/**
* Copyright 2014 Netflix, Inc.
*
* 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 rx.internal.operators;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import rx.Observable;
import rx.Observable.Operator;
import rx.Observer;
import rx.Subscriber;
import rx.functions.Func0;
import rx.observers.SerializedSubscriber;
import rx.observers.Subscribers;
/**
* Creates non-overlapping windows of items where each window is terminated by
* an event from a secondary observable and a new window is started immediately.
*
* @param <T> the value type
* @param <U> the boundary value type
*/
public final class OperatorWindowWithObservable<T, U> implements Operator<Observable<T>, T> {
final Func0<? extends Observable<? extends U>> otherFactory;
public OperatorWindowWithObservable(Func0<? extends Observable<? extends U>> otherFactory) {
this.otherFactory = otherFactory;
}
public OperatorWindowWithObservable(final Observable<U> other) {
this.otherFactory = new Func0<Observable<U>>() {
@Override
public Observable<U> call() {
return other;
}
};
}
@Override
public Subscriber<? super T> call(Subscriber<? super Observable<T>> child) {
Observable<? extends U> other;
try {
other = otherFactory.call();
} catch (Throwable e) {
child.onError(e);
return Subscribers.empty();
}
SourceSubscriber<T> sub = new SourceSubscriber<T>(child);
BoundarySubscriber<T, U> bs = new BoundarySubscriber<T, U>(child, sub);
sub.replaceWindow();
other.unsafeSubscribe(bs);
return sub;
}
/** Indicate the current subject should complete and a new subject be emitted. */
static final Object NEXT_SUBJECT = new Object();
/** For error and completion indication. */
static final NotificationLite<Object> nl = NotificationLite.instance();
/** Observes the source. */
static final class SourceSubscriber<T> extends Subscriber<T> {
final Subscriber<? super Observable<T>> child;
final Object guard;
/** Accessed from the serialized part. */
Observer<T> consumer;
/** Accessed from the serialized part. */
Observable<T> producer;
/** Guarded by guard. */
boolean emitting;
/** Guarded by guard. */
List<Object> queue;
public SourceSubscriber(Subscriber<? super Observable<T>> child) {
super(child);
this.child = new SerializedSubscriber<Observable<T>>(child);
this.guard = new Object();
}
@Override
public void onStart() {
request(Long.MAX_VALUE);
}
@Override
public void onNext(T t) {
List<Object> localQueue;
synchronized (guard) {
if (emitting) {
if (queue == null) {
queue = new ArrayList<Object>();
}
queue.add(t);
return;
}
localQueue = queue;
queue = null;
emitting = true;
}
boolean once = true;
boolean skipFinal = false;
try {
do {
drain(localQueue);
if (once) {
once = true;
emitValue(t);
}
synchronized (guard) {
localQueue = queue;
queue = null;
if (localQueue == null) {
emitting = false;
skipFinal = true;
return;
}
}
} while (!child.isUnsubscribed());
} finally {
if (!skipFinal) {
synchronized (guard) {
emitting = false;
}
}
}
}
void drain(List<Object> queue) {
if (queue == null) {
return;
}
for (Object o : queue) {
if (o == NEXT_SUBJECT) {
replaceSubject();
} else
if (nl.isError(o)) {
error(nl.getError(o));
break;
} else
if (nl.isCompleted(o)) {
complete();
break;
} else {
@SuppressWarnings("unchecked")
T t = (T)o;
emitValue(t);
}
}
}
void replaceSubject() {
Observer<T> s = consumer;
if (s != null) {
s.onCompleted();
}
createNewWindow();
child.onNext(producer);
}
void createNewWindow() {
BufferUntilSubscriber<T> bus = BufferUntilSubscriber.create();
consumer = bus;
producer = bus;
}
void emitValue(T t) {
Observer<T> s = consumer;
if (s != null) {
s.onNext(t);
}
}
@Override
public void onError(Throwable e) {
synchronized (guard) {
if (emitting) {
queue = Collections.singletonList(nl.error(e));
return;
}
queue = null;
emitting = true;
}
error(e);
}
@Override
public void onCompleted() {
List<Object> localQueue;
synchronized (guard) {
if (emitting) {
if (queue == null) {
queue = new ArrayList<Object>();
}
queue.add(nl.completed());
return;
}
localQueue = queue;
queue = null;
emitting = true;
}
try {
drain(localQueue);
} catch (Throwable e) {
error(e);
return;
}
complete();
}
void replaceWindow() {
List<Object> localQueue;
synchronized (guard) {
if (emitting) {
if (queue == null) {
queue = new ArrayList<Object>();
}
queue.add(NEXT_SUBJECT);
return;
}
localQueue = queue;
queue = null;
emitting = true;
}
boolean once = true;
boolean skipFinal = false;
try {
do {
drain(localQueue);
if (once) {
once = false;
replaceSubject();
}
synchronized (guard) {
localQueue = queue;
queue = null;
if (localQueue == null) {
emitting = false;
skipFinal = true;
return;
}
}
} while (!child.isUnsubscribed());
} finally {
if (!skipFinal) {
synchronized (guard) {
emitting = false;
}
}
}
}
void complete() {
Observer<T> s = consumer;
consumer = null;
producer = null;
if (s != null) {
s.onCompleted();
}
child.onCompleted();
unsubscribe();
}
void error(Throwable e) {
Observer<T> s = consumer;
consumer = null;
producer = null;
if (s != null) {
s.onError(e);
}
child.onError(e);
unsubscribe();
}
}
/** Observes the boundary. */
static final class BoundarySubscriber<T, U> extends Subscriber<U> {
final SourceSubscriber<T> sub;
public BoundarySubscriber(Subscriber<?> child, SourceSubscriber<T> sub) {
super(child);
this.sub = sub;
}
@Override
public void onStart() {
request(Long.MAX_VALUE);
}
@Override
public void onNext(U t) {
sub.replaceWindow();
}
@Override
public void onError(Throwable e) {
sub.onError(e);
}
@Override
public void onCompleted() {
sub.onCompleted();
}
}
}