From 8add6d71cff28d087872215b02c7a0b84ba786c4 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 4 Sep 1999 18:36:45 +0000
Subject: [PATCH] Modify sinval so that InvalidateSharedInvalid() does not hold
the SInval spinlock while it is calling the passed invalFunction or
resetFunction. This is necessary to avoid deadlock with lmgr change;
InvalidateSharedInvalid can be called recursively now. It should be a good
performance improvement anyway --- holding a spinlock for more than a very
short interval is a no-no.
---
src/backend/storage/ipc/sinval.c | 57 ++++++++---
src/backend/storage/ipc/sinvaladt.c | 142 +++++++++++++---------------
src/include/storage/sinvaladt.h | 8 +-
3 files changed, 114 insertions(+), 93 deletions(-)
diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c
index 21585cc2406..e993cef74aa 100644
--- a/src/backend/storage/ipc/sinval.c
+++ b/src/backend/storage/ipc/sinval.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.16 1999/07/15 22:39:49 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.17 1999/09/04 18:36:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -21,9 +21,9 @@
#include "storage/sinval.h"
#include "storage/sinvaladt.h"
-extern SISeg *shmInvalBuffer; /* the shared buffer segment, set by */
-
- /* SISegmentAttach() */
+extern SISeg *shmInvalBuffer; /* the shared buffer segment, set by
+ * SISegmentAttach()
+ */
extern BackendId MyBackendId;
extern BackendTag MyBackendTag;
@@ -127,21 +127,20 @@ RegisterSharedInvalid(int cacheId, /* XXX */
ItemPointerSetInvalid(&newInvalid.pointerData);
SpinAcquire(SInvalLock);
- if (!SISetDataEntry(shmInvalBuffer, &newInvalid))
+ while (!SISetDataEntry(shmInvalBuffer, &newInvalid))
{
/* buffer full */
/* release a message, mark process cache states to be invalid */
SISetProcStateInvalid(shmInvalBuffer);
- if (!SIDelDataEntry(shmInvalBuffer))
+ if (!SIDelDataEntries(shmInvalBuffer, 1))
{
/* inconsistent buffer state -- shd never happen */
SpinRelease(SInvalLock);
elog(FATAL, "RegisterSharedInvalid: inconsistent buffer state");
}
- /* write again */
- SISetDataEntry(shmInvalBuffer, &newInvalid);
+ /* loop around to try write again */
}
SpinRelease(SInvalLock);
}
@@ -157,13 +156,41 @@ RegisterSharedInvalid(int cacheId, /* XXX */
/* should be called by a backend */
/****************************************************************************/
void
- InvalidateSharedInvalid(void (*invalFunction) (),
- void (*resetFunction) ())
+InvalidateSharedInvalid(void (*invalFunction) (),
+ void (*resetFunction) ())
{
- SpinAcquire(SInvalLock);
- SIReadEntryData(shmInvalBuffer, MyBackendId,
- invalFunction, resetFunction);
+ SharedInvalidData data;
+ int getResult;
+ bool gotMessage = false;
- SIDelExpiredDataEntries(shmInvalBuffer);
- SpinRelease(SInvalLock);
+ for (;;)
+ {
+ SpinAcquire(SInvalLock);
+ getResult = SIGetDataEntry(shmInvalBuffer, MyBackendId, &data);
+ SpinRelease(SInvalLock);
+ if (getResult == 0)
+ break; /* nothing more to do */
+ if (getResult < 0)
+ {
+ /* got a reset message */
+ elog(NOTICE, "InvalidateSharedInvalid: cache state reset");
+ resetFunction();
+ }
+ else
+ {
+ /* got a normal data message */
+ invalFunction(data.cacheId,
+ data.hashIndex,
+ &data.pointerData);
+ }
+ gotMessage = true;
+ }
+
+ /* If we got any messages, try to release dead messages */
+ if (gotMessage)
+ {
+ SpinAcquire(SInvalLock);
+ SIDelExpiredDataEntries(shmInvalBuffer);
+ SpinRelease(SInvalLock);
+ }
}
diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index cffc4aac229..2e64d027f31 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.23 1999/07/17 20:17:44 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.24 1999/09/04 18:36:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -450,20 +450,11 @@ SIGetLastDataEntry(SISeg *segP)
/************************************************************************/
/* SIGetNextDataEntry(segP, offset) returns next data entry */
/************************************************************************/
-static SISegEntry *
-SIGetNextDataEntry(SISeg *segP, Offset offset)
-{
- SISegEntry *eP;
-
- if (offset == InvalidOffset)
- return NULL;
-
- eP = (SISegEntry *) ((Pointer) segP +
- SIGetStartEntrySection(segP) +
- offset);
- return eP;
-}
-
+#define SIGetNextDataEntry(segP,offset) \
+ (((offset) == InvalidOffset) ? (SISegEntry *) NULL : \
+ (SISegEntry *) ((Pointer) (segP) + \
+ (segP)->startEntrySection + \
+ (Offset) (offset)))
/************************************************************************/
/* SIGetNthDataEntry(segP, n) returns the n-th data entry in chain */
@@ -566,31 +557,38 @@ SIDecProcLimit(SISeg *segP, int num)
/************************************************************************/
-/* SIDelDataEntry(segP) - free the FIRST entry */
+/* SIDelDataEntries(segP, n) - free the FIRST n entries */
/************************************************************************/
bool
-SIDelDataEntry(SISeg *segP)
+SIDelDataEntries(SISeg *segP, int n)
{
- SISegEntry *e1P;
+ int i;
+
+ if (n <= 0)
+ return false;
- if (!SIDecNumEntries(segP, 1))
+ if (!SIDecNumEntries(segP, n))
{
- /* no entries in buffer */
+ /* not that many entries in buffer */
return false;
}
- e1P = SIGetFirstDataEntry(segP);
- SISetStartEntryChain(segP, e1P->next);
- if (SIGetStartEntryChain(segP) == InvalidOffset)
+ for (i = 1; i <= n; i++)
{
- /* it was the last entry */
- SISetEndEntryChain(segP, InvalidOffset);
+ SISegEntry *e1P = SIGetFirstDataEntry(segP);
+ SISetStartEntryChain(segP, e1P->next);
+ if (SIGetStartEntryChain(segP) == InvalidOffset)
+ {
+ /* it was the last entry */
+ SISetEndEntryChain(segP, InvalidOffset);
+ }
+ /* free the entry */
+ e1P->isfree = true;
+ e1P->next = SIGetStartFreeSpace(segP);
+ SISetStartFreeSpace(segP, SIEntryOffset(segP, e1P));
}
- /* free the entry */
- e1P->isfree = true;
- e1P->next = SIGetStartFreeSpace(segP);
- SISetStartFreeSpace(segP, SIEntryOffset(segP, e1P));
- SIDecProcLimit(segP, 1);
+
+ SIDecProcLimit(segP, n);
return true;
}
@@ -621,51 +619,51 @@ SISetProcStateInvalid(SISeg *segP)
}
/************************************************************************/
-/* SIReadEntryData(segP, backendId, function) */
-/* - marks messages to be read by id */
-/* and executes function */
+/* SIGetDataEntry(segP, backendId, data) */
+/* get next SI message for specified backend, if there is one */
+/* */
+/* Possible return values: */
+/* 0: no SI message available */
+/* 1: next SI message has been extracted into *data */
+/* (there may be more messages available after this one!) */
+/* -1: SI reset message extracted */
/************************************************************************/
-void
-SIReadEntryData(SISeg *segP,
- int backendId,
- void (*invalFunction) (),
- void (*resetFunction) ())
+int
+SIGetDataEntry(SISeg *segP, int backendId,
+ SharedInvalidData *data)
{
- int i = 0;
- SISegEntry *data;
+ SISegEntry *msg;
Assert(segP->procState[backendId - 1].tag == MyBackendTag);
- if (!segP->procState[backendId - 1].resetState)
+ if (segP->procState[backendId - 1].resetState)
