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/*
* Copyright (C) 2009 The Guava Authors
*
* 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 com.google.common.util.concurrent;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Supplier;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.j2objc.annotations.WeakOuter;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Base class for services that do not need a thread while "running" but may need one during startup
* and shutdown. Subclasses can implement {@link #startUp} and {@link #shutDown} methods, each which
* run in a executor which by default uses a separate thread for each method.
*
* @author Chris Nokleberg
* @since 1.0
*/
@Beta
@GwtIncompatible
public abstract class AbstractIdleService implements Service {
/* Thread names will look like {@code "MyService STARTING"}. */
private final Supplier<String> threadNameSupplier = new ThreadNameSupplier();
@WeakOuter
private final class ThreadNameSupplier implements Supplier<String> {
@Override
public String get() {
return serviceName() + " " + state();
}
}
/* use AbstractService for state management */
private final Service delegate = new DelegateService();
@WeakOuter
private final class DelegateService extends AbstractService {
@Override
protected final void doStart() {
MoreExecutors.renamingDecorator(executor(), threadNameSupplier)
.execute(
new Runnable() {
@Override
public void run() {
try {
startUp();
notifyStarted();
} catch (Throwable t) {
notifyFailed(t);
}
}
});
}
@Override
protected final void doStop() {
MoreExecutors.renamingDecorator(executor(), threadNameSupplier)
.execute(
new Runnable() {
@Override
public void run() {
try {
shutDown();
notifyStopped();
} catch (Throwable t) {
notifyFailed(t);
}
}
});
}
@Override
public String toString() {
return AbstractIdleService.this.toString();
}
}
/** Constructor for use by subclasses. */
protected AbstractIdleService() {}
/** Start the service. */
protected abstract void startUp() throws Exception;
/** Stop the service. */
protected abstract void shutDown() throws Exception;
/**
* Returns the {@link Executor} that will be used to run this service. Subclasses may override
* this method to use a custom {@link Executor}, which may configure its worker thread with a
* specific name, thread group or priority. The returned executor's {@link
* Executor#execute(Runnable) execute()} method is called when this service is started and
* stopped, and should return promptly.
*/
protected Executor executor() {
return new Executor() {
@Override
public void execute(Runnable command) {
MoreExecutors.newThread(threadNameSupplier.get(), command).start();
}
};
}
@Override
public String toString() {
return serviceName() + " [" + state() + "]";
}
@Override
public final boolean isRunning() {
return delegate.isRunning();
}
@Override
public final State state() {
return delegate.state();
}
/** @since 13.0 */
@Override
public final void addListener(Listener listener, Executor executor) {
delegate.addListener(listener, executor);
}
/** @since 14.0 */
@Override
public final Throwable failureCause() {
return delegate.failureCause();
}
/** @since 15.0 */
@CanIgnoreReturnValue
@Override
public final Service startAsync() {
delegate.startAsync();
return this;
}
/** @since 15.0 */
@CanIgnoreReturnValue
@Override
public final Service stopAsync() {
delegate.stopAsync();
return this;
}
/** @since 15.0 */
@Override
public final void awaitRunning() {
delegate.awaitRunning();
}
/** @since 15.0 */
@Override
public final void awaitRunning(long timeout, TimeUnit unit) throws TimeoutException {
delegate.awaitRunning(timeout, unit);
}
/** @since 15.0 */
@Override
public final void awaitTerminated() {
delegate.awaitTerminated();
}
/** @since 15.0 */
@Override
public final void awaitTerminated(long timeout, TimeUnit unit) throws TimeoutException {
delegate.awaitTerminated(timeout, unit);
}
/**
* Returns the name of this service. {@link AbstractIdleService} may include the name in debugging
* output.
*
* @since 14.0
*/
protected String serviceName() {
return getClass().getSimpleName();
}
}
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