Re: async notification patch for dblink - Mailing list pgsql-hackers

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In reference to:
http://archives.postgresql.org/message-id/6534f7ae0811181547v1dc1f096g6222e8273b461606@mail.gmail.com

Had to fix a lot of bit rot, but otherwise looks good. My updated patch
attached. Will commit in a day or so if no objections.

BTW, some commitfest procedural comments/questions:

1) I couldn't figure out how to attach my patch to the commitfest page
short of cut-n-paste into the small comment text box -- is that my only
choice?

2) It would be nice if the mail archive web page of the original message
had a "Reply To" button. Otherwise I guess I can do what I've done above.

3) I couldn't see any way to assign myself as the committer.

Joe
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Index: contrib/dblink/dblink.c
===================================================================
RCS file: /opt/src/cvs/pgsql/contrib/dblink/dblink.c,v
retrieving revision 1.82
diff -c -r1.82 dblink.c
*** contrib/dblink/dblink.c    11 Jun 2009 14:48:50 -0000    1.82
--- contrib/dblink/dblink.c    4 Aug 2009 01:05:49 -0000
***************
*** 1635,1640 ****
--- 1635,1681 ----
      PG_RETURN_DATUM(current_query(fcinfo));
  }

+ /*
+  * Retrieve async notifications for a connection.
+  *
+  * Returns an array of notifications, or NULL if none recieved.
+  * Can optionally take a named connection as parameter, but uses the unnamed connection per default.
+  *
+  */
+ PG_FUNCTION_INFO_V1(dblink_get_notify);
+ Datum
+ dblink_get_notify(PG_FUNCTION_ARGS)
+ {
+     PGconn        *conn = NULL;
+     remoteConn     *rconn = NULL;
+     ArrayBuildState    *astate = NULL;
+     PGnotify    *notify;
+
+     DBLINK_INIT;
+     if (PG_NARGS() == 1)
+         DBLINK_GET_NAMED_CONN;
+     else
+         conn = pconn->conn;
+
+     PQconsumeInput(conn);
+
+     while ((notify = PQnotifies(conn)) != NULL)
+     {
+         /* stash away current value */
+         astate = accumArrayResult(astate,
+                             PointerGetDatum(cstring_to_text(notify->relname)),
+                             false, TEXTOID, CurrentMemoryContext);
+         PQfreemem(notify);
+         PQconsumeInput(conn);
+     }
+
+     if (astate)
+         PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate,
+                                 CurrentMemoryContext));
+     else
+         PG_RETURN_NULL();
+ }
+
  /*************************************************************
   * internal functions
   */
Index: contrib/dblink/dblink.h
===================================================================
RCS file: /opt/src/cvs/pgsql/contrib/dblink/dblink.h,v
retrieving revision 1.22
diff -c -r1.22 dblink.h
*** contrib/dblink/dblink.h    9 Jun 2009 17:41:02 -0000    1.22
--- contrib/dblink/dblink.h    4 Aug 2009 00:56:56 -0000
***************
*** 57,61 ****
--- 57,62 ----
  extern Datum dblink_build_sql_delete(PG_FUNCTION_ARGS);
  extern Datum dblink_build_sql_update(PG_FUNCTION_ARGS);
  extern Datum dblink_current_query(PG_FUNCTION_ARGS);
+ extern Datum dblink_get_notify(PG_FUNCTION_ARGS);

  #endif   /* DBLINK_H */
Index: contrib/dblink/dblink.sql.in
===================================================================
RCS file: /opt/src/cvs/pgsql/contrib/dblink/dblink.sql.in,v
retrieving revision 1.18
diff -c -r1.18 dblink.sql.in
*** contrib/dblink/dblink.sql.in    9 Jun 2009 17:41:02 -0000    1.18
--- contrib/dblink/dblink.sql.in    4 Aug 2009 00:58:52 -0000
***************
*** 202,204 ****
--- 202,214 ----
  RETURNS text
  AS 'MODULE_PATHNAME', 'dblink_error_message'
  LANGUAGE C STRICT;
+
+ CREATE OR REPLACE FUNCTION dblink_get_notify()
+ RETURNS text[]
+ AS 'MODULE_PATHNAME', 'dblink_get_notify'
+ LANGUAGE C STRICT;
+
+ CREATE OR REPLACE FUNCTION dblink_get_notify(conname text)
+ RETURNS text[]
+ AS 'MODULE_PATHNAME', 'dblink_get_notify'
+ LANGUAGE C STRICT;
Index: contrib/dblink/uninstall_dblink.sql
===================================================================
RCS file: /opt/src/cvs/pgsql/contrib/dblink/uninstall_dblink.sql,v
retrieving revision 1.7
diff -c -r1.7 uninstall_dblink.sql
*** contrib/dblink/uninstall_dblink.sql    5 Apr 2008 02:26:14 -0000    1.7
--- contrib/dblink/uninstall_dblink.sql    4 Aug 2009 00:56:56 -0000
***************
*** 76,78 ****
--- 76,82 ----
  DROP FUNCTION dblink_is_busy(text);

