*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.81 2006/03/05 15:58:27 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.82 2006/04/26 00:34:57 tgl Exp $
*
* NOTES
* This should be moved to a more appropriate place. It is here
* for lack of a better place.
*
- * These functions operate in a private MemoryContext, which means
- * that large object descriptors hang around until we destroy the context
- * at transaction end. It'd be possible to prolong the lifetime
+ * These functions store LargeObjectDesc structs in a private MemoryContext,
+ * which means 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
*
* As of PostgreSQL 8.0, 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.
+ * open across transactions. (Snapshot relevancy would still be an issue.)
+ * However backwards compatibility suggests that we should stick to the
+ * status quo.
*
*-------------------------------------------------------------------------
*/
* LO "FD"s are indexes into the cookies array.
*
* A non-null entry is a pointer to a LargeObjectDesc allocated in the
- * LO private memory context. The cookies array itself is also dynamically
- * allocated in that context. Its current allocated size is cookies_len
- * entries, of which any unused entries will be NULL.
+ * LO private memory context "fscxt". The cookies array itself is also
+ * dynamically allocated in that context. Its current allocated size is
+ * cookies_len entries, of which any unused entries will be NULL.
*/
static LargeObjectDesc **cookies = NULL;
static int cookies_size = 0;
int32 mode = PG_GETARG_INT32(1);
LargeObjectDesc *lobjDesc;
int fd;
- MemoryContext currentContext;
#if FSDB
elog(DEBUG4, "lo_open(%u,%d)", lobjId, mode);
CreateFSContext();
- currentContext = MemoryContextSwitchTo(fscxt);
-
- lobjDesc = inv_open(lobjId, mode);
+ lobjDesc = inv_open(lobjId, mode, fscxt);
if (lobjDesc == NULL)
{ /* lookup failed */
- MemoryContextSwitchTo(currentContext);
#if FSDB
elog(DEBUG4, "could not open large object %u", lobjId);
#endif
fd = newLOfd(lobjDesc);
- MemoryContextSwitchTo(currentContext);
-
PG_RETURN_INT32(fd);
}
lo_close(PG_FUNCTION_ARGS)
{
int32 fd = PG_GETARG_INT32(0);
- MemoryContext currentContext;
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
{
elog(DEBUG4, "lo_close(%d)", fd);
#endif
- Assert(fscxt != NULL);
- currentContext = MemoryContextSwitchTo(fscxt);
-
inv_close(cookies[fd]);
deleteLOfd(fd);
- MemoryContextSwitchTo(currentContext);
-
PG_RETURN_INT32(0);
}
int
lo_read(int fd, char *buf, int len)
{
- MemoryContext currentContext;
int status;
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
return -1;
}
- Assert(fscxt != NULL);
- currentContext = MemoryContextSwitchTo(fscxt);
-
status = inv_read(cookies[fd], buf, len);
- MemoryContextSwitchTo(currentContext);
-
return status;
}
int
lo_write(int fd, char *buf, int len)
{
- MemoryContext currentContext;
int status;
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
errmsg("large object descriptor %d was not opened for writing",
fd)));
- Assert(fscxt != NULL);
- currentContext = MemoryContextSwitchTo(fscxt);
-
status = inv_write(cookies[fd], buf, len);
- MemoryContextSwitchTo(currentContext);
-
return status;
}
int32 fd = PG_GETARG_INT32(0);
int32 offset = PG_GETARG_INT32(1);
int32 whence = PG_GETARG_INT32(2);
- MemoryContext currentContext;
int status;
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
PG_RETURN_INT32(-1);
}
- Assert(fscxt != NULL);
- currentContext = MemoryContextSwitchTo(fscxt);
-
status = inv_seek(cookies[fd], offset, whence);
- MemoryContextSwitchTo(currentContext);
-
PG_RETURN_INT32(status);
}
lo_creat(PG_FUNCTION_ARGS)
{
Oid lobjId;
- MemoryContext currentContext;
- /* do we actually need fscxt for this? */
+ /*
+ * We don't actually need to store into fscxt, but create it anyway to
+ * ensure that AtEOXact_LargeObject knows there is state to clean up
+ */
CreateFSContext();
- currentContext = MemoryContextSwitchTo(fscxt);
-
lobjId = inv_create(InvalidOid);
- MemoryContextSwitchTo(currentContext);
-
PG_RETURN_OID(lobjId);
}
lo_create(PG_FUNCTION_ARGS)
{
Oid lobjId = PG_GETARG_OID(0);
- MemoryContext currentContext;
- /* do we actually need fscxt for this? */
+ /*
+ * We don't actually need to store into fscxt, but create it anyway to
+ * ensure that AtEOXact_LargeObject knows there is state to clean up
+ */
CreateFSContext();
- currentContext = MemoryContextSwitchTo(fscxt);
-
lobjId = inv_create(lobjId);
- MemoryContextSwitchTo(currentContext);
-
PG_RETURN_OID(lobjId);
}
PG_RETURN_INT32(-1);
}
- /*
- * We assume we do not need to switch contexts for inv_tell. That is true
- * for now, but is probably more than this module ought to assume...
