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Implement dblink_get_notify().

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Adds the ability to retrieve async notifications using dblink,
via the addition of the function dblink_get_notify(). Original patch
by Marcus Kempe, suggestions by Tom Lane and Alvaro Herrera, patch
review and adjustments by Joe Conway.
This commit is contained in:
Joe Conway
2009-08-05 16:11:07 +00:00
parent 16f3cf8c0c
commit f4095b4c4b
7 changed files with 253 additions and 5 deletions
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85
contrib/dblink/dblink.c
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@ -8,7 +8,7 @@
* Darko Prenosil <Darko.Prenosil@finteh.hr>
* Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
*
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.82 2009/06/11 14:48:50 momjian Exp $
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.83 2009/08/05 16:11:07 joe Exp $
* Copyright (c) 2001-2009, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
@ -1635,6 +1635,89 @@ dblink_current_query(PG_FUNCTION_ARGS)
PG_RETURN_DATUM(current_query(fcinfo));
}
/*
* Retrieve async notifications for a connection.
*
* Returns an setof record of notifications, or an empty set if none recieved.
* Can optionally take a named connection as parameter, but uses the unnamed connection per default.
*
*/
#define DBLINK_NOTIFY_COLS 3
PG_FUNCTION_INFO_V1(dblink_get_notify);
Datum
dblink_get_notify(PG_FUNCTION_ARGS)
{
PGconn *conn = NULL;
remoteConn *rconn = NULL;
PGnotify *notify;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
DBLINK_INIT;
if (PG_NARGS() == 1)
DBLINK_GET_NAMED_CONN;
else
conn = pconn->conn;
/* create the tuplestore */
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
tupdesc = CreateTemplateTupleDesc(DBLINK_NOTIFY_COLS, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "notify_name",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "be_pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "extra",
TEXTOID, -1, 0);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
PQconsumeInput(conn);
while ((notify = PQnotifies(conn)) != NULL)
{
Datum values[DBLINK_NOTIFY_COLS];
bool nulls[DBLINK_NOTIFY_COLS];
memset(values, 0, sizeof(values));
memset(nulls, 0, sizeof(nulls));
if (notify->relname != NULL)
values[0] = CStringGetTextDatum(notify->relname);
else
nulls[0] = true;
values[1] = Int32GetDatum(notify->be_pid);
if (notify->extra != NULL)
values[2] = CStringGetTextDatum(notify->extra);
else
nulls[2] = true;
/* switch to appropriate context while storing the tuple */
MemoryContextSwitchTo(per_query_ctx);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
MemoryContextSwitchTo(oldcontext);
PQfreemem(notify);
PQconsumeInput(conn);
}
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
return (Datum) 0;
}
/*************************************************************
* internal functions
*/