Make EventExecutor.shutdownGracefully() return Future

- Also added EventExecutor.terminationFuture()
- Also fixed type signature problem with Future.add/removeListener()
- Related issue: #1389

common/src/main/java/io/netty/util/concurrent/AbstractEventExecutor.java

@@ -45,8 +45,8 @@ public abstract class AbstractEventExecutor extends AbstractExecutorService impl
     }
 
     @Override
-    public void shutdownGracefully() {
+    public Future<?> shutdownGracefully() {
-        shutdownGracefully(2, 15, TimeUnit.SECONDS);
+        return shutdownGracefully(2, 15, TimeUnit.SECONDS);
     }
 
     /**

common/src/main/java/io/netty/util/concurrent/AbstractEventExecutorGroup.java

@@ -65,8 +65,8 @@ public abstract class AbstractEventExecutorGroup implements EventExecutorGroup {
     }
 
     @Override
-    public void shutdownGracefully() {
+    public Future<?> shutdownGracefully() {
-        shutdownGracefully(2, 15, TimeUnit.SECONDS);
+        return shutdownGracefully(2, 15, TimeUnit.SECONDS);
     }
 
     /**

common/src/main/java/io/netty/util/concurrent/CompleteFuture.java

@@ -39,7 +39,7 @@ public abstract class CompleteFuture<V> extends AbstractFuture<V> {
     }
 
     @Override
-    public Future<V> addListener(GenericFutureListener<? extends Future<V>> listener) {
+    public Future<V> addListener(GenericFutureListener<? extends Future<? super V>> listener) {
         if (listener == null) {
             throw new NullPointerException("listener");
         }
@@ -48,11 +48,11 @@ public abstract class CompleteFuture<V> extends AbstractFuture<V> {
     }
 
     @Override
-    public Future<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public Future<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         if (listeners == null) {
             throw new NullPointerException("listeners");
         }
-        for (GenericFutureListener<? extends Future<V>> l: listeners) {
+        for (GenericFutureListener<? extends Future<? super V>> l: listeners) {
             if (l == null) {
                 break;
             }
@@ -62,13 +62,13 @@ public abstract class CompleteFuture<V> extends AbstractFuture<V> {
     }
 
     @Override
-    public Future<V> removeListener(GenericFutureListener<? extends Future<V>> listener) {
+    public Future<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener) {
         // NOOP
         return this;
     }
 
     @Override
-    public Future<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public Future<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         // NOOP
         return this;
     }

common/src/main/java/io/netty/util/concurrent/CompletePromise.java

@@ -63,22 +63,22 @@ public abstract class CompletePromise<V> extends CompleteFuture<V> implements Pr
     }
 
     @Override
-    public Promise<V> addListener(GenericFutureListener<? extends Future<V>> listener) {
+    public Promise<V> addListener(GenericFutureListener<? extends Future<? super V>> listener) {
         return (Promise<V>) super.addListener(listener);
     }
 
     @Override
-    public Promise<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public Promise<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         return (Promise<V>) super.addListeners(listeners);
     }
 
     @Override
-    public Promise<V> removeListener(GenericFutureListener<? extends Future<V>> listener) {
+    public Promise<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener) {
         return (Promise<V>) super.removeListener(listener);
     }
 
     @Override
-    public Promise<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public Promise<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         return (Promise<V>) super.removeListeners(listeners);
     }
 }

common/src/main/java/io/netty/util/concurrent/DefaultProgressivePromise.java

@@ -58,25 +58,25 @@ public class DefaultProgressivePromise<V> extends DefaultPromise<V> implements P
     }
 
     @Override
-    public ProgressivePromise<V> addListener(GenericFutureListener<? extends Future<V>> listener) {
+    public ProgressivePromise<V> addListener(GenericFutureListener<? extends Future<? super V>> listener) {
         super.addListener(listener);
         return this;
     }
 
     @Override
-    public ProgressivePromise<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public ProgressivePromise<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         super.addListeners(listeners);
         return this;
     }
 
     @Override
-    public ProgressivePromise<V> removeListener(GenericFutureListener<? extends Future<V>> listener) {
+    public ProgressivePromise<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener) {
         super.removeListener(listener);
         return this;
     }
 
     @Override
-    public ProgressivePromise<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public ProgressivePromise<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         super.removeListeners(listeners);
         return this;
     }

common/src/main/java/io/netty/util/concurrent/DefaultPromise.java

@@ -113,7 +113,7 @@ public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
     }
 
