On Sun, Jun 20, 2004 at 08:49:22PM -0400, Tom Lane wrote:
> There's a good deal more than that missing :-(. Here are the modules or
> actions that are called in CommitTransaction and/or AbortTransaction
> that have not yet been touched by the patch:
>
> localbuf.c (refcounts need fixed same as bufmgr)
Here is a patch against the original versions of these files; cleaned up
bufmgr.c somewhat. Adds the same logic to local buffers (moving the
BufferRefCount struct declaration to buf_internals.h so it's shared by
both bufmgr.c and localbuf.c). Needs xact.c and xact.h patched as in
the second patch.
As with the bufmgr.c original patch, I don't really know how to test
that this actually works. I fooled around with printing what it was
doing during a subtrans commit/abort, and it seems OK, but that's about
it. In what situations can a transaction roll back with a nonzero
reference count in a local buffer?
--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"I dream about dreams about dreams", sang the nightingale
under the pale moon (Sandman)
Index: src/include/storage/bufmgr.h
===================================================================
RCS file: /home/alvherre/cvs/pgsql-server/src/include/storage/bufmgr.h,v
retrieving revision 1.82
diff -c -r1.82 bufmgr.h
*** src/include/storage/bufmgr.h 31 May 2004 19:24:05 -0000 1.82
--- src/include/storage/bufmgr.h 21 Jun 2004 20:29:08 -0000
***************
*** 148,153 ****
--- 148,155 ----
extern char *ShowBufferUsage(void);
extern void ResetBufferUsage(void);
extern void AtEOXact_Buffers(bool isCommit);
+ extern void AtSubStart_Buffers(void);
+ extern void AtEOSubXact_Buffers(bool commit);
extern void FlushBufferPool(void);
extern BlockNumber BufferGetBlockNumber(Buffer buffer);
extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
Index: src/include/storage/buf_internals.h
===================================================================
RCS file: /home/alvherre/cvs/pgsql-server/src/include/storage/buf_internals.h,v
retrieving revision 1.71
diff -c -r1.71 buf_internals.h
*** src/include/storage/buf_internals.h 18 Jun 2004 06:14:13 -0000 1.71
--- src/include/storage/buf_internals.h 29 Jun 2004 13:21:23 -0000
***************
*** 175,180 ****
--- 175,189 ----
extern long int BufferFlushCount;
extern long int LocalBufferFlushCount;
+ /*
+ * We use a list of this struct to keep track of buffer reference
+ * count checking at subtransaction boundaries.
+ */
+ typedef struct BufferRefCount
+ {
+ Buffer buffer;
+ int refcount;
+ } BufferRefCount;
/*
* Bufmgr Interface:
***************
*** 211,215 ****
--- 220,226 ----
bool *foundPtr);
extern void WriteLocalBuffer(Buffer buffer, bool release);
extern void AtEOXact_LocalBuffers(bool isCommit);
+ extern void AtSubStart_LocalBuffers(void);
+ extern void AtSubEnd_LocalBuffers(bool isCommit);
#endif /* BUFMGR_INTERNALS_H */
Index: src/backend/storage/buffer/bufmgr.c
===================================================================
RCS file: /home/alvherre/cvs/pgsql-server/src/backend/storage/buffer/bufmgr.c,v
retrieving revision 1.171
diff -c -r1.171 bufmgr.c
*** src/backend/storage/buffer/bufmgr.c 18 Jun 2004 06:13:33 -0000 1.171
--- src/backend/storage/buffer/bufmgr.c 29 Jun 2004 20:26:09 -0000
***************
*** 38,43 ****
--- 38,44 ----
#include <sys/file.h>
#include <unistd.h>
+ #include "access/xact.h"
#include "lib/stringinfo.h"
#include "miscadmin.h"
#include "storage/buf_internals.h"
***************
*** 46,51 ****
--- 47,53 ----
#include "storage/proc.h"
#include "storage/smgr.h"
#include "utils/relcache.h"
+ #include "utils/memutils.h"
#include "pgstat.h"
***************
*** 67,72 ****
--- 69,75 ----
static void PinBuffer(BufferDesc *buf);
static void UnpinBuffer(BufferDesc *buf);
+ static inline void BufferFixLeak(Buffer buffer, int should, bool warn);
static void WaitIO(BufferDesc *buf);
static void StartBufferIO(BufferDesc *buf, bool forInput);
static void TerminateBufferIO(BufferDesc *buf, int err_flag);
***************
*** 826,853 ****
for (i = 0; i < NBuffers; i++)
{
if (PrivateRefCount[i] != 0)
! {
! BufferDesc *buf = &(BufferDescriptors[i]);
! if (isCommit)
! elog(WARNING,
! "buffer refcount leak: [%03d] "
! "(rel=%u/%u/%u, blockNum=%u, flags=0x%x,
refcount=%u %d)",
! i,
! buf->tag.rnode.spcNode, buf->tag.rnode.dbNode,
! buf->tag.rnode.relNode,
! buf->tag.blockNum, buf->flags,
! buf->refcount, PrivateRefCount[i]);
! PrivateRefCount[i] = 1; /* make sure we release shared
pin */
! LWLockAcquire(BufMgrLock, LW_EXCLUSIVE);
! UnpinBuffer(buf);
! LWLockRelease(BufMgrLock);
! Assert(PrivateRefCount[i] == 0);
}
}
! AtEOXact_LocalBuffers(isCommit);
}
/*
--- 829,958 ----
for (i = 0; i < NBuffers; i++)
{
if (PrivateRefCount[i] != 0)
! BufferFixLeak(i, 0, isCommit);
! }
! AtEOXact_LocalBuffers(isCommit);
! }
! /*
! * During subtransaction start, save buffer reference counts
! * that are nonzero.
! */
! void
! AtSubStart_Buffers(void)
! {
! List *refcounts = NIL;
! MemoryContext old_cxt;
! int i;
!
! /*
! * XXX It would be better to have a per-subxact memory context
! * where we could keep this things. We don't have one ATM
! * so we free them by hand afterwards.
! */
! old_cxt = MemoryContextSwitchTo(TopTransactionContext);
!
! for (i = 0; i < NBuffers; i++)
! {
! BufferRefCount *brc;
!
! if (PrivateRefCount[i] == 0)
! continue;
!
! brc = (BufferRefCount *) palloc(sizeof(BufferRefCount));
! brc->buffer = i;
! brc->refcount = PrivateRefCount[i];
!
! refcounts = lappend(refcounts, brc);
! }
!
! TransactionSetBufferRefcounts(refcounts);
!
! MemoryContextSwitchTo(old_cxt);
!
! AtSubStart_LocalBuffers();
! }
!
! /*
! * AtEOSubXact_Buffers
! *
! * At subtransaction end, we restore the saved counts. If committing, we croak
! * if the refcounts don't match; if aborting, just restore silently.
! *
! * This only works because we know the list is in ascending order.
! */
! void
! AtEOSubXact_Buffers(bool commit)
! {
! List *counts = TransactionGetBufferRefcounts();
! ListCell *nextElt;
! int i, j;
! Buffer nextSaved;
!
! nextElt = list_head(counts);
!
! for (i = 0; i < NBuffers; i++)
! {
! BufferRefCount *brc = NULL;
!
! if (nextElt)
! {
! brc = (BufferRefCount *) lfirst(nextElt);
! nextSaved = brc->buffer;
}
+ else
+ nextSaved = NBuffers;
+
+ /*
+ * Buffers that are not on the saved list are supposed
+ * to have refcount 0. If they do not, unpin them.
+ * In the commit case, emit a message.
+ */
+ for (j = i; j < nextSaved; j++, i++)
+ if (PrivateRefCount[j] != 0)
+ BufferFixLeak(j, 0, commit);
+
+ /* No more buffers to check. */
+ if (nextSaved == NBuffers)
+ break;
+
+ if (PrivateRefCount[i] != brc->refcount)
+ BufferFixLeak(i, brc->refcount, commit);
+
+ if (nextElt)
+ nextElt = nextElt->next;
}
! /* Free the whole list, including the elements. */
! list_free_deep(counts);
!
