Change `!future.isSuccess()` to `future.isFailed()` where it makes sense (#11616)

Motivation:
The expression "not is success" can mean that either the future failed, or it has not yet completed.
However, many places where such an expression is used is expecting the future to have completed.
Specifically, they are expecting to be able to call `cause()` on the future.
It is both more correct, and semantically clearer, to call `isFailed()` instead of `!isSuccess()`.

Modification:
Change all places that used `!isSuccess()` to  mean that the future had failed, to use `isFailed()`.
A few places are relying on `isSuccess()` returning `false` for _incomplete_ futures, and these places have been left unchanged.

Result:
Clearer code, with potentially fewer latent bugs.

codec-haproxy/src/test/java/io/netty/handler/codec/haproxy/HAProxyMessageDecoderTest.java

@@ -233,7 +233,7 @@ public class HAProxyMessageDecoderTest {
             // swallow this exception since we're just testing to be sure the channel was closed
         }
         boolean isComplete = closeFuture.awaitUninterruptibly(5000);
-        if (!isComplete || !closeFuture.isDone() || !closeFuture.isSuccess()) {
+        if (!isComplete || !closeFuture.isDone() || closeFuture.isFailed()) {
             fail("Expected channel close");
         }
     }

codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectAggregator.java

@@ -251,14 +251,14 @@ public class HttpObjectAggregator
                 !HttpUtil.is100ContinueExpected(oversized) && !HttpUtil.isKeepAlive(oversized)) {
                 Future<Void> future = ctx.writeAndFlush(TOO_LARGE_CLOSE.retainedDuplicate());
                 future.addListener(future1 -> {
-                    if (!future1.isSuccess()) {
+                    if (future1.isFailed()) {
                         logger.debug("Failed to send a 413 Request Entity Too Large.", future1.cause());
                     }
                     ctx.close();
                 });
             } else {
                 ctx.writeAndFlush(TOO_LARGE.retainedDuplicate()).addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         logger.debug("Failed to send a 413 Request Entity Too Large.", future.cause());
                         ctx.close();
                     }

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientProtocolHandshakeHandler.java

@@ -54,7 +54,7 @@ class WebSocketClientProtocolHandshakeHandler implements ChannelHandler {
     public void channelActive(final ChannelHandlerContext ctx) throws Exception {
         ctx.fireChannelActive();
         handshaker.handshake(ctx.channel()).addListener(future -> {
-            if (!future.isSuccess()) {
+            if (future.isFailed()) {
                 handshakePromise.tryFailure(future.cause());
                 ctx.fireExceptionCaught(future.cause());
             } else {

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketServerProtocolHandshakeHandler.java

@@ -86,7 +86,7 @@ class WebSocketServerProtocolHandshakeHandler implements ChannelHandler {
 
                 Future<Void> handshakeFuture = handshaker.handshake(ctx.channel(), req);
                 handshakeFuture.addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         localHandshakePromise.tryFailure(future.cause());
                         ctx.fireExceptionCaught(future.cause());
                     } else {

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionEncoder.java

@@ -583,7 +583,7 @@ public class DefaultHttp2ConnectionEncoder implements Http2ConnectionEncoder, Ht
             Future<Void> f = sendHeaders(frameWriter, ctx, stream.id(), headers, hasPriority, streamDependency,
                                          weight, exclusive, padding, endOfStream, promise);
             // Writing headers may fail during the encode state if they violate HPACK limits.
-            if (f.isSuccess() || !f.isDone()) {
+            if (!f.isFailed()) { // "not failed" means either not done, or completed successfully.
                 // This just sets internal stream state which is used elsewhere in the codec and doesn't
                 // necessarily mean the write will complete successfully.
                 stream.headersSent(isInformational);
@@ -623,7 +623,7 @@ public class DefaultHttp2ConnectionEncoder implements Http2ConnectionEncoder, Ht
 
         @Override
         public void operationComplete(Future<? extends Void> future) throws Exception {
-            if (!future.isSuccess()) {
+            if (future.isFailed()) {
                 error(flowController().channelHandlerContext(), future.cause());
             }
         }

