| /* |
| * Copyright 2006 The Apache Software Foundation |
| * |
| * 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 org.apache.felix.dependencymanager; |
| |
| import java.lang.reflect.AccessibleObject; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.Proxy; |
| |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.InvalidSyntaxException; |
| import org.osgi.framework.ServiceReference; |
| |
| /** |
| * Service dependency that can track an OSGi service. |
| * |
| * @author <a href="mailto:felix-dev@incubator.apache.org">Felix Project Team</a> |
| */ |
| public class ServiceDependency implements Dependency, ServiceTrackerCustomizer { |
| private boolean m_isRequired; |
| private Service m_service; |
| private ServiceTracker m_tracker; |
| private BundleContext m_context; |
| private boolean m_isAvailable; |
| private Class m_trackedServiceName; |
| private Object m_nullObject; |
| private String m_trackedServiceFilter; |
| private ServiceReference m_trackedServiceReference; |
| private boolean m_isStarted; |
| private Object m_callbackInstance; |
| private String m_callbackAdded; |
| private String m_callbackChanged; |
| private String m_callbackRemoved; |
| private boolean m_autoConfig; |
| private ServiceReference m_reference; |
| private Object m_serviceInstance; |
| |
| /** |
| * Creates a new service dependency. |
| * |
| * @param context the bundle context |
| */ |
| public ServiceDependency(BundleContext context) { |
| m_context = context; |
| m_autoConfig = true; |
| } |
| |
| public boolean isRequired() { |
| return m_isRequired; |
| } |
| |
| public boolean isAvailable() { |
| return m_isAvailable; |
| } |
| |
| public boolean isAutoConfig() { |
| return m_autoConfig; |
| } |
| |
| public synchronized Object getService() { |
| Object service = null; |
| if (m_isStarted) { |
| service = m_tracker.getService(); |
| } |
| if (service == null) { |
| service = getNullObject(); |
| } |
| return service; |
| } |
| |
| private Object getNullObject() { |
| if (m_nullObject == null) { |
| m_nullObject = Proxy.newProxyInstance(m_trackedServiceName.getClassLoader(), new Class[] {m_trackedServiceName}, new DefaultNullObject()); |
| } |
| return m_nullObject; |
| } |
| |
| public Class getInterface() { |
| return m_trackedServiceName; |
| } |
| |
| public synchronized void start(Service service) { |
| if (m_isStarted) { |
| throw new IllegalStateException("Service dependency was already started." + m_trackedServiceName); |
| } |
| m_service = service; |
| if (m_trackedServiceName != null) { |
| if (m_trackedServiceFilter != null) { |
| try { |
| m_tracker = new ServiceTracker(m_context, m_context.createFilter(m_trackedServiceFilter), this); |
| } |
| catch (InvalidSyntaxException e) { |
| throw new IllegalStateException("Invalid filter definition for dependency."); |
| } |
| } |
| else if (m_trackedServiceReference != null) { |
| m_tracker = new ServiceTracker(m_context, m_trackedServiceReference, this); |
| } |
| else { |
| m_tracker = new ServiceTracker(m_context, m_trackedServiceName.getName(), this); |
| } |
| } |
| else { |
| throw new IllegalStateException("Could not create tracker for dependency, no service name specified."); |
| } |
| m_isStarted = true; |
| m_tracker.open(); |
| } |
| |
| public synchronized void stop(Service service) { |
| if (!m_isStarted) { |
| throw new IllegalStateException("Service dependency was not started."); |
| } |
| m_tracker.close(); |
| m_isStarted = false; |
| m_tracker = null; |
| } |
| |
| public Object addingService(ServiceReference ref) { |
| Object service = m_context.getService(ref); |
| // we remember these for future reference, needed for required service callbacks |
| m_reference = ref; |
| m_serviceInstance = service; |
| return service; |
| } |
| |
| public void addedService(ServiceReference ref, Object service) { |
| if (makeAvailable()) { |
| m_service.dependencyAvailable(this); |
| } |
| else { |
| m_service.dependencyChanged(this); |
| } |
| // try to invoke callback, if specified, but only for optional dependencies |
| // because callbacks for required dependencies are handled differently |
| if (!isRequired()) { |
| invokeAdded(ref, service); |
| } |
| } |
| |
| public void invokeAdded() { |
| invokeAdded(m_reference, m_serviceInstance); |
| } |
| |
| public void invokeAdded(ServiceReference reference, Object serviceInstance) { |
| Object callbackInstance = getCallbackInstance(); |
| if ((callbackInstance != null) && (m_callbackAdded != null)) { |
| try { |
