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Merge pull request #1728 from benjchristensen/observeOnErrorPropagation
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ObserveOn Error Propagation
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@benjchristensen
benjchristensen committed Oct 6, 2014
2 parents 0d74d98 + 50b2d8d commit 80f7f30
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Showing 2 changed files with 103 additions and 39 deletions.
72 changes: 34 additions & 38 deletions src/main/java/rx/internal/operators/OperatorObserveOn.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,6 @@
import rx.exceptions.MissingBackpressureException;
import rx.functions.Action0;
import rx.internal.util.RxRingBuffer;
import rx.internal.util.SynchronizedSubscription;
import rx.schedulers.ImmediateScheduler;
import rx.schedulers.TrampolineScheduler;

Expand Down Expand Up @@ -97,12 +96,10 @@ public void request(long n) {
}

});
add(scheduledUnsubscribe);
child.add(recursiveScheduler);
child.add(this);

}

@Override
public void onStart() {
// signal that this is an async operator capable of receiving this many
Expand Down Expand Up @@ -160,53 +157,52 @@ public void call() {
}
}

// only execute this from schedule()
private void pollQueue() {
int emitted = 0;
while (true) {
do {
/*
* Set to 1 otherwise it could have grown very large while in the last poll loop
* and then we can end up looping all those times again here before exiting even once we've drained
*/
COUNTER_UPDATER.set(this, 1);

while (!scheduledUnsubscribe.isUnsubscribed()) {
if (REQUESTED.getAndDecrement(this) != 0) {
if (failure) {
// special handling to short-circuit an error propagation
Object o = queue.poll();
if (o == null) {
// nothing in queue
REQUESTED.incrementAndGet(this);
break;
} else {
if (failure) {
// completed so we will skip onNext if they exist and only emit terminal events
if (on.isError(o)) {
System.out.println("Error: " + o);
// only emit error
on.accept(child, o);
}
// completed so we will skip onNext if they exist and only emit terminal events
if (on.isError(o)) {
// only emit error
on.accept(child, o);
// we have emitted a terminal event so return (exit the loop we're in)
return;
}
} else {
if (REQUESTED.getAndDecrement(this) != 0) {
Object o = queue.poll();
if (o == null) {
// nothing in queue
REQUESTED.incrementAndGet(this);
break;
} else {
if (!on.accept(child, o)) {
// non-terminal event so let's increment count
emitted++;
}
}
} else {
// we hit the end ... so increment back to 0 again
REQUESTED.incrementAndGet(this);
break;
}
} else {
// we hit the end ... so increment back to 0 again
REQUESTED.incrementAndGet(this);
break;
}
}
long c = COUNTER_UPDATER.decrementAndGet(this);
if (c <= 0) {
// request the number of items that we emitted in this poll loop
if (emitted > 0) {
request(emitted);
}
break;
} else {
/*
* Set down to 1 and then iterate again.
* we lower it to 1 otherwise it could have grown very large while in the last poll loop
* and then we can end up looping all those times again here before existing even once we've drained
*/
COUNTER_UPDATER.set(this, 1);
// we now loop again, and if anything tries scheduling again after this it will increment and cause us to loop again after
}
} while (COUNTER_UPDATER.decrementAndGet(this) > 0);

// request the number of items that we emitted in this poll loop
if (emitted > 0) {
request(emitted);
}
}
}
Expand Down
70 changes: 69 additions & 1 deletion src/test/java/rx/internal/operators/OperatorObserveOnTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -34,9 +34,11 @@
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;

import org.junit.Ignore;
import org.junit.Test;
import org.mockito.InOrder;

import rx.Notification;
import rx.Observable;
import rx.Observable.OnSubscribe;
import rx.Observer;
Expand All @@ -48,6 +50,7 @@
import rx.functions.Action0;
import rx.functions.Action1;
import rx.functions.Func1;
import rx.functions.Func2;
import rx.internal.util.RxRingBuffer;
import rx.observers.TestSubscriber;
import rx.schedulers.Schedulers;
Expand Down Expand Up @@ -391,7 +394,7 @@ public void testDelayedErrorDeliveryWhenSafeSubscriberUnsubscribes() {
inOrder.verify(o, never()).onNext(anyInt());
inOrder.verify(o, never()).onCompleted();
}

@Test
public void testAfterUnsubscribeCalledThenObserverOnNextNeverCalled() {
final TestScheduler testScheduler = new TestScheduler();
Expand Down Expand Up @@ -647,6 +650,71 @@ public void onNext(Long t) {
assertTrue(ts.getOnNextEvents().size() == ts.getOnNextEvents().get(ts.getOnNextEvents().size() - 1) + 1);
// we should emit the error without emitting the full buffer size
assertTrue(ts.getOnNextEvents().size() < RxRingBuffer.SIZE);
}

/**
* Make sure we get a MissingBackpressureException propagated through when we have a fast temporal (hot) producer.
*/
@Test
public void testHotOperatorBackpressure() {
TestSubscriber<String> ts = new TestSubscriber<String>();
Observable.timer(0, 1, TimeUnit.MICROSECONDS)
.observeOn(Schedulers.computation())
.map(new Func1<Long, String>() {

@Override
public String call(Long t1) {
System.out.println(t1);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
return t1 + " slow value";
}

}).subscribe(ts);

ts.awaitTerminalEvent();
System.out.println("Errors: " + ts.getOnErrorEvents());
assertEquals(1, ts.getOnErrorEvents().size());
assertEquals(MissingBackpressureException.class, ts.getOnErrorEvents().get(0).getClass());
}

@Test
public void testErrorPropagatesWhenNoOutstandingRequests() {
Observable<Long> timer = Observable.timer(0, 1, TimeUnit.MICROSECONDS)
.doOnEach(new Action1<Notification<? super Long>>() {

@Override
public void call(Notification<? super Long> n) {
// System.out.println("BEFORE " + n);
}

})
.observeOn(Schedulers.newThread())
.doOnEach(new Action1<Notification<? super Long>>() {

@Override
public void call(Notification<? super Long> n) {
// System.out.println("AFTER " + n);
}

});

TestSubscriber<Long> ts = new TestSubscriber<Long>();

Observable.combineLatest(timer, Observable.<Integer> never(), new Func2<Long, Integer, Long>() {

@Override
public Long call(Long t1, Integer t2) {
return t1;
}

}).take(RxRingBuffer.SIZE * 2).subscribe(ts);

ts.awaitTerminalEvent();
assertEquals(1, ts.getOnErrorEvents().size());
assertEquals(MissingBackpressureException.class, ts.getOnErrorEvents().get(0).getClass());
}

}

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