diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index bc8b859f3001ce4849d29dfa1092f30d900bf059..bbec926434d0c33f529e43ffe00762890b9a6725 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.285 2002/08/18 03:03:25 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.286 2002/08/29 21:02:12 momjian Exp $
*
* NOTES
*
@@ -151,6 +151,18 @@ char *VirtualHost;
*/
int MaxBackends = DEF_MAXBACKENDS;
+/*
+ * ReservedBackends is the number of backends reserved for superuser use.
+ * This number is taken out of the pool size given by MaxBackends so
+ * number of backend slots available to none super users is
+ * (MaxBackends - ReservedBackends). Note, existing super user
+ * connections are not taken into account once this lower limit has
+ * been reached, i.e. superuser connections made before the lower limit
+ * is reached always count towards that limit and are not taken from
+ * ReservedBackends.
+ */
+int ReservedBackends = 2;
+
static char *progname = (char *) NULL;
@@ -567,6 +579,12 @@ PostmasterMain(int argc, char *argv[])
ProcessConfigFile(PGC_POSTMASTER);
+ /*
+ * Force an exit if ReservedBackends is not less than MaxBackends.
+ */
+ if (ReservedBackends >= MaxBackends)
+ elog(FATAL,"superuser_reserved_connections must be less than max_connections.");
+
/*
* Now that we are done processing the postmaster arguments, reset
* getopt(3) library so that it will work correctly in subprocesses.
diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c
index 940ab32b3311af4fa644849c1e4dfcb08e1ab3d8..745a9c068deb25c80237f8bb768a4ff2ef54537a 100644
--- a/src/backend/storage/ipc/sinval.c
+++ b/src/backend/storage/ipc/sinval.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.49 2002/06/20 20:29:35 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.50 2002/08/29 21:02:12 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -538,3 +538,27 @@ BackendIdGetProc(BackendId procId)
return NULL;
}
+
+/*
+ * CountEmptyBackendSlots - count empty slots in backend process table
+ *
+ * Doesn't count since the procState array could be large and we've already
+ * allowed for that by running a freeBackends counter in the SI segment.
+ * Unlike CountActiveBackends() we do not need to interrogate the
+ * backends to determine the free slot count.
+ * Goes for a lock despite being a trival look up in case other backends
+ * are busy starting or exiting since there is scope for confusion.
+ */
+int
+CountEmptyBackendSlots(void)
+{
+ int count;
+
+ LWLockAcquire(SInvalLock, LW_SHARED);
+
+ count = shmInvalBuffer->freeBackends;
+
+ LWLockRelease(SInvalLock);
+
+ return count;
+}
diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index c88055c07b51e4e6018b408d6fa38a69945955d8..b4ab1689f942de57ccdde5cc43c6b4cc0486265f 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.47 2002/06/20 20:29:35 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.48 2002/08/29 21:02:12 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -60,6 +60,7 @@ SIBufferInit(int maxBackends)
segP->maxMsgNum = 0;
segP->lastBackend = 0;
segP->maxBackends = maxBackends;
+ segP->freeBackends = maxBackends;
/* The buffer[] array is initially all unused, so we need not fill it */
@@ -91,6 +92,13 @@ SIBackendInit(SISeg *segP)
int index;
ProcState *stateP = NULL;
+ if (segP->freeBackends == 0)
+ {
+ /* out of procState slots */
+ MyBackendId = InvalidBackendId;
+ return 0;
+ }
+
/* Look for a free entry in the procState array */
for (index = 0; index < segP->lastBackend; index++)
{
@@ -103,18 +111,9 @@ SIBackendInit(SISeg *segP)
if (stateP == NULL)
{
- if (segP->lastBackend < segP->maxBackends)
- {
- stateP = &segP->procState[segP->lastBackend];
- Assert(stateP->nextMsgNum < 0);
- segP->lastBackend++;
- }
- else
- {
- /* out of procState slots */
- MyBackendId = InvalidBackendId;
