Make it possible to use a wrapped EventLoop with a Channel (#8677)

Motiviation:

Because of how we implemented the registration / deregistration of an EventLoop it was not possible to wrap an EventLoop implementation and use it with a Channel.

Modification:

- Introduce EventLoop.Unsafe which is responsible for the actual registration.
- Move validation of EventLoop / Channel combo to the EventLoop
- Add unit test that verifies that wrapping works

Result:

Be able to wrap an EventLoop and so add some extra functionality.

codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionTest.java

@@ -17,7 +17,7 @@ package io.netty.handler.codec.http2;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.handler.codec.http2.Http2Connection.Endpoint;
 import io.netty.handler.codec.http2.Http2Stream.State;
 import io.netty.util.concurrent.Future;
@@ -61,7 +61,7 @@ public class DefaultHttp2ConnectionTest {
 
     private DefaultHttp2Connection server;
     private DefaultHttp2Connection client;
-    private static DefaultEventLoopGroup group;
+    private static LocalEventLoopGroup group;
 
     @Mock
     private Http2Connection.Listener clientListener;
@@ -71,7 +71,7 @@ public class DefaultHttp2ConnectionTest {
 
     @BeforeClass
     public static void beforeClass() {
-        group = new DefaultEventLoopGroup(2);
+        group = new LocalEventLoopGroup(2);
     }
 
     @AfterClass

codec-http2/src/test/java/io/netty/handler/codec/http2/Http2ConnectionRoundtripTest.java

@@ -29,7 +29,7 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
 import io.netty.channel.local.LocalServerChannel;
@@ -1136,7 +1136,7 @@ public class Http2ConnectionRoundtripTest {
 
         final AtomicReference<Http2ConnectionHandler> serverHandlerRef = new AtomicReference<Http2ConnectionHandler>();
         final CountDownLatch serverInitLatch = new CountDownLatch(1);
-        sb.group(new DefaultEventLoopGroup());
+        sb.group(new LocalEventLoopGroup());
         sb.channel(LocalServerChannel.class);
         sb.childHandler(new ChannelInitializer<Channel>() {
             @Override
@@ -1156,7 +1156,7 @@ public class Http2ConnectionRoundtripTest {
             }
         });
 
-        cb.group(new DefaultEventLoopGroup());
+        cb.group(new LocalEventLoopGroup());
         cb.channel(LocalChannel.class);
         cb.handler(new ChannelInitializer<Channel>() {
             @Override

codec-http2/src/test/java/io/netty/handler/codec/http2/Http2MultiplexCodecBuilderTest.java

@@ -27,10 +27,10 @@ import io.netty.channel.ChannelHandlerAdapter;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
-import io.netty.channel.DefaultEventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalServerChannel;
 import org.junit.After;
 import org.junit.AfterClass;
@@ -61,7 +61,7 @@ public class Http2MultiplexCodecBuilderTest {
 
     @BeforeClass
     public static void init() {
-        group = new DefaultEventLoop();
+        group = new LocalEventLoopGroup(1);
     }
 
     @Before

codec-http2/src/test/java/io/netty/handler/codec/http2/HttpToHttp2ConnectionHandlerTest.java

@@ -25,7 +25,7 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
 import io.netty.channel.local.LocalServerChannel;
@@ -508,7 +508,7 @@ public class HttpToHttp2ConnectionHandlerTest {
         sb = new ServerBootstrap();
         cb = new Bootstrap();
 
-        sb.group(new DefaultEventLoopGroup());
+        sb.group(new LocalEventLoopGroup());
         sb.channel(LocalServerChannel.class);
         sb.childHandler(new ChannelInitializer<Channel>() {
             @Override
@@ -525,7 +525,7 @@ public class HttpToHttp2ConnectionHandlerTest {
             }
         });
 
-        cb.group(new DefaultEventLoopGroup());
+        cb.group(new LocalEventLoopGroup());
         cb.channel(LocalChannel.class);
         cb.handler(new ChannelInitializer<Channel>() {
             @Override

codec-http2/src/test/java/io/netty/handler/codec/http2/InboundHttp2ToHttpAdapterTest.java

@@ -26,7 +26,7 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.SimpleChannelInboundHandler;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
@@ -667,7 +667,7 @@ public class InboundHttp2ToHttpAdapterTest {
         sb = new ServerBootstrap();
         cb = new Bootstrap();
 
-        sb.group(new DefaultEventLoopGroup());
+        sb.group(new LocalEventLoopGroup());
         sb.channel(LocalServerChannel.class);
         sb.childHandler(new ChannelInitializer<Channel>() {
             @Override
@@ -695,7 +695,7 @@ public class InboundHttp2ToHttpAdapterTest {
             }
         });
 
-        cb.group(new DefaultEventLoopGroup());
+        cb.group(new LocalEventLoopGroup());
         cb.channel(LocalChannel.class);
         cb.handler(new ChannelInitializer<Channel>() {
             @Override

example/src/main/java/io/netty/example/localecho/LocalEcho.java

@@ -20,7 +20,7 @@ import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelInitializer;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
@@ -40,7 +40,7 @@ public final class LocalEcho {
         // Address to bind on / connect to.
         final LocalAddress addr = new LocalAddress(PORT);
 
-        EventLoopGroup serverGroup = new DefaultEventLoopGroup();
+        EventLoopGroup serverGroup = new LocalEventLoopGroup();
         EventLoopGroup clientGroup = new NioEventLoopGroup(); // NIO event loops are also OK
         try {
             // Note that we can use any event loop to ensure certain local channels

handler/src/test/java/io/netty/handler/ssl/CipherSuiteCanaryTest.java

@@ -24,7 +24,7 @@ import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.SimpleChannelInboundHandler;
 import io.netty.channel.local.LocalAddress;
@@ -75,7 +75,7 @@ public class CipherSuiteCanaryTest {
 
     @BeforeClass
     public static void init() throws Exception {
-        GROUP = new DefaultEventLoopGroup();
+        GROUP = new LocalEventLoopGroup();
         CERT = new SelfSignedCertificate();
     }
 

handler/src/test/java/io/netty/handler/ssl/SniClientJava8TestUtil.java

@@ -22,7 +22,7 @@ import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
@@ -79,7 +79,7 @@ final class SniClientJava8TestUtil {
         final String sniHost = "sni.netty.io";
         SelfSignedCertificate cert = new SelfSignedCertificate();
         LocalAddress address = new LocalAddress("test");
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         SslContext sslServerContext = null;
         SslContext sslClientContext = null;
 

handler/src/test/java/io/netty/handler/ssl/SniClientTest.java

@@ -20,7 +20,7 @@ import io.netty.bootstrap.ServerBootstrap;
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelInitializer;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
@@ -29,7 +29,6 @@ import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
 import io.netty.handler.ssl.util.SelfSignedCertificate;
 import io.netty.util.Mapping;
 import io.netty.util.ReferenceCountUtil;
-import io.netty.util.ReferenceCounted;
 import io.netty.util.concurrent.Promise;
 import io.netty.util.internal.PlatformDependent;
 import org.junit.Assert;
@@ -96,7 +95,7 @@ public class SniClientTest {
     private static void testSniClient(SslProvider sslServerProvider, SslProvider sslClientProvider) throws Exception {
         String sniHostName = "sni.netty.io";
         LocalAddress address = new LocalAddress("test");
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         SelfSignedCertificate cert = new SelfSignedCertificate();
         SslContext sslServerContext = null;
         SslContext sslClientContext = null;

handler/src/test/java/io/netty/handler/ssl/SniHandlerTest.java

@@ -27,7 +27,7 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.embedded.EmbeddedChannel;
 import io.netty.channel.local.LocalAddress;
@@ -418,7 +418,7 @@ public class SniHandlerTest {
             case OPENSSL_REFCNT:
                 final String sniHost = "sni.netty.io";
                 LocalAddress address = new LocalAddress("testReplaceHandler-" + Math.random());
-                EventLoopGroup group = new DefaultEventLoopGroup(1);
+                EventLoopGroup group = new LocalEventLoopGroup(1);
                 Channel sc = null;
                 Channel cc = null;
                 SslContext sslContext = null;

handler/src/test/java/io/netty/handler/ssl/SslHandlerTest.java

@@ -32,7 +32,7 @@ import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOutboundHandlerAdapter;
 import io.netty.channel.ChannelPromise;
 import io.netty.channel.DefaultChannelId;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.SimpleChannelInboundHandler;
 import io.netty.channel.embedded.EmbeddedChannel;
@@ -451,7 +451,7 @@ public class SslHandlerTest {
         final BlockingQueue<Object> events = new LinkedBlockingQueue<Object>();
         Channel serverChannel = null;
         Channel clientChannel = null;
-        EventLoopGroup group = new DefaultEventLoopGroup();
+        EventLoopGroup group = new LocalEventLoopGroup();
         try {
             ServerBootstrap sb = new ServerBootstrap();
             sb.group(group)
@@ -614,7 +614,7 @@ public class SslHandlerTest {
                 .trustManager(new SelfSignedCertificate().cert())
                 .build();
 
-        EventLoopGroup group = new NioEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         Channel sc = null;
         Channel cc = null;
         try {

handler/src/test/java/io/netty/handler/ssl/ocsp/OcspTest.java

@@ -26,7 +26,7 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPipeline;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
@@ -344,7 +344,7 @@ public class OcspTest {
                         .build();
 
                 try {
-                    EventLoopGroup group = new DefaultEventLoopGroup();
+                    EventLoopGroup group = new LocalEventLoopGroup();
                     try {
                         LocalAddress address = new LocalAddress("handshake-" + Math.random());
                         Channel server = newServer(group, address, serverSslContext, response, serverHandler);

microbench/src/main/java/io/netty/microbench/concurrent/ScheduledFutureTaskBenchmark.java

@@ -15,8 +15,8 @@
  */
 package io.netty.microbench.concurrent;
 
-import io.netty.channel.DefaultEventLoop;
+import io.netty.channel.EventLoopGroup;
-import io.netty.channel.EventLoop;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.microbench.util.AbstractMicrobenchmark;
 import io.netty.util.concurrent.Future;
 import io.netty.util.concurrent.ScheduledFuture;
@@ -36,7 +36,7 @@ import java.util.concurrent.TimeUnit;
 @State(Scope.Benchmark)
 public class ScheduledFutureTaskBenchmark extends AbstractMicrobenchmark {
 
