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repmgrd-physical.c
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/*
* repmgrd-physical.c - physical replication functionality for repmgrd
*
* Copyright (c) 2ndQuadrant, 2010-2017
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <signal.h>
#include "repmgr.h"
#include "repmgrd.h"
#include "repmgrd-physical.h"
typedef enum
{
FAILOVER_STATE_UNKNOWN = -1,
FAILOVER_STATE_NONE,
FAILOVER_STATE_PROMOTED,
FAILOVER_STATE_PROMOTION_FAILED,
FAILOVER_STATE_PRIMARY_REAPPEARED,
FAILOVER_STATE_LOCAL_NODE_FAILURE,
FAILOVER_STATE_WAITING_NEW_PRIMARY,
FAILOVER_STATE_REQUIRES_MANUAL_FAILOVER,
FAILOVER_STATE_FOLLOWED_NEW_PRIMARY,
FAILOVER_STATE_FOLLOWING_ORIGINAL_PRIMARY,
FAILOVER_STATE_NO_NEW_PRIMARY,
FAILOVER_STATE_FOLLOW_FAIL,
FAILOVER_STATE_NODE_NOTIFICATION_ERROR
} FailoverState;
typedef enum
{
ELECTION_NOT_CANDIDATE = -1,
ELECTION_WON,
ELECTION_LOST,
ELECTION_CANCELLED
} ElectionResult;
static PGconn *upstream_conn = NULL;
static PGconn *primary_conn = NULL;
#ifndef BDR_ONLY
static FailoverState failover_state = FAILOVER_STATE_UNKNOWN;
static int primary_node_id = UNKNOWN_NODE_ID;
static t_node_info upstream_node_info = T_NODE_INFO_INITIALIZER;
static NodeInfoList standby_nodes = T_NODE_INFO_LIST_INITIALIZER;
static ElectionResult do_election(void);
static const char *_print_voting_status(NodeVotingStatus voting_status);
static const char *_print_election_result(ElectionResult result);
static FailoverState promote_self(void);
static void notify_followers(NodeInfoList *standby_nodes, int follow_node_id);
static t_node_info *poll_best_candidate(NodeInfoList *standby_nodes);
static void check_connection(t_node_info *node_info, PGconn **conn);
static bool wait_primary_notification(int *new_primary_id);
static FailoverState follow_new_primary(int new_primary_id);
static void reset_node_voting_status(void);
void close_connections_physical();
static bool do_primary_failover(void);
static bool do_upstream_standby_failover(void);
static void update_monitoring_history(void);
#endif
/* perform some sanity checks on the node's configuration */
void
do_physical_node_check(void)
{
#ifndef BDR_ONLY
/*
* Check if node record is active - if not, and `failover=automatic`, the
* node won't be considered as a promotion candidate; this often happens
* when a failed primary is recloned and the node was not re-registered,
* giving the impression failover capability is there when it's not. In
* this case abort with an error and a hint about registering.
*
* If `failover=manual`, repmgrd can continue to passively monitor the
* node, but we should nevertheless issue a warning and the same hint.
