/**
* 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.
TimeUnit;
import java.util.concurrent.atomic.
AtomicReference;
import rx.*;
import rx.
Observable.
Operator;
import rx.
Scheduler.
Worker;
import rx.exceptions.
Exceptions;
import rx.functions.
Action0;
import rx.observers.
SerializedSubscriber;
/**
* Returns an Observable that emits the results of sampling the items emitted by the source
* Observable at a specified time interval.
* <p>
* <img width="640" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/sample.png" alt="">
*
* @param <T> the value type
*/
public final class
OperatorSampleWithTime<T> implements
Operator<T, T> {
final long
time;
final
TimeUnit unit;
final
Scheduler scheduler;
public
OperatorSampleWithTime(long
time,
TimeUnit unit,
Scheduler scheduler) {
this.
time =
time;
this.
unit =
unit;
this.
scheduler =
scheduler;
}
@
Override
public
Subscriber<? super T>
call(
Subscriber<? super T>
child) {
final
SerializedSubscriber<T>
s = new
SerializedSubscriber<T>(
child);
final
Worker worker =
scheduler.
createWorker();
child.
add(
worker);
SamplerSubscriber<T>
sampler = new
SamplerSubscriber<T>(
s);
child.
add(
sampler);
worker.
schedulePeriodically(
sampler,
time,
time,
unit);
return
sampler;
}
/**
* The source subscriber and sampler.
*/
static final class
SamplerSubscriber<T> extends
Subscriber<T> implements
Action0 {
private final
Subscriber<? super T>
subscriber;
/** Indicates that no value is available. */
private static final
Object EMPTY_TOKEN = new
Object();
/** The shared value between the observer and the timed action. */
final
AtomicReference<
Object>
value = new
AtomicReference<
Object>(
EMPTY_TOKEN);
public
SamplerSubscriber(
Subscriber<? super T>
subscriber) {
this.
subscriber =
subscriber;
}
@
Override
public void
onStart() {
request(
Long.
MAX_VALUE);
}
@
Override
public void
onNext(T
t) {
value.
set(
t);
}
@
Override
public void
onError(
Throwable e) {
subscriber.
onError(
e);
unsubscribe();
}
@
Override
public void
onCompleted() {
emitIfNonEmpty();
subscriber.
onCompleted();
unsubscribe();
}
@
Override
public void
call() {
emitIfNonEmpty();
}
private void
emitIfNonEmpty() {
Object localValue =
value.
getAndSet(
EMPTY_TOKEN);
if (
localValue !=
EMPTY_TOKEN) {
try {
@
SuppressWarnings("unchecked")
T
v = (T)
localValue;
subscriber.
onNext(
v);
} catch (
Throwable e) {
Exceptions.
throwOrReport(
e, this);
}
}
}
}
}