-    static final EventLoop executor = new DefaultEventLoop();
+    static final EventLoopGroup executor = new LocalEventLoopGroup(1);
 
     @State(Scope.Thread)
     public static class FuturesHolder {

resolver-dns/src/test/java/io/netty/resolver/dns/DefaultAuthoritativeDnsServerCacheTest.java

@@ -15,7 +15,7 @@
  */
 package io.netty.resolver.dns;
 
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.nio.NioEventLoopGroup;
@@ -25,7 +25,6 @@ import org.junit.Test;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.util.Comparator;
-import java.util.List;
 import java.util.concurrent.Callable;
 import java.util.concurrent.TimeUnit;
 
@@ -39,7 +38,7 @@ public class DefaultAuthoritativeDnsServerCacheTest {
                 InetAddress.getByAddress("ns1", new byte[] { 10, 0, 0, 1 }), 53);
         InetSocketAddress resolved2 = new InetSocketAddress(
                 InetAddress.getByAddress("ns2", new byte[] { 10, 0, 0, 2 }), 53);
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -91,7 +90,7 @@ public class DefaultAuthoritativeDnsServerCacheTest {
                 InetAddress.getByAddress("ns1", new byte[] { 10, 0, 0, 1 }), 53);
         InetSocketAddress resolved2 = new InetSocketAddress(
                 InetAddress.getByAddress("ns2", new byte[] { 10, 0, 0, 2 }), 53);
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -115,7 +114,7 @@ public class DefaultAuthoritativeDnsServerCacheTest {
                 InetAddress.getByAddress("ns2", new byte[] { 10, 0, 0, 2 }), 53);
         InetSocketAddress resolved2 = new InetSocketAddress(
                 InetAddress.getByAddress("ns1", new byte[] { 10, 0, 0, 1 }), 53);
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -153,7 +152,7 @@ public class DefaultAuthoritativeDnsServerCacheTest {
         InetSocketAddress unresolved = InetSocketAddress.createUnresolved("ns1", 53);
         InetSocketAddress resolved = new InetSocketAddress(
                 InetAddress.getByAddress("ns2", new byte[] { 10, 0, 0, 2 }), 53);
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();

resolver-dns/src/test/java/io/netty/resolver/dns/DefaultDnsCacheTest.java

@@ -15,7 +15,7 @@
  */
 package io.netty.resolver.dns;
 
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 
@@ -40,7 +40,7 @@ public class DefaultDnsCacheTest {
     public void testExpire() throws Throwable {
         InetAddress addr1 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 1 });
         InetAddress addr2 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 2 });
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -103,7 +103,7 @@ public class DefaultDnsCacheTest {
     public void testAddMultipleAddressesForSameHostname() throws Exception {
         InetAddress addr1 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 1 });
         InetAddress addr2 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 2 });
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -123,7 +123,7 @@ public class DefaultDnsCacheTest {
     @Test
     public void testAddSameAddressForSameHostname() throws Exception {
         InetAddress addr1 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 1 });
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -148,7 +148,7 @@ public class DefaultDnsCacheTest {
     public void testCacheFailed() throws Exception {
         InetAddress addr1 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 1 });
         InetAddress addr2 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 2 });
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -177,7 +177,7 @@ public class DefaultDnsCacheTest {
     public void testDotHandling() throws Exception {
         InetAddress addr1 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 1 });
         InetAddress addr2 = InetAddress.getByAddress(new byte[] { 10, 0, 0, 2 });
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();

resolver-dns/src/test/java/io/netty/resolver/dns/DefaultDnsCnameCacheTest.java

@@ -15,7 +15,7 @@
  */
 package io.netty.resolver.dns;
 
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import org.junit.Test;
@@ -29,7 +29,7 @@ public class DefaultDnsCnameCacheTest {
 
     @Test
     public void testExpire() throws Throwable {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -63,7 +63,7 @@ public class DefaultDnsCnameCacheTest {
     }
 
     private static void testExpireWithTTL0(int days) {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -77,7 +77,7 @@ public class DefaultDnsCnameCacheTest {
 
     @Test
     public void testMultipleCnamesForSameHostname() throws Exception {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -93,7 +93,7 @@ public class DefaultDnsCnameCacheTest {
 
     @Test
     public void testAddSameCnameForSameHostname() throws Exception {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();
@@ -109,7 +109,7 @@ public class DefaultDnsCnameCacheTest {
 
     @Test
     public void testClear() throws Exception {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
 
         try {
             EventLoop loop = group.next();

transport-native-epoll/src/main/java/io/netty/channel/epoll/AbstractEpollChannel.java

@@ -68,6 +68,7 @@ abstract class AbstractEpollChannel extends AbstractChannel implements UnixChann
     private ChannelPromise connectPromise;
     private ScheduledFuture<?> connectTimeoutFuture;
     private SocketAddress requestedRemoteAddress;
+    private EpollRegistration registration;
 
     private volatile SocketAddress local;
     private volatile SocketAddress remote;
@@ -126,6 +127,11 @@ abstract class AbstractEpollChannel extends AbstractChannel implements UnixChann
         }
     }
 
+    protected EpollRegistration registration() {
+        assert registration != null;
+        return registration;
+    }
+
     boolean isFlagSet(int flag) {
         return (flags & flag) != 0;
     }
@@ -199,19 +205,23 @@ abstract class AbstractEpollChannel extends AbstractChannel implements UnixChann
         doClose();
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof EpollEventLoop;
-    }
-
     @Override
     public boolean isOpen() {
         return socket.isOpen();
     }
 
-    @Override
+    void register0(EpollRegistration registration) throws Exception {
-    protected void doDeregister() throws Exception {
+        // Just in case the previous EventLoop was shutdown abruptly, or an event is still pending on the old EventLoop
-        ((EpollEventLoop) eventLoop()).remove(this);
+        // make sure the epollInReadyRunnablePending variable is reset so we will be able to execute the Runnable on the
+        // new EventLoop.
+        epollInReadyRunnablePending = false;
+        this.registration = registration;
+    }
+
+    void deregister0() throws Exception {
+        if (registration != null) {
+            registration.remove();
+        }
     }
 
     @Override
@@ -268,20 +278,11 @@ abstract class AbstractEpollChannel extends AbstractChannel implements UnixChann
     }
 
     private void modifyEvents() throws IOException {
-        if (isOpen() && isRegistered()) {
+        if (isOpen() && isRegistered() && registration != null) {
-            ((EpollEventLoop) eventLoop()).modify(this);
+            registration.update();
         }
     }
 
-    @Override
-    protected void doRegister() throws Exception {
-        // Just in case the previous EventLoop was shutdown abruptly, or an event is still pending on the old EventLoop
-        // make sure the epollInReadyRunnablePending variable is reset so we will be able to execute the Runnable on the
-        // new EventLoop.
-        epollInReadyRunnablePending = false;
-        ((EpollEventLoop) eventLoop()).add(this);
-    }
-
     @Override
     protected abstract AbstractEpollUnsafe newUnsafe();
 

transport-native-epoll/src/main/java/io/netty/channel/epoll/AbstractEpollServerChannel.java

@@ -58,11 +58,6 @@ public abstract class AbstractEpollServerChannel extends AbstractEpollChannel im
         return METADATA;
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof EpollEventLoop;
-    }
-
     @Override
     protected InetSocketAddress remoteAddress0() {
         return null;

transport-native-epoll/src/main/java/io/netty/channel/epoll/AbstractEpollStreamChannel.java

@@ -513,7 +513,7 @@ public abstract class AbstractEpollStreamChannel extends AbstractEpollChannel im
      */
     private int doWriteMultiple(ChannelOutboundBuffer in) throws Exception {
         final long maxBytesPerGatheringWrite = config().getMaxBytesPerGatheringWrite();
-        IovArray array = ((EpollEventLoop) eventLoop()).cleanIovArray();
+        IovArray array = registration().cleanIovArray();
         array.maxBytes(maxBytesPerGatheringWrite);
         in.forEachFlushedMessage(array);
 

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollDatagramChannel.java

@@ -271,7 +271,7 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
             try {
                 // Check if sendmmsg(...) is supported which is only the case for GLIBC 2.14+
                 if (Native.IS_SUPPORTING_SENDMMSG && in.size() > 1) {
-                    NativeDatagramPacketArray array = ((EpollEventLoop) eventLoop()).cleanDatagramPacketArray();
+                    NativeDatagramPacketArray array = registration().cleanDatagramPacketArray();
                     in.forEachFlushedMessage(array);
                     int cnt = array.count();
 
@@ -349,7 +349,7 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
                         remoteAddress.getAddress(), remoteAddress.getPort());
             }
         } else if (data.nioBufferCount() > 1) {
-            IovArray array = ((EpollEventLoop) eventLoop()).cleanIovArray();
+            IovArray array = registration().cleanIovArray();
             array.add(data);
             int cnt = array.count();
             assert cnt != 0;

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollEventLoop.java

@@ -15,6 +15,7 @@
  */
 package io.netty.channel.epoll;
 
+import io.netty.channel.Channel;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.SelectStrategy;
@@ -28,6 +29,7 @@ import io.netty.util.collection.IntObjectMap;
 import io.netty.util.concurrent.RejectedExecutionHandler;
 import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.StringUtil;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
@@ -79,6 +81,49 @@ class EpollEventLoop extends SingleThreadEventLoop {
     // See http://man7.org/linux/man-pages/man2/timerfd_create.2.html.
     private static final long MAX_SCHEDULED_TIMERFD_NS = 999999999;
 