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2ConnectionHandler.java

@@ -842,7 +842,7 @@ public class Http2ConnectionHandler extends ByteToMessageDecoder implements Http
     }
 
     private void closeConnectionOnError(ChannelHandlerContext ctx, Future<?> future) {
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             onConnectionError(ctx, true, future.cause(), null);
         }
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2FrameCodec.java

@@ -463,7 +463,7 @@ public class Http2FrameCodec extends Http2ConnectionHandler {
     }
 
     private void handleHeaderFuture(Future<?> channelFuture, int streamId) {
-        if (!channelFuture.isSuccess()) {
+        if (channelFuture.isFailed()) {
             frameStreamToInitializeMap.remove(streamId);
         }
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexHandler.java

@@ -129,7 +129,7 @@ public final class Http2MultiplexHandler extends Http2ChannelDuplexHandler {
         // Handle any errors that occurred on the local thread while registering. Even though
         // failures can happen after this point, they will be handled by the channel by closing the
         // childChannel.
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             if (childChannel.isRegistered()) {
                 childChannel.close();
             } else {

codec/src/main/java/io/netty/handler/codec/MessageAggregator.java

@@ -225,7 +225,7 @@ public abstract class MessageAggregator<I, S, C extends ByteBufHolder, O extends
                 FutureContextListener<ChannelHandlerContext, Void> listener = continueResponseWriteListener;
                 if (listener == null) {
                     continueResponseWriteListener = listener = (context, future) -> {
-                        if (!future.isSuccess()) {
+                        if (future.isFailed()) {
                             context.fireExceptionCaught(future.cause());
                         }
                     };

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

@@ -51,7 +51,7 @@ public final class PromiseCombiner {
         private void operationComplete0(Future<?> future) {
             assert executor.inEventLoop();
             ++doneCount;
-            if (!future.isSuccess() && cause == null) {
+            if (future.isFailed() && cause == null) {
                 cause = future.cause();
             }
             if (doneCount == expectedCount && aggregatePromise != null) {

common/src/test/java/io/netty/util/concurrent/PromiseCombinerTest.java

@@ -215,6 +215,7 @@ public class PromiseCombinerTest {
     private static void mockFailedPromise(Promise<Void> p, Throwable cause, FutureListenerConsumer consumer) {
         when(p.isDone()).thenReturn(true);
         when(p.isSuccess()).thenReturn(false);
+        when(p.isFailed()).thenReturn(true);
         when(p.cause()).thenReturn(cause);
         mockListener(p, consumer);
     }

example/src/main/java/io/netty/example/http2/helloworld/client/Http2SettingsHandler.java

@@ -48,7 +48,7 @@ public class Http2SettingsHandler extends SimpleChannelInboundHandler<Http2Setti
         if (!promise.awaitUninterruptibly(timeout, unit)) {
             throw new IllegalStateException("Timed out waiting for settings");
         }
-        if (!promise.isSuccess()) {
+        if (promise.isFailed()) {
             throw new RuntimeException(promise.cause());
         }
     }

example/src/main/java/io/netty/example/http2/helloworld/client/HttpResponseHandler.java

@@ -71,14 +71,14 @@ public class HttpResponseHandler extends SimpleChannelInboundHandler<FullHttpRes
             if (!writeFuture.awaitUninterruptibly(timeout, unit)) {
                 throw new IllegalStateException("Timed out waiting to write for stream id " + entry.getKey());
             }
-            if (!writeFuture.isSuccess()) {
+            if (writeFuture.isFailed()) {
                 throw new RuntimeException(writeFuture.cause());
             }
             Promise<Void> promise = entry.getValue().getValue();
             if (!promise.awaitUninterruptibly(timeout, unit)) {
                 throw new IllegalStateException("Timed out waiting for response on stream id " + entry.getKey());
             }
-            if (!promise.isSuccess()) {
+            if (promise.isFailed()) {
                 throw new RuntimeException(promise.cause());
             }
             System.out.println("---Stream id: " + entry.getKey() + " received---");

