Replace the pg_listener-based LISTEN/NOTIFY mechanism with an in-memory queue.

In addition, add support for a "payload" string to be passed along with
each notify event.

This implementation should be significantly more efficient than the old one,
and is also more compatible with Hot Standby usage.  There is not yet any
facility for HS slaves to receive notifications generated on the master,
although such a thing is possible in future.

Joachim Wieland, reviewed by Jeff Davis; also hacked on by me.

4 files changed, 8 insertions, 4 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 271a7a2129b..371d1f245eb 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.461 2010/02/12 17:33:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.462 2010/02/16 22:34:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2777,6 +2777,7 @@ _copyNotifyStmt(NotifyStmt *from)
 	NotifyStmt *newnode = makeNode(NotifyStmt);
 
 	COPY_STRING_FIELD(conditionname);
+	COPY_STRING_FIELD(payload);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 001c2096b4e..7dfc1969f5d 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -22,7 +22,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.382 2010/02/12 17:33:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.383 2010/02/16 22:34:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1325,6 +1325,7 @@ static bool
 _equalNotifyStmt(NotifyStmt *a, NotifyStmt *b)
 {
 	COMPARE_STRING_FIELD(conditionname);
+	COMPARE_STRING_FIELD(payload);
 
 	return true;
 }
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 593fe397d3f..878e4b3b94c 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.382 2010/02/12 17:33:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.383 2010/02/16 22:34:43 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -1820,6 +1820,7 @@ _outNotifyStmt(StringInfo str, NotifyStmt *node)
 	WRITE_NODE_TYPE("NOTIFY");
 
 	WRITE_STRING_FIELD(conditionname);
+	WRITE_STRING_FIELD(payload);
 }
 
 static void
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 35ba22203fe..f28191d2d00 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.231 2010/02/12 17:33:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.232 2010/02/16 22:34:43 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -231,6 +231,7 @@ _readNotifyStmt(void)
 	READ_LOCALS(NotifyStmt);
 
 	READ_STRING_FIELD(conditionname);
+	READ_STRING_FIELD(payload);
 
 	READ_DONE();
 }