Simplify Netty 4 transport implementations

The Netty 4 transport implementations have an unnecessary dependency on
SocketChannels, and can instead just use plain Channels.

Author: jasontedor

modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpServerTransport.java

@@ -525,7 +525,7 @@ public ChannelHandler configureServerChannelHandler() {
         return new HttpChannelHandler(this, detailedErrorsEnabled, threadPool.getThreadContext());
     }
 
-    protected static class HttpChannelHandler extends ChannelInitializer<SocketChannel> {
+    protected static class HttpChannelHandler extends ChannelInitializer<Channel> {
 
         private final Netty4HttpServerTransport transport;
         private final Netty4HttpRequestHandler requestHandler;
@@ -539,7 +539,7 @@ protected HttpChannelHandler(
         }
 
         @Override
-        protected void initChannel(SocketChannel ch) throws Exception {
+        protected void initChannel(Channel ch) throws Exception {
             ch.pipeline().addLast("openChannels", transport.serverOpenChannels);
             final HttpRequestDecoder decoder = new HttpRequestDecoder(
                 Math.toIntExact(transport.maxInitialLineLength.bytes()),

modules/transport-netty4/src/main/java/org/elasticsearch/transport/netty4/Netty4Transport.java

@@ -25,6 +25,7 @@
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
@@ -310,11 +311,11 @@ private void createServerBootstrap(String name, Settings settings) {
         serverBootstraps.put(name, serverBootstrap);
     }
 
-    protected ChannelInitializer<SocketChannel> getServerChannelInitializer(String name, Settings settings) {
+    protected ChannelHandler getServerChannelInitializer(String name, Settings settings) {
         return new ServerChannelInitializer(name, settings);
     }
 
-    protected ChannelInitializer<SocketChannel> getClientChannelInitializer() {
+    protected ChannelHandler getClientChannelInitializer() {
         return new ClientChannelInitializer();
     }
 
@@ -506,18 +507,18 @@ protected void stopInternal() {
         });
     }
 
-    protected class ClientChannelInitializer extends ChannelInitializer<SocketChannel> {
+    protected class ClientChannelInitializer extends ChannelInitializer<Channel> {
 
         @Override
-        protected void initChannel(SocketChannel ch) throws Exception {
+        protected void initChannel(Channel ch) throws Exception {
             ch.pipeline().addLast("size", new Netty4SizeHeaderFrameDecoder());
             // using a dot as a prefix means this cannot come from any settings parsed
             ch.pipeline().addLast("dispatcher", new Netty4MessageChannelHandler(Netty4Transport.this, ".client"));
         }
 
     }
 
-    protected class ServerChannelInitializer extends ChannelInitializer<SocketChannel> {
+    protected class ServerChannelInitializer extends ChannelInitializer<Channel> {
 
         protected final String name;
         protected final Settings settings;
@@ -528,10 +529,11 @@ protected ServerChannelInitializer(String name, Settings settings) {
         }
 
         @Override
-        protected void initChannel(SocketChannel ch) throws Exception {
+        protected void initChannel(Channel ch) throws Exception {
             ch.pipeline().addLast("open_channels", Netty4Transport.this.serverOpenChannels);
             ch.pipeline().addLast("size", new Netty4SizeHeaderFrameDecoder());
             ch.pipeline().addLast("dispatcher", new Netty4MessageChannelHandler(Netty4Transport.this, name));
         }
     }
+
 }

modules/transport-netty4/src/test/java/org/elasticsearch/http/netty4/Netty4HttpServerPipeliningTests.java

@@ -21,6 +21,7 @@
 
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.SimpleChannelInboundHandler;
@@ -179,7 +180,7 @@ private class CustomHttpChannelHandler extends Netty4HttpServerTransport.HttpCha
         }
 
         @Override
-        protected void initChannel(SocketChannel ch) throws Exception {
+        protected void initChannel(Channel ch) throws Exception {
             super.initChannel(ch);
             ch.pipeline().replace("handler", "handler", new PossiblySlowUpstreamHandler(executorService));
         }