| /* |
| * 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.felix.dm.impl; |
| |
| import java.lang.reflect.InvocationHandler; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.Proxy; |
| |
| import org.apache.felix.dm.DependencyActivatorBase; |
| import org.apache.felix.dm.ServiceDependency; |
| import org.apache.felix.dm.context.DependencyContext; |
| import org.apache.felix.dm.context.EventType; |
| import org.osgi.framework.Bundle; |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.ServiceReference; |
| |
| /** |
| * Temporal Service dependency implementation, used to hide temporary service dependency "outage". |
| * Only works with a required dependency. |
| * |
| * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> |
| */ |
| public class TemporalServiceDependencyImpl extends ServiceDependencyImpl implements ServiceDependency, InvocationHandler { |
| // Max millis to wait for service availability. |
| private final long m_timeout; |
| |
| // Framework bundle (we use it to detect if the framework is stopping) |
| private final Bundle m_frameworkBundle; |
| |
| // The service proxy, which blocks when service is not available. |
| private volatile Object m_serviceInstance; |
| |
| /** |
| * Creates a new Temporal Service Dependency. |
| * |
| * @param context The bundle context of the bundle which is instantiating this dependency object |
| * @param logger the logger our Internal logger for logging events. |
| * @see DependencyActivatorBase#createTemporalServiceDependency() |
| */ |
| public TemporalServiceDependencyImpl(BundleContext context, long timeout) { |
| super.setRequired(true); |
| if (timeout < 0) { |
| throw new IllegalArgumentException("Invalid timeout value: " + timeout); |
| } |
| m_timeout = timeout; |
| m_frameworkBundle = context.getBundle(0); |
| } |
| |
| /** |
| * Creates a clone of an existing temporal service dependency. |
| */ |
| public TemporalServiceDependencyImpl(TemporalServiceDependencyImpl prototype) { |
| super(prototype); |
| super.setRequired(true); |
| m_timeout = prototype.m_timeout; |
| m_frameworkBundle = prototype.m_frameworkBundle; |
| } |
| |
| @Override |
| public DependencyContext createCopy() { |
| return new TemporalServiceDependencyImpl(this); |
| } |
| |
| /** |
| * Sets the required flag which determines if this service is required or not. This method |
| * just override the superclass method in order to check if the required flag is true |
| * (optional dependency is not supported by this class). |
| * |
| * @param required the required flag, which must be set to true |
| * @return this service dependency |
| * @throws IllegalArgumentException if the "required" parameter is not true. |
| */ |
| @Override |
| public ServiceDependency setRequired(boolean required) { |
| if (! required) { |
| throw new IllegalArgumentException("A Temporal Service dependency can't be optional"); |
| } |
| super.setRequired(required); |
| return this; |
| } |
| |
| /** |
| * The ServiceTracker calls us here in order to inform about a service arrival. |
| */ |
| @SuppressWarnings("rawtypes") |
| @Override |
| public void addedService(ServiceReference ref, Object event) { |
| // Update our service cache, using the tracker. We do this because the |
| // just added service might not be the service with the highest rank ... |
| boolean makeAvailable = false; |
| synchronized (this) { |
| if (m_serviceInstance == null) { |
| m_serviceInstance = Proxy.newProxyInstance(m_trackedServiceName.getClassLoader(), new Class[] { m_trackedServiceName }, this); |
| makeAvailable = true; |
| } |
| } |
| if (makeAvailable) { |
| getComponentContext().handleEvent(this, EventType.ADDED, |
| new ServiceEventImpl(m_component, ref, m_serviceInstance)); |
| } else { |
| // This added will possibly unblock our invoke() method (if it's blocked in m_tracker.waitForService method). |
| } |
| } |
| |
| /** |
| * The ServiceTracker calls us here when a tracked service properties are modified. |
| */ |
| @SuppressWarnings("rawtypes") |
| @Override |
| public void modifiedService(ServiceReference ref, Object service) { |
| // We don't care. |
| } |
| |
| /** |
| * The ServiceTracker calls us here when a tracked service is lost. |
| */ |
| @SuppressWarnings("rawtypes") |
| @Override |
| public void removedService(ServiceReference ref, Object event) { |
| ServiceEventImpl eventImpl = (ServiceEventImpl) event; |
| |
| // If we detect that the fwk is stopping, we behave as our superclass. That is: |
| // the lost dependency has to trigger our service deactivation, since the fwk is stopping |
| // and the lost dependency won't come up anymore. |
| if (m_frameworkBundle.getState() == Bundle.STOPPING) { |
| // Important: Notice that calling "super.removedService() might invoke our service "stop" |
| // callback, which in turn might invoke the just removed service dependency. In this case, |
| // our "invoke" method won't use the tracker to get the service dependency (because at this point, |
| // the tracker has withdrawn its reference to the lost service). So, you will see that the "invoke" |
| // method will use the "m_cachedService" instead ... |
| boolean makeUnavailable = false; |
| synchronized (this) { |
| if (m_tracker.getService() == null) { |
| makeUnavailable = true; |
| } |
| } |
| if (makeUnavailable) { |
| // the event.close method will unget the service. |
| m_component.handleEvent(this, EventType.REMOVED, new ServiceEventImpl(m_component, ref, m_serviceInstance)); |
| } |
| } else { |
| eventImpl.close(); // will unget the service. |
| // if there is no available services, the next call to invoke() method will block until another service |
| // becomes available. Else the next call to invoke() will return that highest ranked available service. |
| } |
| } |
| |
| @Override |
| public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { |
| ServiceEventImpl event = null; |
| try { |
| event = (ServiceEventImpl) m_tracker.waitForService(m_timeout); |
| } catch (InterruptedException e) { |
| } |
| |
| if (event == null) { |
| throw new IllegalStateException("Service unavailable: " + m_trackedServiceName.getName()); |
| } |
| |
| Object service = event.getEvent(); |
| if (service == null) { |
| throw new IllegalStateException("Service unavailable: " + m_trackedServiceName.getName()); |
| } |
| |
| try { |
| try { |
| return method.invoke(service, args); |
| } catch (IllegalAccessException iae) { |
| method.setAccessible(true); |
| return method.invoke(service, args); |
| } |
| } catch (InvocationTargetException e) { |
| throw e.getTargetException(); |
| } |
| } |
| } |