Add EventLoopFactory and make MultithreadEventLoop use it

- based on the feed back from @normanmaurer

example/src/main/java/io/netty/example/echo/EchoClient.java

@@ -26,8 +26,6 @@ import io.netty.channel.MultithreadEventLoop;
 import io.netty.channel.socket.SocketChannel;
 import io.netty.channel.socket.nio.NioSocketChannel;
 import io.netty.channel.socket.nio.SelectorEventLoop;
-import io.netty.handler.logging.LoggingHandler;
-import io.netty.logging.InternalLogLevel;
 
 import java.net.InetSocketAddress;
 import java.util.concurrent.atomic.AtomicLong;
@@ -52,10 +50,10 @@ public class EchoClient {
     }
 
     public void run() throws Exception {
-        EventLoop loop = new MultithreadEventLoop(SelectorEventLoop.class);
+        EventLoop loop = new MultithreadEventLoop(SelectorEventLoop.FACTORY);
         SocketChannel s = new NioSocketChannel();
         s.config().setTcpNoDelay(true);
-        s.pipeline().addLast("logger", new LoggingHandler(InternalLogLevel.INFO));
+        //s.pipeline().addLast("logger", new LoggingHandler(InternalLogLevel.INFO));
         s.pipeline().addLast("echoer", new ChannelInboundHandlerAdapter<Byte>() {
 
             private final ChannelBuffer firstMessage;

example/src/main/java/io/netty/example/echo/EchoServer.java

@@ -49,7 +49,7 @@ public class EchoServer {
 
     public void run() throws Exception {
         // Configure the server.
-        final EventLoop loop = new MultithreadEventLoop(SelectorEventLoop.class);
+        final EventLoop loop = new MultithreadEventLoop(SelectorEventLoop.FACTORY);
         ServerSocketChannel ssc = new NioServerSocketChannel();
         ssc.pipeline().addLast("logger", new LoggingHandler(InternalLogLevel.INFO));
         ssc.pipeline().addLast("acceptor", new ChannelInboundHandlerAdapter<SocketChannel>() {
@@ -72,7 +72,7 @@ public class EchoServer {
                         break;
                     }
                     s.config().setTcpNoDelay(true);
-                    s.pipeline().addLast("logger", new LoggingHandler(InternalLogLevel.INFO));
+                    //s.pipeline().addLast("logger", new LoggingHandler(InternalLogLevel.INFO));
                     s.pipeline().addLast("echoer", new ChannelInboundHandlerAdapter<Byte>() {
                         @Override
                         public ChannelBufferHolder<Byte> newInboundBuffer(ChannelInboundHandlerContext<Byte> ctx) {

transport/src/main/java/io/netty/channel/EventLoopFactory.java

@@ -0,0 +1,7 @@
+package io.netty.channel;
+
+import java.util.concurrent.ThreadFactory;
+
+public interface EventLoopFactory<T extends EventLoop> {
+    T newEventLoop(ThreadFactory threadFactory) throws Exception;
+}

transport/src/main/java/io/netty/channel/MultithreadEventLoop.java

@@ -18,20 +18,21 @@ public class MultithreadEventLoop implements EventLoop {
     private final EventLoop[] children;
     private final AtomicInteger childIndex = new AtomicInteger();
 
-    public MultithreadEventLoop(Class<? extends SingleThreadEventLoop> loopType) {
+    public MultithreadEventLoop(EventLoopFactory<? extends SingleThreadEventLoop> loopFactory) {
-        this(loopType, Runtime.getRuntime().availableProcessors() * 2);
+        this(loopFactory, Runtime.getRuntime().availableProcessors() * 2);
     }
 
-    public MultithreadEventLoop(Class<? extends SingleThreadEventLoop> loopType, int nThreads) {
+    public MultithreadEventLoop(EventLoopFactory<? extends SingleThreadEventLoop> loopFactory, int nThreads) {
-        this(loopType, nThreads, Executors.defaultThreadFactory());
+        this(loopFactory, nThreads, Executors.defaultThreadFactory());
     }
 
-    public MultithreadEventLoop(Class<? extends SingleThreadEventLoop> loopType, int nThreads, ThreadFactory threadFactory) {
+    public MultithreadEventLoop(EventLoopFactory<? extends SingleThreadEventLoop> loopFactory, int nThreads, ThreadFactory threadFactory) {
-        if (loopType == null) {
+        if (loopFactory == null) {
-            throw new NullPointerException("loopType");
+            throw new NullPointerException("loopFactory");
         }
         if (nThreads <= 0) {
-            throw new IllegalArgumentException("nThreads: " + nThreads + " (expected: > 0)");
+            throw new IllegalArgumentException(String.format(
+                    "nThreads: %d (expected: > 0)", nThreads));
         }
         if (threadFactory == null) {
             throw new NullPointerException("threadFactory");
@@ -41,10 +42,10 @@ public class MultithreadEventLoop implements EventLoop {
         for (int i = 0; i < nThreads; i ++) {
             boolean success = false;
             try {
-                children[i] = loopType.getConstructor(ThreadFactory.class).newInstance(threadFactory);
+                children[i] = loopFactory.newEventLoop(threadFactory);
                 success = true;
             } catch (Exception e) {
-                throw new EventLoopException("failed to create a child event loop: " + loopType.getName(), e);
+                throw new EventLoopException("failed to create a child event loop", e);
             } finally {
                 if (!success) {
                     for (int j = 0; j < i; j ++) {

transport/src/main/java/io/netty/channel/socket/nio/SelectorEventLoop.java

@@ -17,6 +17,7 @@ package io.netty.channel.socket.nio;
 
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelException;
+import io.netty.channel.EventLoopFactory;
 import io.netty.channel.SingleThreadEventLoop;
 import io.netty.logging.InternalLogger;
 import io.netty.logging.InternalLoggerFactory;
@@ -35,6 +36,15 @@ import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 public class SelectorEventLoop extends SingleThreadEventLoop {
+
+    public static final EventLoopFactory<SelectorEventLoop> FACTORY = new EventLoopFactory<SelectorEventLoop>() {
+        @Override
+        public SelectorEventLoop newEventLoop(ThreadFactory threadFactory)
+                throws Exception {
+            return new SelectorEventLoop(threadFactory);
+        }
+    };
+
     /**
      * Internal Netty logger.
      */