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Fix issue #1522 #1523

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merged 3 commits into from
Jul 29, 2014
Merged

Fix issue #1522 #1523

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212af0a
Fix issue #1522
zsxwing Jul 26, 2014
a2a7a29
Optimize the fix for takeLast and handle the race condition
zsxwing Jul 29, 2014
c1ec1f4
Make "single" support backpressure
zsxwing Jul 29, 2014
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3 changes: 3 additions & 0 deletions rxjava-core/src/main/java/rx/internal/operators/OperatorSingle.java
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,9 @@ public void onNext(T value) {
} else {
this.value = value;
isNonEmpty = true;
// Issue: https://github.com/Netflix/RxJava/pull/1527
// Because we cache a value and don't emit now, we need to request another one.
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Good catch.

request(1);
}
}

Expand Down
47 changes: 32 additions & 15 deletions rxjava-core/src/main/java/rx/internal/operators/OperatorTakeLast.java
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Expand Up @@ -108,9 +108,12 @@ void startEmitting() {

@Override
public void request(long n) {
long _c = 0;
if (requested == Long.MAX_VALUE) {
return;
}
long _c;
if (n == Long.MAX_VALUE) {
requested = Long.MAX_VALUE;
_c = REQUESTED_UPDATER.getAndSet(this, Long.MAX_VALUE);
} else {
_c = REQUESTED_UPDATER.getAndAdd(this, n);
}
Expand All @@ -122,16 +125,20 @@ public void request(long n) {
}

void emit(long previousRequested) {
if (requested < 0) {
if (requested == Long.MAX_VALUE) {
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Ha! That's a fun bug, totally missed that when we went from -1 to MAX_VALUE.

I bet it isn't even worth having the complexity of a fast-path because the cost of queue/deque is far worse than the counter, and we only hit the counter at the very end anyways.

// fast-path without backpressure
try {
for (Object value : deque) {
notification.accept(subscriber, value);
if (previousRequested == 0) {
try {
for (Object value : deque) {
notification.accept(subscriber, value);
}
} catch (Throwable e) {
subscriber.onError(e);
} finally {
deque.clear();
}
} catch (Throwable e) {
subscriber.onError(e);
} finally {
deque.clear();
} else {
// backpressure path will handle Long.MAX_VALUE and emit the rest events.
}
} else {
// backpressure is requested
Expand All @@ -155,12 +162,22 @@ void emit(long previousRequested) {
emitted++;
}
}

if (REQUESTED_UPDATER.addAndGet(this, -emitted) == 0) {
// we're done emitting the number requested so return
return;
for (;;) {
long oldRequested = requested;
long newRequested = oldRequested - emitted;
if (oldRequested == Long.MAX_VALUE) {
// became unbounded during the loop
// continue the outer loop to emit the rest events.
break;
}
if (REQUESTED_UPDATER.compareAndSet(this, oldRequested, newRequested)) {
if (newRequested == 0) {
// we're done emitting the number requested so return
return;
}
break;
}
}

}
}
}
Expand Down
55 changes: 52 additions & 3 deletions rxjava-core/src/test/java/rx/internal/operators/OperatorSingleTest.java
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Expand Up @@ -15,10 +15,9 @@
*/
package rx.internal.operators;

import static org.junit.Assert.assertEquals;
import static org.mockito.Matchers.isA;
import static org.mockito.Mockito.inOrder;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.*;

import java.util.NoSuchElementException;

Expand All @@ -27,7 +26,9 @@

import rx.Observable;
import rx.Observer;
import rx.Subscriber;
import rx.functions.Func1;
import rx.functions.Func2;

public class OperatorSingleTest {

Expand Down Expand Up @@ -241,4 +242,52 @@ public Boolean call(Integer t1) {
inOrder.verify(observer, times(1)).onCompleted();
inOrder.verifyNoMoreInteractions();
}

@Test
public void testSingleWithBackpressure() {
Observable<Integer> observable = Observable.from(1, 2).single();

Subscriber<Integer> subscriber = spy(new Subscriber<Integer>() {

@Override
public void onStart() {
request(1);
}

@Override
public void onCompleted() {

}

@Override
public void onError(Throwable e) {

}

@Override
public void onNext(Integer integer) {
request(1);
}
});
observable.subscribe(subscriber);

InOrder inOrder = inOrder(subscriber);
inOrder.verify(subscriber, times(1)).onError(isA(IllegalArgumentException.class));
inOrder.verifyNoMoreInteractions();
}

@Test(timeout = 30000)
public void testIssue1527() throws InterruptedException {
//https://github.com/Netflix/RxJava/pull/1527
Observable<Integer> source = Observable.from(1, 2, 3, 4, 5, 6);
Observable<Integer> reduced = source.reduce(new Func2<Integer, Integer, Integer>() {
@Override
public Integer call(Integer i1, Integer i2) {
return i1 + i2;
}
});

Integer r = reduced.toBlocking().first();
assertEquals(21, r.intValue());
}
}
116 changes: 116 additions & 0 deletions rxjava-core/src/test/java/rx/internal/operators/OperatorTakeLastTest.java
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Expand Up @@ -30,7 +30,9 @@

import rx.Observable;
import rx.Observer;
import rx.Subscriber;
import rx.functions.Func1;
import rx.functions.Functions;
import rx.internal.util.RxRingBuffer;
import rx.observers.TestSubscriber;
import rx.schedulers.Schedulers;
Expand Down Expand Up @@ -148,4 +150,118 @@ public Integer call(Integer i) {
};
}

@Test
public void testIssue1522() {
// https://github.com/Netflix/RxJava/issues/1522
assertEquals(0, Observable
.empty()
.count()
.filter(Functions.alwaysFalse())
.toList()
.toBlocking().single().size());
}

@Test
public void testIgnoreRequest1() {
// If `takeLast` does not ignore `request` properly, StackOverflowError will be thrown.
Observable.range(0, 100000).takeLast(100000).subscribe(new Subscriber<Integer>() {

@Override
public void onStart() {
request(Long.MAX_VALUE);
}

@Override
public void onCompleted() {

}

@Override
public void onError(Throwable e) {
}

@Override
public void onNext(Integer integer) {
request(Long.MAX_VALUE);
}
});
}

@Test
public void testIgnoreRequest2() {
// If `takeLast` does not ignore `request` properly, StackOverflowError will be thrown.
Observable.range(0, 100000).takeLast(100000).subscribe(new Subscriber<Integer>() {

@Override
public void onStart() {
request(1);
}

@Override
public void onCompleted() {
}

@Override
public void onError(Throwable e) {
}

@Override
public void onNext(Integer integer) {
request(1);
}
});
}

@Test(timeout = 30000)
public void testIgnoreRequest3() {
// If `takeLast` does not ignore `request` properly, it will enter an infinite loop.
Observable.range(0, 100000).takeLast(100000).subscribe(new Subscriber<Integer>() {

@Override
public void onStart() {
request(1);
}

@Override
public void onCompleted() {

}

@Override
public void onError(Throwable e) {
}

@Override
public void onNext(Integer integer) {
request(Long.MAX_VALUE);
}
});
}


@Test
public void testIgnoreRequest4() {
// If `takeLast` does not ignore `request` properly, StackOverflowError will be thrown.
Observable.range(0, 100000).takeLast(100000).subscribe(new Subscriber<Integer>() {

@Override
public void onStart() {
request(Long.MAX_VALUE);
}

@Override
public void onCompleted() {

}

@Override
public void onError(Throwable e) {
}

@Override
public void onNext(Integer integer) {
request(1);
}
});
}
}