The attached patch modifies libpgtcl per previous discussion: the

pg_notifies statement is eliminated, and callbacks defined by
pg_listen are instead invoked automatically from the Tcl idle loop
whenever a NOTIFY message is received.

I have done only cursory testing, so there may be problems still
lurking (particularly on non-Unix machines?).  But it seems to
work.

Patch is against today's cvs sources.  Note that this will not work
with the 6.3.2 release since it depends on the new libpq.

The diffs are a bit large so I've gzipped them.  A patch to update
libpgtcl.sgml is included too.

			regards, tom lane

1 files changed, 23 insertions, 10 deletions

diff --git a/src/interfaces/libpgtcl/pgtclCmds.h b/src/interfaces/libpgtcl/pgtclCmds.h
index f0f8513da44..052a1a0a6f2 100644
--- a/src/interfaces/libpgtcl/pgtclCmds.h
+++ b/src/interfaces/libpgtcl/pgtclCmds.h
@@ -5,7 +5,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pgtclCmds.h,v 1.9 1998/03/15 08:02:59 scrappy Exp $
+ * $Id: pgtclCmds.h,v 1.10 1998/06/16 04:10:17 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -14,13 +14,29 @@
 #define PGTCLCMDS_H
 
 #include "tcl.h"
-#include "libpq/pqcomm.h"
 #include "libpq-fe.h"
-#include "libpq/libpq-fs.h"
 
 #define RES_HARD_MAX 128
 #define RES_START 16
 
+/*
+ * Each Pg_ConnectionId has a list of Pg_TclNotifies structs, one for each
+ * Tcl interpreter that has executed any pg_listens on the connection.
+ * We need this arrangement to be able to clean up if an interpreter is
+ * deleted while the connection remains open.  A free side benefit is that
+ * multiple interpreters can be registered to listen for the same notify
+ * name.  (All their callbacks will be called, but in an unspecified order.)
+ */
+
+typedef struct Pg_TclNotifies_s {
+    struct Pg_TclNotifies_s	*next;		/* list link */
+    Tcl_Interp 			*interp;	/* This Tcl interpreter */
+    /* NB: if interp == NULL, the interpreter is gone but we haven't
+     * yet got round to deleting the Pg_TclNotifies structure.
+     */
+    Tcl_HashTable		notify_hash;	/* Active pg_listen requests */
+} Pg_TclNotifies;
+
 typedef struct Pg_ConnectionId_s {
     char		id[32];
     PGconn		*conn;
@@ -31,10 +47,11 @@ typedef struct Pg_ConnectionId_s {
     int			res_copy;	/* Query result with active copy */
     int			res_copyStatus; /* Copying status */
     PGresult		**results;	/* The results */
-    
-    Tcl_HashTable	notify_hash;
-} Pg_ConnectionId;
 
+    Pg_TclNotifies	*notify_list;	/* head of list of notify info */
+    int			notifier_running;  /* notify event source is live */
+
+} Pg_ConnectionId;
 
 #define RES_COPY_NONE	0
 #define RES_COPY_INPROGRESS	1
@@ -78,9 +95,5 @@ extern int Pg_lo_export(
     ClientData cData, Tcl_Interp *interp, int argc, char* argv[]);
 extern int Pg_listen(
     ClientData cData, Tcl_Interp *interp, int argc, char* argv[]);
-extern int Pg_notifies(
-    ClientData cData, Tcl_Interp *interp, int argc, char* argv[]);
-
 
 #endif /*PGTCLCMDS_H*/
-