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Add MASTER REGISTER and STANDBY REGISTER commands.

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This commit is contained in:
Jaime Casanova
2010-10-18 02:21:55 -05:00
parent 6779a96b0b
commit 378bdd7bd4
6 changed files with 427 additions and 111 deletions
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80
dbutils.c
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@@ -128,3 +128,83 @@ get_cluster_size(PGconn *conn)
PQclear(res);
return size;
}
/*
* 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
*/
PGconn *
getMasterConnection(PGconn *standby_conn, int id, char *cluster, int *master_id)
{
PGconn *master_conn = NULL;
PGresult *res1;
PGresult *res2;
char sqlquery[8192];
char master_conninfo[8192];
int i;
/* find all nodes belonging to this cluster */
sprintf(sqlquery, "SELECT * FROM repmgr_%s.repl_nodes "
" WHERE cluster = '%s' and id <> %d",
cluster, cluster, id);
res1 = PQexec(standby_conn, sqlquery);
if (PQresultStatus(res1) != PGRES_TUPLES_OK)
{
fprintf(stderr, "Can't get nodes info: %s\n", PQerrorMessage(standby_conn));
PQclear(res1);
PQfinish(standby_conn);
exit(1);
}
for (i = 0; i < PQntuples(res1); i++)
{
/* initialize with the values of the current node being processed */
*master_id = atoi(PQgetvalue(res1, i, 0));
strcpy(master_conninfo, PQgetvalue(res1, i, 2));
master_conn = establishDBConnection(master_conninfo, false);
/*
* I can't use the is_standby() function here because on error that
* function closes the connection i pass and exit, but i still need to close
* standby_conn
*/
res2 = PQexec(master_conn, "SELECT pg_is_in_recovery()");
if (PQresultStatus(res2) != PGRES_TUPLES_OK)
{
fprintf(stderr, "Can't get nodes info: %s\n", PQerrorMessage(master_conn));
PQclear(res2);
PQfinish(master_conn);
continue;
}
/* if false, this is the master */
if (strcmp(PQgetvalue(res2, 0, 0), "f") == 0)
{
PQclear(res2);
PQclear(res1);
return master_conn;
}
else
{
/* if it is a standby clear info */
PQclear(res2);
PQfinish(master_conn);
*master_id = -1;
}
}
/* If we finish this loop without finding a master then
* we doesn't have the info or the master has failed (or we
* reached max_connections or superuser_reserved_connections,
* anything else i'm missing?),
* Probably we will need to check the error to know if we need
* to start failover procedure or just fix some situation on the
* standby.
*/
fprintf(stderr, "There isn't a master node in the cluster\n");
PQclear(res1);
PQfinish(master_conn);
return (PGconn *) NULL;
}