{
- /* invalidate data, but only those, you have not seen yet !! */
- /* therefore skip read messages */
- data = SIGetNthDataEntry(segP,
- SIGetProcStateLimit(segP, backendId - 1) + 1);
- while (data != NULL)
- {
- i++;
- segP->procState[backendId - 1].limit++; /* one more message read */
- invalFunction(data->entryData.cacheId,
- data->entryData.hashIndex,
- &data->entryData.pointerData);
- data = SIGetNextDataEntry(segP, data->next);
- }
- /* SIDelExpiredDataEntries(segP); */
- }
- else
- {
- /* backend must not read messages, its own state has to be reset */
- elog(NOTICE, "SIReadEntryData: cache state reset");
- resetFunction(); /* XXXX call it here, parameters? */
-
/* new valid state--mark all messages "read" */
segP->procState[backendId - 1].resetState = false;
segP->procState[backendId - 1].limit = SIGetNumEntries(segP);
+ return -1;
}
- /* check whether we can remove dead messages */
- if (i > MAXNUMMESSAGES)
- elog(FATAL, "SIReadEntryData: Invalid segment state");
+
+ /* Get next message for this backend, if any */
+
+ /* This is fairly inefficient if there are many messages,
+ * but normally there should not be...
+ */
+ msg = SIGetNthDataEntry(segP,
+ SIGetProcStateLimit(segP, backendId - 1) + 1);
+
+ if (msg == NULL)
+ return 0; /* nothing to read */
+
+ *data = msg->entryData; /* return contents of message */
+
+ segP->procState[backendId - 1].limit++; /* one more message read */
+
+ /* There may be other backends that haven't read the message,
+ * so we cannot delete it here.
+ * SIDelExpiredDataEntries() should be called to remove dead messages.
+ */
+ return 1; /* got a message */
}
/************************************************************************/
@@ -688,15 +686,12 @@ SIDelExpiredDataEntries(SISeg *segP)
min = h;
}
}
- if (min != 9999999)
+ if (min < 9999999 && min > 0)
{
/* we can remove min messages */
- for (i = 1; i <= min; i++)
- {
- /* this adjusts also the state limits! */
- if (!SIDelDataEntry(segP))
- elog(FATAL, "SIDelExpiredDataEntries: Invalid segment state");
- }
+ /* this adjusts also the state limits! */
+ if (!SIDelDataEntries(segP, min))
+ elog(FATAL, "SIDelExpiredDataEntries: Invalid segment state");
}
}
@@ -784,8 +779,7 @@ SISegmentAttach(IpcMemoryId shmid)
if (shmInvalBuffer == IpcMemAttachFailed)
{
/* XXX use validity function */
- elog(NOTICE, "SISegmentAttach: Could not attach segment");
- elog(FATAL, "SISegmentAttach: %m");
+ elog(FATAL, "SISegmentAttach: Could not attach segment: %m");
}
}
diff --git a/src/include/storage/sinvaladt.h b/src/include/storage/sinvaladt.h
index 4885b7380c8..e008e52d30f 100644
--- a/src/include/storage/sinvaladt.h
+++ b/src/include/storage/sinvaladt.h
@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
- * $Id: sinvaladt.h,v 1.16 1999/07/16 17:07:38 momjian Exp $
+ * $Id: sinvaladt.h,v 1.17 1999/09/04 18:36:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -128,9 +128,9 @@ extern int SISegmentInit(bool killExistingSegment, IPCKey key,
extern bool SISetDataEntry(SISeg *segP, SharedInvalidData *data);
extern void SISetProcStateInvalid(SISeg *segP);
-extern bool SIDelDataEntry(SISeg *segP);
-extern void SIReadEntryData(SISeg *segP, int backendId,
- void (*invalFunction) (), void (*resetFunction) ());
+extern int SIGetDataEntry(SISeg *segP, int backendId,
+ SharedInvalidData *data);
+extern bool SIDelDataEntries(SISeg *segP, int n);
extern void SIDelExpiredDataEntries(SISeg *segP);
#endif /* SINVALADT_H */
--
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