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Code review for holdable-cursors patch. Fix error recovery, memory

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context sloppiness, some other things.  Includes Neil's mopup patch
of 22-Apr.
This commit is contained in:
Tom Lane
2003-04-29 03:21:30 +00:00
parent 6a17d226b5
commit 4a5f38c4e6
18 changed files with 379 additions and 316 deletions
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137
src/backend/utils/mmgr/portalmem.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.54 2003/03/27 16:51:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.55 2003/04/29 03:21:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -33,6 +33,7 @@
#include "postgres.h"
#include "commands/portalcmds.h"
#include "executor/executor.h"
#include "utils/hsearch.h"
#include "utils/memutils.h"
@@ -156,14 +157,14 @@ GetPortalByName(const char *name)
/*
* PortalSetQuery
* Attaches a "query" to the specified portal. Note that in the
* case of DECLARE CURSOR, some Portal options have already been
* set based upon the parsetree of the original DECLARE statement.
* Attaches a QueryDesc to the specified portal. This should be
* called only after successfully doing ExecutorStart for the query.
*
* Note that in the case of DECLARE CURSOR, some Portal options have
* already been set in portalcmds.c's PreparePortal(). This is grotty.
*/
void
PortalSetQuery(Portal portal,
QueryDesc *queryDesc,
void (*cleanup) (Portal portal))
PortalSetQuery(Portal portal, QueryDesc *queryDesc)
{
AssertArg(PortalIsValid(portal));
@@ -174,18 +175,15 @@ PortalSetQuery(Portal portal,
*/
if (portal->scrollType == DEFAULT_SCROLL)
{
bool backwardPlan;
backwardPlan = ExecSupportsBackwardScan(queryDesc->plantree);
if (backwardPlan)
if (ExecSupportsBackwardScan(queryDesc->plantree))
portal->scrollType = ENABLE_SCROLL;
else
portal->scrollType = DISABLE_SCROLL;
}
portal->queryDesc = queryDesc;
portal->cleanup = cleanup;
portal->executorRunning = true; /* now need to shut down executor */
portal->atStart = true;
portal->atEnd = false; /* allow fetches */
portal->portalPos = 0;
@@ -228,12 +226,13 @@ CreatePortal(const char *name)
/* initialize portal query */
portal->queryDesc = NULL;
portal->cleanup = NULL;
portal->cleanup = PortalCleanup;
portal->scrollType = DEFAULT_SCROLL;
portal->executorRunning = false;
portal->holdOpen = false;
portal->createXact = GetCurrentTransactionId();
portal->holdStore = NULL;
portal->holdContext = NULL;
portal->createXact = GetCurrentTransactionId();
portal->atStart = true;
portal->atEnd = true; /* disallow fetches until query is set */
portal->portalPos = 0;
@@ -249,67 +248,34 @@ CreatePortal(const char *name)
* PortalDrop
* Destroy the portal.
*
* keepHoldable: if true, holdable portals should not be removed by
* this function. More specifically, invoking this function with
* keepHoldable = true on a holdable portal prepares the portal for
* access outside of its creating transaction.
* isError: if true, we are destroying portals at the end of a failed
* transaction. (This causes PortalCleanup to skip unneeded steps.)
*/
void
PortalDrop(Portal portal, bool persistHoldable)
PortalDrop(Portal portal, bool isError)
{
AssertArg(PortalIsValid(portal));
if (portal->holdOpen && persistHoldable)
{
/*
* We're "dropping" a holdable portal, but what we really need
* to do is prepare the portal for access outside of its
* creating transaction.
*/
/*
* Create the memory context that is used for storage of
* long-term (cross transaction) data needed by the holdable
* portal.
*/
portal->holdContext =
AllocSetContextCreate(PortalMemory,
"PortalHeapMemory",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* Note that PersistHoldablePortal() releases any resources used
* by the portal that are local to the creating txn.
*/
PersistHoldablePortal(portal);
return;
}
/* remove portal from hash table */
/*
* Remove portal from hash table. Because we do this first, we will
* not come back to try to remove the portal again if there's any error
* in the subsequent steps. Better to leak a little memory than to get
* into an infinite error-recovery loop.
*/
PortalHashTableDelete(portal);
/* reset portal */
/* let portalcmds.c clean up the state it knows about */
if (PointerIsValid(portal->cleanup))
(*portal->cleanup) (portal);
(*portal->cleanup) (portal, isError);
/*
* delete short-term memory context; in the case of a holdable
* portal, this has already been done
*/
if (PortalGetHeapMemory(portal))
MemoryContextDelete(PortalGetHeapMemory(portal));
/*
* delete long-term memory context; in the case of a non-holdable
* portal, this context has never been created, so we don't need to
* do anything
*/
/* delete tuplestore storage, if any */
if (portal->holdContext)
MemoryContextDelete(portal->holdContext);
/* release subsidiary storage */
if (PortalGetHeapMemory(portal))
MemoryContextDelete(PortalGetHeapMemory(portal));
/* release name and portal data (both are in PortalMemory) */
pfree(portal->name);
pfree(portal);
@@ -320,8 +286,8 @@ PortalDrop(Portal portal, bool persistHoldable)
* transaction was aborted, all the portals created in this transaction
* should be removed. If the transaction was successfully committed, any
* holdable cursors created in this transaction need to be kept
* open. Only cursors created in the current transaction should be
* removed in this fashion.
* open. In any case, portals remaining from prior transactions should
* be left untouched.
*
* XXX This assumes that portals can be deleted in a random order, ie,
* no portal has a reference to any other (at least not one that will be
@@ -340,7 +306,42 @@ AtEOXact_portals(bool isCommit)
while ((hentry = (PortalHashEnt *) hash_seq_search(&status)) != NULL)
{
if (hentry->portal->createXact == xact)
PortalDrop(hentry->portal, isCommit);
Portal portal = hentry->portal;
if (portal->createXact != xact)
continue;
if (portal->holdOpen && isCommit)
{
/*
* We are exiting the transaction that created a holdable
* cursor. Instead of dropping the portal, prepare it for
* access by later transactions.
*/
/*
* Create the memory context that is used for storage of
* the held cursor's tuple set.
*/
portal->holdContext =
AllocSetContextCreate(PortalMemory,
"PortalHeapMemory",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* Transfer data into the held tuplestore.
*
* Note that PersistHoldablePortal() must release all
* resources used by the portal that are local to the creating
* transaction.
*/
PersistHoldablePortal(portal);
}
else
{
PortalDrop(portal, !isCommit);
}
}
}