+    private static AbstractEpollChannel cast(Channel channel) {
+        if (channel instanceof AbstractEpollChannel) {
+            return (AbstractEpollChannel) channel;
+        }
+        throw new IllegalArgumentException("Channel of type " + StringUtil.simpleClassName(channel) + " not supported");
+    }
+
+    private final Unsafe unsafe = new Unsafe() {
+        @Override
+        public void register(Channel channel) throws Exception {
+            assert inEventLoop();
+            final AbstractEpollChannel epollChannel = cast(channel);
+            epollChannel.register0(new EpollRegistration() {
+                @Override
+                public void update() throws IOException {
+                    EpollEventLoop.this.modify(epollChannel);
+                }
+
+                @Override
+                public void remove() throws IOException {
+                    EpollEventLoop.this.remove(epollChannel);
+                }
+
+                @Override
+                public IovArray cleanIovArray() {
+                    return EpollEventLoop.this.cleanIovArray();
+                }
+
+                @Override
+                public NativeDatagramPacketArray cleanDatagramPacketArray() {
+                    return EpollEventLoop.this.cleanDatagramPacketArray();
+                }
+            });
+            add(epollChannel);
+        }
+
+        @Override
+        public void deregister(Channel channel) throws Exception {
+            assert inEventLoop();
+            cast(channel).deregister0();
+        }
+    };
+
     EpollEventLoop(EventLoopGroup parent, Executor executor, int maxEvents,
                    SelectStrategy strategy, RejectedExecutionHandler rejectedExecutionHandler) {
         super(parent, executor, false, DEFAULT_MAX_PENDING_TASKS, rejectedExecutionHandler);
@@ -160,6 +205,11 @@ class EpollEventLoop extends SingleThreadEventLoop {
         return datagramPacketArray;
     }
 
+    @Override
+    public Unsafe unsafe() {
+        return unsafe;
+    }
+
     @Override
     protected void wakeup(boolean inEventLoop) {
         if (!inEventLoop && WAKEN_UP_UPDATER.compareAndSet(this, 0, 1)) {

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollRegistration.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2018 The Netty Project
+ *
+ * The Netty Project 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 io.netty.channel.epoll;
+
+import io.netty.channel.unix.IovArray;
+
+import java.io.IOException;
+
+/**
+ * Registration with an {@link EpollEventLoop}.
+ */
+interface EpollRegistration {
+
+    /**
+     * Update the registration as some flags did change.
+     */
+    void update() throws IOException;
+
+    /**
+     * Remove the registration. No more IO will be handled for it.
+     */
+    void remove() throws IOException;
+
+    /**
+     * Returns an {@link IovArray} that can be used for {@code writev}.
+     */
+    IovArray cleanIovArray();
+
+    /**
+     * Returns a {@link NativeDatagramPacketArray} that can used for {@code sendmmsg}.
+     */
+    NativeDatagramPacketArray cleanDatagramPacketArray();
+}

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollServerSocketChannel.java

@@ -61,11 +61,6 @@ public final class EpollServerSocketChannel extends AbstractEpollServerChannel i
         config = new EpollServerSocketChannelConfig(this);
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof EpollEventLoop;
-    }
-
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
         super.doBind(localAddress);

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannel.java

@@ -122,7 +122,7 @@ public final class EpollSocketChannel extends AbstractEpollStreamChannel impleme
                     // because we try to read or write until the actual close happens which may be later due
                     // SO_LINGER handling.
                     // See https://github.com/netty/netty/issues/4449
-                    ((EpollEventLoop) eventLoop()).remove(EpollSocketChannel.this);
+                    doDeregister();
                     return GlobalEventExecutor.INSTANCE;
                 }
             } catch (Throwable ignore) {

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/AbstractKQueueChannel.java

@@ -63,12 +63,14 @@ abstract class AbstractKQueueChannel extends AbstractChannel implements UnixChan
     private ChannelPromise connectPromise;
     private ScheduledFuture<?> connectTimeoutFuture;
     private SocketAddress requestedRemoteAddress;
+    private KQueueRegistration registration;
 
     final BsdSocket socket;
     private boolean readFilterEnabled;
     private boolean writeFilterEnabled;
     boolean readReadyRunnablePending;
     boolean inputClosedSeenErrorOnRead;
+
     protected volatile boolean active;
     private volatile SocketAddress local;
     private volatile SocketAddress remote;
@@ -103,6 +105,11 @@ abstract class AbstractKQueueChannel extends AbstractChannel implements UnixChan
         }
     }
 
+    protected KQueueRegistration registration() {
+        assert registration != null;
+        return registration;
+    }
+
     @Override
     public final FileDescriptor fd() {
         return socket;
@@ -160,26 +167,11 @@ abstract class AbstractKQueueChannel extends AbstractChannel implements UnixChan
         doClose();
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof KQueueEventLoop;
-    }
-
     @Override
     public boolean isOpen() {
         return socket.isOpen();
     }
 
-    @Override
-    protected void doDeregister() throws Exception {
-        // Make sure we unregister our filters from kqueue!
-        readFilter(false);
-        writeFilter(false);
-        evSet0(Native.EVFILT_SOCK, Native.EV_DELETE, 0);
-
-        ((KQueueEventLoop) eventLoop()).remove(this);
-    }
-
     @Override
     protected final void doBeginRead() throws Exception {
         // Channel.read() or ChannelHandlerContext.read() was called
@@ -198,23 +190,31 @@ abstract class AbstractKQueueChannel extends AbstractChannel implements UnixChan
         }
     }
 
-    @Override
+    void register0(KQueueRegistration registration)  {
-    protected void doRegister() throws Exception {
+        this.registration = registration;
         // Just in case the previous EventLoop was shutdown abruptly, or an event is still pending on the old EventLoop
         // make sure the readReadyRunnablePending variable is reset so we will be able to execute the Runnable on the
         // new EventLoop.
         readReadyRunnablePending = false;
 
-        ((KQueueEventLoop) eventLoop()).add(this);
-
         // Add the write event first so we get notified of connection refused on the client side!
         if (writeFilterEnabled) {
-            evSet0(Native.EVFILT_WRITE, Native.EV_ADD_CLEAR_ENABLE);
+            evSet0(registration, Native.EVFILT_WRITE, Native.EV_ADD_CLEAR_ENABLE);
         }
         if (readFilterEnabled) {
-            evSet0(Native.EVFILT_READ, Native.EV_ADD_CLEAR_ENABLE);
+            evSet0(registration, Native.EVFILT_READ, Native.EV_ADD_CLEAR_ENABLE);
+        }
+        evSet0(registration, Native.EVFILT_SOCK, Native.EV_ADD, Native.NOTE_RDHUP);
+    }
+
+    void deregister0() throws IOException {
+        // Make sure we unregister our filters from kqueue!
+        readFilter(false);
+        writeFilter(false);
+        if (registration != null) {
+            evSet0(registration, Native.EVFILT_SOCK, Native.EV_DELETE, 0);
+            registration = null;
         }
-        evSet0(Native.EVFILT_SOCK, Native.EV_ADD, Native.NOTE_RDHUP);
     }
 
     @Override
@@ -360,16 +360,16 @@ abstract class AbstractKQueueChannel extends AbstractChannel implements UnixChan
 
     private void evSet(short filter, short flags) {
         if (isOpen() && isRegistered()) {
-            evSet0(filter, flags);
+            evSet0(registration, filter, flags);
         }
     }
 
-    private void evSet0(short filter, short flags) {
+    private void evSet0(KQueueRegistration registration, short filter, short flags) {
-        evSet0(filter, flags, 0);
+        evSet0(registration, filter, flags, 0);
     }
 
-    private void evSet0(short filter, short flags, int fflags) {
+    private void evSet0(KQueueRegistration registration, short filter, short flags, int fflags) {
-        ((KQueueEventLoop) eventLoop()).evSet(this, filter, flags, fflags);
+        registration.evSet(filter, flags, fflags);
     }
 
     abstract class AbstractKQueueUnsafe extends AbstractUnsafe {

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/AbstractKQueueServerChannel.java

@@ -53,11 +53,6 @@ public abstract class AbstractKQueueServerChannel extends AbstractKQueueChannel
         return METADATA;
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof KQueueEventLoop;
-    }
-
     @Override
     protected InetSocketAddress remoteAddress0() {
         return null;

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/AbstractKQueueStreamChannel.java

@@ -344,7 +344,7 @@ public abstract class AbstractKQueueStreamChannel extends AbstractKQueueChannel
      */
     private int doWriteMultiple(ChannelOutboundBuffer in) throws Exception {
         final long maxBytesPerGatheringWrite = config().getMaxBytesPerGatheringWrite();
-        IovArray array = ((KQueueEventLoop) eventLoop()).cleanArray();
+        IovArray array = registration().cleanArray();
         array.maxBytes(maxBytesPerGatheringWrite);
         in.forEachFlushedMessage(array);
 

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueDatagramChannel.java

@@ -321,7 +321,7 @@ public final class KQueueDatagramChannel extends AbstractKQueueChannel implement
                         remoteAddress.getAddress(), remoteAddress.getPort());
             }
         } else if (data.nioBufferCount() > 1) {
-            IovArray array = ((KQueueEventLoop) eventLoop()).cleanArray();
+            IovArray array = registration().cleanArray();
             array.add(data);
             int cnt = array.count();
             assert cnt != 0;

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueEventLoop.java

@@ -15,6 +15,7 @@
  */
 package io.netty.channel.kqueue;
 
+import io.netty.channel.Channel;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.SelectStrategy;
@@ -28,6 +29,7 @@ import io.netty.util.collection.IntObjectMap;
 import io.netty.util.concurrent.RejectedExecutionHandler;
 import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.StringUtil;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
@@ -70,6 +72,43 @@ final class KQueueEventLoop extends SingleThreadEventLoop {
     private volatile int wakenUp;
     private volatile int ioRatio = 50;
 
