From cac693d8e1c529c325962fdf6ad81fd0f6b3168b Mon Sep 17 00:00:00 2001
From: Martin Furmanski <martin.furmanski@neotechnology.com>
Date: Tue, 7 Mar 2017 16:07:48 +0100
Subject: [PATCH] make cluster binder cope with an eventual topology

Because the topology is now cached and refreshed periodically,
the cluster binder can no longer rely on the initial state.
---
 .../identity/ClusterIdentity.java             | 61 +++++++++----------
 1 file changed, 29 insertions(+), 32 deletions(-)

diff --git a/enterprise/causal-clustering/src/main/java/org/neo4j/causalclustering/identity/ClusterIdentity.java b/enterprise/causal-clustering/src/main/java/org/neo4j/causalclustering/identity/ClusterIdentity.java
index 5832a433b8b9c..5c5c4c12363b5 100644
--- a/enterprise/causal-clustering/src/main/java/org/neo4j/causalclustering/identity/ClusterIdentity.java
+++ b/enterprise/causal-clustering/src/main/java/org/neo4j/causalclustering/identity/ClusterIdentity.java
@@ -71,50 +71,47 @@ public void bindToCluster( ThrowingConsumer<CoreSnapshot, Throwable> snapshotIns
     {
         if ( clusterIdStorage.exists() )
         {
-            ClusterId localClusterId = clusterIdStorage.readState();
-            publishClusterId( localClusterId );
-            clusterId = localClusterId;
+            clusterId = clusterIdStorage.readState();
+            publishClusterId( clusterId );
+            log.info( "Already bound to cluster: " + clusterId );
+            return;
         }
-        else
+
+        CoreTopology topology;
+        long endTime = clock.millis() + timeoutMillis;
+
+        do
         {
-            ClusterId commonClusterId;
-            CoreTopology topology = topologyService.coreServers();
-            if ( topology.canBeBootstrapped() )
+            topology = topologyService.coreServers();
+
+            if ( topology.clusterId() != null )
+            {
+                clusterId = topology.clusterId();
+                log.info( "Bound to cluster: " + clusterId );
+            }
+            else if ( topology.canBeBootstrapped() )
             {
-                commonClusterId = new ClusterId( UUID.randomUUID() );
+                clusterId = new ClusterId( UUID.randomUUID() );
                 CoreSnapshot snapshot = coreBootstrapper.bootstrap( topology.members() );
-                log.info( String.format( "Bootstrapped with snapshot: %s and clusterId: %s", snapshot, commonClusterId ) );
+                log.info( String.format( "Bootstrapped with snapshot: %s and clusterId: %s", snapshot, clusterId ) );
 
                 snapshotInstaller.accept( snapshot );
-                publishClusterId( commonClusterId );
+                publishClusterId( clusterId );
             }
             else
             {
-                long endTime = clock.millis() + timeoutMillis;
-
-                log.info( "Attempting to bind to : " + topology );
-                while ( (commonClusterId = topology.clusterId()) == null )
-                {
-                    if ( clock.millis() < endTime )
-                    {
-                        retryWaiter.apply();
-                        topology = topologyService.coreServers();
-                    }
-                    else
-                    {
-                        throw new TimeoutException( String.format( "Failed to join a cluster with members %s. Another" +
-                                " member should have published a clusterId but none was detected. Please restart the " +
-                                "cluster.", topology ));
-                    }
-                }
-
-                log.info( "Bound to cluster: " + commonClusterId );
+                retryWaiter.apply();
             }
+        } while ( clusterId == null && clock.millis() < endTime );
 
-            clusterIdStorage.writeState( commonClusterId );
-
-            clusterId = commonClusterId;
+        if ( clusterId == null )
+        {
+            throw new TimeoutException( String.format(
+                    "Failed to join a cluster with members %s. Another member should have published " +
+                    "a clusterId but none was detected. Please restart the cluster.", topology ) );
         }
+
+        clusterIdStorage.writeState( clusterId );
     }
 
     public ClusterId clusterId()