| invokeCallbackMethod(callbackInstance, m_callbackAdded, reference, serviceInstance); |
| } catch (NoSuchMethodException e) { |
| // silently ignore this |
| } |
| } |
| } |
| |
| public void modifiedService(ServiceReference ref, Object service) { |
| m_reference = ref; |
| m_serviceInstance = service; |
| m_service.dependencyChanged(this); |
| // only invoke the changed callback if the service itself is "active" |
| if (((ServiceImpl) m_service).isRegistered()) { |
| invokeChanged(ref, service); |
| } |
| } |
| |
| public void invokeChanged(ServiceReference reference, Object serviceInstance) { |
| Object callbackInstance = getCallbackInstance(); |
| if ((callbackInstance != null) && (m_callbackChanged != null)) { |
| try { |
| if (m_reference == null) { |
| Thread.dumpStack(); |
| } |
| invokeCallbackMethod(callbackInstance, m_callbackChanged, reference, serviceInstance); |
| } |
| catch (NoSuchMethodException e) { |
| // ignore when the service has no such method |
| } |
| } |
| } |
| |
| public void removedService(ServiceReference ref, Object service) { |
| if (makeUnavailable()) { |
| m_service.dependencyUnavailable(this); |
| } |
| // try to invoke callback, if specified, but only for optional dependencies |
| // because callbacks for required dependencies are handled differently |
| if (!isRequired()) { |
| invokeRemoved(ref, service); |
| } |
| m_context.ungetService(ref); |
| } |
| |
| public void invokeRemoved() { |
| invokeRemoved(m_reference, m_serviceInstance); |
| } |
| |
| public void invokeRemoved(ServiceReference reference, Object serviceInstance) { |
| Object callbackInstance = getCallbackInstance(); |
| if ((callbackInstance != null) && (m_callbackRemoved != null)) { |
| try { |
| if (m_reference == null) { |
| Thread.dumpStack(); |
| } |
| invokeCallbackMethod(callbackInstance, m_callbackRemoved, reference, serviceInstance); |
| } |
| catch (NoSuchMethodException e) { |
| // ignore when the service has no such method |
| } |
| } |
| } |
| |
| private synchronized boolean makeAvailable() { |
| if (!m_isAvailable) { |
| m_isAvailable = true; |
| return true; |
| } |
| return false; |
| } |
| |
| private synchronized boolean makeUnavailable() { |
| if ((m_isAvailable) && (m_tracker.getServiceReference() == null)) { |
| m_isAvailable = false; |
| return true; |
| } |
| return false; |
| } |
| |
| private Object getCallbackInstance() { |
| Object callbackInstance = m_callbackInstance; |
| if (callbackInstance == null) { |
| callbackInstance = m_service.getService(); |
| } |
| return callbackInstance; |
| } |
| |
| // TODO a lot of things in this method can be cached instead of done each time |
| // TODO Richard had an example where he could not invoke a private method |
| private void invokeCallbackMethod(Object instance, String methodName, ServiceReference reference, Object service) throws NoSuchMethodException { |
| Method method = null; |
| Class clazz = instance.getClass(); |
| while (clazz != null) { |
| AccessibleObject.setAccessible(clazz.getDeclaredMethods(), true); |
| try { |
| try { |
| method = clazz.getDeclaredMethod(methodName, new Class[] {ServiceReference.class, Object.class}); |
| method.invoke(instance, new Object[] {reference, service}); |
| return; |
| } |
| catch (NoSuchMethodException e) { |
| try { |
| method = clazz.getDeclaredMethod(methodName, new Class[] {ServiceReference.class}); |
| method.invoke(instance, new Object[] {reference}); |
| return; |
| } |
| catch (NoSuchMethodException e1) { |
| try { |
| method = clazz.getDeclaredMethod(methodName, new Class[] {Object.class}); |
| method.invoke(instance, new Object[] {service}); |
| return; |
| } |
| catch (NoSuchMethodException e2) { |
| try { |
| method = clazz.getDeclaredMethod(methodName, new Class[] {m_trackedServiceName}); |
| method.invoke(instance, new Object[] {service}); |
| return; |
| } |
| catch (NoSuchMethodException e3) { |
| method = clazz.getDeclaredMethod(methodName, null); |
| method.invoke(instance, null); |
| return; |
| } |
| } |
| } |
| } |
| } |
| catch (IllegalArgumentException e1) { |
| // ignore this exception |
| } |
| catch (IllegalAccessException e1) { |
| // ignore this exception |
| } |
| catch (InvocationTargetException e1) { |
| // ignore this exception |
| } |
| clazz = clazz.getSuperclass(); |
| } |
| } |
| |
| // ----- CREATION |
| |
| /** |
| * Sets the name of the service that should be tracked. |
| * |
| * @param serviceName the name of the service |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setService(Class serviceName) { |
| ensureNotActive(); |
