Per previous discussions, here are two functions to send INT and TERM

(cancel and terminate) signals to other backends.   They permit only INT
and TERM, and permits sending only to postgresql backends.

Magnus Hagander

diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c
index 570feab25e6e6cb7008926ea69eb63b64f836830..856d0f0a73f2b65218a69212d33e945b79f079f9 100644 (file)
--- a/src/backend/storage/ipc/sinval.c
+++ b/src/backend/storage/ipc/sinval.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.63 2004/05/23 03:50:45 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.64 2004/06/02 21:29:28 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -463,6 +463,40 @@ TransactionIdIsInProgress(TransactionId xid)
        return result;
 }
 
+/*
+ * IsBackendPid -- is a given pid a running backend
+ */
+bool
+IsBackendPid(int pid)
+{
+       bool            result = false;
+       SISeg      *segP = shmInvalBuffer;
+       ProcState  *stateP = segP->procState;
+       int                     index;
+
+       LWLockAcquire(SInvalLock, LW_SHARED);
+
+       for (index = 0; index < segP->lastBackend; index++)
+       {
+               SHMEM_OFFSET pOffset = stateP[index].procStruct;
+
+               if (pOffset != INVALID_OFFSET)
+               {
+                       PGPROC     *proc = (PGPROC *) MAKE_PTR(pOffset);
+
+                       if (proc->pid == pid)
+                       {
+                               result = true;
+                               break;
+                       }
+               }
+       }
+
+       LWLockRelease(SInvalLock);
+
+       return result;
+}
+
 /*
  * GetOldestXmin -- returns oldest transaction that was running
  *                                     when any current transaction was started.

diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 673b175bbc042c4a3fed81304b381d13563a3db8..8ab6953cb02c151148a9fabc449b0b9c157128b9 100644 (file)
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -8,16 +8,18 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/misc.c,v 1.33 2004/05/21 05:08:02 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/misc.c,v 1.34 2004/06/02 21:29:29 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
 #include <sys/file.h>
+#include <signal.h>
 
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "storage/sinval.h"
 #include "utils/builtins.h"
 
 
@@ -57,3 +59,47 @@ current_database(PG_FUNCTION_ARGS)
        namestrcpy(db, get_database_name(MyDatabaseId));
        PG_RETURN_NAME(db);
 }
+
+
+/*
+ * Functions to terminate a backend or cancel a query running on
+ * a different backend.
+ */
+
+static int pg_signal_backend(int pid, int sig) 
+{
+       if (!superuser()) 
+               ereport(ERROR,
+                               (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+                                (errmsg("only superuser can signal other backends"))));
+       
+       if (!IsBackendPid(pid))
+       {
+               /* This is just a warning so a loop-through-resultset will not abort
+                * if one backend terminated on it's own during the run */
+               ereport(WARNING,
+                               (errmsg("pid %i is not a postgresql backend",pid)));
+               return 0;
+       }
+
+       if (kill(pid, sig)) 
+       {
+               /* Again, just a warning to allow loops */
+               ereport(WARNING,
+                               (errmsg("failed to send signal to backend %i: %m",pid)));
+               return 0;
+       }
+       return 1;
+}
+
+Datum
+pg_terminate_backend(PG_FUNCTION_ARGS)
+{
+       PG_RETURN_INT32(pg_signal_backend(PG_GETARG_INT32(0),SIGTERM));
+}
+
+Datum
+pg_cancel_backend(PG_FUNCTION_ARGS)
+{
+       PG_RETURN_INT32(pg_signal_backend(PG_GETARG_INT32(0),SIGINT));
+}

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index f0c2f8269197ce965166dbd1daeb64b7275d7da3..bf6ded488cad8cfc5a0564dd794bdeb951f61d7e 100644 (file)
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.232 2004/05/26 18:37:33 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.233 2004/06/02 21:29:29 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*                                                     yyyymmddN */
-#define CATALOG_VERSION_NO     200405262
+#define CATALOG_VERSION_NO     200406021
 
 #endif

diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index c87eb2155658212cc0ea0e9b4b992d474f3bd9f4..cb3279747b03a934c4d0ef4cdd96850540ca3b61 100644 (file)
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.333 2004/05/26 18:37:33 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.334 2004/06/02 21:29:29 momjian Exp $
  *
  * NOTES
  *       The script catalog/genbki.sh reads this file and generates .bki
@@ -2808,6 +2808,11 @@ DESCR("Statistics: Blocks fetched for database");
 DATA(insert OID = 1945 (  pg_stat_get_db_blocks_hit            PGNSP PGUID 12 f f t f s 1 20 "26" _null_       pg_stat_get_db_blocks_hit - _null_ ));
 DESCR("Statistics: Blocks found in cache for database");
 
+DATA(insert OID = 2171 ( pg_terminate_backend           PGNSP PGUID 12 f f t f s 1 23 "23" _null_ pg_terminate_backend - _null_ ));
+DESCR("Terminate a backend process");
+DATA(insert OID = 2172 ( pg_cancel_backend              PGNSP PGUID 12 f f t f s 1 23 "23" _null_ pg_cancel_backend - _null_ ));
+DESCR("Cancel running query on a backend process");
+
 DATA(insert OID = 1946 (  encode                                               PGNSP PGUID 12 f f t f i 2 25 "17 25" _null_  binary_encode - _null_ ));
 DESCR("Convert bytea value into some ascii-only text string");
 DATA(insert OID = 1947 (  decode                                               PGNSP PGUID 12 f f t f i 2 17 "25 25" _null_  binary_decode - _null_ ));

diff --git a/src/include/storage/sinval.h b/src/include/storage/sinval.h
index a1c731024cf8c4d51550af8dca33e475f010384b..84769200504450f8c5089c028465e8429c9592ba 100644 (file)
--- a/src/include/storage/sinval.h
+++ b/src/include/storage/sinval.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/sinval.h,v 1.34 2004/05/23 03:50:45 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/storage/sinval.h,v 1.35 2004/06/02 21:29:29 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -97,6 +97,7 @@ extern void ReceiveSharedInvalidMessages(
 
 extern bool DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself);
 extern bool TransactionIdIsInProgress(TransactionId xid);
+extern bool IsBackendPid(int pid);
 extern TransactionId GetOldestXmin(bool allDbs);
 extern int     CountActiveBackends(void);
 extern int     CountEmptyBackendSlots(void);

diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 267ededb1303af7684e6ecbdce148946dc1f2744..1fc26e69a1f5d59f3dce1950f2121bbd443d34b1 100644 (file)
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.240 2004/05/26 18:35:46 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.241 2004/06/02 21:29:29 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -354,6 +354,8 @@ extern Datum float84ge(PG_FUNCTION_ARGS);
 extern Datum nullvalue(PG_FUNCTION_ARGS);
 extern Datum nonnullvalue(PG_FUNCTION_ARGS);
 extern Datum current_database(PG_FUNCTION_ARGS);
+extern Datum pg_terminate_backend(PG_FUNCTION_ARGS);
+extern Datum pg_cancel_backend(PG_FUNCTION_ARGS);
 
 /* not_in.c */
 extern Datum int4notin(PG_FUNCTION_ARGS);