*/
if (local_node_info.active == false)
{
char *hint = "Check that 'repmgr (primary|standby) register' was executed for this node";
switch (config_file_options.failover)
{
/* "failover" is an enum, all values should be covered here */
case FAILOVER_AUTOMATIC:
log_error(_("this node is marked as inactive and cannot be used as a failover target"));
log_hint(_("%s"), hint);
PQfinish(local_conn);
terminate(ERR_BAD_CONFIG);
case FAILOVER_MANUAL:
log_warning(_("this node is marked as inactive and will be passively monitored only"));
log_hint(_("%s"), hint);
break;
}
}
if (config_file_options.failover == FAILOVER_AUTOMATIC)
{
/*
* check that promote/follow commands are defined, otherwise repmgrd
* won't be able to perform any useful action
*/
bool required_param_missing = false;
if (config_file_options.promote_command[0] == '\0')
{
log_error(_("\"promote_command\" must be defined in the configuration file"));
if (config_file_options.service_promote_command[0] != '\0')
{
/*
* if repmgrd executes "service_promote_command" directly,
* repmgr metadata won't get updated
*/
log_hint(_("\"service_promote_command\" is set, but can only be executed by \"repmgr standby promote\""));
}
required_param_missing = true;
}
if (config_file_options.follow_command[0] == '\0')
{
log_error(_("\"follow_command\" must be defined in the configuration file"));
required_param_missing = true;
}
if (required_param_missing == true)
{
log_hint(_("add the missing configuration parameter(s) and start repmgrd again"));
PQfinish(local_conn);
exit(ERR_BAD_CONFIG);
}
}
#endif
}
/*
* repmgrd running on the primary server
*/
void
monitor_streaming_primary(void)
{
#ifndef BDR_ONLY
instr_time log_status_interval_start;
PQExpBufferData event_details;
reset_node_voting_status();
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("monitoring cluster primary \"%s\" (node ID: %i)"),
local_node_info.node_name,
local_node_info.node_id);
/* Log startup event */
if (startup_event_logged == false)
{
create_event_notification(local_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_start",
true,
event_details.data);
startup_event_logged = true;
}
else
{
create_event_notification(local_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_reload",
true,
event_details.data);
}
log_notice("%s", event_details.data);
termPQExpBuffer(&event_details);
INSTR_TIME_SET_CURRENT(log_status_interval_start);
local_node_info.node_status = NODE_STATUS_UP;
while (true)
{
/*
* TODO: cache node list here, refresh at `node_list_refresh_interval`
* also return reason for inavailability so we can log it
*/
if (is_server_available(local_node_info.conninfo) == false)
{
/* local node is down, we were expecting it to be up */
if (local_node_info.node_status == NODE_STATUS_UP)
{
PQExpBufferData event_details;
instr_time local_node_unreachable_start;
INSTR_TIME_SET_CURRENT(local_node_unreachable_start);
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("unable to connect to local node"));
log_warning("%s", event_details.data);
local_node_info.node_status = NODE_STATUS_UNKNOWN;
PQfinish(local_conn);
/*
* as we're monitoring the primary, no point in trying to
* write the event to the database
*
* XXX possible pre-action event
*/
create_event_notification(NULL,
&config_file_options,
config_file_options.node_id,
"repmgrd_local_disconnect",
true,
event_details.data);
termPQExpBuffer(&event_details);
local_conn = try_reconnect(&local_node_info);
if (local_node_info.node_status == NODE_STATUS_UP)
{
int local_node_unreachable_elapsed = calculate_elapsed(local_node_unreachable_start);
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("reconnected to local node after %i seconds"),
local_node_unreachable_elapsed);
log_notice("%s", event_details.data);
create_event_notification(local_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_local_reconnect",
true,
event_details.data);
termPQExpBuffer(&event_details);
goto loop;
}
monitoring_state = MS_DEGRADED;
INSTR_TIME_SET_CURRENT(degraded_monitoring_start);
}
}
if (monitoring_state == MS_DEGRADED)
{
int degraded_monitoring_elapsed = calculate_elapsed(degraded_monitoring_start);
if (config_file_options.degraded_monitoring_timeout > 0
&& degraded_monitoring_elapsed > config_file_options.degraded_monitoring_timeout)
{
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("degraded monitoring timeout (%i seconds) exceeded, terminating"),
degraded_monitoring_elapsed);
log_notice("%s", event_details.data);
create_event_notification(NULL,
&config_file_options,
config_file_options.node_id,
"repmgrd_terminate",
true,
event_details.data);
termPQExpBuffer(&event_details);
terminate(ERR_MONITORING_TIMEOUT);
}
log_debug("monitoring node in degraded state for %i seconds", degraded_monitoring_elapsed);