+    private static AbstractKQueueChannel cast(Channel channel) {
+        if (channel instanceof AbstractKQueueChannel) {
+            return (AbstractKQueueChannel) channel;
+        }
+        throw new IllegalArgumentException("Channel of type " + StringUtil.simpleClassName(channel) + " not supported");
+    }
+
+    private final Unsafe unsafe = new Unsafe() {
+        @Override
+        public void register(Channel channel) {
+            assert inEventLoop();
+            final AbstractKQueueChannel kQueueChannel = cast(channel);
+            final int id = kQueueChannel.fd().intValue();
+            channels.put(id, kQueueChannel);
+
+            kQueueChannel.register0(new KQueueRegistration() {
+                @Override
+                public void evSet(short filter, short flags, int fflags) {
+                    KQueueEventLoop.this.evSet(kQueueChannel, filter, flags, fflags);
+                }
+
+                @Override
+                public IovArray cleanArray() {
+                    return KQueueEventLoop.this.cleanArray();
+                }
+            });
+        }
+
+        @Override
+        public void deregister(Channel channel) throws Exception {
+            assert inEventLoop();
+            AbstractKQueueChannel kQueueChannel = cast(channel);
+            channels.remove(kQueueChannel.fd().intValue());
+            kQueueChannel.deregister0();
+        }
+    };
+
     KQueueEventLoop(EventLoopGroup parent, Executor executor, int maxEvents,
                     SelectStrategy strategy, RejectedExecutionHandler rejectedExecutionHandler) {
         super(parent, executor, false, DEFAULT_MAX_PENDING_TASKS, rejectedExecutionHandler);
@@ -90,24 +129,19 @@ final class KQueueEventLoop extends SingleThreadEventLoop {
         }
     }
 
-    void add(AbstractKQueueChannel ch) {
+    @Override
-        assert inEventLoop();
+    public Unsafe unsafe() {
-        channels.put(ch.fd().intValue(), ch);
+        return unsafe;
     }
 
-    void evSet(AbstractKQueueChannel ch, short filter, short flags, int fflags) {
+    private void evSet(AbstractKQueueChannel ch, short filter, short flags, int fflags) {
         changeList.evSet(ch, filter, flags, fflags);
     }
 
-    void remove(AbstractKQueueChannel ch) {
-        assert inEventLoop();
-        channels.remove(ch.fd().intValue());
-    }
-
     /**
      * Return a cleared {@link IovArray} that can be used for writes in this {@link EventLoop}.
      */
-    IovArray cleanArray() {
+    private IovArray cleanArray() {
         iovArray.clear();
         return iovArray;
     }
@@ -167,7 +201,7 @@ final class KQueueEventLoop extends SingleThreadEventLoop {
                 // This may happen if the channel has already been closed, and it will be removed from kqueue anyways.
                 // We also handle EV_ERROR above to skip this even early if it is a result of a referencing a closed and
                 // thus removed from kqueue FD.
-                logger.warn("events[{}]=[{}, {}] had no channel!", i, eventList.fd(i), filter);
+                logger.warn("events[{}]=[{}, {}] had no channel!", i, fd, filter);
                 continue;
             }
 

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueRegistration.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2018 The Netty Project
+ *
+ * The Netty Project 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 io.netty.channel.kqueue;
+
+import io.netty.channel.unix.IovArray;
+
+
+/**
+ * Registration with an {@link KQueueEventLoop}.
+ */
+interface KQueueRegistration {
+
+    /**
+     * Update the event-set for the registration.
+     */
+    void evSet(short filter, short flags, int fflags);
+
+    /**
+     * Returns an {@link IovArray} that can be used for {@code writev}.
+     */
+    IovArray cleanArray();
+}

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueServerSocketChannel.java

@@ -52,11 +52,6 @@ public final class KQueueServerSocketChannel extends AbstractKQueueServerChannel
         config = new KQueueServerSocketChannelConfig(this);
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof KQueueEventLoop;
-    }
-
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
         super.doBind(localAddress);

transport-native-kqueue/src/main/java/io/netty/channel/kqueue/KQueueSocketChannel.java

@@ -80,7 +80,7 @@ public final class KQueueSocketChannel extends AbstractKQueueStreamChannel imple
                     // because we try to read or write until the actual close happens which may be later due
                     // SO_LINGER handling.
                     // See https://github.com/netty/netty/issues/4449
-                    ((KQueueEventLoop) eventLoop()).remove(KQueueSocketChannel.this);
+                    doDeregister();
                     return GlobalEventExecutor.INSTANCE;
                 }
             } catch (Throwable ignore) {

transport/src/main/java/io/netty/bootstrap/FailedChannel.java

@@ -38,11 +38,6 @@ final class FailedChannel extends AbstractChannel {
         return new FailedChannelUnsafe();
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return true;
-    }
-
     @Override
     protected SocketAddress localAddress0() {
         return null;

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

@@ -102,10 +102,7 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
     }
 
     private EventLoop validateEventLoop(EventLoop eventLoop) {
-        if (!isCompatible(ObjectUtil.checkNotNull(eventLoop, "eventLoop"))) {
+        return ObjectUtil.checkNotNull(eventLoop, "eventLoop");
-           throw new IllegalArgumentException("incompatible event loop type: " + eventLoop.getClass().getName());
-        }
-        return eventLoop;
     }
 
     @Override
@@ -1035,11 +1032,6 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
         }
     }
 
-    /**
-     * Return {@code true} if the given {@link EventLoop} is compatible with this instance.
-     */
-    protected abstract boolean isCompatible(EventLoop loop);
-
     /**
      * Returns the {@link SocketAddress} which is bound locally.
      */
@@ -1056,7 +1048,7 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
      * Sub-classes may override this method
      */
     protected void doRegister() throws Exception {
-        // NOOP
+        eventLoop().unsafe().register(this);
     }
 
     /**
@@ -1089,7 +1081,7 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
      * Sub-classes may override this method
      */
     protected void doDeregister() throws Exception {
-        // NOOP
+        eventLoop().unsafe().deregister(this);
     }
 
     /**

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

@@ -1,63 +0,0 @@
-/*
- * Copyright 2012 The Netty Project
- *
- * The Netty Project 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 io.netty.channel;
-
-import io.netty.util.concurrent.DefaultThreadFactory;
-
-import java.util.concurrent.Executor;
-import java.util.concurrent.ThreadFactory;
-
-public class DefaultEventLoop extends SingleThreadEventLoop {
-
-    public DefaultEventLoop() {
-        this((EventLoopGroup) null);
-    }
-
-    public DefaultEventLoop(ThreadFactory threadFactory) {
-        this(null, threadFactory);
-    }
-
-    public DefaultEventLoop(Executor executor) {
-        this(null, executor);
-    }
-
-    public DefaultEventLoop(EventLoopGroup parent) {
-        this(parent, new DefaultThreadFactory(DefaultEventLoop.class));
-    }
-
-    public DefaultEventLoop(EventLoopGroup parent, ThreadFactory threadFactory) {
-        super(parent, threadFactory, true);
-    }
-
-    public DefaultEventLoop(EventLoopGroup parent, Executor executor) {
-        super(parent, executor, true);
-    }
-
-    @Override
-    protected void run() {
-        for (;;) {
-            Runnable task = takeTask();
-            if (task != null) {
-                task.run();
-                updateLastExecutionTime();
-            }
-
-            if (confirmShutdown()) {
-                break;
-            }
-        }
-    }
-}

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

@@ -1,66 +0,0 @@
-/*
- * Copyright 2012 The Netty Project
- *
- * The Netty Project 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 io.netty.channel;
-
-import java.util.concurrent.Executor;
-import java.util.concurrent.ThreadFactory;
-
-/**
- * {@link MultithreadEventLoopGroup} which must be used for the local transport.
- */
-public class DefaultEventLoopGroup extends MultithreadEventLoopGroup {
-
-    /**
-     * Create a new instance with the default number of threads.
-     */
-    public DefaultEventLoopGroup() {
-        this(0);
-    }
-
-    /**
-     * Create a new instance
-     *
-     * @param nThreads          the number of threads to use
-     */
-    public DefaultEventLoopGroup(int nThreads) {
-        this(nThreads, (ThreadFactory) null);
-    }
-
-    /**
-     * Create a new instance
-     *
-     * @param nThreads          the number of threads to use
-     * @param threadFactory     the {@link ThreadFactory} or {@code null} to use the default
-     */
-    public DefaultEventLoopGroup(int nThreads, ThreadFactory threadFactory) {
-        super(nThreads, threadFactory);
-    }
-
-    /**
-     * Create a new instance
-     *
-     * @param nThreads          the number of threads to use
-     * @param executor          the Executor to use, or {@code null} if the default should be used.
-     */
-    public DefaultEventLoopGroup(int nThreads, Executor executor) {
-        super(nThreads, executor);
-    }
-
-    @Override
-    protected EventLoop newChild(Executor executor, Object... args) throws Exception {
-        return new DefaultEventLoop(this, executor);
-    }
-}

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

@@ -27,4 +27,25 @@ import io.netty.util.concurrent.OrderedEventExecutor;
 public interface EventLoop extends OrderedEventExecutor, EventLoopGroup {
     @Override
     EventLoopGroup parent();
+
+    /**
+     * Returns an <em>internal-use-only</em> object that provides unsafe operations.
+     */
+    Unsafe unsafe();
+
+    /**
+     * <em>Unsafe</em> operations that should <em>never</em> be called from user-code. These methods
+     * are only provided to implement the actual transport, and must be invoked from the {@link EventLoop} itself.
+     */
+    interface Unsafe {
+        /**
+         * Register the {@link Channel} to the {@link EventLoop}.
+         */
+        void register(Channel channel) throws Exception;
+
+        /**
+         * Deregister the {@link Channel} from the {@link EventLoop}.
+         */
+        void deregister(Channel channel) throws Exception;
+    }
 }

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

@@ -18,7 +18,6 @@ package io.netty.channel;
 import io.netty.util.concurrent.RejectedExecutionHandler;
 import io.netty.util.concurrent.RejectedExecutionHandlers;
 import io.netty.util.concurrent.SingleThreadEventExecutor;
-import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.SystemPropertyUtil;
 
 import java.util.concurrent.Executor;

transport/src/main/java/io/netty/channel/embedded/EmbeddedChannel.java

@@ -673,11 +673,6 @@ public class EmbeddedChannel extends AbstractChannel {
         }
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof EmbeddedEventLoop;
-    }
-
     @Override
     protected SocketAddress localAddress0() {
         return isActive()? LOCAL_ADDRESS : null;
@@ -688,8 +683,7 @@ public class EmbeddedChannel extends AbstractChannel {
         return isActive()? REMOTE_ADDRESS : null;
     }
 
-    @Override
+    void setActive() {
-    protected void doRegister() throws Exception {
         state = State.ACTIVE;
     }
 

transport/src/main/java/io/netty/channel/embedded/EmbeddedEventLoop.java

@@ -15,10 +15,12 @@
  */
 package io.netty.channel.embedded;
 