     @Override
-    public Promise<V> addListener(GenericFutureListener<? extends Future<V>> listener) {
+    public Promise<V> addListener(GenericFutureListener<? extends Future<? super V>> listener) {
         if (listener == null) {
             throw new NullPointerException("listener");
         }
@@ -146,12 +146,12 @@ public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
     }
 
     @Override
-    public Promise<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public Promise<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         if (listeners == null) {
             throw new NullPointerException("listeners");
         }
 
-        for (GenericFutureListener<? extends Future<V>> l: listeners) {
+        for (GenericFutureListener<? extends Future<? super V>> l: listeners) {
             if (l == null) {
                 break;
             }
@@ -161,7 +161,7 @@ public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
     }
 
     @Override
-    public Promise<V> removeListener(GenericFutureListener<? extends Future<V>> listener) {
+    public Promise<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener) {
         if (listener == null) {
             throw new NullPointerException("listener");
         }
@@ -184,12 +184,12 @@ public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
     }
 
     @Override
-    public Promise<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners) {
+    public Promise<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
         if (listeners == null) {
             throw new NullPointerException("listeners");
         }
 
-        for (GenericFutureListener<? extends Future<V>> l: listeners) {
+        for (GenericFutureListener<? extends Future<? super V>> l: listeners) {
             if (l == null) {
                 break;
             }

common/src/main/java/io/netty/util/concurrent/EventExecutorGroup.java

@@ -37,8 +37,10 @@ public interface EventExecutorGroup extends ScheduledExecutorService, Iterable<E
 
     /**
      * Shortcut method for {@link #shutdownGracefully(long, long, TimeUnit)} with sensible default values.
+     *
+     * @return the {@link #terminationFuture()}
      */
-    void shutdownGracefully();
+    Future<?> shutdownGracefully();
 
     /**
      * Signals this executor that the caller wants the executor to be shut down.  Once this method is called,
@@ -51,8 +53,15 @@ public interface EventExecutorGroup extends ScheduledExecutorService, Iterable<E
      * @param timeout     the maximum amount of time to wait until the executor is {@linkplain #shutdown()}
      *                    regardless if a task was submitted during the quiet period
      * @param unit        the unit of {@code quietPeriod} and {@code timeout}
+     *
+     * @return the {@link #terminationFuture()}
      */
-    void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit);
+    Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit);
+
+    /**
+     * Returns the {@link Future} which is notified when this executor has been terminated.
+     */
+    Future<?> terminationFuture();
 
     /**
      * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or {@link #shutdownGracefully()} instead.

common/src/main/java/io/netty/util/concurrent/Future.java

@@ -52,7 +52,7 @@ public interface Future<V> extends java.util.concurrent.Future<V> {
      * {@linkplain #isDone() done}.  If this future is already
      * completed, the specified listener is notified immediately.
      */
-    Future<V> addListener(GenericFutureListener<? extends Future<V>> listener);
+    Future<V> addListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     /**
      * Adds the specified listeners to this future.  The
@@ -60,7 +60,7 @@ public interface Future<V> extends java.util.concurrent.Future<V> {
      * {@linkplain #isDone() done}.  If this future is already
      * completed, the specified listeners are notified immediately.
      */
-    Future<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    Future<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     /**
      * Removes the specified listener from this future.
@@ -69,7 +69,7 @@ public interface Future<V> extends java.util.concurrent.Future<V> {
      * listener is not associated with this future, this method
      * does nothing and returns silently.
      */
-    Future<V> removeListener(GenericFutureListener<? extends Future<V>> listener);
+    Future<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     /**
      * Removes the specified listeners from this future.
@@ -78,7 +78,7 @@ public interface Future<V> extends java.util.concurrent.Future<V> {
      * listeners are not associated with this future, this method
      * does nothing and returns silently.
      */
-    Future<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    Future<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     /**
      * Waits for this future until it is done, and rethrows the cause of the failure if this future

common/src/main/java/io/netty/util/concurrent/GlobalEventExecutor.java

@@ -58,6 +58,8 @@ public final class GlobalEventExecutor extends AbstractEventExecutor {
     volatile Thread thread;
     private volatile int state = ST_NOT_STARTED;
 