if (is_server_available(local_node_info.conninfo) == true)
{
local_conn = establish_db_connection(local_node_info.conninfo, false);
if (PQstatus(local_conn) == CONNECTION_OK)
{
local_node_info.node_status = NODE_STATUS_UP;
monitoring_state = MS_NORMAL;
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("reconnected to primary node after %i seconds, resuming monitoring"),
degraded_monitoring_elapsed);
create_event_notification(local_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_local_reconnect",
true,
event_details.data);
log_notice("%s", event_details.data);
termPQExpBuffer(&event_details);
goto loop;
}
}
/*
* possibly attempt to find another node from cached list check if
* there's a new primary - if so add hook for fencing? loop, if
* starts up check status, switch monitoring mode
*/
}
loop:
/* emit "still alive" log message at regular intervals, if requested */
if (config_file_options.log_status_interval > 0)
{
int log_status_interval_elapsed = calculate_elapsed(log_status_interval_start);
if (log_status_interval_elapsed >= config_file_options.log_status_interval)
{
log_info(_("monitoring primary node \"%s\" (node ID: %i) in %s state"),
local_node_info.node_name,
local_node_info.node_id,
print_monitoring_state(monitoring_state));
if (monitoring_state == MS_DEGRADED)
{
log_detail(_("waiting for primary to reappear"));
}
INSTR_TIME_SET_CURRENT(log_status_interval_start);
}
}
if (got_SIGHUP)
{
log_debug("SIGHUP received");
if (reload_config(&config_file_options))
{
PQfinish(local_conn);
local_conn = establish_db_connection(config_file_options.conninfo, true);
if (*config_file_options.log_file)
{
FILE *fd;
fd = freopen(config_file_options.log_file, "a", stderr);
if (fd == NULL)
{
fprintf(stderr, "error reopening stderr to \"%s\": %s",
config_file_options.log_file, strerror(errno));
}
}
}
got_SIGHUP = false;
}
log_verbose(LOG_DEBUG, "sleeping %i seconds (parameter \"monitor_interval_secs\")",
config_file_options.monitor_interval_secs);
sleep(config_file_options.monitor_interval_secs);
}
#endif
}
void
monitor_streaming_standby(void)
{
#ifndef BDR_ONLY
RecordStatus record_status;
instr_time log_status_interval_start;
PQExpBufferData event_details;
reset_node_voting_status();
log_debug("monitor_streaming_standby()");
/*
* If no upstream node id is specified in the metadata, we'll try and
* determine the current cluster primary in the assumption we should
* connect to that by default.
*/
if (local_node_info.upstream_node_id == UNKNOWN_NODE_ID)
{
local_node_info.upstream_node_id = get_primary_node_id(local_conn);
/*
* Terminate if there doesn't appear to be an active cluster primary.
* There could be one or more nodes marked as inactive primaries, and
* one of them could actually be a primary, but we can't sensibly
* monitor in that state.
*/
if (local_node_info.upstream_node_id == NODE_NOT_FOUND)
{
log_error(_("unable to determine an active primary for this cluster, terminating"));
PQfinish(local_conn);
exit(ERR_BAD_CONFIG);
}
}
record_status = get_node_record(local_conn, local_node_info.upstream_node_id, &upstream_node_info);
/*
* Terminate if we can't find the record for the node we're supposed to
* monitor. This is a "fix-the-config" situation, not a lot else we can
* do.
*/
if (record_status == RECORD_NOT_FOUND)
{
log_error(_("no record found for upstream node (ID: %i), terminating"),
local_node_info.upstream_node_id);
log_hint(_("ensure the upstream node is registered correctly"));
PQfinish(local_conn);
exit(ERR_DB_CONN);
}
else if (record_status == RECORD_ERROR)
{
log_error(_("unable to retrieve record for upstream node (ID: %i), terminating"),
local_node_info.upstream_node_id);
PQfinish(local_conn);
exit(ERR_DB_CONN);
}
log_debug("connecting to upstream node %i: \"%s\"", upstream_node_info.node_id, upstream_node_info.conninfo);
upstream_conn = establish_db_connection(upstream_node_info.conninfo, false);
/*
* Upstream node must be running at repmgrd startup.
*
* We could possibly have repmgrd skip to degraded monitoring mode until
* it comes up, but there doesn't seem to be much point in doing that.
*/
if (PQstatus(upstream_conn) != CONNECTION_OK)
{
log_error(_("unable connect to upstream node (ID: %i), terminating"),
local_node_info.upstream_node_id);
log_hint(_("upstream node must be running before repmgrd can start"));
PQfinish(local_conn);
exit(ERR_DB_CONN);
}
/*
* refresh upstream node record from upstream node, so it's as up-to-date
* as possible
*/
record_status = get_node_record(upstream_conn, upstream_node_info.node_id, &upstream_node_info);
if (upstream_node_info.type == STANDBY)
{
/*
* Currently cascaded standbys need to be able to connect to the
* primary. We could possibly add a limited connection mode for cases
* where this isn't possible.