| if (serviceName == null) { |
| throw new IllegalArgumentException("Service name cannot be null."); |
| } |
| m_trackedServiceName = serviceName; |
| m_trackedServiceReference = null; |
| m_trackedServiceFilter = null; |
| return this; |
| } |
| |
| /** |
| * Sets the name of the service that should be tracked. You can either specify |
| * only the name, or the name and a filter. In the latter case, the filter is used |
| * to track the service and should only return services of the type that was specified |
| * in the name. |
| * |
| * @param serviceName the name of the service |
| * @param serviceFilter the filter condition |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setService(Class serviceName, String serviceFilter) { |
| ensureNotActive(); |
| if (serviceName == null) { |
| throw new IllegalArgumentException("Service name cannot be null."); |
| } |
| m_trackedServiceName = serviceName; |
| m_trackedServiceFilter = serviceFilter; |
| m_trackedServiceReference = null; |
| return this; |
| } |
| |
| /** |
| * Sets the name of the service that should be tracked. You can either specify |
| * only the name, or the name and a reference. In the latter case, the service reference |
| * is used to track the service and should only return services of the type that was |
| * specified in the name. |
| * |
| * @param serviceName the name of the service |
| * @param serviceReference the service reference to track |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setService(Class serviceName, ServiceReference serviceReference) { |
| ensureNotActive(); |
| if (serviceName == null) { |
| throw new IllegalArgumentException("Service name cannot be null."); |
| } |
| m_trackedServiceName = serviceName; |
| m_trackedServiceReference = serviceReference; |
| m_trackedServiceFilter = null; |
| return this; |
| } |
| |
| /** |
| * Sets the required flag which determines if this service is required or not. |
| * |
| * @param required the required flag |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setRequired(boolean required) { |
| ensureNotActive(); |
| m_isRequired = required; |
| return this; |
| } |
| |
| /** |
| * Sets auto configuration for this service. Auto configuration allows the |
| * dependency to fill in any attributes in the service implementation that |
| * are of the same type as this dependency. Default is on. |
| * |
| * @param autoConfig the value of auto config |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setAutoConfig(boolean autoConfig) { |
| ensureNotActive(); |
| m_autoConfig = autoConfig; |
| return this; |
| } |
| |
| /** |
| * Sets the callbacks for this service. These callbacks can be used as hooks whenever |
| * a dependency is added or removed. They are called on the service implementation. |
| * |
| * @param added the method to call when a service was added |
| * @param removed the method to call when a service was removed |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setCallbacks(String added, String removed) { |
| return setCallbacks(null, added, null, removed); |
| } |
| public synchronized ServiceDependency setCallbacks(String added, String changed, String removed) { |
| return setCallbacks(null, added, changed, removed); |
| } |
| public synchronized ServiceDependency setCallbacks(Object instance, String added, String removed) { |
| return setCallbacks(instance, added, null, removed); |
| } |
| |
| /** |
| * Sets the callbacks for this service. These callbacks can be used as hooks whenever |
| * a dependency is added or removed. They are called on the instance you provide. |
| * |
| * @param instance the instance to call the callbacks on |
| * @param added the method to call when a service was added |
| * @param changed the method to call when a service was changed |
| * @param removed the method to call when a service was removed |
| * @return this service dependency |
| */ |
| public synchronized ServiceDependency setCallbacks(Object instance, String added, String changed, String removed) { |
| ensureNotActive(); |
| m_callbackInstance = instance; |
| m_callbackAdded = added; |
| m_callbackChanged = changed; |
| m_callbackRemoved = removed; |
| return this; |
| } |
| |
| |
| private void ensureNotActive() { |
| if (m_tracker != null) { |
| throw new IllegalStateException("Cannot modify state while active."); |
| } |
| } |
| |
| public String toString() { |
| return "ServiceDependency[" + m_trackedServiceName + " " + m_trackedServiceFilter + " " + m_isRequired + "] for " + m_service; |
| } |
| } |