+    private final Future<?> terminationFuture = new FailedFuture<Object>(this, new UnsupportedOperationException());
+
     private GlobalEventExecutor() {
         delayedTaskQueue.add(purgeTask);
     }
@@ -157,8 +159,13 @@ public final class GlobalEventExecutor extends AbstractEventExecutor {
     }
 
     @Override
-    public void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
-        throw new UnsupportedOperationException();
+        return terminationFuture();
+    }
+
+    @Override
+    public Future<?> terminationFuture() {
+        return terminationFuture;
     }
 
     @Override

common/src/main/java/io/netty/util/concurrent/ImmediateEventExecutor.java

@@ -23,6 +23,9 @@ import java.util.concurrent.TimeUnit;
 public final class ImmediateEventExecutor extends AbstractEventExecutor {
     public static final ImmediateEventExecutor INSTANCE = new ImmediateEventExecutor();
 
+    private final Future<?> terminationFuture = new FailedFuture<Object>(
+            GlobalEventExecutor.INSTANCE, new UnsupportedOperationException());
+
     private ImmediateEventExecutor() {
         // use static instance
     }
@@ -43,7 +46,14 @@ public final class ImmediateEventExecutor extends AbstractEventExecutor {
     }
 
     @Override
-    public void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) { }
+    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+        return terminationFuture();
+    }
+
+    @Override
+    public Future<?> terminationFuture() {
+        return terminationFuture;
+    }
 
     @Override
     @Deprecated

common/src/main/java/io/netty/util/concurrent/MultithreadEventExecutorGroup.java

@@ -31,6 +31,8 @@ public abstract class MultithreadEventExecutorGroup extends AbstractEventExecuto
 
     private final EventExecutor[] children;
     private final AtomicInteger childIndex = new AtomicInteger();
+    private final AtomicInteger terminatedChildren = new AtomicInteger();
+    private final Promise<?> terminationFuture = new DefaultPromise(GlobalEventExecutor.INSTANCE);
 
     /**
      * Create a new instance.
@@ -77,6 +79,19 @@ public abstract class MultithreadEventExecutorGroup extends AbstractEventExecuto
                 }
             }
         }
+
+        final FutureListener<Object> terminationListener = new FutureListener<Object>() {
+            @Override
+            public void operationComplete(Future<Object> future) throws Exception {
+                if (terminatedChildren.incrementAndGet() == children.length) {
+                    terminationFuture.setSuccess(null);
+                }
+            }
+        };
+
+        for (EventExecutor e: children) {
+            e.terminationFuture().addListener(terminationListener);
+        }
     }
 
     protected ThreadFactory newDefaultThreadFactory() {
@@ -119,10 +134,16 @@ public abstract class MultithreadEventExecutorGroup extends AbstractEventExecuto
             ThreadFactory threadFactory, Object... args) throws Exception;
 
     @Override
-    public void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
         for (EventExecutor l: children) {
             l.shutdownGracefully(quietPeriod, timeout, unit);
         }
+        return terminationFuture();
+    }
+
+    @Override
+    public Future<?> terminationFuture() {
+        return terminationFuture;
     }
 
     @Override

common/src/main/java/io/netty/util/concurrent/ProgressiveFuture.java

@@ -22,16 +22,16 @@ package io.netty.util.concurrent;
 public interface ProgressiveFuture<V> extends Future<V> {
 
     @Override
-    ProgressiveFuture<V> addListener(GenericFutureListener<? extends Future<V>> listener);
+    ProgressiveFuture<V> addListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     @Override
-    ProgressiveFuture<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    ProgressiveFuture<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     @Override
-    ProgressiveFuture<V> removeListener(GenericFutureListener<? extends Future<V>> listener);
+    ProgressiveFuture<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     @Override
-    ProgressiveFuture<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    ProgressiveFuture<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     @Override
     ProgressiveFuture<V> sync() throws InterruptedException;

common/src/main/java/io/netty/util/concurrent/ProgressivePromise.java

@@ -40,16 +40,16 @@ public interface ProgressivePromise<V> extends Promise<V>, ProgressiveFuture<V>
     ProgressivePromise<V> setFailure(Throwable cause);
 
     @Override
-    ProgressivePromise<V> addListener(GenericFutureListener<? extends Future<V>> listener);
+    ProgressivePromise<V> addListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     @Override
-    ProgressivePromise<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    ProgressivePromise<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     @Override
-    ProgressivePromise<V> removeListener(GenericFutureListener<? extends Future<V>> listener);
+    ProgressivePromise<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     @Override
-    ProgressivePromise<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    ProgressivePromise<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     @Override
     ProgressivePromise<V> await() throws InterruptedException;

common/src/main/java/io/netty/util/concurrent/Promise.java

@@ -65,16 +65,16 @@ public interface Promise<V> extends Future<V> {
     boolean setUncancellable();
 