+import io.netty.channel.Channel;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.util.concurrent.AbstractScheduledEventExecutor;
 import io.netty.util.concurrent.Future;
+import io.netty.util.internal.StringUtil;
 
 import java.util.ArrayDeque;
 import java.util.Queue;
@@ -28,6 +30,31 @@ final class EmbeddedEventLoop extends AbstractScheduledEventExecutor implements
 
     private final Queue<Runnable> tasks = new ArrayDeque<Runnable>(2);
 
+    private static EmbeddedChannel cast(Channel channel) {
+        if (channel instanceof EmbeddedChannel) {
+            return (EmbeddedChannel) channel;
+        }
+        throw new IllegalArgumentException("Channel of type " + StringUtil.simpleClassName(channel) + " not supported");
+    }
+
+    private final Unsafe unsafe = new Unsafe() {
+        @Override
+        public void register(Channel channel) {
+            assert inEventLoop();
+            cast(channel).setActive();
+        }
+
+        @Override
+        public void deregister(Channel channel) {
+            assert inEventLoop();
+        }
+    };
+
+    @Override
+    public Unsafe unsafe() {
+        return unsafe;
+    }
+
     @Override
     public EventLoopGroup parent() {
         return (EventLoopGroup) super.parent();

transport/src/main/java/io/netty/channel/local/LocalChannel.java

@@ -26,10 +26,8 @@ import io.netty.channel.DefaultChannelConfig;
 import io.netty.channel.EventLoop;
 import io.netty.channel.PreferHeapByteBufAllocator;
 import io.netty.channel.RecvByteBufAllocator;
-import io.netty.channel.SingleThreadEventLoop;
 import io.netty.util.ReferenceCountUtil;
 import io.netty.util.concurrent.Future;
-import io.netty.util.concurrent.SingleThreadEventExecutor;
 import io.netty.util.internal.InternalThreadLocalMap;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.ThrowableUtil;
@@ -144,11 +142,6 @@ public class LocalChannel extends AbstractChannel {
         return new LocalUnsafe();
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof SingleThreadEventLoop;
-    }
-
     @Override
     protected SocketAddress localAddress0() {
         return localAddress;
@@ -159,43 +152,6 @@ public class LocalChannel extends AbstractChannel {
         return remoteAddress;
     }
 
-    @Override
-    protected void doRegister() throws Exception {
-        // Check if both peer and parent are non-null because this channel was created by a LocalServerChannel.
-        // This is needed as a peer may not be null also if a LocalChannel was connected before and
-        // deregistered / registered later again.
-        //
-        // See https://github.com/netty/netty/issues/2400
-        if (peer != null && parent() != null) {
-            // Store the peer in a local variable as it may be set to null if doClose() is called.
-            // See https://github.com/netty/netty/issues/2144
-            final LocalChannel peer = this.peer;
-            state = State.CONNECTED;
-
-            peer.remoteAddress = parent() == null ? null : parent().localAddress();
-            peer.state = State.CONNECTED;
-
-            // Always call peer.eventLoop().execute() even if peer.eventLoop().inEventLoop() is true.
-            // This ensures that if both channels are on the same event loop, the peer's channelActive
-            // event is triggered *after* this channel's channelRegistered event, so that this channel's
-            // pipeline is fully initialized by ChannelInitializer before any channelRead events.
-            peer.eventLoop().execute(new Runnable() {
-                @Override
-                public void run() {
-                    ChannelPromise promise = peer.connectPromise;
-
-                    // Only trigger fireChannelActive() if the promise was not null and was not completed yet.
-                    // connectPromise may be set to null if doClose() was called in the meantime.
-                    if (promise != null && promise.trySuccess()) {
-                        peer.pipeline().fireChannelActive();
-                        peer.readIfIsAutoRead();
-                    }
-                }
-            });
-        }
-        ((SingleThreadEventExecutor) eventLoop()).addShutdownHook(shutdownHook);
-    }
-
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
         this.localAddress =
@@ -294,12 +250,6 @@ public class LocalChannel extends AbstractChannel {
         }
     }
 
-    @Override
-    protected void doDeregister() throws Exception {
-        // Just remove the shutdownHook as this Channel may be closed later or registered to another EventLoop
-        ((SingleThreadEventExecutor) eventLoop()).removeShutdownHook(shutdownHook);
-    }
-
     private void readInbound() {
         RecvByteBufAllocator.Handle handle = unsafe().recvBufAllocHandle();
         handle.reset(config());
@@ -456,7 +406,7 @@ public class LocalChannel extends AbstractChannel {
         }
     }
 
-    private class LocalUnsafe extends AbstractUnsafe {
+    private class LocalUnsafe extends AbstractUnsafe implements LocalChannelUnsafe {
 
         @Override
         public void connect(final SocketAddress remoteAddress,
@@ -506,5 +456,48 @@ public class LocalChannel extends AbstractChannel {
             LocalServerChannel serverChannel = (LocalServerChannel) boundChannel;
             peer = serverChannel.serve(LocalChannel.this);
         }
+
+        @Override
+        public void register0(LocalEventLoop eventLoop) {
+            // Check if both peer and parent are non-null because this channel was created by a LocalServerChannel.
+            // This is needed as a peer may not be null also if a LocalChannel was connected before and
+            // deregistered / registered later again.
+            //
+            // See https://github.com/netty/netty/issues/2400
+            if (peer != null && parent() != null) {
+                // Store the peer in a local variable as it may be set to null if doClose() is called.
+                // See https://github.com/netty/netty/issues/2144
+                final LocalChannel peer = LocalChannel.this.peer;
+                state = State.CONNECTED;
+
+                peer.remoteAddress = parent() == null ? null : parent().localAddress();
+                peer.state = State.CONNECTED;
+
+                // Always call peer.eventLoop().execute() even if peer.eventLoop().inEventLoop() is true.
+                // This ensures that if both channels are on the same event loop, the peer's channelActive
+                // event is triggered *after* this channel's channelRegistered event, so that this channel's
+                // pipeline is fully initialized by ChannelInitializer before any channelRead events.
+                peer.eventLoop().execute(new Runnable() {
+                    @Override
+                    public void run() {
+                        ChannelPromise promise = peer.connectPromise;
+
+                        // Only trigger fireChannelActive() if the promise was not null and was not completed yet.
+                        // connectPromise may be set to null if doClose() was called in the meantime.
+                        if (promise != null && promise.trySuccess()) {
+                            peer.pipeline().fireChannelActive();
+                            peer.readIfIsAutoRead();
+                        }
+                    }
+                });
+            }
+            eventLoop.addShutdownHook(shutdownHook);
+        }
+
+        @Override
+        public void deregister0(LocalEventLoop eventLoop) {
+            // Just remove the shutdownHook as this Channel may be closed later or registered to another EventLoop
+            eventLoop.removeShutdownHook(shutdownHook);
+        }
     }
 }

transport/src/main/java/io/netty/channel/local/LocalChannelUnsafe.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2018 The Netty Project
+ *
+ * The Netty Project 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 io.netty.channel.local;
+
+import io.netty.channel.Channel;
+
+interface LocalChannelUnsafe extends Channel.Unsafe {
+    void register0(LocalEventLoop eventLoop);
+    void deregister0(LocalEventLoop eventLoop);
+}

transport/src/main/java/io/netty/channel/local/LocalEventLoop.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2012 The Netty Project
+ *
+ * The Netty Project 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 io.netty.channel.local;
+
+import io.netty.channel.Channel;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.SingleThreadEventLoop;
+import io.netty.util.internal.StringUtil;
+
+import java.util.concurrent.Executor;
+
+class LocalEventLoop extends SingleThreadEventLoop {
+
+    private static LocalChannelUnsafe cast(Channel channel) {
+        Channel.Unsafe unsafe = channel.unsafe();
+        if (unsafe instanceof LocalChannelUnsafe) {
+            return (LocalChannelUnsafe) unsafe;
+        }
+        throw new IllegalArgumentException("Channel of type " + StringUtil.simpleClassName(channel) + " not supported");
+    }
+
+    private final Unsafe unsafe = new Unsafe() {
+        @Override
+        public void register(Channel channel) {
+            assert inEventLoop();
+            cast(channel).register0(LocalEventLoop.this);
+        }
+
+        @Override
+        public void deregister(Channel channel) {
+            assert inEventLoop();
+            cast(channel).deregister0(LocalEventLoop.this);
+        }
+    };
+
+    LocalEventLoop(EventLoopGroup parent, Executor executor) {
+        super(parent, executor, true);
+    }
+
+    @Override
+    public Unsafe unsafe() {
+        return unsafe;
+    }
+
+    @Override
+    protected void run() {
+        for (;;) {
+            Runnable task = takeTask();
+            if (task != null) {
+                task.run();
+                updateLastExecutionTime();
+            }
+
+            if (confirmShutdown()) {
+                break;
+            }
+        }
+    }
+}

transport/src/main/java/io/netty/channel/local/LocalEventLoopGroup.java

@@ -15,20 +15,23 @@
  */
 package io.netty.channel.local;
 
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.EventLoop;
+import io.netty.channel.MultithreadEventLoopGroup;
 
+import java.util.concurrent.Executor;
 import java.util.concurrent.ThreadFactory;
 
 /**
- * @deprecated Use {@link DefaultEventLoopGroup} instead.
+ * {@link MultithreadEventLoopGroup} which must be used for the local transport.
  */
-@Deprecated
+public class LocalEventLoopGroup extends MultithreadEventLoopGroup {
-public class LocalEventLoopGroup extends DefaultEventLoopGroup {
 
     /**
      * Create a new instance with the default number of threads.
      */
-    public LocalEventLoopGroup() { }
+    public LocalEventLoopGroup() {
+        this(0);
+    }
 
     /**
      * Create a new instance
@@ -36,7 +39,7 @@ public class LocalEventLoopGroup extends DefaultEventLoopGroup {
      * @param nThreads          the number of threads to use
      */
     public LocalEventLoopGroup(int nThreads) {
-        super(nThreads);
+        this(nThreads, (ThreadFactory) null);
     }
 