example/src/main/java/io/netty/example/redis/RedisClient.java

@@ -78,7 +78,7 @@ public class RedisClient {
                 // Sends the received line to the server.
                 lastWriteFuture = ch.writeAndFlush(line);
                 lastWriteFuture.addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         System.err.print("write failed: ");
                         future.cause().printStackTrace(System.err);
                     }

handler-proxy/src/main/java/io/netty/handler/proxy/ProxyHandler.java

@@ -62,7 +62,7 @@ public abstract class ProxyHandler implements ChannelHandler {
     private final Promise<Channel> connectPromise = new LazyPromise();
     private ScheduledFuture<?> connectTimeoutFuture;
     private final FutureListener<Void> writeListener = future -> {
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             setConnectFailure(future.cause());
         }
     };

handler-proxy/src/test/java/io/netty/handler/proxy/ProxyServer.java

@@ -169,7 +169,7 @@ abstract class ProxyServer {
                 this.finished = true;
                 Future<Channel> f = connectToDestination(ctx.channel().executor(), new BackendHandler(ctx));
                 f.addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         recordException(future.cause());
                         ctx.close();
                     } else {

handler/src/main/java/io/netty/handler/ssl/SniHandler.java

@@ -100,7 +100,7 @@ public class SniHandler extends AbstractSniHandler<SslContext> {
     @Override
     protected final void onLookupComplete(ChannelHandlerContext ctx,
                                           String hostname, Future<? extends SslContext> future) throws Exception {
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             final Throwable cause = future.cause();
             if (cause instanceof Error) {
                 throw (Error) cause;

handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java

@@ -300,7 +300,7 @@ public class ChunkedWriteHandler implements ChannelHandler {
 
     private static void handleEndOfInputFuture(Future<?> future, PendingWrite currentWrite) {
         ChunkedInput<?> input = (ChunkedInput<?>) currentWrite.msg;
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             closeInput(input);
             currentWrite.fail(future.cause());
         } else {
@@ -314,7 +314,7 @@ public class ChunkedWriteHandler implements ChannelHandler {
 
     private void handleFuture(Channel channel, Future<?> future, PendingWrite currentWrite, boolean resume) {
         ChunkedInput<?> input = (ChunkedInput<?>) currentWrite.msg;
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             closeInput(input);
             currentWrite.fail(future.cause());
         } else {

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

@@ -433,7 +433,7 @@ public class ParameterizedSslHandlerTest {
                             PromiseNotifier.cascade(handler.sslCloseFuture(), serverPromise);
 
                             handler.handshakeFuture().addListener(future -> {
-                                if (!future.isSuccess()) {
+                                if (future.isFailed()) {
                                     // Something bad happened during handshake fail the promise!
                                     serverPromise.tryFailure(future.cause());
                                 }

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

@@ -81,7 +81,7 @@ public abstract class RenegotiateTest {
 
                                             renegotiate = true;
                                             handler.renegotiate().addListener((FutureListener<Channel>) future -> {
-                                                if (!future.isSuccess()) {
+                                                if (future.isFailed()) {
                                                     error.compareAndSet(null, future.cause());
                                                     ctx.close();
                                                 }

resolver-dns/src/main/java/io/netty/resolver/dns/DnsNameResolver.java

@@ -1276,7 +1276,7 @@ public class DnsNameResolver extends InetNameResolver {
             .channelFactory(socketChannelFactory)
             .handler(TCP_ENCODER);
             bs.connect(res.sender()).addListener(future -> {
-                if (!future.isSuccess()) {
+                if (future.isFailed()) {
                     if (logger.isDebugEnabled()) {
                         logger.debug("{} Unable to fallback to TCP [{}]", queryId, future.cause());
                     }

resolver-dns/src/main/java/io/netty/resolver/dns/DnsQueryContext.java

@@ -147,7 +147,7 @@ abstract class DnsQueryContext implements FutureListener<AddressedEnvelope<DnsRe
     }
 
     private void onQueryWriteCompletion(Future<? extends Void> writeFuture, Promise<Void> writePromise) {
-        if (!writeFuture.isSuccess()) {
+        if (writeFuture.isFailed()) {
             writePromise.setFailure(writeFuture.cause());
             tryFailure("failed to send a query via " + protocol(), writeFuture.cause(), false);
             return;

testsuite/src/main/java/io/netty/testsuite/transport/socket/AbstractSocketReuseFdTest.java