     @Override
-    Promise<V> addListener(GenericFutureListener<? extends Future<V>> listener);
+    Promise<V> addListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     @Override
-    Promise<V> addListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    Promise<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     @Override
-    Promise<V> removeListener(GenericFutureListener<? extends Future<V>> listener);
+    Promise<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener);
 
     @Override
-    Promise<V> removeListeners(GenericFutureListener<? extends Future<V>>... listeners);
+    Promise<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners);
 
     @Override
     Promise<V> await() throws InterruptedException;

common/src/main/java/io/netty/util/concurrent/SingleThreadEventExecutor.java

@@ -72,6 +72,8 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
     private volatile long gracefulShutdownTimeout;
     private long gracefulShutdownStartTime;
 
+    private final Promise<?> terminationFuture = new DefaultPromise<Void>(GlobalEventExecutor.INSTANCE);
+
     /**
      * Create a new instance
      *
@@ -133,6 +135,8 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
                                         "An event executor terminated with " +
                                         "non-empty task queue (" + taskQueue.size() + ')');
                             }
+
+                            terminationFuture.setSuccess(null);
                         }
                     }
                 }
@@ -476,7 +480,7 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
     }
 
     @Override
-    public void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
         if (quietPeriod < 0) {
             throw new IllegalArgumentException("quietPeriod: " + quietPeriod + " (expected >= 0)");
         }
@@ -489,7 +493,7 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
         }
 
         if (isShuttingDown()) {
-            return;
+            return terminationFuture();
         }
 
         boolean inEventLoop = inEventLoop();
@@ -497,7 +501,7 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
 
         synchronized (stateLock) {
             if (isShuttingDown()) {
-                return;
+                return terminationFuture();
             }
 
             gracefulShutdownQuietPeriod = unit.toNanos(quietPeriod);
@@ -524,6 +528,13 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
         if (wakeup) {
             wakeup(inEventLoop);
         }
+
+        return terminationFuture();
+    }
+
+    @Override
+    public Future<?> terminationFuture() {
+        return terminationFuture;
     }
 
     @Override

testsuite/src/test/java/io/netty/testsuite/transport/socket/SocketEchoTest.java

@@ -54,8 +54,8 @@ public class SocketEchoTest extends AbstractSocketTest {
     }
 
     @AfterClass
-    public static void destroyGroup() {
+    public static void destroyGroup() throws Exception {
-        group.shutdownGracefully();
+        group.shutdownGracefully().sync();
     }
 
     @Test(timeout = 30000)

testsuite/src/test/java/io/netty/testsuite/transport/socket/SocketStartTlsTest.java

@@ -55,8 +55,8 @@ public class SocketStartTlsTest extends AbstractSocketTest {
     }
 
     @AfterClass
-    public static void shutdownExecutor() {
+    public static void shutdownExecutor() throws Exception {
-        executor.shutdownGracefully();
+        executor.shutdownGracefully().sync();
     }
 
     @Test(timeout = 30000)

testsuite/src/test/java/io/netty/testsuite/transport/udt/UDTClientServerConnectionTest.java

@@ -100,7 +100,7 @@ public class UDTClientServerConnectionTest {
             } catch (final Throwable e) {
                 log.error("Client failed.", e);
             } finally {
-                connectGroup.shutdownGracefully();
+                connectGroup.shutdownGracefully().syncUninterruptibly();
             }
         }
 
@@ -238,6 +238,9 @@ public class UDTClientServerConnectionTest {
             } finally {
                 acceptGroup.shutdownGracefully();
                 connectGroup.shutdownGracefully();
+
+                acceptGroup.terminationFuture().syncUninterruptibly();
+                connectGroup.terminationFuture().syncUninterruptibly();
             }
         }
 

transport-udt/src/test/java/io/netty/test/udt/nio/NioUdtByteRendezvousChannelTest.java

@@ -44,7 +44,7 @@ public class NioUdtByteRendezvousChannelTest extends AbstractUdtTest {
      */
     @Test
     public void metadata() throws Exception {
-        assertEquals(false, new NioUdtByteRendezvousChannel().metadata().hasDisconnect());
+        assertFalse(new NioUdtByteRendezvousChannel().metadata().hasDisconnect());
     }
 