     /**
@@ -48,4 +51,20 @@ public class LocalEventLoopGroup extends DefaultEventLoopGroup {
     public LocalEventLoopGroup(int nThreads, ThreadFactory threadFactory) {
         super(nThreads, threadFactory);
     }
+
+    /**
+     * Create a new instance
+     *
+     * @param nThreads          the number of threads to use
+     * @param executor          the Executor to use, or {@code null} if the default should be used.
+     */
+    public LocalEventLoopGroup(int nThreads, Executor executor) {
+        super(nThreads, executor);
+    }
+
+    @Override
+    protected EventLoop newChild(Executor executor, Object... args) throws Exception {
+        assert args == null || args.length == 0;
+        return new LocalEventLoop(this, executor);
+    }
 }

transport/src/main/java/io/netty/channel/local/LocalServerChannel.java

@@ -18,14 +18,13 @@ package io.netty.channel.local;
 import io.netty.channel.AbstractServerChannel;
 import io.netty.channel.ChannelConfig;
 import io.netty.channel.ChannelPipeline;
+import io.netty.channel.ChannelPromise;
 import io.netty.channel.DefaultChannelConfig;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.PreferHeapByteBufAllocator;
 import io.netty.channel.RecvByteBufAllocator;
 import io.netty.channel.ServerChannel;
-import io.netty.channel.SingleThreadEventLoop;
-import io.netty.util.concurrent.SingleThreadEventExecutor;
 
 import java.net.SocketAddress;
 import java.util.ArrayDeque;
@@ -79,21 +78,11 @@ public class LocalServerChannel extends AbstractServerChannel {
         return state == 1;
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof SingleThreadEventLoop;
-    }
-
     @Override
     protected SocketAddress localAddress0() {
         return localAddress;
     }
 
-    @Override
-    protected void doRegister() throws Exception {
-        ((SingleThreadEventExecutor) eventLoop()).addShutdownHook(shutdownHook);
-    }
-
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
         this.localAddress = LocalChannelRegistry.register(this, this.localAddress, localAddress);
@@ -112,11 +101,6 @@ public class LocalServerChannel extends AbstractServerChannel {
         }
     }
 
-    @Override
-    protected void doDeregister() throws Exception {
-        ((SingleThreadEventExecutor) eventLoop()).removeShutdownHook(shutdownHook);
-    }
-
     @Override
     protected void doBeginRead() throws Exception {
         if (acceptInProgress) {
@@ -179,4 +163,26 @@ public class LocalServerChannel extends AbstractServerChannel {
             readInbound();
         }
     }
+
+    @Override
+    protected AbstractUnsafe newUnsafe() {
+        return new DefaultServerUnsafe();
+    }
+
+    private final class DefaultServerUnsafe extends AbstractUnsafe implements LocalChannelUnsafe {
+        @Override
+        public void connect(SocketAddress remoteAddress, SocketAddress localAddress, ChannelPromise promise) {
+            safeSetFailure(promise, new UnsupportedOperationException());
+        }
+
+        @Override
+        public void register0(LocalEventLoop eventLoop) {
+            eventLoop.addShutdownHook(shutdownHook);
+        }
+
+        @Override
+        public void deregister0(LocalEventLoop eventLoop) {
+            eventLoop.removeShutdownHook(shutdownHook);
+        }
+    }
 }

transport/src/main/java/io/netty/channel/nio/AbstractNioChannel.java

@@ -35,7 +35,6 @@ import io.netty.util.internal.logging.InternalLoggerFactory;
 
 import java.io.IOException;
 import java.net.SocketAddress;
-import java.nio.channels.CancelledKeyException;
 import java.nio.channels.ClosedChannelException;
 import java.nio.channels.ConnectionPendingException;
 import java.nio.channels.SelectableChannel;
@@ -115,11 +114,6 @@ public abstract class AbstractNioChannel extends AbstractChannel {
         return ch;
     }
 
-    @Override
-    public NioEventLoop eventLoop() {
-        return (NioEventLoop) super.eventLoop();
-    }
-
     /**
      * Return the current {@link SelectionKey}
      */
@@ -375,36 +369,14 @@ public abstract class AbstractNioChannel extends AbstractChannel {
         }
     }
 
-    @Override
-    protected boolean isCompatible(EventLoop loop) {
-        return loop instanceof NioEventLoop;
-    }
-
     @Override
     protected void doRegister() throws Exception {
-        boolean selected = false;
+       eventLoop().unsafe().register(this);
-        for (;;) {
-            try {
-                selectionKey = javaChannel().register(eventLoop().unwrappedSelector(), 0, this);
-                return;
-            } catch (CancelledKeyException e) {
-                if (!selected) {
-                    // Force the Selector to select now as the "canceled" SelectionKey may still be
-                    // cached and not removed because no Select.select(..) operation was called yet.
-                    eventLoop().selectNow();
-                    selected = true;
-                } else {
-                    // We forced a select operation on the selector before but the SelectionKey is still cached
-                    // for whatever reason. JDK bug ?
-                    throw e;
-                }
-            }
-        }
     }
 
     @Override
     protected void doDeregister() throws Exception {
-        eventLoop().cancel(selectionKey());
+        eventLoop().unsafe().deregister(this);
     }
 
     @Override

transport/src/main/java/io/netty/channel/nio/NioEventLoop.java

@@ -17,7 +17,6 @@ package io.netty.channel.nio;
 
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelException;
-import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopException;
 import io.netty.channel.SelectStrategy;
 import io.netty.channel.SingleThreadEventLoop;
@@ -25,6 +24,7 @@ import io.netty.util.IntSupplier;
 import io.netty.util.concurrent.RejectedExecutionHandler;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.ReflectionUtil;
+import io.netty.util.internal.StringUtil;
 import io.netty.util.internal.SystemPropertyUtil;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
@@ -116,6 +116,46 @@ public final class NioEventLoop extends SingleThreadEventLoop {
 
     private final SelectorProvider provider;
 
+    private static AbstractNioChannel cast(Channel channel) {
+        if (channel instanceof AbstractNioChannel) {
+            return (AbstractNioChannel) channel;
+        }
+        throw new IllegalArgumentException("Channel of type " + StringUtil.simpleClassName(channel) + " not supported");
+    }
+
+    private final Unsafe unsafe = new Unsafe() {
+        @Override
+        public void register(Channel channel) throws Exception {
+            assert inEventLoop();
+            AbstractNioChannel nioChannel = cast(channel);
+            boolean selected = false;
+            for (;;) {
+                try {
+                    nioChannel.selectionKey = nioChannel.javaChannel().register(unwrappedSelector(), 0, nioChannel);
+                    return;
+                } catch (CancelledKeyException e) {
+                    if (!selected) {
+                        // Force the Selector to select now as the "canceled" SelectionKey may still be
+                        // cached and not removed because no Select.select(..) operation was called yet.
+                        selectNow();
+                        selected = true;
+                    } else {
+                        // We forced a select operation on the selector before but the SelectionKey is still cached
+                        // for whatever reason. JDK bug ?
+                        throw e;
+                    }
+                }
+            }
+        }
+
+        @Override
+        public void deregister(Channel channel) {
+            assert inEventLoop();
+            AbstractNioChannel nioChannel = cast(channel);
+            cancel(nioChannel.selectionKey());
+        }
+    };
+
     /**
      * Boolean that controls determines if a blocked Selector.select should
      * break out of its selection process. In our case we use a timeout for
@@ -263,6 +303,11 @@ public final class NioEventLoop extends SingleThreadEventLoop {
         return provider;
     }
 
+    @Override
+    public Unsafe unsafe() {
+        return unsafe;
+    }
+
     @Override
     protected Queue<Runnable> newTaskQueue(int maxPendingTasks) {
         // This event loop never calls takeTask()

transport/src/test/java/io/netty/bootstrap/BootstrapTest.java

@@ -26,7 +26,7 @@ import io.netty.channel.ChannelInboundHandler;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelOutboundHandlerAdapter;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.ServerChannel;
@@ -59,8 +59,8 @@ import static org.junit.Assert.*;
 
 public class BootstrapTest {
 
-    private static final EventLoopGroup groupA = new DefaultEventLoopGroup(1);
+    private static final EventLoopGroup groupA = new LocalEventLoopGroup(1);
-    private static final EventLoopGroup groupB = new DefaultEventLoopGroup(1);
+    private static final EventLoopGroup groupB = new LocalEventLoopGroup(1);
     private static final ChannelInboundHandler dummyHandler = new DummyHandler();
 
     @AfterClass
@@ -145,7 +145,7 @@ public class BootstrapTest {
 
     @Test
     public void testLateRegisterSuccess() throws Exception {
-        DefaultEventLoopGroup group = new DefaultEventLoopGroup(1);
+        LocalEventLoopGroup group = new LocalEventLoopGroup(1);
         try {
             LateRegisterHandler registerHandler = new LateRegisterHandler();
             ServerBootstrap bootstrap = new ServerBootstrap();
@@ -175,7 +175,7 @@ public class BootstrapTest {
 
     @Test
     public void testLateRegisterSuccessBindFailed() throws Exception {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         LateRegisterHandler registerHandler = new LateRegisterHandler();
         try {
             ServerBootstrap bootstrap = new ServerBootstrap();
@@ -226,7 +226,7 @@ public class BootstrapTest {
 
     @Test(expected = ConnectException.class, timeout = 10000)
     public void testLateRegistrationConnect() throws Exception {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         LateRegisterHandler registerHandler = new LateRegisterHandler();
         try {
             final Bootstrap bootstrapA = new Bootstrap();

transport/src/test/java/io/netty/bootstrap/ServerBootstrapTest.java

@@ -21,11 +21,10 @@ import io.netty.channel.ChannelHandlerAdapter;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
-import io.netty.channel.DefaultEventLoopGroup;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
-import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalServerChannel;
 import org.junit.Test;
 
@@ -97,7 +96,7 @@ public class ServerBootstrapTest {
             }
         };
 
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         Channel sch = null;
         Channel cch = null;
         try {

transport/src/test/java/io/netty/channel/AbstractChannelTest.java

@@ -31,6 +31,7 @@ public class AbstractChannelTest {
         EventLoop eventLoop = mock(EventLoop.class);
         // This allows us to have a single-threaded test
         when(eventLoop.inEventLoop()).thenReturn(true);
+        when(eventLoop.unsafe()).thenReturn(mock(EventLoop.Unsafe.class));
 
