/**
* 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.concurrent.atomic.AtomicReference;
import rx.Observable;
import rx.Observable.Operator;
import rx.Subscriber;
import rx.observers.SerializedSubscriber;
/**
* Sample with the help of another observable.
*
* @see <a href='http://msdn.microsoft.com/en-us/library/hh229742.aspx'>MSDN: Observable.Sample</a>
*
* @param <T> the source and result value type
* @param <U> the element type of the sampler Observable
*/
public final class OperatorSampleWithObservable<T, U> implements Operator<T, T> {
final Observable<U> sampler;
/** Indicates that no value is available. */
static final Object EMPTY_TOKEN = new Object();
public OperatorSampleWithObservable(Observable<U> sampler) {
this.sampler = sampler;
}
@Override
public Subscriber<? super T> call(Subscriber<? super T> child) {
final SerializedSubscriber<T> s = new SerializedSubscriber<T>(child);
final AtomicReference<Object> value = new AtomicReference<Object>(EMPTY_TOKEN);
Subscriber<U> samplerSub = new Subscriber<U>(child) {
@Override
public void onNext(U t) {
Object localValue = value.getAndSet(EMPTY_TOKEN);
if (localValue != EMPTY_TOKEN) {
@SuppressWarnings("unchecked")
T v = (T)localValue;
s.onNext(v);
}
}
@Override
public void onError(Throwable e) {
s.onError(e);
unsubscribe();
}
@Override
public void onCompleted() {
s.onCompleted();
unsubscribe();
}
};
Subscriber<T> result = new Subscriber<T>(child) {
@Override
public void onNext(T t) {
value.set(t);
}
@Override
public void onError(Throwable e) {
s.onError(e);
unsubscribe();
}
@Override
public void onCompleted() {
s.onCompleted();
unsubscribe();
}
};
sampler.unsafeSubscribe(samplerSub);
return result;
}
}