- return 0;
- }
+ stateP = &segP->procState[segP->lastBackend];
+ Assert(stateP->nextMsgNum < 0);
+ segP->lastBackend++;
}
MyBackendId = (stateP - &segP->procState[0]) + 1;
@@ -123,6 +122,9 @@ SIBackendInit(SISeg *segP)
elog(DEBUG1, "SIBackendInit: backend id %d", MyBackendId);
#endif /* INVALIDDEBUG */
+ /* Reduce free slot count */
+ segP->freeBackends--;
+
/* mark myself active, with all extant messages already read */
stateP->nextMsgNum = segP->maxMsgNum;
stateP->resetState = false;
@@ -166,6 +168,9 @@ CleanupInvalidationState(int status, Datum arg)
}
segP->lastBackend = i;
+ /* Adjust free slot count */
+ segP->freeBackends++;
+
LWLockRelease(SInvalLock);
}
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index f36c1d981fa08c6a2721b44f7c47b2a9e7737aa8..b02e371a8182f6739d5645b103dcd29f5dcd36a5 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.110 2002/08/29 07:22:28 ishii Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.111 2002/08/29 21:02:12 momjian Exp $
*
*
*-------------------------------------------------------------------------
@@ -395,6 +395,16 @@ InitPostgres(const char *dbname, const char *username)
/* close the transaction we started above */
if (!bootstrap)
CommitTransactionCommand();
+
+ /*
+ * Check a normal user hasn't connected to a superuser reserved slot.
+ * Do this here since we need the user information and that only happens
+ * after we've started bringing the shared memory online. So we wait
+ * until we've registered exit handlers and potentially shut an open
+ * transaction down for an as safety conscious rejection as possible.
+ */
+ if (CountEmptyBackendSlots() < ReservedBackends && !superuser())
+ elog(ERROR, "Non-superuser connection limit exceeded");
}
/*
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 5114fcc38f29d5745e0a7067b169eb1f7fac1127..e88882def408f2e5467382e11b8889fee7ddcfeb 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -5,7 +5,7 @@
* command, configuration file, and command line options.
* See src/backend/utils/misc/README for more information.
*
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.86 2002/08/29 17:14:33 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.87 2002/08/29 21:02:12 momjian Exp $
*
* Copyright 2000 by PostgreSQL Global Development Group
* Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -537,13 +537,20 @@ static struct config_int
/*
* Note: There is some postprocessing done in PostmasterMain() to make
* sure the buffers are at least twice the number of backends, so the
- * constraints here are partially unused.
+ * constraints here are partially unused. Similarly, the superuser
+ * reserved number is checked to ensure it is less than the max
+ * backends number.
*/
{
{ "max_connections", PGC_POSTMASTER }, &MaxBackends,
DEF_MAXBACKENDS, 1, INT_MAX, NULL, NULL
},
+ {
+ { "superuser_reserved_connections", PGC_POSTMASTER }, &ReservedBackends,
+ 2, 0, INT_MAX, NULL, NULL
+ },
+
{
{ "shared_buffers", PGC_POSTMASTER }, &NBuffers,
DEF_NBUFFERS, 16, INT_MAX, NULL, NULL
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c3e065ecdb857776ffba8f1ea65a187392f161dc..11e9caaabcf97e4059a52dece4322352e2c32d8b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -31,6 +31,7 @@
#ssl = false
#max_connections = 32
+#superuser_reserved_connections = 2
#port = 5432
#hostname_lookup = false
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index f2f6f5c67603f61c4fa45ec1b35da83ad21c3fdb..fce4fea4b402af1e3b4816ec0d634917e87b51a9 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 7af8f444470bb1c2dcb09cd632adfe8e1e98be69..1188c68c95add98786b8fbb79b2433e468fe3c19 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 3e95342c9f8887aaffc9c26584d47a67bd39152e..39c895026b438f5c0583b515ca27c5b84c99b388 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