*/
primary_conn = establish_primary_db_connection(upstream_conn, false);
if (PQstatus(primary_conn) != CONNECTION_OK)
{
log_error(_("unable to connect to primary node"));
log_hint(_("ensure the primary node is reachable from this node"));
exit(ERR_DB_CONN);
}
log_verbose(LOG_DEBUG, "connected to primary");
}
else
{
primary_conn = upstream_conn;
}
primary_node_id = get_primary_node_id(primary_conn);
/* Log startup event */
if (startup_event_logged == false)
{
PQExpBufferData event_details;
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("monitoring connection to upstream node \"%s\" (node ID: %i)"),
upstream_node_info.node_name,
upstream_node_info.node_id);
create_event_notification(primary_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_start",
true,
event_details.data);
startup_event_logged = true;
log_info("%s", event_details.data);
termPQExpBuffer(&event_details);
}
monitoring_state = MS_NORMAL;
INSTR_TIME_SET_CURRENT(log_status_interval_start);
upstream_node_info.node_status = NODE_STATUS_UP;
while (true)
{
if (is_server_available(upstream_node_info.conninfo) == false)
{
/* upstream node is down, we were expecting it to be up */
if (upstream_node_info.node_status == NODE_STATUS_UP)
{
instr_time upstream_node_unreachable_start;
INSTR_TIME_SET_CURRENT(upstream_node_unreachable_start);
initPQExpBuffer(&event_details);
upstream_node_info.node_status = NODE_STATUS_UNKNOWN;
appendPQExpBuffer(&event_details,
_("unable to connect to upstream node \"%s\" (node ID: %i)"),
upstream_node_info.node_name, upstream_node_info.node_id);
if (upstream_node_info.type == STANDBY)
{
/* XXX possible pre-action event */
create_event_record(primary_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_upstream_disconnect",
true,
event_details.data);
}
log_warning("%s", event_details.data);
termPQExpBuffer(&event_details);
PQfinish(upstream_conn);
upstream_conn = try_reconnect(&upstream_node_info);
/* Node has recovered - log and continue */
if (upstream_node_info.node_status == NODE_STATUS_UP)
{
int upstream_node_unreachable_elapsed = calculate_elapsed(upstream_node_unreachable_start);
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("reconnected to upstream node after %i seconds"),
upstream_node_unreachable_elapsed);
log_notice("%s", event_details.data);
create_event_notification(local_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_upstream_reconnect",
true,
event_details.data);
termPQExpBuffer(&event_details);
goto loop;
}
/* still down after reconnect attempt(s) */
if (upstream_node_info.node_status == NODE_STATUS_DOWN)
{
bool failover_done = false;
if (upstream_node_info.type == PRIMARY)
{
failover_done = do_primary_failover();
}
else if (upstream_node_info.type == STANDBY)
{
failover_done = do_upstream_standby_failover();
}
/*
* XXX it's possible it will make sense to return in all
* cases to restart monitoring
*/
if (failover_done == true)
{
primary_node_id = get_primary_node_id(local_conn);
return;
}
}
}
}
if (monitoring_state == MS_DEGRADED)
{
int degraded_monitoring_elapsed = calculate_elapsed(degraded_monitoring_start);
log_debug("monitoring node %i in degraded state for %i seconds",
upstream_node_info.node_id,
degraded_monitoring_elapsed);
if (is_server_available(upstream_node_info.conninfo) == true)
{
upstream_conn = establish_db_connection(upstream_node_info.conninfo, false);
if (PQstatus(upstream_conn) == CONNECTION_OK)
{
/* XXX check here if upstream is still primary */
/*
* -> will be a problem if another node was promoted in
* the meantime
*/
/* and upstream is now former primary */
/* XXX scan other nodes to see if any has become primary */
upstream_node_info.node_status = NODE_STATUS_UP;
monitoring_state = MS_NORMAL;
if (upstream_node_info.type == PRIMARY)
{
primary_conn = upstream_conn;
}
else
{
