| /** |
| * Copyright (C) 2010 Google 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 com.google.inject.service; |
| |
| import com.google.inject.Inject; |
| import com.google.inject.Injector; |
| import com.google.inject.Key; |
| import com.google.inject.internal.util.ImmutableList; |
| import com.google.inject.internal.util.Lists; |
| import com.google.inject.internal.util.Preconditions; |
| import com.google.inject.internal.util.Sets; |
| import java.util.List; |
| import java.util.Set; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.FutureTask; |
| |
| /** |
| * A service that composes other services together in a fixed order. |
| * |
| * @author dhanji@gmail.com (Dhanji R. Prasanna) |
| */ |
| public class CompositeService { |
| private final Injector injector; |
| |
| private final Set<Key<? extends Service>> services = Sets.newLinkedHashSet(); |
| |
| /** |
| * Represents the state of this composite service. Will equal FAILED |
| * even if only one component service fails to start or stop. In other |
| * words, all component services must start successfully for this |
| * service to be considered started and similarly for stopped. |
| */ |
| private volatile Service.State compositeState; |
| private boolean composed; |
| |
| @Inject |
| CompositeService(Injector injector) { |
| this.injector = injector; |
| } |
| |
| public CompositeService add(Class<? extends Service> service) { |
| return add(Key.get(service)); |
| } |
| |
| public CompositeService add(Key<? extends Service> service) { |
| Preconditions.checkState(!composed, |
| "Cannot reuse a CompositeService after it has been compose()d. Please create a new one."); |
| // Verify that the binding exists. Throws an exception if not. |
| injector.getBinding(service); |
| |
| services.add(service); |
| return this; |
| } |
| |
| public Service compose() { |
| Preconditions.checkState(!composed, |
| "Cannot reuse a CompositeService after it has been compose()d. Please create a new one."); |
| composed = true; |
| |
| // Defensive copy. |
| final List<Key<? extends Service>> services = ImmutableList.copyOf(this.services); |
| |
| return new Service() { |
| public Future<State> start() { |
| final List<Future<State>> tasks = Lists.newArrayList(); |
| for (Key<? extends Service> service : services) { |
| tasks.add(injector.getInstance(service).start()); |
| } |
| |
| return futureGet(tasks, State.STARTED); |
| } |
| |
| public Future<State> stop() { |
| final List<Future<State>> tasks = Lists.newArrayList(); |
| for (Key<? extends Service> service : services) { |
| tasks.add(injector.getInstance(service).stop()); |
| } |
| |
| return futureGet(tasks, State.STOPPED); |
| } |
| |
| public State state() { |
| return compositeState; |
| } |
| }; |
| } |
| |
| private FutureTask<Service.State> futureGet(final List<Future<Service.State>> tasks, |
| final Service.State state) { |
| return new FutureTask<Service.State>(new Callable<Service.State>() { |
| public Service.State call() { |
| boolean ok = true; |
| for (Future<Service.State> task : tasks) { |
| try { |
| ok = state == task.get(); |
| } catch (InterruptedException e) { |
| return compositeState = Service.State.FAILED; |
| } catch (ExecutionException e) { |
| return compositeState = Service.State.FAILED; |
| } |
| } |
| |
| return compositeState = ok ? state : Service.State.FAILED; |
| } |
| }); |
| } |
| } |