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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.base.Throwables;
+
+import java.util.concurrent.Executor;
+
+/**
+ * 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
+public abstract class AbstractIdleService implements Service {
+
+ /* use AbstractService for state management */
+ private final Service delegate = new AbstractService() {
+ @Override protected final void doStart() {
+ executor(State.STARTING).execute(new Runnable() {
+ @Override public void run() {
+ try {
+ startUp();
+ notifyStarted();
+ } catch (Throwable t) {
+ notifyFailed(t);
+ throw Throwables.propagate(t);
+ }
+ }
+ });
+ }
+
+ @Override protected final void doStop() {
+ executor(State.STOPPING).execute(new Runnable() {
+ @Override public void run() {
+ try {
+ shutDown();
+ notifyStopped();
+ } catch (Throwable t) {
+ notifyFailed(t);
+ throw Throwables.propagate(t);
+ }
+ }
+ });
+ }
+ };
+
+ /** 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.
+ *
+ * @param state {@link Service.State#STARTING} or
+ * {@link Service.State#STOPPING}, used by the default implementation for
+ * naming the thread
+ */
+ protected Executor executor(final State state) {
+ return new Executor() {
+ @Override
+ public void execute(Runnable command) {
+ new Thread(command, getServiceName() + " " + state).start();
+ }
+ };
+ }
+
+ @Override public String toString() {
+ return getServiceName() + " [" + state() + "]";
+ }
+
+ // We override instead of using ForwardingService so that these can be final.
+
+ @Override public final ListenableFuture<State> start() {
+ return delegate.start();
+ }
+
+ @Override public final State startAndWait() {
+ return delegate.startAndWait();
+ }
+
+ @Override public final boolean isRunning() {
+ return delegate.isRunning();
+ }
+
+ @Override public final State state() {
+ return delegate.state();
+ }
+
+ @Override public final ListenableFuture<State> stop() {
+ return delegate.stop();
+ }
+
+ @Override public final State stopAndWait() {
+ return delegate.stopAndWait();
+ }
+
+ @Override public final void addListener(Listener listener, Executor executor) {
+ delegate.addListener(listener, executor);
+ }
+
+ private String getServiceName() {
+ return getClass().getSimpleName();
+ }
+}