if (primary_conn == NULL || PQstatus(primary_conn) != CONNECTION_OK)
{
primary_conn = establish_primary_db_connection(upstream_conn, false);
}
}
initPQExpBuffer(&event_details);
appendPQExpBuffer(&event_details,
_("reconnected to upstream node %i after %i seconds, resuming monitoring"),
upstream_node_info.node_id,
degraded_monitoring_elapsed);
create_event_notification(primary_conn,
&config_file_options,
config_file_options.node_id,
"repmgrd_upstream_reconnect",
true,
event_details.data);
log_notice("%s", event_details.data);
termPQExpBuffer(&event_details);
goto loop;
}
}
else
{
/*
* unable to connect to former primary - check if another node
* has been promoted
*/
NodeInfoListCell *cell;
int follow_node_id = UNKNOWN_NODE_ID;
/* local node has been promoted */
if (get_recovery_type(local_conn) == RECTYPE_PRIMARY)
{
log_notice(_("local node is primary, checking local node record"));
/*
* There may be a delay between the node being promoted
* and the local record being updated, so if the node
* record still shows it as a standby, do nothing, we'll
* catch the update during the next loop. (e.g. node was
* manually promoted) we'll do nothing, as the repmgr
* metadata is now out-of-sync. If it does get fixed,
* we'll catch it here on a future iteration.
*/
/* refresh own internal node record */
record_status = get_node_record(local_conn, local_node_info.node_id, &local_node_info);
if (local_node_info.type == PRIMARY)
{
int degraded_monitoring_elapsed = calculate_elapsed(degraded_monitoring_start);
log_notice(_("resuming monitoring as primary node after %i seconds"),
degraded_monitoring_elapsed);
/* this will restart monitoring in primary mode */
monitoring_state = MS_NORMAL;
return;
}
}
if (config_file_options.failover == FAILOVER_AUTOMATIC)
{
get_active_sibling_node_records(local_conn,
local_node_info.node_id,
local_node_info.upstream_node_id,
&standby_nodes);
if (standby_nodes.node_count > 0)
{
log_debug("scanning %i node records to detect new primary...", standby_nodes.node_count);
for (cell = standby_nodes.head; cell; cell = cell->next)
{
/* skip local node check, we did that above */
if (cell->node_info->node_id == local_node_info.node_id)
{
continue;
}
cell->node_info->conn = establish_db_connection(cell->node_info->conninfo, false);
if (PQstatus(cell->node_info->conn) != CONNECTION_OK)
{
log_debug("unable to connect to %i ... ", cell->node_info->node_id);
continue;
}
if (get_recovery_type(cell->node_info->conn) == RECTYPE_PRIMARY)
{
follow_node_id = cell->node_info->node_id;
PQfinish(cell->node_info->conn);
cell->node_info->conn = NULL;
break;
}
PQfinish(cell->node_info->conn);
cell->node_info->conn = NULL;
}
if (follow_node_id != UNKNOWN_NODE_ID)
{
follow_new_primary(follow_node_id);
}
}
}
}
}
loop:
/* emit "still alive" log message at regular intervals, if requested */
if (config_file_options.log_status_interval > 0)
{
int log_status_interval_elapsed = calculate_elapsed(log_status_interval_start);
if (log_status_interval_elapsed >= config_file_options.log_status_interval)
{
PQExpBufferData monitoring_summary;
initPQExpBuffer(&monitoring_summary);
appendPQExpBuffer(
&monitoring_summary,
_("node \"%s\" (node ID: %i) monitoring upstream node \"%s\" (node ID: %i) in %s state"),
local_node_info.node_name,
local_node_info.node_id,
upstream_node_info.node_name,
upstream_node_info.node_id,
print_monitoring_state(monitoring_state));
if (config_file_options.failover == FAILOVER_MANUAL)
{
appendPQExpBuffer(
&monitoring_summary,
_(" (automatic failover disabled)"));
}
log_info("%s", monitoring_summary.data);
termPQExpBuffer(&monitoring_summary);
if (monitoring_state == MS_DEGRADED && config_file_options.failover == FAILOVER_AUTOMATIC)
{
log_detail(_("waiting for upstream or another primary to reappear"));
}
INSTR_TIME_SET_CURRENT(log_status_interval_start);
