Inline super SubscriberAdapter with ChannelSendOperator

Add support for CoreSubscriber context passing

spring-web/src/main/java/org/springframework/http/server/reactive/ChannelSendOperator.java

@@ -26,6 +26,7 @@ import reactor.core.Scannable;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.core.publisher.Operators;
+import reactor.util.context.Context;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -75,7 +76,13 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 
 
 	@SuppressWarnings("deprecation")
-	private class WriteWithBarrier extends SubscriberAdapter<T, Void> implements Publisher<T> {
+	private final class WriteWithBarrier 
+			implements Publisher<T>, CoreSubscriber<T>, Subscription {
+
+		private final CoreSubscriber<? super Void> subscriber;
+
+		@Nullable
+		private Subscription subscription;
 
 		/**
 		 * We've at at least one emission, we've called the write function, the write
@@ -102,42 +109,47 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		@Nullable
 		private Subscriber<? super T> writeSubscriber;
 
-		public WriteWithBarrier(Subscriber<? super Void> subscriber) {
-			super(subscriber);
+		WriteWithBarrier(CoreSubscriber<? super Void> subscriber) {
+			this.subscriber = subscriber;
 		}
 
 		@Override
-		protected void doOnSubscribe(Subscription subscription) {
-			super.doOnSubscribe(subscription);
-			super.upstream().request(1);  // bypass doRequest
+		public void cancel() {
+			Subscription s = this.subscription;
+			if (s != null) {
+				this.subscription = null;
+				s.cancel();
+			}
+		}
+
+		@Override
+		public Context currentContext() {
+			return subscriber.currentContext();
 		}
 
 		@Override
-		public void doNext(T item) {
+		public final void onComplete() {
 			if (this.readyToWrite) {
-				obtainWriteSubscriber().onNext(item);
+				obtainWriteSubscriber().onComplete();
 				return;
 			}
 			synchronized (this) {
 				if (this.readyToWrite) {
-					obtainWriteSubscriber().onNext(item);
+					obtainWriteSubscriber().onComplete();
 				}
 				else if (this.beforeFirstEmission) {
-					this.item = item;
+					this.completed = true;
 					this.beforeFirstEmission = false;
-					writeFunction.apply(this).subscribe(new DownstreamBridge(downstream()));
+					writeFunction.apply(this).subscribe(new DownstreamBridge(subscriber));
 				}
 				else {
-					if (this.subscription != null) {
-						this.subscription.cancel();
-					}
-					downstream().onError(new IllegalStateException("Unexpected item."));
+					this.completed = true;
 				}
 			}
 		}
 
 		@Override
-		public void doError(Throwable ex) {
+		public final void onError(Throwable ex) {
 			if (this.readyToWrite) {
 				obtainWriteSubscriber().onError(ex);
 				return;
@@ -148,7 +160,7 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 				}
 				else if (this.beforeFirstEmission) {
 					this.beforeFirstEmission = false;
-					downstream().onError(ex);
+					subscriber.onError(ex);
 				}
 				else {
 					this.error = ex;
@@ -157,26 +169,39 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		}
 
 		@Override
-		public void doComplete() {
+		public final void onNext(T item) {
 			if (this.readyToWrite) {
-				obtainWriteSubscriber().onComplete();
+				obtainWriteSubscriber().onNext(item);
 				return;
 			}
+			//FIXME revisit in case of reentrant sync deadlock
 			synchronized (this) {
 				if (this.readyToWrite) {
-					obtainWriteSubscriber().onComplete();
+					obtainWriteSubscriber().onNext(item);
 				}
 				else if (this.beforeFirstEmission) {
-					this.completed = true;
+					this.item = item;
 					this.beforeFirstEmission = false;
-					writeFunction.apply(this).subscribe(new DownstreamBridge(downstream()));
+					writeFunction.apply(this).subscribe(new DownstreamBridge(subscriber));
 				}
 				else {
-					this.completed = true;
+					if (this.subscription != null) {
+						this.subscription.cancel();
+					}
+					subscriber.onError(new IllegalStateException("Unexpected item."));
 				}
 			}
 		}
 
+		@Override
+		public final void onSubscribe(Subscription s) {
+			if (Operators.validate(this.subscription, s)) {
+				this.subscription = s;
+				this.subscriber.onSubscribe(this);
+				s.request(1);  // bypass doRequest
+			}
+		}
+
 		@Override
 		public void subscribe(Subscriber<? super T> writeSubscriber) {
 			synchronized (this) {
@@ -212,9 +237,13 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		}
 