@@ -91,7 +91,7 @@ public abstract class AbstractSocketReuseFdTest extends AbstractSocketTest {
         });
 
         FutureListener<Channel> listener = future -> {
-            if (!future.isSuccess()) {
+            if (future.isFailed()) {
                 clientDonePromise.tryFailure(future.cause());
             }
         };

transport-native-epoll/src/test/java/io/netty/channel/epoll/EpollDomainSocketFdTest.java

@@ -65,7 +65,7 @@ public class EpollDomainSocketFdTest extends AbstractSocketTest {
                 final EpollDomainSocketChannel ch = new EpollDomainSocketChannel(ctx.channel().executor());
 
                 ctx.writeAndFlush(ch.fd()).addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         Throwable cause = future.cause();
                         queue.offer(cause);
                     }

transport-native-kqueue/src/test/java/io/netty/channel/kqueue/KQueueDomainSocketFdTest.java

@@ -65,7 +65,7 @@ public class KQueueDomainSocketFdTest extends AbstractSocketTest {
                 final KQueueDomainSocketChannel ch = new KQueueDomainSocketChannel(ctx.channel().executor());
 
                 ctx.writeAndFlush(ch.fd()).addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         Throwable cause = future.cause();
                         queue.offer(cause);
                     }

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

@@ -301,7 +301,7 @@ public abstract class AbstractBootstrap<B extends AbstractBootstrap<B, C, F>, C
         Channel channel = newChannel(loop);
 
         init(channel).addListener(future -> {
-            if (!future.isSuccess()) {
+            if (future.isFailed()) {
                 channel.unsafe().closeForcibly();
             }
         });

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

@@ -190,7 +190,7 @@ public class Bootstrap extends AbstractBootstrap<Bootstrap, Channel, ChannelFact
 
         Promise<Channel> resolveAndConnectPromise = new DefaultPromise<>(loop);
         if (regFuture.isDone()) {
-            if (!regFuture.isSuccess()) {
+            if (regFuture.isFailed()) {
                 return regFuture;
             }
             Channel channel = regFuture.getNow();

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

@@ -263,7 +263,7 @@ public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerCh
                 child.pipeline().addLast(childHandler);
 
                 child.register().addListener(future -> {
-                    if (!future.isSuccess()) {
+                    if (future.isFailed()) {
                         forceClose(child, future.cause());
                     }
                 });

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

@@ -49,12 +49,12 @@ public enum ChannelFutureListeners implements FutureContextListener<Channel, Obj
             channel.close();
             break;
         case CLOSE_ON_FAILURE:
-            if (!future.isSuccess()) {
+            if (future.isFailed()) {
                 channel.close();
             }
             break;
         case FIRE_EXCEPTION_ON_FAILURE:
-            if (!future.isSuccess()) {
+            if (future.isFailed()) {
                 channel.pipeline().fireExceptionCaught(future.cause());
             }
         }

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

@@ -586,7 +586,7 @@ public class EmbeddedChannel extends AbstractChannel {
     }
 
     private void recordException(Future<?> future) {
-        if (!future.isSuccess()) {
+        if (future.isFailed()) {
             recordException(future.cause());
         }
     }

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

@@ -62,7 +62,7 @@ final class DefaultChannelGroupFuture extends DefaultPromise<Void> implements Ch
                     List<Map.Entry<Channel, Throwable>> failed =
                             new ArrayList<>(failureCount);
                     for (Entry<Channel, Future<Void>> entry: futures.entrySet()) {
-                        if (!entry.getValue().isSuccess()) {
+                        if (entry.getValue().isFailed()) {
                             failed.add(new DefaultEntry<>(entry.getKey(), entry.getValue().cause()));
                         }
                     }