     /**
@@ -114,5 +114,8 @@ public class NioUdtByteRendezvousChannelTest extends AbstractUdtTest {
 
         group1.shutdownGracefully();
         group2.shutdownGracefully();
+
+        group1.terminationFuture().sync();
+        group2.terminationFuture().sync();
     }
 }

transport-udt/src/test/java/io/netty/test/udt/nio/NioUdtMessageRendezvousChannelTest.java

@@ -44,7 +44,7 @@ public class NioUdtMessageRendezvousChannelTest extends AbstractUdtTest {
      */
     @Test
     public void metadata() throws Exception {
-        assertEquals(false, new NioUdtMessageRendezvousChannel().metadata().hasDisconnect());
+        assertFalse(new NioUdtMessageRendezvousChannel().metadata().hasDisconnect());
     }
 
     /**
@@ -108,5 +108,8 @@ public class NioUdtMessageRendezvousChannelTest extends AbstractUdtTest {
 
         group1.shutdownGracefully();
         group2.shutdownGracefully();
+
+        group1.terminationFuture().sync();
+        group2.terminationFuture().sync();
     }
 }

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

@@ -171,16 +171,16 @@ public interface ChannelFuture extends Future<Void> {
     Channel channel();
 
     @Override
-    ChannelFuture addListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelFuture addListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelFuture addListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelFuture addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
-    ChannelFuture removeListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelFuture removeListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelFuture removeListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelFuture removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
     ChannelFuture sync() throws InterruptedException;

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

@@ -24,16 +24,16 @@ import io.netty.util.concurrent.ProgressiveFuture;
  */
 public interface ChannelProgressiveFuture extends ChannelFuture, ProgressiveFuture<Void> {
     @Override
-    ChannelProgressiveFuture addListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelProgressiveFuture addListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelProgressiveFuture addListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelProgressiveFuture addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
-    ChannelProgressiveFuture removeListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelProgressiveFuture removeListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelProgressiveFuture removeListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelProgressiveFuture removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
     ChannelProgressiveFuture sync() throws InterruptedException;

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

@@ -25,16 +25,16 @@ import io.netty.util.concurrent.ProgressivePromise;
 public interface ChannelProgressivePromise extends ProgressivePromise<Void>, ChannelProgressiveFuture, ChannelPromise {
 
     @Override
-    ChannelProgressivePromise addListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelProgressivePromise addListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelProgressivePromise addListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelProgressivePromise addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
-    ChannelProgressivePromise removeListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelProgressivePromise removeListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelProgressivePromise removeListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelProgressivePromise removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
     ChannelProgressivePromise sync() throws InterruptedException;

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

@@ -38,16 +38,16 @@ public interface ChannelPromise extends ChannelFuture, Promise<Void> {
     ChannelPromise setFailure(Throwable cause);
 
     @Override
-    ChannelPromise addListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelPromise addListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelPromise addListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelPromise addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
-    ChannelPromise removeListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelPromise removeListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelPromise removeListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelPromise removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
     ChannelPromise sync() throws InterruptedException;

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

@@ -52,25 +52,25 @@ abstract class CompleteChannelFuture extends CompleteFuture<Void> implements Cha
     }
 
     @Override
-    public ChannelFuture addListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelFuture addListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.addListener(listener);
         return this;
     }
 
     @Override
-    public ChannelFuture addListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelFuture addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.addListeners(listeners);
         return this;
     }
 
     @Override
-    public ChannelFuture removeListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelFuture removeListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.removeListener(listener);
         return this;
     }
 
     @Override
-    public ChannelFuture removeListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelFuture removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.removeListeners(listeners);
         return this;
     }

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

@@ -67,22 +67,22 @@ abstract class CompleteChannelPromise extends CompleteChannelFuture implements C
     }
 
     @Override
-    public ChannelPromise addListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelPromise addListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         return (ChannelPromise) super.addListener(listener);
     }
 
     @Override
-    public ChannelPromise addListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelPromise addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         return (ChannelPromise) super.addListeners(listeners);
     }
 
     @Override
-    public ChannelPromise removeListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelPromise removeListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         return (ChannelPromise) super.removeListener(listener);
     }
 
     @Override
-    public ChannelPromise removeListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelPromise removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         return (ChannelPromise) super.removeListeners(listeners);
     }
 

