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Refactor get_master_connection() and update description

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Use 'remote_conn' instead of 'master_conn', as the connection
handle can potentially be used for any node.
This commit is contained in:
Ian Barwick
2015-11-17 13:56:14 +09:00
parent e3111d37ba
commit fc6225a511
1 changed files with 30 additions and 26 deletions
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56
dbutils.c
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@@ -574,23 +574,26 @@ get_upstream_connection(PGconn *standby_conn, char *cluster, int node_id,
/* /*
* get a connection to master by reading repl_nodes, creating a connection * Read the node list from the local node and attempt to connect to each node
* to each node (one at a time) and finding if it is a master or a standby * in turn to definitely establish if it's the cluster primary.
* *
* NB: If master_conninfo_out may be NULL. If it is non-null, it is assumed to * The node list is returned in the order which makes it likely that the
* point to allocated memory of MAXCONNINFO in length, and the master server * current primary will be returned first, reducing the number of speculative
* connection string is placed there. * connections which need to be made to other nodes.
*
* If master_conninfo_out points to allocated memory of MAXCONNINFO in length,
* the primary server's conninfo string will be copied there.
*/ */
PGconn * PGconn *
get_master_connection(PGconn *standby_conn, char *cluster, get_master_connection(PGconn *standby_conn, char *cluster,
int *master_id, char *master_conninfo_out) int *master_id, char *master_conninfo_out)
{ {
PGconn *master_conn = NULL; PGconn *remote_conn = NULL;
PGresult *res1; PGresult *res;
char sqlquery[QUERY_STR_LEN]; char sqlquery[QUERY_STR_LEN];
char master_conninfo_stack[MAXCONNINFO]; char remote_conninfo_stack[MAXCONNINFO];
char *master_conninfo = &*master_conninfo_stack; char *remote_conninfo = &*remote_conninfo_stack;
int i, int i,
node_id; node_id;
@@ -610,50 +613,51 @@ get_master_connection(PGconn *standby_conn, char *cluster,
" FROM %s.repl_nodes " " FROM %s.repl_nodes "
" WHERE cluster = '%s' " " WHERE cluster = '%s' "
" AND type != 'witness' " " AND type != 'witness' "
"ORDER BY type_priority, priority, active, id", "ORDER BY active DESC, type_priority, priority, id",
get_repmgr_schema_quoted(standby_conn), get_repmgr_schema_quoted(standby_conn),
cluster); cluster);
log_verbose(LOG_DEBUG, "get_master_connection():\n%s\n", sqlquery); log_verbose(LOG_DEBUG, "get_master_connection():\n%s\n", sqlquery);
res1 = PQexec(standby_conn, sqlquery); res = PQexec(standby_conn, sqlquery);
if (PQresultStatus(res1) != PGRES_TUPLES_OK) if (PQresultStatus(res) != PGRES_TUPLES_OK)
{ {
log_err(_("unable to retrieve node records: %s\n"), log_err(_("unable to retrieve node records: %s\n"),
PQerrorMessage(standby_conn)); PQerrorMessage(standby_conn));
PQclear(res1); PQclear(res);
return NULL; return NULL;
} }
for (i = 0; i < PQntuples(res1); i++) for (i = 0; i < PQntuples(res); i++)
{ {
int is_node_standby; int is_node_standby;
/* initialize with the values of the current node being processed */ /* initialize with the values of the current node being processed */
node_id = atoi(PQgetvalue(res1, i, 0)); node_id = atoi(PQgetvalue(res, i, 0));
strncpy(master_conninfo, PQgetvalue(res1, i, 1), MAXCONNINFO); strncpy(remote_conninfo, PQgetvalue(res, i, 1), MAXCONNINFO);
log_verbose(LOG_INFO, log_verbose(LOG_INFO,
_("checking role of cluster node '%i'\n"), _("checking role of cluster node '%i'\n"),
node_id); node_id);
master_conn = establish_db_connection(master_conninfo, false); remote_conn = establish_db_connection(remote_conninfo, false);
if (PQstatus(master_conn) != CONNECTION_OK) if (PQstatus(remote_conn) != CONNECTION_OK)
continue; continue;
is_node_standby = is_standby(master_conn); is_node_standby = is_standby(remote_conn);
if (is_node_standby == -1) if (is_node_standby == -1)
{ {
log_err(_("unable to retrieve recovery state from this node: %s\n"), log_err(_("unable to retrieve recovery state from node %i:\n%s\n"),
PQerrorMessage(master_conn)); node_id,
PQfinish(master_conn); PQerrorMessage(remote_conn));
PQfinish(remote_conn);
continue; continue;
} }
/* if is_standby() returns 0, queried node is the master */ /* if is_standby() returns 0, queried node is the master */
if (is_node_standby == 0) if (is_node_standby == 0)
{ {
PQclear(res1); PQclear(res);
log_debug(_("get_master_connection(): current master node is %i\n"), node_id); log_debug(_("get_master_connection(): current master node is %i\n"), node_id);
if (master_id != NULL) if (master_id != NULL)
@@ -661,12 +665,12 @@ get_master_connection(PGconn *standby_conn, char *cluster,
*master_id = node_id; *master_id = node_id;
} }
return master_conn; return remote_conn;
} }
/* if it is a standby, clear connection info and continue*/ /* if it is a standby, clear connection info and continue*/
PQfinish(master_conn); PQfinish(remote_conn);
} }
/* /*
@@ -677,7 +681,7 @@ get_master_connection(PGconn *standby_conn, char *cluster,
* Probably we will need to check the error to know if we need to start * 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. * failover procedure or just fix some situation on the standby.
*/ */
PQclear(res1); PQclear(res);
return NULL; return NULL;
} }