! AtSubEnd_LocalBuffers(commit);
! }
!
! /*
! * Fix a buffer refcount leak.
! */
! inline void
! BufferFixLeak(Buffer buffer, int should, bool emitWarning)
! {
! BufferDesc *buf = &(BufferDescriptors[buffer]);
!
! if (emitWarning)
! elog(WARNING,
! "buffer refcount leak: [%03d] "
! "(rel=%u/%u/%u, blockNum=%u, flags=0x%x, refcount=%u
%d, should be=%d)",
! buffer,
! buf->tag.rnode.spcNode, buf->tag.rnode.dbNode,
! buf->tag.rnode.relNode,
! buf->tag.blockNum, buf->flags,
! buf->refcount, PrivateRefCount[buffer], should);
!
! PrivateRefCount[buffer] = 1; /* make sure we release shared pin */
! LWLockAcquire(BufMgrLock, LW_EXCLUSIVE);
! UnpinBuffer(buf);
! LWLockRelease(BufMgrLock);
! Assert(PrivateRefCount[buffer] == 0);
}
/*
Index: src/backend/storage/buffer/localbuf.c
===================================================================
RCS file: /home/alvherre/cvs/pgsql-server/src/backend/storage/buffer/localbuf.c,v
retrieving revision 1.56
diff -c -r1.56 localbuf.c
*** src/backend/storage/buffer/localbuf.c 18 Jun 2004 06:13:33 -0000 1.56
--- src/backend/storage/buffer/localbuf.c 29 Jun 2004 13:21:39 -0000
***************
*** 15,23 ****
--- 15,25 ----
*/
#include "postgres.h"
+ #include "access/xact.h"
#include "storage/buf_internals.h"
#include "storage/bufmgr.h"
#include "storage/smgr.h"
+ #include "utils/memutils.h"
#include "utils/relcache.h"
***************
*** 32,37 ****
--- 34,40 ----
static int nextFreeLocalBuf = 0;
+ static inline void LocalBufferFixLeak(Buffer buffer, int should, bool emitWarning);
/*
* LocalBufferAlloc -
***************
*** 229,248 ****
int i;
for (i = 0; i < NLocBuffer; i++)
- {
if (LocalRefCount[i] != 0)
! {
! BufferDesc *buf = &(LocalBufferDescriptors[i]);
! if (isCommit)
! elog(WARNING,
! "local buffer leak: [%03d] (rel=%u/%u/%u,
blockNum=%u, flags=0x%x, refcount=%u %d)",
! i,
! buf->tag.rnode.spcNode, buf->tag.rnode.dbNode,
! buf->tag.rnode.relNode, buf->tag.blockNum,
buf->flags,
! buf->refcount, LocalRefCount[i]);
! LocalRefCount[i] = 0;
}
}
}
--- 232,343 ----
int i;
for (i = 0; i < NLocBuffer; i++)
if (LocalRefCount[i] != 0)
! LocalBufferFixLeak(i, 0, isCommit);
! }
!
! inline void
! LocalBufferFixLeak(Buffer buffer, int should, bool emitWarning)
! {
! BufferDesc *buf = &(LocalBufferDescriptors[buffer]);
!
! if (emitWarning)
! elog(WARNING,
! "local buffer leak: [%03d] (rel=%u/%u/%u, blockNum=%u,
flags=0x%x, refcount=%u %d should be=%d)",
! buffer,
! buf->tag.rnode.spcNode, buf->tag.rnode.dbNode,
! buf->tag.rnode.relNode, buf->tag.blockNum, buf->flags,
! buf->refcount, LocalRefCount[buffer], should);
!
! LocalRefCount[buffer] = should;
! }
!
!
! /*
! * AtSubStart_LocalBuffers
! *
! * Save reference counts for local buffers.
! */
! void
! AtSubStart_LocalBuffers(void)
! {
! MemoryContext old_cxt;
! List *refcounts = NIL;
! int i;
!
! old_cxt = MemoryContextSwitchTo(TopTransactionContext);
!
! for (i = 0; i < NLocBuffer; i++)
! {
! BufferRefCount *brc;
! if (LocalRefCount[i] == 0)
! continue;
!