 		@Override
-		protected void doRequest(long n) {
+		public void request(long n) {
+			Subscription s = this.subscription;
+			if (s == null) {
+				return;
+			}
 			if (readyToWrite) {
-				super.doRequest(n);
+				s.request(n);
 				return;
 			}
 			synchronized (this) {
@@ -227,9 +256,9 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 					if (n == 0) {
 						return;
 					}
-					super.doRequest(n);
 				}
 			}
+			s.request(n);
 		}
 
 		private Subscriber<? super T> obtainWriteSubscriber() {
@@ -239,139 +268,11 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 	}
 
 
-	// TODO Remove this copy of Reactor 3.0.x Operators.SubscriberAdapter
-	private static class SubscriberAdapter<I, O> implements Subscriber<I>, Subscription {
-
-		protected final Subscriber<? super O> subscriber;
-
-		@Nullable
-		protected Subscription subscription;
-
-		public SubscriberAdapter(Subscriber<? super O> subscriber) {
-			this.subscriber = subscriber;
-		}
+	private class DownstreamBridge implements CoreSubscriber<Void> {
 
-		public Subscriber<? super O> downstream() {
-			return this.subscriber;
-		}
+		private final CoreSubscriber<? super Void> downstream;
 
-		@Override
-		public final void cancel() {
-			try {
-				doCancel();
-			}
-			catch (Throwable throwable) {
-				doOnSubscriberError(Operators.onOperatorError(this.subscription, throwable));
-			}
-		}
-
-		@Override
-		public final void onComplete() {
-			try {
-				doComplete();
-			}
-			catch (Throwable throwable) {
-				doOnSubscriberError(Operators.onOperatorError(throwable));
-			}
-		}
-
-		@Override
-		public final void onError(Throwable t) {
-			doError(t);
-		}
-
-		@Override
-		public final void onNext(I i) {
-			try {
-				doNext(i);
-			}
-			catch (Throwable throwable) {
-				doOnSubscriberError(Operators.onOperatorError(this.subscription, throwable, i));
-			}
-		}
-
-		@Override
-		public final void onSubscribe(Subscription s) {
-			if (Operators.validate(this.subscription, s)) {
-				try {
-					this.subscription = s;
-					doOnSubscribe(s);
-				}
-				catch (Throwable throwable) {
-					doOnSubscriberError(Operators.onOperatorError(s, throwable));
-				}
-			}
-		}
-
-		@Override
-		public final void request(long n) {
-			try {
-				Operators.checkRequest(n);
-				doRequest(n);
-			}
-			catch (Throwable throwable) {
-				doCancel();
-				doOnSubscriberError(Operators.onOperatorError(throwable));
-			}
-		}
-
-		@Override
-		public String toString() {
-			return getClass().getSimpleName();
-		}
-
-		/**
-		 * Hook for further processing of onSubscribe's Subscription.
-		 * @param subscription the subscription to optionally process
-		 */
-		protected void doOnSubscribe(Subscription subscription) {
-			this.subscriber.onSubscribe(this);
-		}
-
-		public Subscription upstream() {
-			Assert.state(this.subscription != null, "No subscription");
-			return this.subscription;
-		}
-
-		@SuppressWarnings("unchecked")
-		protected void doNext(I i) {
-			this.subscriber.onNext((O) i);
-		}
-
-		protected void doError(Throwable throwable) {
-			this.subscriber.onError(throwable);
-		}
-
-		protected void doOnSubscriberError(Throwable throwable){
-			this.subscriber.onError(throwable);
-		}
-
-		protected void doComplete() {
-			this.subscriber.onComplete();
-		}
-
-		protected void doRequest(long n) {
-			Subscription s = this.subscription;
-			if (s != null) {
-				s.request(n);
-			}
-		}
-
-		protected void doCancel() {
-			Subscription s = this.subscription;
-			if (s != null) {
-				this.subscription = null;
-				s.cancel();
-			}
-		}
-	}
-
-
-	private class DownstreamBridge implements Subscriber<Void> {
-
-		private final Subscriber<? super Void> downstream;
-
-		public DownstreamBridge(Subscriber<? super Void> downstream) {
+		public DownstreamBridge(CoreSubscriber<? super Void> downstream) {
 			this.downstream = downstream;
 		}
 
@@ -393,6 +294,11 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		public void onComplete() {
 			this.downstream.onComplete();
 		}
+
+		@Override
+		public Context currentContext() {
+			return downstream.currentContext();
+		}
 	}
 
 }