poke it around until it works less badly

config.c

@@ -16,6 +16,10 @@ static bool config_file_provided = false;
 bool config_file_found = false;
 
 static void	_parse_config(t_configuration_options *options, ItemList *error_list, ItemList *warning_list);
+static bool		parse_bool(const char *s,
+					   const char *config_item,
+					   ItemList *error_list);
+
 static void	_parse_line(char *buf, char *name, char *value);
 static void	parse_event_notifications_list(t_configuration_options *options, const char *arg);
 static void	tablespace_list_append(t_configuration_options *options, const char *arg);
@@ -774,7 +778,7 @@ repmgr_atoi(const char *value, const char *config_item, ItemList *error_list, in
  *
  *   https://www.postgresql.org/docs/current/static/config-setting.html
  */
-bool
+static bool
 parse_bool(const char *s, const char *config_item, ItemList *error_list)
 {
 	PQExpBufferData errors;

config.h

@@ -158,9 +158,6 @@ int			repmgr_atoi(const char *s,
 						ItemList *error_list,
 						int minval);
 
-bool		parse_bool(const char *s,
-					   const char *config_item,
-					   ItemList *error_list);
 
 bool parse_pg_basebackup_options(const char *pg_basebackup_options,
 								 t_basebackup_options *backup_options,

dbutils.c

@@ -2364,6 +2364,32 @@ set_voting_status_initiated(PGconn *conn)
 }
 
 
+bool
+announce_candidature(PGconn *conn, t_node_info *this_node, t_node_info *other_node)
+{
+	PQExpBufferData	  query;
+	PGresult   *res;
+
+	bool retval;
+
+	initPQExpBuffer(&query);
+
+	appendPQExpBuffer(&query,
+					  "SELECT repmgr.other_node_is_candidate(%i)",
+					  this_node->node_id);
+
+	res = PQexec(conn, query.data);
+	termPQExpBuffer(&query);
+
+	retval = (strcmp(PQgetvalue(res, 0, 0), "t") == 0)
+		? true
+		: false;
+
+	PQclear(res);
+
+	return retval;
+}
+
 /* ============================ */
 /* replication status functions */
 /* ============================ */

dbutils.h

@@ -248,7 +248,7 @@ bool		is_server_available(const char *conninfo);
 NodeVotingStatus get_voting_status(PGconn *conn);
 int	request_vote(PGconn *conn, t_node_info *this_node, t_node_info *other_node, XLogRecPtr last_wal_receive_lsn);
 void set_voting_status_initiated(PGconn *conn);
-
+bool announce_candidature(PGconn *conn, t_node_info *this_node, t_node_info *other_node);
 
 /* replication status functions */
 

repmgr--4.0.sql

@@ -51,3 +51,8 @@ CREATE FUNCTION set_voting_status_initiated()
   RETURNS VOID
   AS '$libdir/repmgr', 'set_voting_status_initiated'
   LANGUAGE C STRICT;
+
+CREATE FUNCTION other_node_is_candidate(INT)
+  RETURNS BOOL
+  AS '$libdir/repmgr', 'other_node_is_candidate'
+  LANGUAGE C STRICT;

repmgr.c

@@ -30,6 +30,8 @@
 
 #include "voting.h"
 
+#define UNKNOWN_NODE_ID		-1
+
 #define MAXFNAMELEN		64
 #define TRANCHE_NAME "repmgrd"
 
@@ -46,6 +48,7 @@ typedef struct repmgrdSharedState
 	LWLockId	lock;			/* protects search/modification */
 	NodeState	node_state;
 	NodeVotingStatus voting_status;
+	int candidate_node_id;
 }	repmgrdSharedState;
 
 static repmgrdSharedState *shared_state = NULL;
@@ -67,6 +70,8 @@ PG_FUNCTION_INFO_V1(get_voting_status);
 Datum		set_voting_status_initiated(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(set_voting_status_initiated);
 
+Datum other_node_is_candidate(PG_FUNCTION_ARGS);
+PG_FUNCTION_INFO_V1(other_node_is_candidate);
 /*
  * Module load callback
  */
@@ -130,7 +135,7 @@ repmgr_shmem_startup(void)
 
 	if (!found)
 	{
-		/* First time through ... */
+		/* Initialise shared memory struct */
 #if (PG_VERSION_NUM >= 90600)
 		shared_state->lock = &(GetNamedLWLockTranche(TRANCHE_NAME))->lock;
 #else
@@ -138,6 +143,7 @@ repmgr_shmem_startup(void)
 #endif
 
 		shared_state->voting_status = VS_NO_VOTE;
+		shared_state->candidate_node_id = UNKNOWN_NODE_ID;
 	}
 
 	LWLockRelease(AddinShmemInitLock);
@@ -225,3 +231,25 @@ set_voting_status_initiated(PG_FUNCTION_ARGS)
 
 	PG_RETURN_VOID();
 }
+
+Datum
+other_node_is_candidate(PG_FUNCTION_ARGS)
+{
+	int  requesting_node_id = PG_GETARG_INT32(0);
+
+	LWLockAcquire(shared_state->lock, LW_SHARED);
+
+	if (shared_state->candidate_node_id != UNKNOWN_NODE_ID)
+	{
+		elog(INFO, "node %i requesting candidature, but node %i already candidate",
+				  requesting_node_id,
+				  shared_state->candidate_node_id);
+		PG_RETURN_BOOL(false);
+	}
+
+	shared_state->candidate_node_id = requesting_node_id;
+	LWLockRelease(shared_state->lock);
+
+	elog(INFO, "node %i is candidate", requesting_node_id);
+	PG_RETURN_BOOL(true);
+}

repmgrd.c

@@ -576,7 +576,8 @@ monitor_streaming_standby(void)
 	}
 }
 
-
+// store lsndiffs, in the event we're not the best node,
+// i.e. don't get all the votes, we pass the baton to the best node
 static NodeVotingStatus
 do_election(void)
 {
@@ -598,6 +599,8 @@ do_election(void)
 
 	long unsigned rand_wait = (long) ((rand() % 50) + 10) * 10000;
 
+	bool other_node_is_candidate = false;
+
 	log_debug("do_election(): sleeping %li", rand_wait);
 
 	pg_usleep(rand_wait);
@@ -646,10 +649,21 @@ do_election(void)
 			continue;
 		}
 
+		if (announce_candidature(cell->node_info->conn, &local_node_info, cell->node_info) == false)
+		{
+			log_debug("node %i is candidate",  cell->node_info->node_id);
+			other_node_is_candidate = true;
+		}
+
 		cell->node_info->is_visible = true;
 		visible_nodes ++;
 	}
 
+	if (other_node_is_candidate == true)
+	{
+		return VS_NO_VOTE;
+	}
+
 	// XXX check if > 50% visible
 
 	/* check again if we've been asked to vote */