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Fixed deadlock in Subjects + OperatorCache. #972

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merged 1 commit into from
Apr 16, 2014
Merged

Fixed deadlock in Subjects + OperatorCache. #972

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4 changes: 2 additions & 2 deletions rxjava-core/src/main/java/rx/Observable.java
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,6 @@
import rx.operators.OperationAsObservable;
import rx.operators.OperationAverage;
import rx.operators.OperationBuffer;
import rx.operators.OperationCache;
import rx.operators.OperationCombineLatest;
import rx.operators.OperationConcat;
import rx.operators.OperationDebounce;
Expand Down Expand Up @@ -105,6 +104,7 @@
import rx.operators.OperationUsing;
import rx.operators.OperationWindow;
import rx.operators.OperatorAmb;
import rx.operators.OperatorCache;
import rx.operators.OperatorCast;
import rx.operators.OperatorDoOnEach;
import rx.operators.OperatorFilter;
Expand Down Expand Up @@ -3863,7 +3863,7 @@ public final <B> Observable<List<T>> buffer(Observable<B> boundary, int initialC
* @see <a href="https://github.com/Netflix/RxJava/wiki/Observable-Utility-Operators#wiki-cache">RxJava Wiki: cache()</a>
*/
public final Observable<T> cache() {
return create(OperationCache.cache(this));
return create(new OperatorCache<T>(this));
}

/**
Expand Down
52 changes: 30 additions & 22 deletions ...ain/java/rx/operators/OperationCache.java → ...main/java/rx/operators/OperatorCache.java
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Expand Up @@ -18,10 +18,13 @@
import java.util.concurrent.atomic.AtomicBoolean;

import rx.Observable;
import rx.Observable.OnSubscribe;
import rx.Observable.OnSubscribeFunc;
import rx.Observer;
import rx.Subscriber;
import rx.Subscription;
import rx.subjects.ReplaySubject;
import rx.subjects.Subject;

/**
* This method has similar behavior to {@link Observable#replay()} except that this auto-subscribes
Expand All @@ -35,30 +38,35 @@
* NOTE: You sacrifice the ability to unsubscribe from the origin when you use this operator, so be
* careful not to use this operator on Observables that emit infinite or very large numbers of
* items, as this will use up memory.
*
* @param <T> the cached value type
*/
public class OperationCache {

public static <T> OnSubscribeFunc<T> cache(final Observable<? extends T> source) {
return new OnSubscribeFunc<T>() {

final AtomicBoolean subscribed = new AtomicBoolean(false);
private final ReplaySubject<T> cache = ReplaySubject.create();
public final class OperatorCache<T> implements OnSubscribe<T> {
protected final Observable<? extends T> source;
protected final Subject<? super T, ? extends T> cache;
protected final AtomicBoolean sourceSubscribed;

@Override
public Subscription onSubscribe(Observer<? super T> observer) {
if (subscribed.compareAndSet(false, true)) {
// subscribe to the source once
source.subscribe(cache);
/*
* Note that we will never unsubscribe from 'source' as we want to receive and cache all of its values.
*
* This means this should never be used on an infinite or very large sequence, similar to toList().
*/
}

return cache.subscribe(observer);
}
public OperatorCache(Observable<? extends T> source) {
this(source, ReplaySubject.<T>create());
}

/** Test support. */
public OperatorCache(Observable<? extends T> source, Subject<? super T, ? extends T> cache) {
this.source = source;
this.cache = cache;
this.sourceSubscribed = new AtomicBoolean();
}

};
@Override
public void call(Subscriber<? super T> t1) {
if (sourceSubscribed.compareAndSet(false, true)) {
source.subscribe(cache);
/*
* Note that we will never unsubscribe from 'source' as we want to receive and cache all of its values.
*
* This means this should never be used on an infinite or very large sequence, similar to toList().
*/
}
cache.subscribe(t1);
}
}
23 changes: 14 additions & 9 deletions rxjava-core/src/main/java/rx/subjects/AsyncSubject.java
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Expand Up @@ -105,35 +105,40 @@ protected AsyncSubject(OnSubscribe<T> onSubscribe, SubjectSubscriptionManager<T>

@Override
public void onCompleted() {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
for (Observer<? super T> o : observers) {
emitValueToObserver(lastNotification.get(), o);
}
}
});
if (observers != null) {
for (Observer<? super T> o : observers) {
emitValueToObserver(lastNotification.get(), o);
}
}
}

@Override
public void onError(final Throwable e) {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
lastNotification.set(new Notification<T>(e));
for (Observer<? super T> o : observers) {
emitValueToObserver(lastNotification.get(), o);
}
lastNotification.set(Notification.<T>createOnError(e));
}
});
if (observers != null) {
for (Observer<? super T> o : observers) {
emitValueToObserver(lastNotification.get(), o);
}
}

}

@Override
public void onNext(T v) {
lastNotification.set(new Notification<T>(v));
lastNotification.set(Notification.createOnNext(v));
}

