Add signals to repmgrd and teach it to clean things up when

signaled before exit

repmgrd.c

@@ -7,12 +7,16 @@
  * how far are they from master 
  */
 
+#include <signal.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 #include "repmgr.h"
 
+#include "libpq/pqsignal.h"
+
 char    myClusterName[MAXLEN];
 
 /* Local info */
@@ -25,6 +29,7 @@ int		primaryId;
 char	primaryConninfo[MAXLEN];
 PGconn *primaryConn;
 
+char sqlquery[8192];
 
 const char *progname;
 
@@ -37,11 +42,31 @@ static void checkClusterConfiguration(void);
 static void checkNodeConfiguration(char *conninfo);
 static void getPrimaryConnection(void);
 
-static void MonitorCheck(void);
 static void MonitorExecute(void);
 
 static unsigned long long int walLocationToBytes(char *wal_location);
 
+static void handle_sigint(SIGNAL_ARGS);
+static void setup_cancel_handler(void);
+
+#define CloseConnections()	\
+						if (PQisBusy(primaryConn) == 1) \
+							CancelQuery(); \
+						if (myLocalConn != NULL) \
+							PQfinish(myLocalConn);	\
+						if (primaryConn != NULL) \
+							PQfinish(primaryConn);
+
+/*
+ * Every 3 seconds, insert monitor info
+ */
+#define MonitorCheck() \
+						for (;;) \
+						{ \
+							MonitorExecute(); \
+							sleep(3); \
+						} 
+
 
 int
 main(int argc, char **argv)
@@ -89,6 +114,8 @@ main(int argc, char **argv)
 				exit(1);
 		}
 	}
+
+	setup_cancel_handler();
 	
 	if (config_file == NULL)
 		sprintf(config_file, "./%s", CONFIG_FILE);
@@ -125,19 +152,18 @@ main(int argc, char **argv)
 		/* I need the id of the primary as well as a connection to it */
 		getPrimaryConnection();
 		MonitorCheck();		
-		PQfinish(primaryConn);
 	}
 
     /* close the connection to the database and cleanup */
-    PQfinish(myLocalConn);
+    CloseConnections();
 
     return 0;
 }
 
 
 /*
- * This function ask if we are in recovery, if false we are the primary else 
- * we are a standby
+ * get a connection to primary by reading repl_nodes, creating a connection 
+ * to each node (one at a time) and finding if it is a primary or a standby
  */
 static void
 getPrimaryConnection(void)
@@ -146,43 +172,55 @@ getPrimaryConnection(void)
     PGresult *res2;
 	int		  i;
 
-    res1 = PQexec(myLocalConn, "SELECT * FROM repl_nodes");
+	/* find all nodes belonging to this cluster */
+	sprintf(sqlquery, "SELECT * FROM repl_nodes "
+ 					  " WHERE cluster = '%s' ",
+					  myClusterName);
+
+    res1 = PQexec(myLocalConn, sqlquery);
     if (PQresultStatus(res1) != PGRES_TUPLES_OK)
     {
         fprintf(stderr, "Can't get nodes info: %s\n", PQerrorMessage(myLocalConn));
         PQclear(res1);
-        PQfinish(myLocalConn);
+        CloseConnections();
 		exit(1);
     }
 
 	for (i = 0; i < PQntuples(res1); i++)
     {
+		/* initialize with the values of the current node being processed */
 		primaryId   = atoi(PQgetvalue(res1, i, 0));
 		strcpy(primaryConninfo, PQgetvalue(res1, i, 2));
 		primaryConn = establishDBConnection(primaryConninfo, false);
 
+		/* 
+		 * I can't use the is_standby() function here because on error that 
+  		 * function closes the one i pass and exit, but i still need to close
+		 * myLocalConn
+		 */
     	res2 = PQexec(primaryConn, "SELECT pg_is_in_recovery()");
     	if (PQresultStatus(res2) != PGRES_TUPLES_OK)
     	{
     	    fprintf(stderr, "Can't get nodes info: %s\n", PQerrorMessage(primaryConn));
 			PQclear(res1);
     	    PQclear(res2);
-        	PQfinish(primaryConn);
-        	PQfinish(myLocalConn);
+        	CloseConnections();
 			exit(1);
     	}
 