  DROP FUNCTION dblink_send_query(text, text);
+
+ DROP FUNCTION dblink_get_notify();
+
+ DROP FUNCTION dblink_get_notify(text);
Index: contrib/dblink/expected/dblink.out
===================================================================
RCS file: /opt/src/cvs/pgsql/contrib/dblink/expected/dblink.out,v
retrieving revision 1.25
diff -c -r1.25 dblink.out
*** contrib/dblink/expected/dblink.out    6 Jun 2009 21:27:56 -0000    1.25
--- contrib/dblink/expected/dblink.out    4 Aug 2009 01:20:09 -0000
***************
*** 827,829 ****
--- 827,864 ----
  DROP USER MAPPING FOR public SERVER fdtest;
  DROP SERVER fdtest;
  DROP FOREIGN DATA WRAPPER postgresql;
+ -- test asynchronous notifications
+ SELECT dblink_connect('dbname=contrib_regression');
+  dblink_connect
+ ----------------
+  OK
+ (1 row)
+
+ --should return listen
+ SELECT dblink_exec('LISTEN regression');
+  dblink_exec
+ -------------
+  LISTEN
+ (1 row)
+
+ NOTIFY regression;
+ --should return {regression}
+ SELECT dblink_get_notify();
+  dblink_get_notify
+ -------------------
+  {regression}
+ (1 row)
+
+ --should return null
+ SELECT dblink_get_notify();
+  dblink_get_notify
+ -------------------
+
+ (1 row)
+
+ SELECT dblink_disconnect();
+  dblink_disconnect
+ -------------------
+  OK
+ (1 row)
+
Index: contrib/dblink/sql/dblink.sql
===================================================================
RCS file: /opt/src/cvs/pgsql/contrib/dblink/sql/dblink.sql,v
retrieving revision 1.21
diff -c -r1.21 dblink.sql
*** contrib/dblink/sql/dblink.sql    6 Jun 2009 21:27:56 -0000    1.21
--- contrib/dblink/sql/dblink.sql    4 Aug 2009 01:19:48 -0000
***************
*** 389,391 ****
--- 389,407 ----
  DROP USER MAPPING FOR public SERVER fdtest;
  DROP SERVER fdtest;
  DROP FOREIGN DATA WRAPPER postgresql;
+
+ -- test asynchronous notifications
+ SELECT dblink_connect('dbname=contrib_regression');
+
+ --should return listen
+ SELECT dblink_exec('LISTEN regression');
+
+ NOTIFY regression;
+
+ --should return {regression}
+ SELECT dblink_get_notify();
+
+ --should return null
+ SELECT dblink_get_notify();
+
+ SELECT dblink_disconnect();
Index: doc/src/sgml/dblink.sgml
===================================================================
RCS file: /opt/src/cvs/pgsql/doc/src/sgml/dblink.sgml,v
retrieving revision 1.8
diff -c -r1.8 dblink.sgml
*** doc/src/sgml/dblink.sgml    18 Jun 2009 14:34:36 -0000    1.8
--- doc/src/sgml/dblink.sgml    4 Aug 2009 00:52:09 -0000
***************
*** 1260,1265 ****
--- 1260,1339 ----
    </refsect1>
   </refentry>

+  <refentry id="CONTRIB-DBLINK-GET-NOTIFY">
+   <refnamediv>
+    <refname>dblink_get_notify</refname>
+    <refpurpose>retrieve async notifications on a connection</refpurpose>
+   </refnamediv>
+
+   <refsynopsisdiv>
+    <synopsis>
+     dblink_get_notify() returns text[]
+     dblink_get_notify(text connname) returns text[]
+    </synopsis>
+   </refsynopsisdiv>
+
+   <refsect1>
+    <title>Description</title>
+
+    <para>
+     <function>dblink_get_notify</> retrieves notifications on either
+     the unnamed connection, or on a named connection if specified.
+     To receive notifications via dblink, <function>LISTEN</> must
+     first be issued, using <function>dblink_exec</>.
+     For details see <xref linkend="sql-listen"> and <xref linkend="sql-notify">.
+    </para>
+
+   </refsect1>
+
+   <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+     <varlistentry>
+      <term><parameter>conname</parameter></term>
+      <listitem>
+       <para>
+        The name of a named connection to get notifications on.
+       </para>
+      </listitem>
+     </varlistentry>
+    </variablelist>
+   </refsect1>
+
+   <refsect1>
+    <title>Return Value</title>
+     <para>Returns a text array of notification names, or NULL if none.</para>
+   </refsect1>
+
+   <refsect1>
+    <title>Example</title>
+
+    <programlisting>
+ test=# SELECT dblink_exec('LISTEN virtual');
+  dblink_exec
+ -------------
+  LISTEN
+ (1 row)
+
+ test=# SELECT dblink_get_notify();
+  dblink_get_notify
+ -------------------
+
+ (1 row)
+
+ test=# NOTIFY virtual;
+ NOTIFY
+
+ test=# SELECT dblink_get_notify();
+  dblink_get_notify
+ -------------------
+  {virtual}
+ (1 row)
+    </programlisting>
+   </refsect1>
+  </refentry>
+
   <refentry id="CONTRIB-DBLINK-GET-RESULT">
    <refmeta>
     <refentrytitle>dblink_get_result</refentrytitle>