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Fix subtransaction behavior for large objects, temp namespace, files,

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password/group files.  Also allow read-only subtransactions of a read-write
parent, but not vice versa.  These are the reasonably noncontroversial
parts of Alvaro's recent mop-up patch, plus further work on large objects
to minimize use of the TopTransactionResourceOwner.
This commit is contained in:
Tom Lane
2004-07-28 14:23:31 +00:00
parent cc813fc2b8
commit 1bf3d61504
17 changed files with 572 additions and 205 deletions
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73
src/backend/libpq/be-fsstubs.c
View File

@@ -1,24 +1,22 @@
/*-------------------------------------------------------------------------
*
* be-fsstubs.c
* support for filesystem operations on large objects
* Builtin functions for open/close/read/write operations on large objects
*
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.70 2004/02/10 01:55:25 tgl Exp $
* $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.71 2004/07/28 14:23:28 tgl Exp $
*
* NOTES
* This should be moved to a more appropriate place. It is here
* for lack of a better place.
*
* Builtin functions for open/close/read/write operations on large objects.
*
* These functions operate in a private MemoryContext, which means
* that large object descriptors hang around until we destroy the context.
* That happens in lo_commit(). It'd be possible to prolong the lifetime
* that large object descriptors hang around until we destroy the context
* at transaction end. It'd be possible to prolong the lifetime
* of the context so that LO FDs are good across transactions (for example,
* we could release the context only if we see that no FDs remain open).
* But we'd need additional state in order to do the right thing at the
@@ -29,6 +27,11 @@
* existing documented semantics of LO FDs: they're only good within a
* transaction.
*
* As of PostgreSQL 7.5, much of the angst expressed above is no longer
* relevant, and in fact it'd be pretty easy to allow LO FDs to stay
* open across transactions. However backwards compatibility suggests
* that we should stick to the status quo.
*
*-------------------------------------------------------------------------
*/
@@ -46,8 +49,6 @@
#include "utils/memutils.h"
/* [PA] is Pascal Andr<64> <andre@via.ecp.fr> */
/*#define FSDB 1*/
#define BUFSIZE 8192
@@ -68,6 +69,7 @@ static MemoryContext fscxt = NULL;
static int newLOfd(LargeObjectDesc *lobjCookie);
static void deleteLOfd(int fd);
/*****************************************************************************
* File Interfaces for Large Objects
*****************************************************************************/
@@ -399,7 +401,7 @@ lo_import(PG_FUNCTION_ARGS)
lobjOid = lobj->id;
/*
* read in from the Unix file and write to the inversion file
* read in from the filesystem and write to the inversion file
*/
while ((nbytes = FileRead(fd, buf, BUFSIZE)) > 0)
{
@@ -471,7 +473,7 @@ lo_export(PG_FUNCTION_ARGS)
fnamebuf)));
/*
* read in from the inversion file and write to the Unix file
* read in from the inversion file and write to the filesystem
*/
while ((nbytes = inv_read(lobj, buf, BUFSIZE)) > 0)
{
@@ -490,11 +492,11 @@ lo_export(PG_FUNCTION_ARGS)
}
/*
* lo_commit -
* prepares large objects for transaction commit [PA, 7/17/98]
* AtEOXact_LargeObject -
* prepares large objects for transaction commit
*/
void
lo_commit(bool isCommit)
AtEOXact_LargeObject(bool isCommit)
{
int i;
MemoryContext currentContext;
@@ -505,8 +507,8 @@ lo_commit(bool isCommit)
currentContext = MemoryContextSwitchTo(fscxt);
/*
* Clean out still-open index scans (not necessary if aborting) and
* clear cookies array so that LO fds are no longer good.
* Close LO fds and clear cookies array so that LO fds are no longer good.
* On abort we skip the close step.
*/
for (i = 0; i < cookies_size; i++)
{
@@ -514,7 +516,7 @@ lo_commit(bool isCommit)
{
if (isCommit)
inv_close(cookies[i]);
cookies[i] = NULL;
deleteLOfd(i);
}
}
@@ -527,8 +529,47 @@ lo_commit(bool isCommit)
/* Release the LO memory context to prevent permanent memory leaks. */
MemoryContextDelete(fscxt);
fscxt = NULL;
/* Give inv_api.c a chance to clean up, too */
close_lo_relation(isCommit);
}
/*
* AtEOSubXact_LargeObject
* Take care of large objects at subtransaction commit/abort
*
* Reassign LOs created/opened during a committing subtransaction
* to the parent transaction. On abort, just close them.
*/
void
AtEOSubXact_LargeObject(bool isCommit, TransactionId myXid,
TransactionId parentXid)
{
int i;
if (fscxt == NULL) /* no LO operations in this xact */
return;
for (i = 0; i < cookies_size; i++)
{
LargeObjectDesc *lo = cookies[i];
if (lo != NULL && lo->xid == myXid)
{
if (isCommit)
lo->xid = parentXid;
else
{
/*
* Make sure we do not call inv_close twice if it errors out
* for some reason. Better a leak than a crash.
*/
deleteLOfd(i);
inv_close(lo);
}
}
}
}
/*****************************************************************************
* Support routines for this file