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

@@ -97,25 +97,26 @@ public class DefaultChannelProgressivePromise
     }
 
     @Override
-    public ChannelProgressivePromise addListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelProgressivePromise addListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.addListener(listener);
         return this;
     }
 
     @Override
-    public ChannelProgressivePromise addListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelProgressivePromise addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.addListeners(listeners);
         return this;
     }
 
     @Override
-    public ChannelProgressivePromise removeListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelProgressivePromise removeListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.removeListener(listener);
         return this;
     }
 
     @Override
-    public ChannelProgressivePromise removeListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelProgressivePromise removeListeners(
+            GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.removeListeners(listeners);
         return this;
     }

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

@@ -89,25 +89,25 @@ public class DefaultChannelPromise extends DefaultPromise<Void> implements Chann
     }
 
     @Override
-    public ChannelPromise addListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelPromise addListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.addListener(listener);
         return this;
     }
 
     @Override
-    public ChannelPromise addListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelPromise addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.addListeners(listeners);
         return this;
     }
 
     @Override
-    public ChannelPromise removeListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public ChannelPromise removeListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.removeListener(listener);
         return this;
     }
 
     @Override
-    public ChannelPromise removeListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public ChannelPromise removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.removeListeners(listeners);
         return this;
     }

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

@@ -17,7 +17,12 @@ package io.netty.channel;
 
 
 import io.netty.util.concurrent.AbstractEventExecutorGroup;
+import io.netty.util.concurrent.DefaultPromise;
 import io.netty.util.concurrent.EventExecutor;
+import io.netty.util.concurrent.Future;
+import io.netty.util.concurrent.FutureListener;
+import io.netty.util.concurrent.GlobalEventExecutor;
+import io.netty.util.concurrent.Promise;
 import io.netty.util.internal.EmptyArrays;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.ReadOnlyIterator;
@@ -28,6 +33,7 @@ import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.Executors;
+import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
 
@@ -44,6 +50,18 @@ public class ThreadPerChannelEventLoopGroup extends AbstractEventExecutorGroup i
     final Queue<ThreadPerChannelEventLoop> idleChildren = new ConcurrentLinkedQueue<ThreadPerChannelEventLoop>();
     private final ChannelException tooManyChannels;
 
+    private volatile boolean shuttingDown;
+    private final Promise<?> terminationFuture = new DefaultPromise<Void>(GlobalEventExecutor.INSTANCE);
+    private final FutureListener<Object> childTerminationListener = new FutureListener<Object>() {
+        @Override
+        public void operationComplete(Future<Object> future) throws Exception {
+            // Inefficient, but works.
+            if (isTerminated()) {
+                terminationFuture.setSuccess(null);
+            }
+        }
+    };
+
     /**
      * Create a new {@link ThreadPerChannelEventLoopGroup} with no limit in place.
      */
@@ -117,24 +135,45 @@ public class ThreadPerChannelEventLoopGroup extends AbstractEventExecutorGroup i
     }
 
     @Override
-    public void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+        shuttingDown = true;
+
         for (EventLoop l: activeChildren) {
             l.shutdownGracefully(quietPeriod, timeout, unit);
         }
         for (EventLoop l: idleChildren) {
             l.shutdownGracefully(quietPeriod, timeout, unit);
         }
+
+        // Notify the future if there was no children.
+        if (isTerminated()) {
+            terminationFuture.trySuccess(null);
+        }
+
+        return terminationFuture();
+    }
+
+    @Override
+    public Future<?> terminationFuture() {
+        return terminationFuture;
     }
 
     @Override
     @Deprecated
     public void shutdown() {
+        shuttingDown = true;
+
         for (EventLoop l: activeChildren) {
             l.shutdown();
         }
         for (EventLoop l: idleChildren) {
             l.shutdown();
         }
+
+        // Notify the future if there was no children.
+        if (isTerminated()) {
+            terminationFuture.trySuccess(null);
+        }
     }
 
     @Override
@@ -237,12 +276,17 @@ public class ThreadPerChannelEventLoopGroup extends AbstractEventExecutorGroup i
     }
 
     private EventLoop nextChild() throws Exception {
+        if (shuttingDown) {
+            throw new RejectedExecutionException("shutting down");
+        }
+
         ThreadPerChannelEventLoop loop = idleChildren.poll();
         if (loop == null) {
             if (maxChannels > 0 && activeChildren.size() >= maxChannels) {
                 throw tooManyChannels;
             }
             loop = newChild(childArgs);
+            loop.terminationFuture().addListener(childTerminationListener);
         }
         activeChildren.add(loop);
         return loop;

