src/main/java/rx/schedulers/Schedulers.java
/**
* 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.schedulers;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicReference;
import rx.Scheduler;
import rx.internal.schedulers.*;
import rx.plugins.*;
/**
* Static factory methods for creating Schedulers.
* <p>
* System configuration properties:
* <table border='1'>
* <tr><td>Property name</td><td>Description</td><td>Default</td></tr>
* <tr>
* <td>{@code rx.io-scheduler.keepalive}</td><td>time (in seconds) to keep an unused backing
* thread-pool</td><td>60</td>
* </tr>
* <tr>
* <td>{@code rx.scheduler.max-computation-threads}</td><td>number of threads the
* computation scheduler uses (between 1 and number of available processors)</td><td>
* number of available processors.</td>
* </tr>
* <tr>
* <td>{@code rx.scheduler.jdk6.purge-frequency-millis}</td><td>time (in milliseconds) between calling
* purge on any active backing thread-pool on a Java 6 runtime</td><td>1000</td>
* </tr>
* <tr>
* <td>{@code rx.scheduler.jdk6.purge-force}</td><td> boolean forcing the call to purge on any active
* backing thread-pool</td><td>false</td>
* </tr>
* </ul>
* </table>
*/
public final class Schedulers {
private final Scheduler computationScheduler;
private final Scheduler ioScheduler;
private final Scheduler newThreadScheduler;
private static final AtomicReference<Schedulers> INSTANCE = new AtomicReference<Schedulers>();
private static Schedulers getInstance() {
for (;;) {
Schedulers current = INSTANCE.get();
if (current != null) {
return current;
}
current = new Schedulers();
if (INSTANCE.compareAndSet(null, current)) {
return current;
} else {
current.shutdownInstance();
}
}
}
private Schedulers() {
@SuppressWarnings("deprecation")
RxJavaSchedulersHook hook = RxJavaPlugins.getInstance().getSchedulersHook();
Scheduler c = hook.getComputationScheduler();
if (c != null) {
computationScheduler = c;
} else {
computationScheduler = RxJavaSchedulersHook.createComputationScheduler();
}
Scheduler io = hook.getIOScheduler();
if (io != null) {
ioScheduler = io;
} else {
ioScheduler = RxJavaSchedulersHook.createIoScheduler();
}
Scheduler nt = hook.getNewThreadScheduler();
if (nt != null) {
newThreadScheduler = nt;
} else {
newThreadScheduler = RxJavaSchedulersHook.createNewThreadScheduler();
}
}
/**
* Creates and returns a {@link Scheduler} that executes work immediately on the current thread.
*
* @return a {@link Scheduler} that executes work immediately
*/
public static Scheduler immediate() {
return rx.internal.schedulers.ImmediateScheduler.INSTANCE;
}
/**
* Creates and returns a {@link Scheduler} that queues work on the current thread to be executed after the
* current work completes.
*
* @return a {@link Scheduler} that queues work on the current thread
*/
public static Scheduler trampoline() {
return rx.internal.schedulers.TrampolineScheduler.INSTANCE;
}
/**
* Creates and returns a {@link Scheduler} that creates a new {@link Thread} for each unit of work.
* <p>
* Unhandled errors will be delivered to the scheduler Thread's {@link java.lang.Thread.UncaughtExceptionHandler}.
*
* @return a {@link Scheduler} that creates new threads
*/
public static Scheduler newThread() {
return RxJavaHooks.onNewThreadScheduler(getInstance().newThreadScheduler);
}
/**
* Creates and returns a {@link Scheduler} intended for computational work.
* <p>
* This can be used for event-loops, processing callbacks and other computational work.
* <p>
* Do not perform IO-bound work on this scheduler. Use {@link #io()} instead.
* <p>
* Unhandled errors will be delivered to the scheduler Thread's {@link java.lang.Thread.UncaughtExceptionHandler}.
*
* @return a {@link Scheduler} meant for computation-bound work
*/
public static Scheduler computation() {
return RxJavaHooks.onComputationScheduler(getInstance().computationScheduler);
}
/**
* Creates and returns a {@link Scheduler} intended for IO-bound work.
* <p>
* The implementation is backed by an {@link Executor} thread-pool that will grow as needed.
* <p>
* This can be used for asynchronously performing blocking IO.
* <p>
* Do not perform computational work on this scheduler. Use {@link #computation()} instead.
* <p>
* Unhandled errors will be delivered to the scheduler Thread's {@link java.lang.Thread.UncaughtExceptionHandler}.
*
* @return a {@link Scheduler} meant for IO-bound work
*/
public static Scheduler io() {
return RxJavaHooks.onIOScheduler(getInstance().ioScheduler);
}
/**
* Creates and returns a {@code TestScheduler}, which is useful for debugging. It allows you to test
* schedules of events by manually advancing the clock at whatever pace you choose.
*
* @return a {@code TestScheduler} meant for debugging
*/
public static TestScheduler test() { // NOPMD
return new TestScheduler();
}
/**
* Converts an {@link Executor} into a new Scheduler instance.
*
* @param executor
* the executor to wrap
* @return the new Scheduler wrapping the Executor
*/
public static Scheduler from(Executor executor) {
return new ExecutorScheduler(executor);
}
/**
* Resets the current {@link Schedulers} instance.
* This will re-init the cached schedulers on the next usage,
* which can be useful in testing.
* @since 1.3
*/
public static void reset() {
Schedulers s = INSTANCE.getAndSet(null);
if (s != null) {
s.shutdownInstance();
}
}
/**
* Starts those standard Schedulers which support the SchedulerLifecycle interface.
* <p>The operation is idempotent and thread-safe.
*/
public static void start() {
Schedulers s = getInstance();
s.startInstance();
synchronized (s) {
GenericScheduledExecutorService.INSTANCE.start();
}
}
/**
* Shuts down those standard Schedulers which support the SchedulerLifecycle interface.
* <p>The operation is idempotent and thread-safe.
*/
public static void shutdown() {
Schedulers s = getInstance();
s.shutdownInstance();
synchronized (s) {
GenericScheduledExecutorService.INSTANCE.shutdown();
}
}
/**
* Start the instance-specific schedulers.
*/
synchronized void startInstance() { // NOPMD
if (computationScheduler instanceof SchedulerLifecycle) {
((SchedulerLifecycle) computationScheduler).start();
}
if (ioScheduler instanceof SchedulerLifecycle) {
((SchedulerLifecycle) ioScheduler).start();
}
if (newThreadScheduler instanceof SchedulerLifecycle) {
((SchedulerLifecycle) newThreadScheduler).start();
}
}
/**
* Start the instance-specific schedulers.
*/
synchronized void shutdownInstance() { // NOPMD
if (computationScheduler instanceof SchedulerLifecycle) {
((SchedulerLifecycle) computationScheduler).shutdown();
}
if (ioScheduler instanceof SchedulerLifecycle) {
((SchedulerLifecycle) ioScheduler).shutdown();
}
if (newThreadScheduler instanceof SchedulerLifecycle) {
((SchedulerLifecycle) newThreadScheduler).shutdown();
}
}
}