Remove arbitrary limit on number of simultaneously open large objects.

This used to make some sense under the old implementation, but now an
open LO is pretty darn cheap, so why restrict it?

src/backend/libpq/be-fsstubs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.55 2000/10/24 01:38:26 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.56 2000/10/24 03:14:08 tgl Exp $
  *
  * NOTES
  *	  This should be moved to a more appropriate place.  It is here
@@ -49,15 +49,18 @@
 /* [PA] is Pascal Andr <andre@via.ecp.fr> */
 
 /*#define FSDB 1*/
-#define MAX_LOBJ_FDS	256
 #define BUFSIZE			8192
 
 /*
- * LO "FD"s are indexes into this array.
+ * 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.
+ * 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.
  */
-static LargeObjectDesc *cookies[MAX_LOBJ_FDS];
+static LargeObjectDesc **cookies = NULL;
+static int cookies_size = 0;
 
 static MemoryContext fscxt = NULL;
 
@@ -104,14 +107,8 @@ lo_open(PG_FUNCTION_ARGS)
 
 	fd = newLOfd(lobjDesc);
 
-	/* switch context back to orig. */
 	MemoryContextSwitchTo(currentContext);
 
-#if FSDB
-	if (fd < 0)					/* newLOfd couldn't find a slot */
-		elog(NOTICE, "Out of space for large object FDs");
-#endif
-
 	PG_RETURN_INT32(fd);
 }
 
@@ -121,15 +118,10 @@ lo_close(PG_FUNCTION_ARGS)
 	int32		fd = PG_GETARG_INT32(0);
 	MemoryContext currentContext;
 
-	if (fd < 0 || fd >= MAX_LOBJ_FDS)
-	{
-		elog(ERROR, "lo_close: large obj descriptor (%d) out of range", fd);
-		PG_RETURN_INT32(-2);
-	}
-	if (cookies[fd] == NULL)
+	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
 	{
 		elog(ERROR, "lo_close: invalid large obj descriptor (%d)", fd);
-		PG_RETURN_INT32(-3);
+		PG_RETURN_INT32(-1);
 	}
 #if FSDB
 	elog(NOTICE, "lo_close(%d)", fd);
@@ -162,15 +154,10 @@ lo_read(int fd, char *buf, int len)
 	MemoryContext currentContext;
 	int			status;
 
-	if (fd < 0 || fd >= MAX_LOBJ_FDS)
-	{
-		elog(ERROR, "lo_read: large obj descriptor (%d) out of range", fd);
-		return -2;
-	}
-	if (cookies[fd] == NULL)
+	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
 	{
 		elog(ERROR, "lo_read: invalid large obj descriptor (%d)", fd);
-		return -3;
+		return -1;
 	}
 
 	Assert(fscxt != NULL);
@@ -189,15 +176,10 @@ lo_write(int fd, char *buf, int len)
 	MemoryContext currentContext;
 	int			status;
 
-	if (fd < 0 || fd >= MAX_LOBJ_FDS)
-	{
-		elog(ERROR, "lo_write: large obj descriptor (%d) out of range", fd);
-		return -2;
-	}
-	if (cookies[fd] == NULL)
+	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
 	{
 		elog(ERROR, "lo_write: invalid large obj descriptor (%d)", fd);
-		return -3;
+		return -1;
 	}
 
 	Assert(fscxt != NULL);
@@ -220,15 +202,10 @@ lo_lseek(PG_FUNCTION_ARGS)
 	MemoryContext currentContext;
 	int			status;
 
-	if (fd < 0 || fd >= MAX_LOBJ_FDS)
-	{
-		elog(ERROR, "lo_lseek: large obj descriptor (%d) out of range", fd);
-		PG_RETURN_INT32(-2);
-	}
-	if (cookies[fd] == NULL)
+	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
 	{
 		elog(ERROR, "lo_lseek: invalid large obj descriptor (%d)", fd);
-		PG_RETURN_INT32(-3);
+		PG_RETURN_INT32(-1);
 	}
 
 	Assert(fscxt != NULL);
@@ -280,15 +257,10 @@ lo_tell(PG_FUNCTION_ARGS)
 {
 	int32		fd = PG_GETARG_INT32(0);
 
-	if (fd < 0 || fd >= MAX_LOBJ_FDS)
-	{
-		elog(ERROR, "lo_tell: large object descriptor (%d) out of range", fd);
-		PG_RETURN_INT32(-2);
-	}
-	if (cookies[fd] == NULL)
+	if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
 	{
 		elog(ERROR, "lo_tell: invalid large object descriptor (%d)", fd);
-		PG_RETURN_INT32(-3);
+		PG_RETURN_INT32(-1);
 	}
 
 	/*
@@ -304,13 +276,30 @@ lo_unlink(PG_FUNCTION_ARGS)
 {
 	Oid			lobjId = PG_GETARG_OID(0);
 
+	/*
+	 * If there are any open LO FDs referencing that ID, close 'em.
+	 */
+	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)
+			{
+				inv_close(cookies[i]);
+				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.)
-	 *
-	 * XXX there ought to be some code to clean up any open LO FDs that
-	 * reference the specified LO... as is, they remain "open".
 	 */
 	PG_RETURN_INT32(inv_drop(lobjId));
 }
@@ -502,7 +491,7 @@ lo_commit(bool isCommit)
 	 * Clean out still-open index scans (not necessary if aborting) and
 	 * clear cookies array so that LO fds are no longer good.
 	 */
-	for (i = 0; i < MAX_LOBJ_FDS; i++)
+	for (i = 0; i < cookies_size; i++)
 	{
 		if (cookies[i] != NULL)
 		{
@@ -512,6 +501,10 @@ lo_commit(bool isCommit)
 		}
 	}
 
+	/* Needn't actually pfree since we're about to zap context */
+	cookies = NULL;
+	cookies_size = 0;
+
 	MemoryContextSwitchTo(currentContext);
 
 	/* Release the LO memory context to prevent permanent memory leaks. */
@@ -527,18 +520,45 @@ lo_commit(bool isCommit)
 static int
 newLOfd(LargeObjectDesc *lobjCookie)
 {
-	int			i;
+	int			i,
+				newsize;
 
-	for (i = 0; i < MAX_LOBJ_FDS; i++)
+	/* Try to find a free slot */
+	for (i = 0; i < cookies_size; i++)
 	{
-
 		if (cookies[i] == NULL)
 		{
 			cookies[i] = lobjCookie;
 			return i;
 		}
 	}
-	return -1;
+
+	/* No free slot, so make the array bigger */
+	if (cookies_size <= 0)
+	{
+		/* First time through, arbitrarily make 64-element array */
+		i = 0;
+		newsize = 64;
+		cookies = (LargeObjectDesc **)
+			palloc(newsize * sizeof(LargeObjectDesc *));
+		MemSet(cookies, 0, newsize * sizeof(LargeObjectDesc *));
+		cookies_size = newsize;
+	}
+	else
+	{
+		/* Double size of array */
+		i = cookies_size;
+		newsize = cookies_size * 2;
+		cookies = (LargeObjectDesc **)
+			repalloc(cookies, newsize * sizeof(LargeObjectDesc *));
+		MemSet(cookies + cookies_size, 0,
+			   (newsize - cookies_size) * sizeof(LargeObjectDesc *));
+		cookies_size = newsize;
+	}
+
+	Assert(cookies[i] == NULL);
+	cookies[i] = lobjCookie;
+	return i;
 }
 
 static void