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

@@ -41,25 +41,25 @@ final class VoidChannelPromise extends AbstractFuture<Void> implements ChannelPr
     }
 
     @Override
-    public VoidChannelPromise addListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public VoidChannelPromise addListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         fail();
         return this;
     }
 
     @Override
-    public VoidChannelPromise addListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public VoidChannelPromise addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         fail();
         return this;
     }
 
     @Override
-    public VoidChannelPromise removeListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public VoidChannelPromise removeListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         // NOOP
         return this;
     }
 
     @Override
-    public VoidChannelPromise removeListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public VoidChannelPromise removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         // NOOP
         return this;
     }

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

@@ -21,6 +21,7 @@ import io.netty.channel.ChannelPromise;
 import io.netty.channel.EventLoop;
 import io.netty.channel.EventLoopGroup;
 import io.netty.util.concurrent.AbstractEventExecutor;
+import io.netty.util.concurrent.Future;
 
 import java.util.ArrayDeque;
 import java.util.Queue;
@@ -50,11 +51,20 @@ final class EmbeddedEventLoop extends AbstractEventExecutor implements EventLoop
     }
 
     @Override
-    public void shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) { }
+    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Future<?> terminationFuture() {
+        throw new UnsupportedOperationException();
+    }
 
     @Override
     @Deprecated
-    public void shutdown() { }
+    public void shutdown() {
+        throw new UnsupportedOperationException();
+    }
 
     @Override
     public boolean isShuttingDown() {

transport/src/main/java/io/netty/channel/group/ChannelGroupFuture.java

@@ -151,16 +151,16 @@ public interface ChannelGroupFuture extends Future<Void>, Iterable<ChannelFuture
     boolean isPartialFailure();
 
     @Override
-    ChannelGroupFuture addListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelGroupFuture addListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelGroupFuture addListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelGroupFuture addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
-    ChannelGroupFuture removeListener(GenericFutureListener<? extends Future<Void>> listener);
+    ChannelGroupFuture removeListener(GenericFutureListener<? extends Future<? super Void>> listener);
 
     @Override
-    ChannelGroupFuture removeListeners(GenericFutureListener<? extends Future<Void>>... listeners);
+    ChannelGroupFuture removeListeners(GenericFutureListener<? extends Future<? super Void>>... listeners);
 
     @Override
     ChannelGroupFuture await() throws InterruptedException;

transport/src/main/java/io/netty/channel/group/DefaultChannelGroupFuture.java

@@ -153,25 +153,26 @@ final class DefaultChannelGroupFuture extends DefaultPromise<Void> implements Ch
     }
 
     @Override
-    public DefaultChannelGroupFuture addListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public DefaultChannelGroupFuture addListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.addListener(listener);
         return this;
     }
 
     @Override
-    public DefaultChannelGroupFuture addListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public DefaultChannelGroupFuture addListeners(GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.addListeners(listeners);
         return this;
     }
 
     @Override
-    public DefaultChannelGroupFuture removeListener(GenericFutureListener<? extends Future<Void>> listener) {
+    public DefaultChannelGroupFuture removeListener(GenericFutureListener<? extends Future<? super Void>> listener) {
         super.removeListener(listener);
         return this;
     }
 
     @Override
-    public DefaultChannelGroupFuture removeListeners(GenericFutureListener<? extends Future<Void>>... listeners) {
+    public DefaultChannelGroupFuture removeListeners(
+            GenericFutureListener<? extends Future<? super Void>>... listeners) {
         super.removeListeners(listeners);
         return this;
     }

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

@@ -74,6 +74,8 @@ public class BootstrapTest {
         } finally {
             groupA.shutdownGracefully();
             groupB.shutdownGracefully();
+            groupA.terminationFuture().sync();
+            groupB.terminationFuture().sync();
         }
     }
 
@@ -120,6 +122,8 @@ public class BootstrapTest {
         } finally {
             groupA.shutdownGracefully();
             groupB.shutdownGracefully();
+            groupA.terminationFuture().sync();
+            groupB.terminationFuture().sync();
         }
     }
 

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

@@ -45,8 +45,8 @@ public class DefaultChannelPipelineTest {
     private Channel peer;
 