! brc = (BufferRefCount *) palloc(sizeof(BufferRefCount));
! brc->buffer = i;
! brc->refcount = LocalRefCount[i];
!
! refcounts = lappend(refcounts, brc);
! }
!
! TransactionSetLocalBufferRefcounts(refcounts);
!
! MemoryContextSwitchTo(old_cxt);
! }
! /*
! * AtSubEnd_LocalBuffers
! *
! * Restore (and possible croak about) local buffer reference counts
! * at subtransaction end.
! */
! void
! AtSubEnd_LocalBuffers(bool commit)
! {
! List *counts = TransactionGetLocalBufferRefcounts();
! ListCell *nextElt;
! int i, j;
! Buffer nextSaved;
!
! nextElt = list_head(counts);
!
! for (i = 0; i < NLocBuffer; i++)
! {
! BufferRefCount *brc = NULL;
!
! /*
! * If there is a next element in this list, skip
! * all local buffers until that element. If not,
! * skip until the end of the local buffer array.
! */
! if (nextElt)
! {
! brc = (BufferRefCount *) lfirst(nextElt);
! nextSaved = brc->buffer;
}
+ else
+ nextSaved = NLocBuffer;
+
+ /*
+ * Buffers not in the list should have a refcount of 0.
+ */
+ for (j = i; j < nextSaved; j++, i++)
+ if (LocalRefCount[j] != 0)
+ LocalBufferFixLeak(j, 0, commit);
+
+ /*
+ * Stop here if we are at the end of the array.
+ */
+ if (nextSaved == NLocBuffer)
+ break;
+
+ if (LocalRefCount[i] != brc->refcount)
+ LocalBufferFixLeak(i, brc->refcount, commit);
+
+ if (nextElt)
+ nextElt = nextElt->next;
}
+
+ list_free_deep(counts);
}
*** src/backend/access/transam/xact.c~ 2004-06-29 16:38:23.468928928 -0400
--- src/backend/access/transam/xact.c 2004-06-29 16:38:29.306995811 -0400
***************
*** 230,235 ****
--- 230,236 ----
NIL, /* async notifies */
NIL, /* committed child Xids */
NIL, /* bufmgr refcounts */
+ NIL, /* local bufmgr refcounts */
NIL, /* GUC variables */
NULL, /* deferred triggers state */
0, /* XLog record offset
*/
***************
*** 499,504 ****
--- 500,527 ----
}
/*
+ * TransactionSetLocalBufferRefcounts
+ */
+ void
+ TransactionSetLocalBufferRefcounts(List *counts)
+ {
+ TransactionState s = CurrentTransactionState;
+
+ s->localBufRefCnts = counts;
+ }
+
+ /*
+ * TransactionGetLocalBufferRefcounts
+ */
+ List *
+ TransactionGetLocalBufferRefcounts(void)
+ {
+ TransactionState s = CurrentTransactionState;
+
+ return s->localBufRefCnts;
+ }
+
+ /*
* TransactionSaveGucVar
*
* This is called from GUC, so be sure to use the right MemoryContext.
*** src/include/access/xact.h~ 2004-06-29 16:39:24.256213104 -0400
--- src/include/access/xact.h 2004-06-29 16:39:27.125754456 -0400
***************
*** 97,102 ****
--- 97,103 ----
List *notifies;
List *childXids;
List *bufRefCnts;
+ List *localBufRefCnts;
List *GUCvars;
void *deftrigState;
uint32 XLogRecOff;
***************
*** 165,170 ****
--- 166,173 ----
extern void TransactionSetParentNotifies(List *);
extern List *TransactionGetBufferRefcounts(void);
extern void TransactionSetBufferRefcounts(List *);
+ extern List *TransactionGetLocalBufferRefcounts(void);
+ extern void TransactionSetLocalBufferRefcounts(List *);
extern void TransactionSaveGucVar(void *);
extern void TransactionSetDeftrigState(void *);
extern void *TransactionGetDeftrigState(void);
---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ?
http://www.postgresql.org/docs/faqs/FAQ.html
