From 6ffb79766b78b11976ff50cc2080d6313f452bca Mon Sep 17 00:00:00 2001
From: Nikita <abracham.mitchell@gmail.com>
Date: Mon, 1 Oct 2018 18:28:18 +0300
Subject: [PATCH] Master node failover handling improvements

---
 .../redisson/client/handler/CommandsQueue.java   |  2 +-
 .../cluster/ClusterConnectionManager.java        | 16 ++++++++++++----
 .../connection/MasterSlaveConnectionManager.java |  6 ++++--
 .../redisson/connection/MasterSlaveEntry.java    |  2 +-
 4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/redisson/src/main/java/org/redisson/client/handler/CommandsQueue.java b/redisson/src/main/java/org/redisson/client/handler/CommandsQueue.java
index 448e24593..9e1b0fa94 100644
--- a/redisson/src/main/java/org/redisson/client/handler/CommandsQueue.java
+++ b/redisson/src/main/java/org/redisson/client/handler/CommandsQueue.java
@@ -78,7 +78,7 @@ public class CommandsQueue extends ChannelDuplexHandler {
             }
             
             command.getChannelPromise().tryFailure(
-                    new WriteRedisConnectionException("Can't write command: " + command.getCommand() + " to channel: " + ctx.channel()));
+                    new WriteRedisConnectionException("Channel has been closed! Can't write command: " + command.getCommand() + " to channel: " + ctx.channel()));
         }
         
         super.channelInactive(ctx);
diff --git a/redisson/src/main/java/org/redisson/cluster/ClusterConnectionManager.java b/redisson/src/main/java/org/redisson/cluster/ClusterConnectionManager.java
index 7c26ea6b6..974b97cca 100644
--- a/redisson/src/main/java/org/redisson/cluster/ClusterConnectionManager.java
+++ b/redisson/src/main/java/org/redisson/cluster/ClusterConnectionManager.java
@@ -507,7 +507,7 @@ public class ClusterConnectionManager extends MasterSlaveConnectionManager {
         Set<ClusterPartition> lastPartitions = getLastPartitions();
         for (final ClusterPartition newPart : newPartitions) {
             boolean masterFound = false;
-            for (ClusterPartition currentPart : lastPartitions) {
+            for (final ClusterPartition currentPart : lastPartitions) {
                 if (!newPart.getMasterAddress().equals(currentPart.getMasterAddress())) {
                     continue;
                 }
@@ -521,11 +521,19 @@ public class ClusterConnectionManager extends MasterSlaveConnectionManager {
                     // does partition has a new master?
                     if (!newMasterPart.getMasterAddress().equals(currentPart.getMasterAddress())) {
                         URI newUri = newMasterPart.getMasterAddress();
-                        URI oldUri = currentPart.getMasterAddress();
+                        final URI oldUri = currentPart.getMasterAddress();
                         
-                        changeMaster(slot, newUri);
+                        RFuture<RedisClient> future = changeMaster(slot, newUri);
+                        future.addListener(new FutureListener<RedisClient>() {
+                            @Override
+                            public void operationComplete(Future<RedisClient> future) throws Exception {
+                                if (!future.isSuccess()) {
+                                    currentPart.setMasterAddress(oldUri);
+                                }
+                            }
+                        });
                         
-                        currentPart.setMasterAddress(newMasterPart.getMasterAddress());
+                        currentPart.setMasterAddress(newUri);
                     }
                 }
                 break;
diff --git a/redisson/src/main/java/org/redisson/connection/MasterSlaveConnectionManager.java b/redisson/src/main/java/org/redisson/connection/MasterSlaveConnectionManager.java
index 285800204..a167b2a73 100644
--- a/redisson/src/main/java/org/redisson/connection/MasterSlaveConnectionManager.java
+++ b/redisson/src/main/java/org/redisson/connection/MasterSlaveConnectionManager.java
@@ -504,10 +504,11 @@ public class MasterSlaveConnectionManager implements ConnectionManager {
         return slot2entry.get(slot);
     }
     
-    protected final void changeMaster(int slot, URI address) {
+    protected final RFuture<RedisClient> changeMaster(int slot, URI address) {
         final MasterSlaveEntry entry = getEntry(slot);
         final RedisClient oldClient = entry.getClient();
-        entry.changeMaster(address).addListener(new FutureListener<RedisClient>() {
+        RFuture<RedisClient> future = entry.changeMaster(address);
+        future.addListener(new FutureListener<RedisClient>() {
             @Override
             public void operationComplete(Future<RedisClient> future) throws Exception {
                 if (future.isSuccess()) {
@@ -516,6 +517,7 @@ public class MasterSlaveConnectionManager implements ConnectionManager {
                 }
             }
         });
+        return future;
     }
     
     protected final void addEntry(Integer slot, MasterSlaveEntry entry) {
diff --git a/redisson/src/main/java/org/redisson/connection/MasterSlaveEntry.java b/redisson/src/main/java/org/redisson/connection/MasterSlaveEntry.java
index eb06ce46a..03957704d 100644
--- a/redisson/src/main/java/org/redisson/connection/MasterSlaveEntry.java
+++ b/redisson/src/main/java/org/redisson/connection/MasterSlaveEntry.java
@@ -422,7 +422,7 @@ public class MasterSlaveEntry {
             @Override
             public void operationComplete(Future<RedisClient> future) throws Exception {
                 if (!future.isSuccess()) {
-                    log.error("Can't change master to: {}", address);
+                    log.error("Unable to change master from: " + oldMaster.getClient().getAddr() + " to: " + address, future.cause());
                     return;
                 }