.
This commit is contained in:
Tom Lane
2006-03-30 23:03:10 +00:00
parent 4243f2387a
commit 89395bfa6f
4 changed files with 230 additions and 261 deletions
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105
src/backend/access/gist/gist.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.129 2006/03/05 15:58:20 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.130 2006/03/30 23:03:09 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -90,6 +90,7 @@ gistbuild(PG_FUNCTION_ARGS)
double reltuples;
GISTBuildState buildstate;
Buffer buffer;
Page page;
/*
* We expect to be called exactly once for any index relation. If that's
@ -104,33 +105,33 @@ gistbuild(PG_FUNCTION_ARGS)
/* initialize the root page */
buffer = gistNewBuffer(index);
Assert(BufferGetBlockNumber(buffer) == GIST_ROOT_BLKNO);
page = BufferGetPage(buffer);
START_CRIT_SECTION();
GISTInitBuffer(buffer, F_LEAF);
if (!index->rd_istemp)
{
XLogRecPtr recptr;
XLogRecData rdata;
Page page;
rdata.buffer = InvalidBuffer;
rdata.data = (char *) &(index->rd_node);
rdata.len = sizeof(RelFileNode);
rdata.buffer = InvalidBuffer;
rdata.next = NULL;
page = BufferGetPage(buffer);
START_CRIT_SECTION();
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_CREATE_INDEX, &rdata);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
END_CRIT_SECTION();
}
else
PageSetLSN(BufferGetPage(buffer), XLogRecPtrForTemp);
PageSetLSN(page, XLogRecPtrForTemp);
LockBuffer(buffer, GIST_UNLOCK);
WriteBuffer(buffer);
END_CRIT_SECTION();
/* build the index */
buildstate.numindexattrs = indexInfo->ii_NumIndexAttrs;
buildstate.indtuples = 0;
@ -305,6 +306,15 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
bool is_splitted = false;
bool is_leaf = (GistPageIsLeaf(state->stack->page)) ? true : false;
/*
* XXX this code really ought to work by locking, but not modifying,
* all the buffers it needs; then starting a critical section; then
* modifying the buffers in an already-determined way and writing an
* XLOG record to reflect that. Since it doesn't, we've got to put
* a critical section around the entire process, which is horrible
* from a robustness point of view.
*/
START_CRIT_SECTION();
if (!is_leaf)
@ -312,6 +322,11 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
* This node's key has been modified, either because a child split
* occurred or because we needed to adjust our key for an insert in a
* child node. Therefore, remove the old version of this node's key.
*
* Note: for WAL replay, in the non-split case we handle this by
* setting up a one-element todelete array; in the split case, it's
* handled implicitly because the tuple vector passed to gistSplit
* won't include this tuple.
*/
PageIndexTupleDelete(state->stack->page, state->stack->childoffnum);
@ -336,9 +351,7 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
XLogRecData *rdata;
rdata = formSplitRdata(state->r->rd_node, state->stack->blkno,
&(state->key), dist);
START_CRIT_SECTION();
is_leaf, &(state->key), dist);
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_PAGE_SPLIT, rdata);
ptr = dist;
@ -348,8 +361,6 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
PageSetTLI(BufferGetPage(ptr->buffer), ThisTimeLineID);
ptr = ptr->next;
}
END_CRIT_SECTION();
}
else
{
@ -410,7 +421,6 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
else
ourpage = dist;
/* now gets all needed data, and sets nsn's */
page = (Page) BufferGetPage(ourpage->buffer);
opaque = GistPageGetOpaque(page);
@ -437,8 +447,11 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
WriteBuffer(ptr->buffer);
ptr = ptr->next;
}
