Add ConnectionWatchdog as last handler #335

The reuse of handlers causes multiple calls to channelActive/channelInactive/and so on. In some cases, the reconnection is faster than channel deregistration (calls to channelUnregistered) which leads to the call sequence channelRegistered (new channel), channelUnregistered (old channel). Similar for channelActive/channelInactive. This is handled inside the CommandHandler but can still lead to issues. Moving the ConnectionWatchdog to the end reduces the probability of the calls coming in the wrong order. It fixes also the channelActive/channelInactive order in fast reconnect scenarios as the channelInactive call is done before notifying the ConnectionWatchdog.

src/main/java/com/lambdaworks/redis/ConnectionBuilder.java

@@ -53,9 +53,6 @@ protected List<ChannelHandler> buildHandlers() {
         LettuceAssert.assertState(clientResources != null, "clientResources must be set");
 
         List<ChannelHandler> handlers = new ArrayList<>();
-        if (clientOptions.isAutoReconnect()) {
-            handlers.add(createConnectionWatchdog());
-        }
 
         connection.setOptions(clientOptions);
 
@@ -65,6 +62,10 @@ protected List<ChannelHandler> buildHandlers() {
         handlers.add(connection);
         handlers.add(new ConnectionEventTrigger(connectionEvents, connection, clientResources.eventBus()));
 
+        if (clientOptions.isAutoReconnect()) {
+            handlers.add(createConnectionWatchdog());
+        }
+
         return handlers;
     }
 

src/main/java/com/lambdaworks/redis/protocol/ConnectionWatchdog.java

@@ -100,15 +100,6 @@ public SocketAddress get() {
         this.reconnectionHandler = new ReconnectionHandler(clientOptions, bootstrap, wrappedSocketAddressSupplier);
     }
 
-    @Override
-    public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
-
-        if(commandHandler == null) {
-            this.commandHandler = ctx.pipeline().get(CommandHandler.class);
-        }
-        super.channelRegistered(ctx);
-    }
-
     @Override
     public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
 
@@ -139,6 +130,10 @@ void prepareClose(ConnectionEvents.PrepareClose prepareClose) {
     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {
 
+        if(commandHandler == null) {
+            this.commandHandler = ctx.pipeline().get(CommandHandler.class);
+        }
+
         channel = ctx.channel();
         logger.debug("{} channelActive({})", commandHandler.logPrefix(), ctx);
         remoteAddress = channel.remoteAddress();