- */
PG_RETURN_INT32(inv_tell(cookies[fd]));
}
*/
if (fscxt != NULL)
{
- MemoryContext currentContext;
int i;
- currentContext = MemoryContextSwitchTo(fscxt);
for (i = 0; i < cookies_size; i++)
{
if (cookies[i] != NULL && cookies[i]->id == lobjId)
deleteLOfd(i);
}
}
- MemoryContextSwitchTo(currentContext);
}
/*
- * inv_drop does not need a context switch, indeed it doesn't touch any
- * LO-specific data structures at all. (Again, that's probably more than
- * this module ought to be assuming.)
+ * inv_drop does not create a need for end-of-transaction cleanup and
+ * hence we don't need to have created fscxt.
*/
PG_RETURN_INT32(inv_drop(lobjId));
}
errhint("Anyone can use the client-side lo_import() provided by libpq.")));
#endif
- /*
- * We don't actually need to switch into fscxt, but create it anyway to
- * ensure that AtEOXact_LargeObject knows there is state to clean up
- */
CreateFSContext();
/*
/*
* read in from the filesystem and write to the inversion object
*/
- lobj = inv_open(lobjOid, INV_WRITE);
+ lobj = inv_open(lobjOid, INV_WRITE, fscxt);
while ((nbytes = FileRead(fd, buf, BUFSIZE)) > 0)
{
errhint("Anyone can use the client-side lo_export() provided by libpq.")));
#endif
- /*
- * We don't actually need to switch into fscxt, but create it anyway to
- * ensure that AtEOXact_LargeObject knows there is state to clean up
- */
CreateFSContext();
/*
* open the inversion object (no need to test for failure)
*/
- lobj = inv_open(lobjId, INV_READ);
+ lobj = inv_open(lobjId, INV_READ, fscxt);
/*
* open the file to be written to
AtEOXact_LargeObject(bool isCommit)
{
int i;
- MemoryContext currentContext;
if (fscxt == NULL)
return; /* no LO operations in this xact */
- currentContext = MemoryContextSwitchTo(fscxt);
-
/*
* Close LO fds and clear cookies array so that LO fds are no longer good.
* On abort we skip the close step.
cookies = NULL;
cookies_size = 0;
- MemoryContextSwitchTo(currentContext);
-
/* Release the LO memory context to prevent permanent memory leaks. */
MemoryContextDelete(fscxt);
fscxt = NULL;
i = 0;
newsize = 64;
cookies = (LargeObjectDesc **)
- palloc(newsize * sizeof(LargeObjectDesc *));
- MemSet(cookies, 0, newsize * sizeof(LargeObjectDesc *));
+ MemoryContextAllocZero(fscxt, newsize * sizeof(LargeObjectDesc *));
cookies_size = newsize;
}
else
* routines for manipulating inversion fs large objects. This file
* contains the user-level large object application interface routines.
*
+ *
+ * Note: many of these routines leak memory in CurrentMemoryContext, as indeed
+ * does most of the backend code. We expect that CurrentMemoryContext will
+ * be a short-lived context. Data that must persist across function calls
+ * is kept either in CacheMemoryContext (the Relation structs) or in the
+ * memory context given to inv_open (for LargeObjectDesc structs).
+ *
+ *
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/large_object/inv_api.c,v 1.115 2006/03/05 15:58:38 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/large_object/inv_api.c,v 1.116 2006/04/26 00:34:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
* inv_open -- access an existing large object.
*
* Returns:
- * large object descriptor, appropriately filled in.
+ * Large object descriptor, appropriately filled in. The descriptor
+ * and subsidiary data are allocated in the specified memory context,
+ * which must be suitably long-lived for the caller's purposes.
*/
LargeObjectDesc *
-inv_open(Oid lobjId, int flags)
+inv_open(Oid lobjId, int flags, MemoryContext mcxt)
{
LargeObjectDesc *retval;
- retval = (LargeObjectDesc *) palloc(sizeof(LargeObjectDesc));
+ retval = (LargeObjectDesc *) MemoryContextAlloc(mcxt,
+ sizeof(LargeObjectDesc));
retval->id = lobjId;
retval->subid = GetCurrentSubTransactionId();
}
else if (flags & INV_READ)
{
- /* be sure to copy snap into fscxt */
+ /* be sure to copy snap into mcxt */
+ MemoryContext oldContext = MemoryContextSwitchTo(mcxt);
+
retval->snapshot = CopySnapshot(ActiveSnapshot);
retval->flags = IFS_RDLOCK;
+ MemoryContextSwitchTo(oldContext);
}
else
elog(ERROR, "invalid flags: %d", flags);
}
/*
- * Closes an existing large object descriptor.
+ * Closes a large object descriptor previously made by inv_open(), and
+ * releases the long-term memory used by it.
*/
void
inv_close(LargeObjectDesc *obj_desc)
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