}
25 changes: 15 additions & 10 deletions rxjava-core/src/main/java/rx/subjects/BehaviorSubject.java
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Expand Up @@ -144,39 +144,44 @@ protected BehaviorSubject(OnSubscribe<T> onSubscribe, SubjectSubscriptionManager

@Override
public void onCompleted() {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
lastNotification.set(new Notification<T>());
for (Observer<? super T> o : observers) {
o.onCompleted();
}
lastNotification.set(Notification.<T>createOnCompleted());
}
});
if (observers != null) {
for (Observer<? super T> o : observers) {
o.onCompleted();
}
}
}

@Override
public void onError(final Throwable e) {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
lastNotification.set(new Notification<T>(e));
for (Observer<? super T> o : observers) {
o.onError(e);
}
lastNotification.set(Notification.<T>createOnError(e));
}
});

if (observers != null) {
for (Observer<? super T> o : observers) {
o.onError(e);
}
}
}

@Override
public void onNext(T v) {
// do not overwrite a terminal notification
// so new subscribers can get them
if (lastNotification.get().isOnNext()) {
lastNotification.set(new Notification<T>(v));
lastNotification.set(Notification.createOnNext(v));
for (Observer<? super T> o : subscriptionManager.rawSnapshot()) {
o.onNext(v);
}
Expand Down
20 changes: 12 additions & 8 deletions rxjava-core/src/main/java/rx/subjects/PublishSubject.java
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Expand Up @@ -95,31 +95,35 @@ protected PublishSubject(OnSubscribe<T> onSubscribe, SubjectSubscriptionManager<

@Override
public void onCompleted() {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
lastNotification.set(Notification.<T> createOnCompleted());
for (Observer<? super T> o : observers) {
o.onCompleted();
}
}
});
if (observers != null) {
for (Observer<? super T> o : observers) {
o.onCompleted();
}
}
}

@Override
public void onError(final Throwable e) {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
lastNotification.set(Notification.<T>createOnError(e));
for (Observer<? super T> o : observers) {
o.onError(e);
}
}
});

if (observers != null) {
for (Observer<? super T> o : observers) {
o.onError(e);
}
}
}

@Override
Expand Down
26 changes: 16 additions & 10 deletions rxjava-core/src/main/java/rx/subjects/ReplaySubject.java
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Expand Up @@ -122,34 +122,40 @@ protected ReplaySubject(OnSubscribe<T> onSubscribe, SubjectSubscriptionManager<T

@Override
public void onCompleted() {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
state.history.complete(Notification.<T>createOnCompleted());
for (SubjectObserver<? super T> o : observers) {
if (caughtUp(o)) {
o.onCompleted();
}
}
}
});
if (observers != null) {
for (SubjectObserver<? super T> o : observers) {
if (caughtUp(o)) {
o.onCompleted();
}
}
}
}

@Override
public void onError(final Throwable e) {
Collection<SubjectObserver<? super T>> observers =
subscriptionManager.terminate(new Action1<Collection<SubjectObserver<? super T>>>() {

@Override
public void call(Collection<SubjectObserver<? super T>> observers) {
state.history.complete(Notification.<T>createOnError(e));
for (SubjectObserver<? super T> o : observers) {
if (caughtUp(o)) {
o.onError(e);
}
}
}
});
if (observers != null) {
for (SubjectObserver<? super T> o : observers) {
if (caughtUp(o)) {
o.onError(e);
}
}
}
}

@Override
Expand Down
8 changes: 5 additions & 3 deletions rxjava-core/src/main/java/rx/subjects/SubjectSubscriptionManager.java
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Expand Up @@ -113,19 +113,20 @@ public void call() {
}

@SuppressWarnings({ "unchecked", "rawtypes" })
protected void terminate(Action1<Collection<SubjectObserver<? super T>>> onTerminate) {
protected Collection<SubjectObserver<? super T>> terminate(Action1<Collection<SubjectObserver<? super T>>> onTerminate) {
State<T> current;
State<T> newState = null;
do {
current = state.get();
if (current.terminated) {
// already terminated so do nothing
return;
return null;
} else {
newState = current.terminate();
}
} while (!state.compareAndSet(current, newState));

Collection<SubjectObserver<? super T>> observerCollection = (Collection)Arrays.asList(newState.observers);
/*
* if we get here then we won setting the state to terminated
* and have a deterministic set of Observers to emit to (concurrent subscribes
Expand All @@ -134,11 +135,12 @@ protected void terminate(Action1<Collection<SubjectObserver<? super T>>> onTermi
*/
try {
// had to circumvent type check, we know what the array contains
onTerminate.call((Collection) Arrays.asList(newState.observers));
onTerminate.call(observerCollection);
} finally {
// mark that termination is completed
newState.terminationLatch.countDown();
}
return observerCollection;
}

/**
Expand Down
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