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If the node is a witness don't bother asking its position, it always

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will be 0/0. We just need to check that we can connect to it to determine
if we are in the majority.
This commit is contained in:
Jaime Casanova
2013-01-11 03:42:08 -05:00
parent 2a5d431481
commit 4191b77e70
1 changed files with 45 additions and 14 deletions
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59
repmgrd.c
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@@ -54,6 +54,7 @@ typedef struct nodeInfo
int nodeId;
XLogRecPtr xlog_location;
bool is_ready;
bool is_witness;
} nodeInfo;
@@ -574,6 +575,7 @@ do_failover(void)
int total_nodes = 0;
int visible_nodes = 0;
bool find_best = false;
bool witness = false;
int i;
int r;
@@ -593,7 +595,7 @@ do_failover(void)
*/
nodeInfo nodes[50];
/* initialize to keep compiler quiet */
nodeInfo best_candidate = {-1, InvalidXLogRecPtr, false };
nodeInfo best_candidate = {-1, InvalidXLogRecPtr, false, false};
/* first we get info about this node, and update shared memory */
sprintf(sqlquery, "SELECT pg_last_xlog_receive_location()");
@@ -617,7 +619,7 @@ do_failover(void)
sleep(SLEEP_MONITOR + 1);
/* get a list of standby nodes, including myself */
sprintf(sqlquery, "SELECT id, conninfo "
sprintf(sqlquery, "SELECT id, conninfo, witness "
" FROM %s.repl_nodes "
" WHERE id <> %d "
" AND cluster = '%s' "
@@ -633,6 +635,7 @@ do_failover(void)
exit(ERR_DB_QUERY);
}
log_debug(_("%s: there are %d nodes registered"), progname, PQntuples(res1));
/* ask for the locations */
for (i = 0; i < PQntuples(res1); i++)
{
@@ -640,33 +643,48 @@ do_failover(void)
/* Initialize on false so if we can't reach this node we know that later */
nodes[i].is_ready = false;
strncpy(nodeConninfo, PQgetvalue(res1, i, 1), MAXLEN);
witness = (strcmp(PQgetvalue(res1, i, 2), "t") == 0) ? true : false;
log_debug(_("%s: node=%d conninfo=\"%s\" witness=%s"), progname, node, nodeConninfo, (witness) ? "true" : "false");
nodeConn = establishDBConnection(nodeConninfo, false);
/* if we can't see the node just skip it */
if (PQstatus(nodeConn) != CONNECTION_OK)
continue;
sqlquery_snprintf(sqlquery, "SELECT %s.repmgr_get_last_standby_location()", repmgr_schema);
res2 = PQexec(nodeConn, sqlquery);
if (PQresultStatus(res2) != PGRES_TUPLES_OK)
/* the witness will always show 0/0 so avoid a useless query */
if (!witness)
{
log_info(_("Can't get node's last standby location: %s\n"), PQerrorMessage(nodeConn));
log_info(_("Connection details: %s\n"), nodeConninfo);
sqlquery_snprintf(sqlquery, "SELECT %s.repmgr_get_last_standby_location()", repmgr_schema);
res2 = PQexec(nodeConn, sqlquery);
if (PQresultStatus(res2) != PGRES_TUPLES_OK)
{
log_info(_("Can't get node's last standby location: %s\n"), PQerrorMessage(nodeConn));
log_info(_("Connection details: %s\n"), nodeConninfo);
PQclear(res2);
PQfinish(nodeConn);
continue;
}
if (sscanf(PQgetvalue(res2, 0, 0), "%X/%X", &uxlogid, &uxrecoff) != 2)
log_info(_("could not parse transaction log location \"%s\"\n"), PQgetvalue(res2, 0, 0));
PQclear(res2);
PQfinish(nodeConn);
continue;
}
else
{
uxlogid = 0;
uxrecoff = 0;
}
visible_nodes++;
if (sscanf(PQgetvalue(res2, 0, 0), "%X/%X", &uxlogid, &uxrecoff) != 2)
log_info(_("could not parse transaction log location \"%s\"\n"), PQgetvalue(res2, 0, 0));
nodes[i].nodeId = node;
nodes[i].xlog_location.xlogid = uxlogid;
nodes[i].xlog_location.xrecoff = uxrecoff;
nodes[i].is_ready = true;
nodes[i].is_witness = witness;
PQclear(res2);
PQfinish(nodeConn);
}
PQclear(res1);
@@ -696,15 +714,21 @@ do_failover(void)
*/
for (i = 0; i < total_nodes - 1; i++)
{
/* witness is never a good candidate */
if (nodes[i].is_witness)
continue;
if (!nodes[i].is_ready)
continue;
else if (!find_best)
if (!find_best)
{
/* start with the first ready node, and then move on to the next one */
best_candidate.nodeId = nodes[i].nodeId;
best_candidate.xlog_location.xlogid = nodes[i].xlog_location.xlogid;
best_candidate.xlog_location.xrecoff = nodes[i].xlog_location.xrecoff;
best_candidate.is_ready = nodes[i].is_ready;
best_candidate.is_witness = nodes[i].is_witness;
find_best = true;
}
@@ -720,12 +744,19 @@ do_failover(void)
best_candidate.xlog_location.xlogid = nodes[i].xlog_location.xlogid;
best_candidate.xlog_location.xrecoff = nodes[i].xlog_location.xrecoff;
best_candidate.is_ready = nodes[i].is_ready;
best_candidate.is_witness = nodes[i].is_witness;
}
}
/* once we know who is the best candidate, promote it */
if (find_best && (best_candidate.nodeId == local_options.node))
{
if (best_candidate.is_witness)
{
log_err(_("%s: Node selected as new master is a witness. Can't be promoted.\n"), progname);
exit(ERR_FAILOVER_FAIL);
}
if (verbose)
log_info(_("%s: This node is the best candidate to be the new primary, promoting...\n"),
progname);