+		/* if false, this is the primary */
 		if (strcmp(PQgetvalue(res2, 0, 0), "f") == 0)
 		{
 			PQclear(res2);
 			PQclear(res1);
-			/* On the primary the monitor check is asynchronous */
+			/* We turn off synchronous_commit for the monitor info inserts */
     		res1 = PQexec(primaryConn, "SET synchronous_commit TO off");
 			PQclear(res1);
 			return;
 		}
 		else
 		{
+			/* if it is a standby clear info */
 			PQclear(res2);
 			PQfinish(primaryConn);
 			primaryId = -1;
@@ -194,37 +232,26 @@ getPrimaryConnection(void)
      * 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 o just fix some situation on the
+     * to start failover procedure or just fix some situation on the
      * standby.
      */
-   	fprintf(stderr, "There isn't a primary node\n");
+   	fprintf(stderr, "There isn't a primary node the cluster\n");
 	PQclear(res1);
-    PQfinish(myLocalConn);
+	CloseConnections();
 	exit(1);
 }
 
 
-static void
-MonitorCheck(void) { 
-	/*
-	 * Every 3 seconds, insert monitor info
-     */
-	for (;;) 
-	{  
-		MonitorExecute(); 
-		sleep(3); 
-	} 
-}
-
 
 /*
- * Check if its time for next monitor call and if so, do it.
+ * Insert monitor info, this is basically the time and xlog replayed,
+ * applied on standby and current xlog location in primary.
+ * Also do the math to see how far are we in bytes for being uptodate
  */
 static void
 MonitorExecute(void)
 {
     PGresult *res;
-	char sqlquery[8192];
 	char monitor_standby_timestamp[MAXLEN];
 	char last_wal_primary_location[MAXLEN];
 	char last_wal_standby_received[MAXLEN];
@@ -234,6 +261,14 @@ MonitorExecute(void)
 	unsigned long long int lsn_standby_received;
 	unsigned long long int lsn_standby_applied;
 
+	/* 
+	 * first check if there is a command being executed,
+	 * and if that is the case, cancel the query so i can
+     * insert the current record
+     */ 
+	if (PQisBusy(primaryConn) == 1)
+		CancelQuery();
+
 	/* Get local xlog info */
     sprintf(sqlquery,
             "SELECT CURRENT_TIMESTAMP, pg_last_xlog_receive_location(), "
@@ -244,6 +279,7 @@ MonitorExecute(void)
     {
         fprintf(stderr, "PQexec failed: %s\n", PQerrorMessage(myLocalConn));
         PQclear(res);
+		/* if there is any error just let it be and retry in next loop */
         return;
     }
 
@@ -289,8 +325,8 @@ MonitorExecute(void)
 	 * Execute the query asynchronously, but don't check for a result. We
 	 * will check the result next time we pause for a monitor step.
 	 */
-	if (!PQexec(primaryConn, sqlquery))
-		fprintf(stderr, "replication monitor insert failed: %s\n",
+	if (PQsendQuery(primaryConn, sqlquery) == 0)
+		fprintf(stderr, "Query could not be sent to primary. %s\n",
 						PQerrorMessage(primaryConn));
 }
 
@@ -332,7 +368,6 @@ static void
 checkNodeConfiguration(char *conninfo)
 {
     PGresult   *res;
-	char sqlquery[8192];
 
 	/*
 	 * Check if we have my node information in repl_nodes
@@ -414,3 +449,34 @@ help(const char *progname)
     printf(_("new master in the event of a failover\n"));
     printf(_(" standby follow [node] - allows the standby to re-point itself to a new master\n"));
 }
+
+
+
+#ifndef WIN32
+static void
+handle_sigint(SIGNAL_ARGS)
+{
+    CloseConnections();
+}
+
+static void
+setup_cancel_handler(void)
+{
+    pqsignal(SIGINT, handle_sigint);
+}
+#endif
+
+
+static void
+CancelQuery(void)
+{
+    char errbuf[256];
+    PGcancel *pgcancel;
+
+    pgcancel = PQgetCancel(primaryConn);
+
+    if (!pgcancel || PQcancel(pgcancel, errbuf, 256) == 0)
+        fprintf(stderr, "Can't stop current query: %s", errbuf);
+
+    PQfreeCancel(pgcancel);
+}