reactor.rx.broadcast.BehaviorBroadcaster Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2015 Pivotal Software Inc, All Rights Reserved.
*
* Licensed 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 reactor.rx.broadcast;
import org.reactivestreams.Subscriber;
import reactor.Environment;
import reactor.core.Dispatcher;
import reactor.core.dispatch.SynchronousDispatcher;
import reactor.core.processor.CancelException;
import reactor.core.queue.CompletableQueue;
import reactor.core.support.Assert;
import reactor.rx.action.Action;
import reactor.rx.action.Signal;
import reactor.rx.subscription.PushSubscription;
import reactor.rx.subscription.ReactiveSubscription;
/**
* A {@code Broadcaster} is a subclass of {@code Stream} which exposes methods for publishing values into the pipeline.
* It is possible to publish discreet values typed to the generic type of the {@code Stream} as well as error conditions
* and the Reactive Streams "complete" signal via the {@link #onComplete()} method.
*
* @author Stephane Maldini
*/
public final class BehaviorBroadcaster extends Broadcaster {
/**
* Build a {@literal Broadcaster}, rfirst broadcasting the most recent signal then starting with the passed value,
* then ready to broadcast values with {@link reactor.rx.action
* .Broadcaster#onNext(Object)},
* {@link reactor.rx.broadcast.Broadcaster#onError(Throwable)}, {@link reactor.rx.broadcast.Broadcaster#onComplete
* ()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* A serialized broadcaster will make sure that even in a multhithreaded scenario, only one thread will be able to
* broadcast at a time.
* The synchronization is non blocking for the publisher, using thread-stealing and first-in-first-served patterns.
*
* @param the type of values passing through the {@literal action}
* @return a new {@link reactor.rx.action.Action}
*/
public static Broadcaster first(T value) {
return new BehaviorBroadcaster<>(null, SynchronousDispatcher.INSTANCE, Long.MAX_VALUE, value);
}
/**
* Build a {@literal Broadcaster}, first broadcasting the most recent signal then starting with the passed value,
* then ready to broadcast values with {@link
* reactor.rx.broadcast.Broadcaster#onNext(Object)},
* {@link reactor.rx.broadcast.Broadcaster#onError(Throwable)}, {@link reactor.rx.broadcast.Broadcaster#onComplete
* ()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* A serialized broadcaster will make sure that even in a multhithreaded scenario, only one thread will be able to
* broadcast at a time.
* The synchronization is non blocking for the publisher, using thread-stealing and first-in-first-served patterns.
*
* @param env the Reactor {@link reactor.Environment} to use
* @param the type of values passing through the {@literal Broadcaster}
* @return a new {@link reactor.rx.broadcast.Broadcaster}
*/
public static Broadcaster first(T value, Environment env) {
return first(value, env, env.getDefaultDispatcher());
}
/**
* Build a {@literal Broadcaster}, first broadcasting the most recent signal then starting with the passed value,
* then ready to broadcast values with {@link
* reactor.rx.action.Action#onNext(Object)},
* {@link Broadcaster#onError(Throwable)}, {@link Broadcaster#onComplete()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* @param dispatcher the {@link reactor.core.Dispatcher} to use
* @param the type of values passing through the {@literal Broadcaster}
* @return a new {@link Broadcaster}
*/
public static Broadcaster first(T value, Dispatcher dispatcher) {
return first(value, null, dispatcher);
}
/**
* Build a {@literal Broadcaster}, first broadcasting the most recent signal then starting with the passed value,
* then ready to broadcast values with {@link Broadcaster#onNext
* (Object)},
* {@link Broadcaster#onError(Throwable)}, {@link Broadcaster#onComplete()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* @param env the Reactor {@link reactor.Environment} to use
* @param dispatcher the {@link reactor.core.Dispatcher} to use
* @param the type of values passing through the {@literal Stream}
* @return a new {@link Broadcaster}
*/
public static Broadcaster first(T value, Environment env, Dispatcher dispatcher) {
Assert.state(dispatcher.supportsOrdering(), "Dispatcher provided doesn't support event ordering. " +
" For concurrent consume, refer to Stream#partition/groupBy() method and assign individual single " +
"dispatchers");
return new BehaviorBroadcaster<>(env, dispatcher, Action.evaluateCapacity(dispatcher.backlogSize()), value);
}
/**
* Build a {@literal Broadcaster}, first broadcasting the most recent signal then ready to broadcast values with
* {@link
* reactor.rx.broadcast.Broadcaster#onNext(Object)},
* {@link reactor.rx.broadcast.Broadcaster#onError(Throwable)}, {@link reactor.rx.broadcast.Broadcaster#onComplete
* ()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* A serialized broadcaster will make sure that even in a multhithreaded scenario, only one thread will be able to
* broadcast at a time.
* The synchronization is non blocking for the publisher, using thread-stealing and first-in-first-served patterns.