         TestChannel channel = new TestChannel(eventLoop);
         ChannelInboundHandler handler = mock(ChannelInboundHandler.class);
@@ -48,6 +49,7 @@ public class AbstractChannelTest {
         final EventLoop eventLoop = mock(EventLoop.class);
         // This allows us to have a single-threaded test
         when(eventLoop.inEventLoop()).thenReturn(true);
+        when(eventLoop.unsafe()).thenReturn(mock(EventLoop.Unsafe.class));
 
         doAnswer(new Answer() {
             @Override
@@ -126,11 +128,6 @@ public class AbstractChannelTest {
             return new TestUnsafe();
         }
 
-        @Override
-        protected boolean isCompatible(EventLoop loop) {
-            return true;
-        }
-
         @Override
         protected SocketAddress localAddress0() {
             return null;

transport/src/test/java/io/netty/channel/BaseChannelTest.java

@@ -20,6 +20,7 @@ import io.netty.bootstrap.Bootstrap;
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalChannel;
 import io.netty.channel.local.LocalServerChannel;
 
@@ -34,7 +35,7 @@ class BaseChannelTest {
     }
 
     ServerBootstrap getLocalServerBootstrap() {
-        EventLoopGroup serverGroup = new DefaultEventLoopGroup();
+        EventLoopGroup serverGroup = new LocalEventLoopGroup();
         ServerBootstrap sb = new ServerBootstrap();
         sb.group(serverGroup);
         sb.channel(LocalServerChannel.class);
@@ -48,7 +49,7 @@ class BaseChannelTest {
     }
 
     Bootstrap getLocalClientBootstrap() {
-        EventLoopGroup clientGroup = new DefaultEventLoopGroup();
+        EventLoopGroup clientGroup = new LocalEventLoopGroup();
         Bootstrap cb = new Bootstrap();
         cb.channel(LocalChannel.class);
         cb.group(clientGroup);

transport/src/test/java/io/netty/channel/ChannelInitializerTest.java

@@ -18,9 +18,11 @@ package io.netty.channel;
 import io.netty.bootstrap.Bootstrap;
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
 import io.netty.channel.local.LocalServerChannel;
+import io.netty.util.concurrent.AbstractEventExecutor;
 import io.netty.util.concurrent.EventExecutor;
 import io.netty.util.concurrent.Future;
 import org.junit.After;
@@ -54,7 +56,7 @@ public class ChannelInitializerTest {
 
     @Before
     public void setUp() {
-        group = new DefaultEventLoopGroup(1);
+        group = new LocalEventLoopGroup(1);
         server = new ServerBootstrap()
                 .group(group)
                 .channel(LocalServerChannel.class)
@@ -264,7 +266,7 @@ public class ChannelInitializerTest {
         final AtomicReference<Throwable> errorRef = new AtomicReference<Throwable>();
         LocalAddress addr = new LocalAddress("test");
 
-        final EventExecutor executor = new DefaultEventLoop() {
+        final EventExecutor executor = new AbstractEventExecutor() {
             private final ScheduledExecutorService execService = Executors.newSingleThreadScheduledExecutor();
 
             @Override

transport/src/test/java/io/netty/channel/ChannelOutboundBufferTest.java

@@ -18,6 +18,7 @@ package io.netty.channel;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.CompositeByteBuf;
 import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.util.CharsetUtil;
 import io.netty.util.concurrent.DefaultThreadFactory;
 import io.netty.util.concurrent.RejectedExecutionHandlers;
@@ -137,7 +138,7 @@ public class ChannelOutboundBufferTest {
         private final ChannelConfig config = new DefaultChannelConfig(this);
 
         TestChannel() {
-            super(null, new DefaultEventLoop());
+            super(null, new LocalEventLoopGroup(1).next());
         }
 
         @Override
@@ -145,11 +146,6 @@ public class ChannelOutboundBufferTest {
             return new TestUnsafe();
         }
 
-        @Override
-        protected boolean isCompatible(EventLoop loop) {
-            return true;
-        }
-
         @Override
         protected SocketAddress localAddress0() {
             throw new UnsupportedOperationException();

transport/src/test/java/io/netty/channel/DefaultChannelPipelineTailTest.java

@@ -19,25 +19,23 @@ import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import java.io.IOException;
-import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 
+import io.netty.channel.local.LocalEventLoopGroup;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
-import io.netty.bootstrap.Bootstrap;
-
 public class DefaultChannelPipelineTailTest {
 
     private static EventLoopGroup GROUP;
 
     @BeforeClass
     public static void init() {
-        GROUP = new DefaultEventLoopGroup(1);
+        GROUP = new LocalEventLoopGroup(1);
     }
 
     @AfterClass
@@ -56,19 +54,12 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
+        myChannel.pipeline().fireChannelActive();
-                .channelFactory(new MyChannelFactory(myChannel))
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
 
         try {
             assertTrue(latch.await(1L, TimeUnit.SECONDS));
         } finally {
-            channel.close();
+            myChannel.close();
         }
     }
 
@@ -83,16 +74,8 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
+        myChannel.pipeline().fireChannelInactive();
-                .channelFactory(new MyChannelFactory(myChannel))
+        myChannel.close().syncUninterruptibly();
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
-
-        channel.close().syncUninterruptibly();
 
         assertTrue(latch.await(1L, TimeUnit.SECONDS));
     }
@@ -110,22 +93,13 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
-                .channelFactory(new MyChannelFactory(myChannel))
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
-
         try {
             IOException ex = new IOException("testOnUnhandledInboundException");
-            channel.pipeline().fireExceptionCaught(ex);
+            myChannel.pipeline().fireExceptionCaught(ex);
             assertTrue(latch.await(1L, TimeUnit.SECONDS));
             assertSame(ex, causeRef.get());
         } finally {
-            channel.close();
+            myChannel.close();
         }
     }
 
@@ -140,20 +114,11 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
-                .channelFactory(new MyChannelFactory(myChannel))
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
-
         try {
-            channel.pipeline().fireChannelRead("testOnUnhandledInboundMessage");
+            myChannel.pipeline().fireChannelRead("testOnUnhandledInboundMessage");
             assertTrue(latch.await(1L, TimeUnit.SECONDS));
         } finally {
-            channel.close();
+            myChannel.close();
         }
     }
 
@@ -168,20 +133,11 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
-                .channelFactory(new MyChannelFactory(myChannel))
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
-
         try {
-            channel.pipeline().fireChannelReadComplete();
+            myChannel.pipeline().fireChannelReadComplete();
             assertTrue(latch.await(1L, TimeUnit.SECONDS));
         } finally {
-            channel.close();
+            myChannel.close();
         }
     }
 
@@ -196,20 +152,11 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
-                .channelFactory(new MyChannelFactory(myChannel))
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
-
         try {
-            channel.pipeline().fireUserEventTriggered("testOnUnhandledInboundUserEventTriggered");
+            myChannel.pipeline().fireUserEventTriggered("testOnUnhandledInboundUserEventTriggered");
             assertTrue(latch.await(1L, TimeUnit.SECONDS));
         } finally {
-            channel.close();
+            myChannel.close();
         }
     }
 
@@ -224,33 +171,11 @@ public class DefaultChannelPipelineTailTest {
             }
         };
 
-        Bootstrap bootstrap = new Bootstrap()
-                .channelFactory(new MyChannelFactory(myChannel))
-                .group(loop)
-                .handler(new ChannelInboundHandlerAdapter())
-                .remoteAddress(new InetSocketAddress(0));
-
-        Channel channel = bootstrap.connect()
-                .sync().channel();
-
         try {
-            channel.pipeline().fireChannelWritabilityChanged();
+            myChannel.pipeline().fireChannelWritabilityChanged();
             assertTrue(latch.await(1L, TimeUnit.SECONDS));
         } finally {
-            channel.close();
+            myChannel.close();
-        }
-    }
-
-    private static class MyChannelFactory implements ChannelFactory<MyChannel> {
-        private final MyChannel channel;
-
-        public MyChannelFactory(MyChannel channel) {
-            this.channel = channel;
-        }
-
-        @Override
-        public MyChannel newChannel(EventLoop eventLoop) {
-            return channel;
         }
     }
 
@@ -296,11 +221,6 @@ public class DefaultChannelPipelineTailTest {
             return new MyUnsafe();
         }
 
-        @Override
-        protected boolean isCompatible(EventLoop loop) {
-            return true;
-        }
-
         @Override
         protected SocketAddress localAddress0() {
             return null;

transport/src/test/java/io/netty/channel/DefaultChannelPipelineTest.java

@@ -22,6 +22,7 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandler.Sharable;
 import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.channel.local.LocalEventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
 import io.netty.channel.local.LocalServerChannel;
@@ -69,7 +70,7 @@ import static org.junit.Assert.fail;
 
 public class DefaultChannelPipelineTest {
 
-    private static final EventLoopGroup group = new DefaultEventLoopGroup(1);
+    private static final EventLoopGroup group = new LocalEventLoopGroup(1);
 
     private Channel self;
     private Channel peer;
@@ -938,7 +939,7 @@ public class DefaultChannelPipelineTest {
 
     @Test(timeout = 3000)
     public void testAddBefore() throws Throwable {
-        EventLoopGroup defaultGroup = new DefaultEventLoopGroup(2);
+        EventLoopGroup defaultGroup = new LocalEventLoopGroup(2);
         try {
             EventLoop eventLoop1 = defaultGroup.next();
             EventLoop eventLoop2 = defaultGroup.next();
@@ -1034,7 +1035,7 @@ public class DefaultChannelPipelineTest {
     @Test(timeout = 3000)
     public void testUnorderedEventExecutor() throws Throwable {
         EventExecutorGroup eventExecutors = new UnorderedThreadPoolEventExecutor(2);
-        EventLoopGroup defaultGroup = new DefaultEventLoopGroup(1);
+        EventLoopGroup defaultGroup = new LocalEventLoopGroup(1);
         try {
             EventLoop eventLoop1 = defaultGroup.next();
             ChannelPipeline pipeline1 = new LocalChannel(eventLoop1).pipeline();
@@ -1103,7 +1104,7 @@ public class DefaultChannelPipelineTest {
 
