Some infrastructure for supporting cascading replication

Does not fully work yet.

dbutils.c

@@ -356,6 +356,75 @@ get_pg_setting(PGconn *conn, const char *setting, char *output)
 }
 
 
+PGconn *
+get_upstream_connection(PGconn *standby_conn, char *cluster,
+					  int *upstream_node_id, char *upstream_conninfo_out)
+{
+	PGconn	   *upstream_conn = NULL;
+	PGresult   *res;
+	char		sqlquery[QUERY_STR_LEN];
+	char		upstream_conninfo_stack[MAXCONNINFO];
+	char	   *upstream_conninfo = &*upstream_conninfo_stack;
+
+	/*
+	 * If the caller wanted to get a copy of the connection info string, sub
+	 * out the local stack pointer for the pointer passed by the caller.
+	 */
+	if (upstream_conninfo_out != NULL)
+		upstream_conninfo = upstream_conninfo_out;
+
+	/* hacky query */
+	sqlquery_snprintf(sqlquery,
+					  "WITH i AS ( "
+					  "  WITH p AS ( "
+					  "    SELECT repmgr_get_primary_conninfo() AS conninfo "
+					  "  )"
+					  "  SELECT p.conninfo, "
+					  "         unnest(regexp_matches(conninfo,'application_name=(\\S+)')) AS name "
+					  "    FROM p "
+					  ") "
+					  " SELECT rn.conninfo, i.name, rn.id "
+					  "   FROM i "
+					  "INNER JOIN %s.repl_nodes rn "
+					  "        ON rn.name = i.name "
+					  "  WHERE cluster = '%s' ",
+					  get_repmgr_schema_quoted(standby_conn),
+					  cluster);
+
+	log_debug("%s", sqlquery);
+
+	res = PQexec(standby_conn, sqlquery);
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		log_err(_("Unable to get conninfo for upstream server: %s\n"),
+				PQerrorMessage(standby_conn));
+		PQclear(res);
+		return NULL;
+	}
+
+	// ZZZ check for empty result
+	// maybe modify function to return NULL
+
+	strncpy(upstream_conninfo, PQgetvalue(res, 0, 0), MAXCONNINFO);
+	*upstream_node_id = atoi(PQgetvalue(res, 0, 1));
+
+	PQclear(res);
+
+	log_debug("conninfo is: '%s'", upstream_conninfo);
+	upstream_conn = establish_db_connection(upstream_conninfo, false);
+
+	if (PQstatus(upstream_conn) != CONNECTION_OK)
+	{
+		log_err(_("Unable to connect to upstream server: %s\n"),
+				PQerrorMessage(upstream_conn));
+		return NULL;
+	}
+
+	return upstream_conn;
+}
+
+
 /*
  * get a connection to master by reading repl_nodes, creating a connection
  * to each node (one at a time) and finding if it is a master or a standby
@@ -364,6 +433,8 @@ get_pg_setting(PGconn *conn, const char *setting, char *output)
  * point to allocated memory of MAXCONNINFO in length, and the master server
  * connection string is placed there.
  */
+
+// ZZZ value placed in `master_id` used by callers in repmgrd
 PGconn *
 get_master_connection(PGconn *standby_conn, char *cluster,
 					  int *master_id, char *master_conninfo_out)
@@ -377,14 +448,8 @@ get_master_connection(PGconn *standby_conn, char *cluster,
 
 	int			i;
 
-	/*
-	 * If the caller wanted to get a copy of the connection info string, sub
-	 * out the local stack pointer for the pointer passed by the caller.
-	 */
-	if (master_conninfo_out != NULL)
-		master_conninfo = master_conninfo_out;
-
 
+	// ZZZ below old stuff
 	/* find all nodes belonging to this cluster */
 	log_info(_("finding node list for cluster '%s'\n"),
 			 cluster);

dbutils.h

@@ -40,6 +40,9 @@ int			guc_set_typed(PGconn *conn, const char *parameter, const char *op,
 			  const char *value, const char *datatype);
 
 
+PGconn     *get_upstream_connection(PGconn *standby_conn, char *cluster,
+									int *upstream_node_id,
+									char *upstream_conninfo_out);
 PGconn	   *get_master_connection(PGconn *standby_conn, char *cluster,
 					  int *master_id, char *master_conninfo_out);
 

repmgrd.c

@@ -384,12 +384,15 @@ main(int argc, char **argv)
 
 			case WITNESS_MODE:
 			case STANDBY_MODE:
-				/* I need the id of the primary as well as a connection to it */
+
+				/* We need the node id of the upstream server as well as a connection to it */
 				log_info(_("%s Connecting to primary for cluster '%s'\n"),
 						 progname, local_options.cluster_name);
+
 				primary_conn = get_master_connection(my_local_conn,
 													 local_options.cluster_name,
 													 &primary_options.node, NULL);
+
 				if (primary_conn == NULL)
 				{
 					terminate(ERR_BAD_CONFIG);
@@ -398,7 +401,7 @@ main(int argc, char **argv)
 				check_cluster_configuration(my_local_conn);
 				check_node_configuration();
 
-				if (reload_config(config_file, &local_options))
+				if (0 && reload_config(config_file, &local_options))
 				{
 					PQfinish(my_local_conn);
 					my_local_conn = establish_db_connection(local_options.conninfo, true);
@@ -627,11 +630,19 @@ standby_monitor(void)
 				ret;
 	bool		did_retry = false;
 
+	PGconn	   *upstream_conn;
+	int			upstream_node_id;
+
+	upstream_conn = get_upstream_connection(my_local_conn,
+											local_options.cluster_name,
+											&upstream_node_id, NULL);
+
+
 	/*
 	 * Check if the master is still available, if after 5 minutes of retries
 	 * we cannot reconnect, try to get a new master.
 	 */
-	check_connection(primary_conn, "master");	/* this take up to
+	check_connection(upstream_conn, "master");	/* this take up to
 												 * local_options.reconnect_atte
 												 * mpts *
 												 * local_options.reconnect_intv
@@ -643,10 +654,10 @@ standby_monitor(void)
 		terminate(1);
 	}
 
-	if (PQstatus(primary_conn) != CONNECTION_OK)
+	if (PQstatus(upstream_conn) != CONNECTION_OK)
 	{
-		PQfinish(primary_conn);
+		PQfinish(upstream_conn);
-		primary_conn = NULL;
+		upstream_conn = NULL;
 
 		if (local_options.failover == MANUAL_FAILOVER)
 		{
@@ -695,12 +706,14 @@ standby_monitor(void)
 		}
 	}
 
+	PQfinish(upstream_conn);
+
 	/* Check if we still are a standby, we could have been promoted */
 	do
 	{
-		log_debug("standby_monitor() - checking if still standby\n");
+		log_debug("standby_monitor() - checking if still standby\n"); // ZZZ
 		ret = is_standby(my_local_conn);
-
+		log_debug("ret is %i", ret); // ZZZ
 		switch (ret)
 		{
 			case 0: