From 4a6aee131dcf5b05a2ae04d4f4b65c0a6c4c5495 Mon Sep 17 00:00:00 2001
From: glyn <glyn@8kb.co.uk>
Date: Tue, 13 Jan 2015 13:45:58 +0000
Subject: [PATCH] Add an initial state to cluster hash, this way we can tell
 the difference between a cluster that has no suitable target nodes and where
 the previous cluster state has not yet been initialized. We also want to
 register that things have changed and there is now no suitable node, that way
 we can write nothing and effectively shut off the pool.

---
 pgbouncer_follower.pl | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/pgbouncer_follower.pl b/pgbouncer_follower.pl
index c721385..c6b6ede 100755
--- a/pgbouncer_follower.pl
+++ b/pgbouncer_follower.pl
@@ -288,11 +288,11 @@ sub generateConfig {
 sub checkCluster {
     my $infile = shift;
     my $changed = false;
-    my $current_cluster;
-    my $previous_cluster;
+    my $current_state = md5_hex('INIT');
+    my $previous_state;
     foreach (@g_cluster) {
         if (!$g_origins_only || defined($_->[3])) {
-            $current_cluster = md5_hex(($current_cluster // "") . $_->[0] . $_->[2] . (defined($_->[3]) ? 't' : 'f') . $_->[6] . $_->[11]);
+            $current_state = md5_hex(($current_state // "") . $_->[0] . $_->[2] . (defined($_->[3]) ? 't' : 'f') . $_->[6] . $_->[11]);
             if ($g_debug) {
                 printLogLn($g_logfile, "DEBUG: Node " . $_->[0] . " detail = " . $_->[2] . (defined($_->[3]) ? 't' : 'f') . $_->[6] . $_->[11]);
             }
@@ -301,7 +301,7 @@ sub checkCluster {
    
     if (-f $infile) {
         if (open(CLUSTERFILE, "<", $infile)) {
-            $previous_cluster = <CLUSTERFILE>;
+            $previous_state = <CLUSTERFILE>;
             close(CLUSTERFILE);
         }
         else {
@@ -309,12 +309,12 @@ sub checkCluster {
         }
     }
 
-    unless (-f $infile && ($current_cluster eq $previous_cluster)) {
+    unless (-f $infile && ($current_state eq $previous_state)) {
         if ($g_debug) {
                 printLogLn($g_logfile, "DEBUG: Writing to status file");
         }
         if (open(CLUSTERFILE, ">", $infile)) {
-            print CLUSTERFILE $current_cluster;
+            print CLUSTERFILE $current_state;
             close(CLUSTERFILE);
         }
         else {
@@ -322,7 +322,7 @@ sub checkCluster {
         }
     }
 
-    if ((($previous_cluster // "") ne "") && (($current_cluster // "") ne "") && ($current_cluster ne $previous_cluster)){
+    if ((($previous_state // "") ne "") && ($current_state ne $previous_state)){
         $changed = true;
     }
 
-- 
2.39.2