WriteNoReleaseBuffer(state->stack->buffer);
}
WriteNoReleaseBuffer(state->stack->buffer);
END_CRIT_SECTION();
}
else
{
@ -451,7 +464,7 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
if (!state->r->rd_istemp)
{
OffsetNumber noffs = 0,
offs[MAXALIGN(sizeof(OffsetNumber)) / sizeof(OffsetNumber)];
offs[1];
XLogRecPtr recptr;
XLogRecData *rdata;
@ -462,17 +475,14 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
noffs = 1;
}
rdata = formUpdateRdata(state->r->rd_node, state->stack->blkno,
offs, noffs, false, state->itup, state->ituplen,
rdata = formUpdateRdata(state->r->rd_node, state->stack->buffer,
offs, noffs, false,
state->itup, state->ituplen,
&(state->key));
START_CRIT_SECTION();
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_ENTRY_UPDATE, rdata);
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_PAGE_UPDATE, rdata);
PageSetLSN(state->stack->page, recptr);
PageSetTLI(state->stack->page, ThisTimeLineID);
END_CRIT_SECTION();
}
else
PageSetLSN(state->stack->page, XLogRecPtrForTemp);
@ -481,6 +491,8 @@ gistplacetopage(GISTInsertState *state, GISTSTATE *giststate)
state->needInsertComplete = false;
WriteNoReleaseBuffer(state->stack->buffer);
END_CRIT_SECTION();
if (!is_leaf) /* small optimization: inform scan ablout
* deleting... */
gistadjscans(state->r, GISTOP_DEL, state->stack->blkno,
@ -636,30 +648,14 @@ gistfindleaf(GISTInsertState *state, GISTSTATE *giststate)
}
/*
* Should have the same interface as XLogReadBuffer
*/
static Buffer
gistReadAndLockBuffer(Relation r, BlockNumber blkno)
{
Buffer buffer = ReadBuffer(r, blkno);
LockBuffer(buffer, GIST_SHARE);
return buffer;
}
/*
* Traverse the tree to find path from root page.
* Traverse the tree to find path from root page to specified "child" block.
*
* returns from the begining of closest parent;
*
* Function is used in both regular and recovery mode, so must work with
* different read functions (gistReadAndLockBuffer and XLogReadBuffer)
*
* To prevent deadlocks, this should lock only one page simultaneously.
*/
GISTInsertStack *
gistFindPath(Relation r, BlockNumber child,
Buffer (*myReadBuffer) (Relation, BlockNumber))
gistFindPath(Relation r, BlockNumber child)
{
Page page;
Buffer buffer;
@ -677,7 +673,8 @@ gistFindPath(Relation r, BlockNumber child,
while (top && top->blkno != child)
{
buffer = myReadBuffer(r, top->blkno); /* locks buffer */
buffer = ReadBuffer(r, top->blkno);
LockBuffer(buffer, GIST_SHARE);
gistcheckpage(r, buffer);
page = (Page) BufferGetPage(buffer);
@ -833,7 +830,7 @@ gistFindCorrectParent(Relation r, GISTInsertStack *child)
}
/* ok, find new path */
ptr = parent = gistFindPath(r, child->blkno, gistReadAndLockBuffer);
ptr = parent = gistFindPath(r, child->blkno);
Assert(ptr != NULL);
/* read all buffers as expected by caller */
@ -1192,27 +1189,31 @@ gistnewroot(Relation r, Buffer buffer, IndexTuple *itup, int len, ItemPointer ke
Assert(BufferGetBlockNumber(buffer) == GIST_ROOT_BLKNO);
page = BufferGetPage(buffer);
GISTInitBuffer(buffer, 0);
START_CRIT_SECTION();
GISTInitBuffer(buffer, 0); /* XXX not F_LEAF? */
gistfillbuffer(r, page, itup, len, FirstOffsetNumber);
if (!r->rd_istemp)
{
XLogRecPtr recptr;
XLogRecData *rdata;
rdata = formUpdateRdata(r->rd_node, GIST_ROOT_BLKNO,
NULL, 0, false, itup, len, key);
START_CRIT_SECTION();
rdata = formUpdateRdata(r->rd_node, buffer,
NULL, 0, false,
itup, len, key);
recptr = XLogInsert(RM_GIST_ID, XLOG_GIST_NEW_ROOT, rdata);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
END_CRIT_SECTION();
}
else
PageSetLSN(page, XLogRecPtrForTemp);
WriteNoReleaseBuffer(buffer);
END_CRIT_SECTION();
}
void