}
}
/*
* handle local node failure
*
* currently we'll just check the connection, and try to reconnect
*
* TODO: add timeout, after which we run in degraded state
*/
check_connection(&local_node_info, &local_conn);
if (PQstatus(local_conn) != CONNECTION_OK)
{
if (local_node_info.active == true)
{
if (PQstatus(primary_conn) == CONNECTION_OK)
{
if (update_node_record_set_active(primary_conn, local_node_info.node_id, false) == true)
{
PQExpBufferData event_details;
initPQExpBuffer(&event_details);
local_node_info.active = false;
appendPQExpBuffer(
&event_details,
_("unable to connect to local node \"%s\" (ID: %i), marking inactive"),
local_node_info.node_name,
local_node_info.node_id);
log_warning("%s", event_details.data)
create_event_notification(
primary_conn,
&config_file_options,
local_node_info.node_id,
"standby_failure",
false,
event_details.data);
termPQExpBuffer(&event_details);
}
}
}
}
else
{
if (local_node_info.active == false)
{
if (PQstatus(primary_conn) == CONNECTION_OK)
{
if (update_node_record_set_active(primary_conn, local_node_info.node_id, true) == true)
{
PQExpBufferData event_details;
initPQExpBuffer(&event_details);
local_node_info.active = true;
appendPQExpBuffer(
&event_details,
_("reconnected to local node \"%s\" (ID: %i), marking active"),
local_node_info.node_name,
local_node_info.node_id);
log_warning("%s", event_details.data)
create_event_notification(
primary_conn,
&config_file_options,
local_node_info.node_id,
"standby_recovery",
true,
event_details.data);
termPQExpBuffer(&event_details);
}
}
}
}
if (PQstatus(local_conn) == CONNECTION_OK && config_file_options.monitoring_history == true)
update_monitoring_history();
if (got_SIGHUP)
{
log_debug("SIGHUP received");
if (reload_config(&config_file_options))
{
PQfinish(local_conn);
local_conn = establish_db_connection(config_file_options.conninfo, true);
if (*config_file_options.log_file)
{
FILE *fd;
fd = freopen(config_file_options.log_file, "a", stderr);
if (fd == NULL)
{
fprintf(stderr, "error reopening stderr to \"%s\": %s",
config_file_options.log_file, strerror(errno));
}
}
}
got_SIGHUP = false;
}
sleep(config_file_options.monitor_interval_secs);
}
#endif
}
#ifndef BDR_ONLY
static bool
do_primary_failover(void)
{
/* attempt to initiate voting process */
ElectionResult election_result = do_election();
/* TODO add pre-event notification here */
failover_state = FAILOVER_STATE_UNKNOWN;
log_debug("election result: %s", _print_election_result(election_result));
if (election_result == ELECTION_CANCELLED)
{
log_notice(_("election cancelled"));
return false;
}
else if (election_result == ELECTION_WON)
{
log_notice("this node is the winner, will now promote self and inform other nodes");
failover_state = promote_self();
}
else if (election_result == ELECTION_LOST)
{
t_node_info *best_candidate;
log_info(_("I am the candidate but did not get all votes; will now determine the best candidate"));
/* standby_nodes is in the state created by do_election() */
best_candidate = poll_best_candidate(&standby_nodes);
/*
* this can occur in a tie-break situation, where this node
* establishes it is the best candidate
*/
if (best_candidate->node_id == local_node_info.node_id)
{
log_notice("I am the best candidate, will now promote self and inform other nodes");
failover_state = promote_self();
}
else
{
PGconn *candidate_conn = NULL;
log_info("node %i is the best candidate, waiting for it to confirm so I can follow it",
best_candidate->node_id);
/* notify the best candidate so it */
candidate_conn = establish_db_connection(best_candidate->conninfo, false);
if (PQstatus(candidate_conn) == CONNECTION_OK)
{
notify_follow_primary(candidate_conn, best_candidate->node_id);
/* we'll wait for the candidate to get back to us */
failover_state = FAILOVER_STATE_WAITING_NEW_PRIMARY;
}