io.janusproject.kernel.services.jdk.kerneldiscovery.StandardKernelDiscoveryService Maven / Gradle / Ivy

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/*
 * $Id: io/janusproject/kernel/services/jdk/kerneldiscovery/StandardKernelDiscoveryService.java v2.0.3.1 2016-01-24 00:05:13$
 *
 * Janus platform is an open-source multiagent platform.
 * More details on http://www.janusproject.io
 *
 * Copyright (C) 2014-2015 the original authors or 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 io.janusproject.kernel.services.jdk.kerneldiscovery;

import java.net.URI;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;

import com.google.common.util.concurrent.Service;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import io.janusproject.services.AbstractDependentService;
import io.janusproject.services.AsyncStateService;
import io.janusproject.services.executor.ExecutorService;
import io.janusproject.services.kerneldiscovery.KernelDiscoveryService;
import io.janusproject.services.kerneldiscovery.KernelDiscoveryServiceListener;
import io.janusproject.services.network.NetworkService;
import io.janusproject.util.TwoStepConstruction;

/** Service that is providing the access to
 * the repository of the Janus kernels.
 *
 * This implementation is not able to discovered other
 * kernels.
 *
 * @author Stéphane Galland
 * @version 2.0.3.1 2016-01-24 00:05:13
 * @mavengroupid io.janusproject
 * @mavenartifactid io.janusproject.kernel
 */
@Singleton
@TwoStepConstruction
public class StandardKernelDiscoveryService extends AbstractDependentService
		implements KernelDiscoveryService, AsyncStateService {

	private URI localURI;

	private boolean isReady;

	private NetworkService network;

	/** Constructs a KernelRepositoryService.
	 */
	public StandardKernelDiscoveryService() {
		//
	}

	/** Do the post initialization.
	 *
	 * @param networkService - network service to be linked to.
	 * @param executorService - execution service to use.
	 */
	@Inject
	void postConstruction(
			NetworkService networkService,
			ExecutorService executorService) {
		this.network = networkService;
		this.network.addListener(new NetworkStartListener(), executorService.getExecutorService());
	}

	@Override
	public Collection> getServiceDependencies() {
		return Arrays.>asList(
				ExecutorService.class);
	}

	@Override
	public boolean isReadyForOtherServices() {
		return isRunning() && this.isReady;
	}

	@Override
	public final Class getServiceType() {
		return KernelDiscoveryService.class;
	}

	@Override
	public URI getCurrentKernel() {
		return this.localURI;
	}

	@Override
	public synchronized Collection getKernels() {
		Collection col = new ArrayList<>();
		col.add(this.localURI);
		return col;
	}

	@Override
	public void addKernelDiscoveryServiceListener(KernelDiscoveryServiceListener listener) {
		//
	}

	@Override
	public void removeKernelDiscoveryServiceListener(KernelDiscoveryServiceListener listener) {
		//
	}

	@Override
	protected synchronized void doStart() {
		notifyStarted();
	}

	@Override
	protected synchronized void doStop() {
		this.isReady = false;
		notifyStopped();
	}

	/** Listener on network events.
	 *
	 * @author Sebastian Rodriguez
	 * @author Stéphane Galland
	 * @version 2.0.3.1 2016-01-24 00:05:13
	 * @mavengroupid io.janusproject
	 * @mavenartifactid io.janusproject.kernel
	 */
	private class NetworkStartListener extends Listener {

		/** Construct.
		 */
		NetworkStartListener() {
			//
		}

		@SuppressWarnings("synthetic-access")
		@Override
		public void running() {
			// Outside the synchronizing statement to avoid deadlock
			URI uri = StandardKernelDiscoveryService.this.network.getURI();
			if (StandardKernelDiscoveryService.this.localURI == null) {
				synchronized (StandardKernelDiscoveryService.this) {
					StandardKernelDiscoveryService.this.localURI = uri;
					StandardKernelDiscoveryService.this.isReady = true;
				}
			}
		}
	}

}