Harbour PostgreSQL LISTEN

postgres.c

HB_FUNC ( PQ_GET_NOTIFY ) // VAA 07.03.2017
{
   const char *clisten = "LISTEN ";

   PGconn * conn = hb_PGconn_par( 1 );

   const char *source = hb_parcx( 2 );
   HB_SIZE size = strlen(source);

   char *channel;
   char *output;
   int outlen;

   PGresult * res;
   int sock;
   fd_set input_mask;
   PGnotify *notify;

   if( !conn )
      hb_errRT_BASE( EG_ARG, 2020, NULL, HB_ERR_FUNCNAME, HB_ERR_ARGS_BASEPARAMS );

    channel = PQescapeIdentifier( conn, source, ( size_t ) size );

    outlen = strlen(clisten) + strlen(channel);
    
    // #OUTPUT_COMMAND = "LISTEN " + #CHANNEL_NAME    
    output = (char *) hb_xgrab(outlen * 2 + 1);
    memset(output, 0, outlen * 2 + 1);
    strncpy(output, clisten, strlen(clisten));
    strncat(output, channel, strlen(channel));
    PQfreemem(channel);

    res = PQexec(conn, output);
    hb_xfree(output);

    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    	hb_ret();    

    PQclear(res);

    sock = PQsocket(conn);

    if (sock < 0)
	hb_ret();

    FD_ZERO(&input_mask);
    FD_SET(sock, &input_mask);
  
    if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0)
	hb_ret();
    
    PQconsumeInput(conn);
    while ((notify = PQnotifies(conn)) != NULL) {
	 PHB_ITEM aNotify = hb_itemArrayNew( 3 );
	 hb_arraySetNInt(aNotify, 2, notify->be_pid);
	 hb_arraySetC(aNotify, 1, notify->relname);
	 hb_arraySetC(aNotify, 3, notify->extra);
	 hb_itemReturnRelease( aNotify );
    }
}