component-dsl/src/main/java/org/apache/aries/component/dsl/internal/ConfigurationsOSGiImpl.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.aries.component.dsl.internal;

import org.apache.aries.component.dsl.OSGiResult;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.ServiceRegistration;
import org.osgi.service.cm.Configuration;
import org.osgi.service.cm.ConfigurationAdmin;
import org.osgi.service.cm.ConfigurationEvent;
import org.osgi.service.cm.ConfigurationListener;

import java.util.Dictionary;
import java.util.Hashtable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * @author Carlos Sierra Andrés
 */
public class ConfigurationsOSGiImpl extends OSGiImpl<Dictionary<String, ?>> {

	public ConfigurationsOSGiImpl(String factoryPid) {
		super((executionContext, op) -> {
			ConcurrentHashMap<String, Configuration> configurations =
				new ConcurrentHashMap<>();

			ConcurrentHashMap<String, OSGiResult> terminators =
				new ConcurrentHashMap<>();

			AtomicBoolean closed = new AtomicBoolean();

			CountDownLatch countDownLatch = new CountDownLatch(1);

			final BundleContext bundleContext = executionContext.getBundleContext();

			ServiceRegistration<?> serviceRegistration =
				bundleContext.registerService(
					ConfigurationListener.class,
					(ConfigurationEvent configurationEvent) -> {
						String incomingFactoryPid =
							configurationEvent.getFactoryPid();

						if (incomingFactoryPid == null ||
							!factoryPid.equals(incomingFactoryPid)) {

							return;
						}

						try {
							countDownLatch.await(1, TimeUnit.MINUTES);
						}
						catch (InterruptedException e) {
							return;
						}

						String pid = configurationEvent.getPid();

						Configuration configuration;

						if (configurationEvent.getType() ==
							ConfigurationEvent.CM_DELETED) {

							configurations.remove(pid);

							signalLeave(pid, terminators);
						}
						else {
							configuration = getConfiguration(
								bundleContext, configurationEvent);

							Dictionary<String, Object> properties =
								configuration.getProperties();

							configurations.compute(
								pid,
								(__, old) -> {
									if (old == null ||
										configuration.getChangeCount() !=
											old.getChangeCount()) {

										return configuration;
									}

									return old;
								}
							);

							UpdateSupport.runUpdate(() -> {
								signalLeave(pid, terminators);

								terminators.put(pid, op.apply(properties));
							});

							if (closed.get()) {
							/*
							if we have closed while executing the
							effects we have to execute the terminator
							directly instead of storing it
							*/
								signalLeave(pid, terminators);
							}
						}
					},
					new Hashtable<>());

			ServiceReference<ConfigurationAdmin> serviceReference =
				bundleContext.getServiceReference(ConfigurationAdmin.class);

			if (serviceReference != null) {
				Configuration[] configuration = getConfigurations(
					bundleContext, factoryPid, serviceReference);

				for (Configuration c : configuration) {
					configurations.put(c.getPid(), c);

					terminators.put(c.getPid(), op.apply(c.getProperties()));
				}
			}

			countDownLatch.countDown();

			return new OSGiResultImpl(
				() -> {
					closed.set(true);

					serviceRegistration.unregister();

					for (Runnable runnable : terminators.values()) {
						if (runnable != null) {
							runnable.run();
						}
					}
				},
				us -> {
					for (OSGiResult osgiResult : terminators.values()) {
						if (osgiResult != null) {
							osgiResult.run();
						}
					}
				});
		});
	}

	private static Configuration getConfiguration(
		BundleContext bundleContext, ConfigurationEvent configurationEvent) {

		String pid = configurationEvent.getPid();
		String factoryPid = configurationEvent.getFactoryPid();

		ServiceReference<ConfigurationAdmin> reference =
			configurationEvent.getReference();

		return getConfiguration(bundleContext, pid, factoryPid, reference);
	}

	private static Configuration getConfiguration(
		BundleContext bundleContext, String pid, String factoryPid,
		ServiceReference<ConfigurationAdmin> reference) {

		ConfigurationAdmin configurationAdmin = bundleContext.getService(
			reference);

		try {
			Configuration[] configurations =
				configurationAdmin.listConfigurations(
					"(&(service.pid=" + pid + ")" +
						"(service.factoryPid="+ factoryPid + "))");

			if (configurations == null || configurations.length == 0) {
				return null;
			}

			return configurations[0];
		}
		catch (Exception e) {
			return null;
		}
		finally {
			bundleContext.ungetService(reference);
		}
	}

	private static Configuration[] getConfigurations(
		BundleContext bundleContext, String factoryPid,
		ServiceReference<ConfigurationAdmin> serviceReference) {

		ConfigurationAdmin configurationAdmin = bundleContext.getService(
			serviceReference);

		try {
			Configuration[] configurations =
				configurationAdmin.listConfigurations(
					"(&(service.pid=*)(service.factoryPid="+ factoryPid +"))");

			if (configurations == null) {
				return new Configuration[0];
			}

			return configurations;
		}
		catch (Exception e) {
			return new Configuration[0];
		}
		finally {
			bundleContext.ungetService(serviceReference);
		}
	}

	private static void signalLeave(
		String factoryPid, ConcurrentHashMap<String, OSGiResult> terminators) {

		OSGiResult osgiResult = terminators.remove(factoryPid);

		if (osgiResult != null) {
			osgiResult.run();
		}
	}

}