This patch reserves the last superuser_reserved_connections slots for

connections by the superuser only.

This patch replaces the last patch I sent a couple of days ago.

It closes a connection that has not been authorised by a superuser if it would
leave less than the GUC variable ReservedBackends
(superuser_reserved_connections in postgres.conf) backend process slots free
in the SISeg. This differs to the first patch which only reserved the last
ReservedBackends slots in the procState array. This has made the free slot
test more expensive due to the use of a lock.

After thinking about a comment on the first patch I've also made it a fatal
error if the number of reserved slots is not less than the maximum number of
connections.

Nigel J. Andrews

3 files changed, 7 insertions, 3 deletions

diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index f2f6f5c6760..fce4fea4b40 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: miscadmin.h,v 1.106 2002/06/20 20:29:42 momjian Exp $
+ * $Id: miscadmin.h,v 1.107 2002/08/29 21:02:12 momjian Exp $
  *
  * NOTES
  *	  some of the information in this file should be moved to
@@ -179,6 +179,7 @@ extern bool NetServer;
 extern bool EnableSSL;
 extern bool SilentMode;
 extern int	MaxBackends;
+extern int	ReservedBackends;
 extern int	NBuffers;
 extern int	PostPortNumber;
 extern int	Unix_socket_permissions;
diff --git a/src/include/storage/sinval.h b/src/include/storage/sinval.h
index 7af8f444470..1188c68c95a 100644
--- a/src/include/storage/sinval.h
+++ b/src/include/storage/sinval.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: sinval.h,v 1.28 2002/06/20 20:29:52 momjian Exp $
+ * $Id: sinval.h,v 1.29 2002/08/29 21:02:12 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -89,4 +89,6 @@ extern int	CountActiveBackends(void);
 /* Use "struct PGPROC", not PGPROC, to avoid including proc.h here */
 extern struct PGPROC *BackendIdGetProc(BackendId procId);
 
+extern int CountEmptyBackendSlots(void);
+
 #endif   /* SINVAL_H */
diff --git a/src/include/storage/sinvaladt.h b/src/include/storage/sinvaladt.h
index 3e95342c9f8..39c895026b4 100644
--- a/src/include/storage/sinvaladt.h
+++ b/src/include/storage/sinvaladt.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: sinvaladt.h,v 1.32 2002/06/20 20:29:52 momjian Exp $
+ * $Id: sinvaladt.h,v 1.33 2002/08/29 21:02:12 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -85,6 +85,7 @@ typedef struct SISeg
 	int			lastBackend;	/* index of last active procState entry,
 								 * +1 */
 	int			maxBackends;	/* size of procState array */
+	int			freeBackends;	/* number of empty procState slots */
 
 	/*
 	 * Circular buffer holding shared-inval messages