     @Test(timeout = 3000)
     public void testVoidPromiseNotify() throws Throwable {
-        EventLoopGroup defaultGroup = new DefaultEventLoopGroup(1);
+        EventLoopGroup defaultGroup = new LocalEventLoopGroup(1);
         EventLoop eventLoop1 = defaultGroup.next();
         ChannelPipeline pipeline1 = new LocalChannel(eventLoop1).pipeline();
 
@@ -1133,7 +1134,7 @@ public class DefaultChannelPipelineTest {
     // Test for https://github.com/netty/netty/issues/8676.
     @Test
     public void testHandlerRemovedOnlyCalledWhenHandlerAddedCalled() throws Exception {
-        EventLoopGroup group = new DefaultEventLoopGroup(1);
+        EventLoopGroup group = new LocalEventLoopGroup(1);
         try {
             final AtomicReference<Error> errorRef = new AtomicReference<Error>();
 

transport/src/test/java/io/netty/channel/SingleThreadEventLoopTest.java

@@ -484,6 +484,11 @@ public class SingleThreadEventLoopTest {
         protected void cleanup() {
             cleanedUp.incrementAndGet();
         }
+
+        @Override
+        public Unsafe unsafe() {
+            return null;
+        }
     }
 
     private static class SingleThreadEventLoopB extends SingleThreadEventLoop {
@@ -513,5 +518,20 @@ public class SingleThreadEventLoopTest {
         protected void wakeup(boolean inEventLoop) {
             interruptThread();
         }
+
+        @Override
+        public Unsafe unsafe() {
+            return new Unsafe() {
+                @Override
+                public void register(Channel channel)  {
+                    // NOOP
+                }
+
+                @Override
+                public void deregister(Channel channel) {
+                    // NOOP
+                }
+            };
+        }
     }
 }

transport/src/test/java/io/netty/channel/local/LocalChannelTest.java

@@ -28,7 +28,6 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.SimpleChannelInboundHandler;
@@ -71,9 +70,9 @@ public class LocalChannelTest {
 
     @BeforeClass
     public static void beforeClass() {
-        group1 = new DefaultEventLoopGroup(2);
+        group1 = new LocalEventLoopGroup(2);
-        group2 = new DefaultEventLoopGroup(2);
+        group2 = new LocalEventLoopGroup(2);
-        sharedGroup = new DefaultEventLoopGroup(1);
+        sharedGroup = new LocalEventLoopGroup(1);
     }
 
     @AfterClass
@@ -228,11 +227,11 @@ public class LocalChannelTest {
     @Test
     public void localChannelRaceCondition() throws Exception {
         final CountDownLatch closeLatch = new CountDownLatch(1);
-        final EventLoopGroup clientGroup = new DefaultEventLoopGroup(1) {
+        final EventLoopGroup clientGroup = new LocalEventLoopGroup(1) {
             @Override
             protected EventLoop newChild(Executor threadFactory, Object... args)
                     throws Exception {
-                return new SingleThreadEventLoop(this, threadFactory, true) {
+                return new LocalEventLoop(this, threadFactory) {
                     @Override
                     protected void run() {
                         for (;;) {

transport/src/test/java/io/netty/channel/local/LocalTransportThreadModelTest.java

@@ -24,7 +24,6 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.util.ReferenceCountUtil;
 import io.netty.util.concurrent.DefaultEventExecutorGroup;
@@ -50,7 +49,7 @@ public class LocalTransportThreadModelTest {
     @BeforeClass
     public static void init() {
         // Configure a test server
-        group = new DefaultEventLoopGroup();
+        group = new LocalEventLoopGroup();
         ServerBootstrap sb = new ServerBootstrap();
         sb.group(group)
           .channel(LocalServerChannel.class)
@@ -85,7 +84,7 @@ public class LocalTransportThreadModelTest {
 
     @Test(timeout = 5000)
     public void testStagedExecution() throws Throwable {
-        EventLoopGroup l = new DefaultEventLoopGroup(4, new DefaultThreadFactory("l"));
+        EventLoopGroup l = new LocalEventLoopGroup(4, new DefaultThreadFactory("l"));
         EventExecutorGroup e1 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e1"));
         EventExecutorGroup e2 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e2"));
         ThreadNameAuditor h1 = new ThreadNameAuditor();
@@ -228,7 +227,7 @@ public class LocalTransportThreadModelTest {
     @Test(timeout = 30000)
     @Ignore
     public void testConcurrentMessageBufferAccess() throws Throwable {
-        EventLoopGroup l = new DefaultEventLoopGroup(4, new DefaultThreadFactory("l"));
+        EventLoopGroup l = new LocalEventLoopGroup(4, new DefaultThreadFactory("l"));
         EventExecutorGroup e1 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e1"));
         EventExecutorGroup e2 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e2"));
         EventExecutorGroup e3 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e3"));

transport/src/test/java/io/netty/channel/local/LocalTransportThreadModelTest2.java

@@ -22,7 +22,6 @@ import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelHandler.Sharable;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
-import io.netty.channel.DefaultEventLoopGroup;
 import io.netty.util.ReferenceCountUtil;
 import org.junit.Test;
 
@@ -41,14 +40,14 @@ public class LocalTransportThreadModelTest2 {
         ServerBootstrap serverBootstrap = new ServerBootstrap();
         LocalHandler serverHandler = new LocalHandler("SERVER");
         serverBootstrap
-                .group(new DefaultEventLoopGroup(), new DefaultEventLoopGroup())
+                .group(new LocalEventLoopGroup(), new LocalEventLoopGroup())
                 .channel(LocalServerChannel.class)
                 .childHandler(serverHandler);
 
         Bootstrap clientBootstrap = new Bootstrap();
         LocalHandler clientHandler = new LocalHandler("CLIENT");
         clientBootstrap
-                .group(new DefaultEventLoopGroup())
+                .group(new LocalEventLoopGroup())
                 .channel(LocalChannel.class)
                 .remoteAddress(new LocalAddress(LOCAL_CHANNEL)).handler(clientHandler);
 

transport/src/test/java/io/netty/channel/local/LocalTransportThreadModelTest3.java

@@ -23,7 +23,6 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelPromise;
-import io.netty.channel.DefaultEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.util.ReferenceCountUtil;
 import io.netty.util.concurrent.DefaultEventExecutorGroup;
@@ -63,7 +62,7 @@ public class LocalTransportThreadModelTest3 {
     @BeforeClass
     public static void init() {
         // Configure a test server
-        group = new DefaultEventLoopGroup();
+        group = new LocalEventLoopGroup();
         ServerBootstrap sb = new ServerBootstrap();
         sb.group(group)
                 .channel(LocalServerChannel.class)
@@ -117,7 +116,7 @@ public class LocalTransportThreadModelTest3 {
     }
 
     private static void testConcurrentAddRemove(boolean inbound) throws Exception {
-        EventLoopGroup l = new DefaultEventLoopGroup(4, new DefaultThreadFactory("l"));
+        EventLoopGroup l = new LocalEventLoopGroup(4, new DefaultThreadFactory("l"));
         EventExecutorGroup e1 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e1"));
         EventExecutorGroup e2 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e2"));
         EventExecutorGroup e3 = new DefaultEventExecutorGroup(4, new DefaultThreadFactory("e3"));

transport/src/test/java/io/netty/channel/socket/nio/AbstractNioChannelTest.java

@@ -16,15 +16,19 @@
 package io.netty.channel.socket.nio;
 
 import io.netty.channel.ChannelOption;
+import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.nio.AbstractNioChannel;
 import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.util.concurrent.AbstractEventExecutor;
+import io.netty.util.concurrent.Future;
 import org.junit.Test;
 
 import java.io.IOException;
 import java.net.SocketOption;
 import java.net.StandardSocketOptions;
 import java.nio.channels.NetworkChannel;
+import java.util.concurrent.TimeUnit;
 
 import static org.junit.Assert.*;
 
@@ -84,4 +88,87 @@ public abstract class AbstractNioChannelTest<T extends AbstractNioChannel> {
             eventLoopGroup.shutdownGracefully();
         }
     }
+
+    @Test
+    public void testWrapping() {
+        final NioEventLoopGroup eventLoopGroup = new NioEventLoopGroup(1);
+        final EventLoop eventLoop = eventLoopGroup.next();
+
+        class WrappedEventLoop extends AbstractEventExecutor implements EventLoop {
+            private final EventLoop eventLoop;
+
+            WrappedEventLoop(EventLoop eventLoop) {
+                super(eventLoop.parent());
+                this.eventLoop = eventLoop;
+            }
+
+            @Test
+            public EventLoopGroup parent() {
+                return eventLoop.parent();
+            }
+
+            @Test
+            public EventLoop next() {
+                return this;
+            }
+
+            @Override
+            public Unsafe unsafe() {
+                return eventLoop.unsafe();
+            }
+
+            @Override
+            public void shutdown() {
+                eventLoop.shutdown();
+            }
+
+            @Override
+            public boolean inEventLoop(Thread thread) {
+                return eventLoop.inEventLoop(thread);
+            }
+
+            @Override
+            public boolean isShuttingDown() {
+                return eventLoop.isShuttingDown();
+            }
+
+            @Override
+            public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+                return eventLoop.shutdownGracefully(quietPeriod, timeout, unit);
+            }
+
+            @Override
+            public Future<?> terminationFuture() {
+                return eventLoop.terminationFuture();
+            }
+
+            @Override
+            public boolean isShutdown() {
+                return eventLoop.isShutdown();
+            }
+
+            @Override
+            public boolean isTerminated() {
+                return eventLoop.isTerminated();
+            }
+
+            @Override
+            public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
+                return eventLoop.awaitTermination(timeout, unit);
+            }
+
+            @Override
+            public void execute(Runnable command) {
+                eventLoop.execute(command);
+            }
+        }
+
+        EventLoop wrapped = new WrappedEventLoop(eventLoop);
+        T channel = newNioChannel(wrapped);
+        channel.register().syncUninterruptibly();
+
+        assertSame(wrapped, channel.eventLoop());
+        channel.close().syncUninterruptibly();
+        eventLoopGroup.shutdownGracefully();
+    }
 }