support epoll on linux, alternative impl of PR#4493 (#5680)

Author: beiwei30

dubbo-remoting/dubbo-remoting-netty4/src/main/java/org/apache/dubbo/remoting/transport/netty4/NettyClient.java

@@ -34,16 +34,17 @@
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
-import io.netty.channel.nio.NioEventLoopGroup;
-import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.socket.SocketChannel;
 import io.netty.handler.proxy.Socks5ProxyHandler;
 import io.netty.handler.timeout.IdleStateHandler;
-import io.netty.util.concurrent.DefaultThreadFactory;
 
 import java.net.InetSocketAddress;
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static org.apache.dubbo.common.constants.CommonConstants.SSL_ENABLED_KEY;
+import static org.apache.dubbo.remoting.transport.netty4.NettyEventLoopFactory.eventLoopGroup;
+import static org.apache.dubbo.remoting.transport.netty4.NettyEventLoopFactory.socketChannelClass;
 
 /**
  * NettyClient.
@@ -54,7 +55,7 @@ public class NettyClient extends AbstractClient {
     /**
      * netty client bootstrap
      */
-    private static final NioEventLoopGroup nioEventLoopGroup = new NioEventLoopGroup(Constants.DEFAULT_IO_THREADS, new DefaultThreadFactory("NettyClientWorker", true));
+    private static final EventLoopGroup eventLoopGroup = eventLoopGroup(Constants.DEFAULT_IO_THREADS, "NettyClientWorker");
 
     private static final String SOCKS_PROXY_HOST = "socksProxyHost";
 
@@ -90,18 +91,18 @@ public NettyClient(final URL url, final ChannelHandler handler) throws RemotingE
     protected void doOpen() throws Throwable {
         final NettyClientHandler nettyClientHandler = new NettyClientHandler(getUrl(), this);
         bootstrap = new Bootstrap();
-        bootstrap.group(nioEventLoopGroup)
+        bootstrap.group(eventLoopGroup)
                 .option(ChannelOption.SO_KEEPALIVE, true)
                 .option(ChannelOption.TCP_NODELAY, true)
                 .option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
                 //.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, getTimeout())
-                .channel(NioSocketChannel.class);
+                .channel(socketChannelClass());
 
         bootstrap.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, Math.max(3000, getConnectTimeout()));
-        bootstrap.handler(new ChannelInitializer() {
+        bootstrap.handler(new ChannelInitializer<SocketChannel>() {
 
             @Override
-            protected void initChannel(Channel ch) throws Exception {
+            protected void initChannel(SocketChannel ch) throws Exception {
                 int heartbeatInterval = UrlUtils.getHeartbeat(getUrl());
 
                 if (getUrl().getParameter(SSL_ENABLED_KEY, false)) {

dubbo-remoting/dubbo-remoting-netty4/src/main/java/org/apache/dubbo/remoting/transport/netty4/NettyEventLoopFactory.java

@@ -0,0 +1,60 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.remoting.transport.netty4;
+
+import org.apache.dubbo.common.config.Configuration;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.epoll.Epoll;
+import io.netty.channel.epoll.EpollEventLoopGroup;
+import io.netty.channel.epoll.EpollServerSocketChannel;
+import io.netty.channel.epoll.EpollSocketChannel;
+import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.channel.socket.ServerSocketChannel;
+import io.netty.channel.socket.SocketChannel;
+import io.netty.channel.socket.nio.NioServerSocketChannel;
+import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.util.concurrent.DefaultThreadFactory;
+
+import java.util.concurrent.ThreadFactory;
+
+public class NettyEventLoopFactory {
+    public static EventLoopGroup eventLoopGroup(int threads, String threadFactoryName) {
+        ThreadFactory threadFactory = new DefaultThreadFactory(threadFactoryName, true);
+        return shouldEpoll() ? new EpollEventLoopGroup(threads, threadFactory) :
+                new NioEventLoopGroup(threads, threadFactory);
+    }
+
+    public static Class<? extends SocketChannel> socketChannelClass() {
+        return shouldEpoll() ? EpollSocketChannel.class : NioSocketChannel.class;
+    }
+
+    public static Class<? extends ServerSocketChannel> serverSocketChannelClass() {
+        return shouldEpoll() ? EpollServerSocketChannel.class : NioServerSocketChannel.class;
+    }
+
+    private static boolean shouldEpoll() {
+        Configuration configuration = ApplicationModel.getEnvironment().getConfiguration();
+        if (configuration.getBoolean("netty.epoll.enable", false)) {
+            String osName = configuration.getString("os.name");
+            return osName.toLowerCase().contains("linux") && Epoll.isAvailable();
+        }
+
+        return false;
+    }
+}

dubbo-remoting/dubbo-remoting-netty4/src/main/java/org/apache/dubbo/remoting/transport/netty4/NettyServer.java

@@ -16,6 +16,7 @@
  */
 package org.apache.dubbo.remoting.transport.netty4;
 
+import io.netty.channel.socket.SocketChannel;
 import org.apache.dubbo.common.URL;
 import org.apache.dubbo.common.logger.Logger;
 import org.apache.dubbo.common.logger.LoggerFactory;
@@ -36,11 +37,7 @@
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
 import io.netty.channel.EventLoopGroup;
-import io.netty.channel.nio.NioEventLoopGroup;
-import io.netty.channel.socket.nio.NioServerSocketChannel;
-import io.netty.channel.socket.nio.NioSocketChannel;
 import io.netty.handler.timeout.IdleStateHandler;
-import io.netty.util.concurrent.DefaultThreadFactory;
 
 import java.net.InetSocketAddress;
 import java.util.Collection;
@@ -89,21 +86,22 @@ public NettyServer(URL url, ChannelHandler handler) throws RemotingException {
     protected void doOpen() throws Throwable {
         bootstrap = new ServerBootstrap();
 
-        bossGroup = new NioEventLoopGroup(1, new DefaultThreadFactory("NettyServerBoss", true));
-        workerGroup = new NioEventLoopGroup(getUrl().getPositiveParameter(IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS),
-                new DefaultThreadFactory("NettyServerWorker", true));
+        bossGroup = NettyEventLoopFactory.eventLoopGroup(1, "NettyServerBoss");
+        workerGroup = NettyEventLoopFactory.eventLoopGroup(
+                getUrl().getPositiveParameter(IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS),
+                "NettyServerWorker");
 
         final NettyServerHandler nettyServerHandler = new NettyServerHandler(getUrl(), this);
         channels = nettyServerHandler.getChannels();
 
         bootstrap.group(bossGroup, workerGroup)
-                .channel(NioServerSocketChannel.class)
+                .channel(NettyEventLoopFactory.serverSocketChannelClass())
                 .option(ChannelOption.SO_REUSEADDR, Boolean.TRUE)
                 .childOption(ChannelOption.TCP_NODELAY, Boolean.TRUE)
                 .childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
-                .childHandler(new ChannelInitializer<NioSocketChannel>() {
+                .childHandler(new ChannelInitializer<SocketChannel>() {
                     @Override
-                    protected void initChannel(NioSocketChannel ch) throws Exception {
+                    protected void initChannel(SocketChannel ch) throws Exception {
                         // FIXME: should we use getTimeout()?
                         int idleTimeout = UrlUtils.getIdleTimeout(getUrl());
                         NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyServer.this);