*
* @param env the Reactor {@link reactor.Environment} to use
* @param the type of values passing through the {@literal Broadcaster}
* @return a new {@link reactor.rx.broadcast.Broadcaster}
*/
public static Broadcaster create(Environment env) {
return first(null, env);
}
/**
* Build a {@literal Broadcaster}, first broadcasting the most recent signal then ready to broadcast values with
* {@link
* reactor.rx.action.Action#onNext(Object)},
* {@link Broadcaster#onError(Throwable)}, {@link Broadcaster#onComplete()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* @param dispatcher the {@link reactor.core.Dispatcher} to use
* @param the type of values passing through the {@literal Broadcaster}
* @return a new {@link Broadcaster}
*/
public static Broadcaster create(Dispatcher dispatcher) {
return first(null, dispatcher);
}
/**
* Build a {@literal Broadcaster}, first broadcasting the most recent signal then
* ready to broadcast values with {@link Broadcaster#onNext
* (Object)},
* {@link Broadcaster#onError(Throwable)}, {@link Broadcaster#onComplete()}.
* Values broadcasted are directly consumable by subscribing to the returned instance.
*
* @param env the Reactor {@link reactor.Environment} to use
* @param dispatcher the {@link reactor.core.Dispatcher} to use
* @param the type of values passing through the {@literal Stream}
* @return a new {@link Broadcaster}
*/
public static Broadcaster create(Environment env, Dispatcher dispatcher) {
return first(null, env, dispatcher);
}
/**
* INTERNAL
*/
private final BufferedSignal lastSignal = new BufferedSignal(null);
private BehaviorBroadcaster(Environment environment, Dispatcher dispatcher, long capacity, O defaultVal) {
super(environment, dispatcher, capacity);
if (defaultVal != null) {
lastSignal.type = Signal.Type.NEXT;
lastSignal.value = defaultVal;
}
}
private final static class BufferedSignal {
O value;
Throwable error;
Signal.Type type;
public BufferedSignal(Signal.Type type) {
this.type = type;
}
}
@Override
public void onNext(O ev) {
if (!dispatcher.inContext()) {
dispatcher.dispatch(ev, this, null);
} else {
synchronized (this) {
if (lastSignal.type == Signal.Type.COMPLETE ||
lastSignal.type == Signal.Type.ERROR)
return;
lastSignal.value = ev;
lastSignal.error = null;
lastSignal.type = Signal.Type.NEXT;
try {
broadcastNext(ev);
} catch (CancelException ce) {
//IGNORE since cached
}
}
}
}
@Override
protected void doComplete() {
synchronized (this) {
if (lastSignal.type == Signal.Type.COMPLETE ||
lastSignal.type == Signal.Type.ERROR)
return;
lastSignal.error = null;
lastSignal.type = Signal.Type.COMPLETE;
}
super.doComplete();
}
@Override
protected void doError(Throwable ev) {
synchronized (this) {
if (lastSignal.type == Signal.Type.COMPLETE ||
lastSignal.type == Signal.Type.ERROR)
return;
lastSignal.value = null;
lastSignal.error = ev;
lastSignal.type = Signal.Type.ERROR;
}
super.doError(ev);
}
@Override
protected PushSubscription createSubscription(final Subscriber subscriber, CompletableQueue queue) {
final BufferedSignal withDefault;
synchronized (this) {
if (lastSignal.type != null) {
withDefault = new BufferedSignal<>(lastSignal.type);
withDefault.error = lastSignal.error;
withDefault.value = lastSignal.value;
withDefault.type = lastSignal.type;
} else {
withDefault = null;
}
}
if (withDefault != null) {
if (withDefault.type == Signal.Type.COMPLETE) {
return new PushSubscription(this, subscriber) {
@Override
public void request(long n) {
//Promise behavior, emit last value before completing
if (n > 0 && capacity == 1l && withDefault.value != null) {
capacity = 0l;
subscriber.onNext(withDefault.value);
}
onComplete();
}
};
} else if (withDefault.type == Signal.Type.ERROR) {
return new PushSubscription(this, subscriber) {
@Override
public void request(long n) {
onError(withDefault.error);
}
};
} else {
if (queue != null) {
queue.add(withDefault.value);
return new ReactiveSubscription(this, subscriber, queue) {
@Override
protected void onRequest(long elements) {
if (upstreamSubscription != null) {
super.onRequest(elements);
requestUpstream(capacity, buffer.isComplete(), elements);
}
}
};
} else {
return new PushSubscription(this, subscriber) {
boolean started = false;
@Override
public void request(long n) {
if (!started && n > 0) {
started = true;
subscriber.onNext(withDefault.value);
if (n - 1 > 0) {
super.request(n - 1);
}
} else {
super.request(n);
}
}
@Override
protected void onRequest(long elements) {
if (upstreamSubscription == null) {
updatePendingRequests(elements);
} else {
requestUpstream(NO_CAPACITY, isComplete(), elements);
}
}
};
}
}
} else {
return super.createSubscription(subscriber, queue);
}
}
}