     @AfterClass
-    public static void afterClass() {
+    public static void afterClass() throws Exception {
-        group.shutdownGracefully();
+        group.shutdownGracefully().sync();
     }
 
     private void setUp(final ChannelHandler... handlers) throws Exception {

transport/src/test/java/io/netty/channel/group/DefaultChannnelGroupTest.java

@@ -29,7 +29,7 @@ public class DefaultChannnelGroupTest {
 
     // Test for #1183
     @Test
-    public void testNotThrowBlockingOperationException() {
+    public void testNotThrowBlockingOperationException() throws Exception {
         EventLoopGroup bossGroup = new NioEventLoopGroup();
         EventLoopGroup workerGroup = new NioEventLoopGroup();
 
@@ -54,5 +54,7 @@ public class DefaultChannnelGroupTest {
 
         bossGroup.shutdownGracefully();
         workerGroup.shutdownGracefully();
+        bossGroup.terminationFuture().sync();
+        workerGroup.terminationFuture().sync();
     }
 }

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

@@ -88,6 +88,9 @@ public class LocalChannelRegistryTest {
             assertNull(String.format(
                     "Expected null, got channel '%s' for local address '%s'",
                     LocalChannelRegistry.get(addr), addr), LocalChannelRegistry.get(addr));
+
+            serverGroup.terminationFuture().sync();
+            clientGroup.terminationFuture().sync();
         }
     }
 

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

@@ -38,7 +38,6 @@ import java.util.HashSet;
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.ConcurrentLinkedQueue;
-import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 
 public class LocalTransportThreadModelTest {
@@ -69,8 +68,8 @@ public class LocalTransportThreadModelTest {
     }
 
     @AfterClass
-    public static void destroy() {
+    public static void destroy() throws Exception {
-        group.shutdownGracefully();
+        group.shutdownGracefully().sync();
     }
 
     @Test(timeout = 30000)
@@ -216,9 +215,10 @@ public class LocalTransportThreadModelTest {
             l.shutdownGracefully();
             e1.shutdownGracefully();
             e2.shutdownGracefully();
-            l.awaitTermination(5, TimeUnit.SECONDS);
+
-            e1.awaitTermination(5, TimeUnit.SECONDS);
+            l.terminationFuture().sync();
-            e2.awaitTermination(5, TimeUnit.SECONDS);
+            e1.terminationFuture().sync();
+            e2.terminationFuture().sync();
         }
     }
 
@@ -344,6 +344,13 @@ public class LocalTransportThreadModelTest {
             e3.shutdownGracefully();
             e4.shutdownGracefully();
             e5.shutdownGracefully();
+
+            l.terminationFuture().sync();
+            e1.terminationFuture().sync();
+            e2.terminationFuture().sync();
+            e3.terminationFuture().sync();
+            e4.terminationFuture().sync();
+            e5.terminationFuture().sync();
         }
     }
 

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

@@ -83,8 +83,8 @@ public class LocalTransportThreadModelTest3 {
     }
 
     @AfterClass
-    public static void destroy() {
+    public static void destroy() throws Exception {
-        group.shutdownGracefully();
+        group.shutdownGracefully().sync();
     }
 
     @Test(timeout = 60000)
@@ -222,6 +222,13 @@ public class LocalTransportThreadModelTest3 {
             e3.shutdownGracefully();
             e4.shutdownGracefully();
             e5.shutdownGracefully();
+
+            l.terminationFuture().sync();
+            e1.terminationFuture().sync();
+            e2.terminationFuture().sync();
+            e3.terminationFuture().sync();
+            e4.terminationFuture().sync();
+            e5.terminationFuture().sync();
         }
     }
 

transport/src/test/java/io/netty/channel/nio/NioDatagramChannelTest.java

@@ -36,7 +36,7 @@ public class NioDatagramChannelTest {
      * Test try to reproduce issue #1335
      */
     @Test
-    public void testBindMultiple() {
+    public void testBindMultiple() throws Exception {
         DefaultChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
         NioEventLoopGroup group = new NioEventLoopGroup();
         try {
@@ -57,8 +57,8 @@ public class NioDatagramChannelTest {
             }
             Assert.assertEquals(100, channelGroup.size());
         } finally {
-            channelGroup.close().syncUninterruptibly();
+            channelGroup.close().sync();
-            group.shutdownGracefully();
+            group.shutdownGracefully().sync();
         }
     }
 }