| /* |
| * 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.dependencymanager; |
| |
| import java.util.ArrayList; |
| import java.util.Enumeration; |
| import java.util.Hashtable; |
| import java.util.LinkedList; |
| |
| import org.osgi.framework.AllServiceListener; |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.Constants; |
| import org.osgi.framework.Filter; |
| import org.osgi.framework.InvalidSyntaxException; |
| import org.osgi.framework.ServiceEvent; |
| import org.osgi.framework.ServiceListener; |
| import org.osgi.framework.ServiceReference; |
| |
| /** |
| * A modified <code>ServiceTracker</code> class simplifies using services |
| * from the Framework's service registry. This class is used internally |
| * by the dependency manager. It is based on the OSGi R4.1 sources, which |
| * are made available under the same ASF 2.0 license. |
| * |
| * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> |
| */ |
| public class ServiceTracker implements ServiceTrackerCustomizer { |
| /* set this to true to compile in debug messages */ |
| static final boolean DEBUG = false; |
| /** |
| * Bundle context against which this <code>ServiceTracker</code> object is |
| * tracking. |
| */ |
| protected final BundleContext context; |
| /** |
| * Filter specifying search criteria for the services to track. |
| * |
| * @since 1.1 |
| */ |
| protected final Filter filter; |
| /** |
| * <code>ServiceTrackerCustomizer</code> object for this tracker. |
| */ |
| final ServiceTrackerCustomizer customizer; |
| /** |
| * Filter string for use when adding the ServiceListener. If this field is |
| * set, then certain optimizations can be taken since we don't have a user |
| * supplied filter. |
| */ |
| final String listenerFilter; |
| /** |
| * Class name to be tracked. If this field is set, then we are tracking by |
| * class name. |
| */ |
| private final String trackClass; |
| /** |
| * Reference to be tracked. If this field is set, then we are tracking a |
| * single ServiceReference. |
| */ |
| private final ServiceReference trackReference; |
| /** |
| * Tracked services: <code>ServiceReference</code> object -> customized |
| * Object and <code>ServiceListener</code> object |
| */ |
| private volatile Tracked tracked; |
| /** |
| * Modification count. This field is initialized to zero by open, set to -1 |
| * by close and incremented by modified. |
| * |
| * This field is volatile since it is accessed by multiple threads. |
| */ |
| private volatile int trackingCount = -1; |
| /** |
| * Cached ServiceReference for getServiceReference. |
| * |
| * This field is volatile since it is accessed by multiple threads. |
| */ |
| private volatile ServiceReference cachedReference; |
| /** |
| * Cached service object for getService. |
| * |
| * This field is volatile since it is accessed by multiple threads. |
| */ |
| private volatile Object cachedService; |
| |
| /** |
| * Create a <code>ServiceTracker</code> object on the specified |
| * <code>ServiceReference</code> object. |
| * |
| * <p> |
| * The service referenced by the specified <code>ServiceReference</code> |
| * object will be tracked by this <code>ServiceTracker</code> object. |
| * |
| * @param context <code>BundleContext</code> object against which the |
| * tracking is done. |
| * @param reference <code>ServiceReference</code> object for the service |
| * to be tracked. |
| * @param customizer The customizer object to call when services are added, |
| * modified, or removed in this <code>ServiceTracker</code> object. |
| * If customizer is <code>null</code>, then this |
| * <code>ServiceTracker</code> object will be used as the |
| * <code>ServiceTrackerCustomizer</code> object and the |
| * <code>ServiceTracker</code> object will call the |
| * <code>ServiceTrackerCustomizer</code> methods on itself. |
| */ |
| public ServiceTracker(BundleContext context, ServiceReference reference, |
| ServiceTrackerCustomizer customizer) { |
| this.context = context; |
| this.trackReference = reference; |
| this.trackClass = null; |
| this.customizer = (customizer == null) ? this : customizer; |
| this.listenerFilter = "(" + Constants.SERVICE_ID + "=" + reference.getProperty(Constants.SERVICE_ID).toString() + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ |
| try { |
| this.filter = context.createFilter(listenerFilter); |
| } |
| catch (InvalidSyntaxException e) { // we could only get this exception |
| // if the ServiceReference was |
| // invalid |
| throw new IllegalArgumentException( |
| "unexpected InvalidSyntaxException: " + e.getMessage()); //$NON-NLS-1$ |
| } |
| } |
| |
| /** |
| * Create a <code>ServiceTracker</code> object on the specified class |
| * name. |
| * |
| * <p> |
| * Services registered under the specified class name will be tracked by |
| * this <code>ServiceTracker</code> object. |
| * |
| * @param context <code>BundleContext</code> object against which the |
| * tracking is done. |
| * @param clazz Class name of the services to be tracked. |
| * @param customizer The customizer object to call when services are added, |
| * modified, or removed in this <code>ServiceTracker</code> object. |
| * If customizer is <code>null</code>, then this |
| * <code>ServiceTracker</code> object will be used as the |
| * <code>ServiceTrackerCustomizer</code> object and the |
| * <code>ServiceTracker</code> object will call the |
| * <code>ServiceTrackerCustomizer</code> methods on itself. |
| */ |
| public ServiceTracker(BundleContext context, String clazz, |
| ServiceTrackerCustomizer customizer) { |
| this.context = context; |
| this.trackReference = null; |
| this.trackClass = clazz; |
| this.customizer = (customizer == null) ? this : customizer; |
| this.listenerFilter = "(" + Constants.OBJECTCLASS + "=" + clazz + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ |
| try { |
| this.filter = context.createFilter(listenerFilter); |
| } |
| catch (InvalidSyntaxException e) { // we could only get this exception |
| // if the clazz argument was |
| // malformed |
| throw new IllegalArgumentException( |
| "unexpected InvalidSyntaxException: " + e.getMessage()); //$NON-NLS-1$ |
| } |
| } |
| |
| /** |
| * Create a <code>ServiceTracker</code> object on the specified |
| * <code>Filter</code> object. |
| * |
| * <p> |
| * Services which match the specified <code>Filter</code> object will be |
| * tracked by this <code>ServiceTracker</code> object. |
| * |
| * @param context <code>BundleContext</code> object against which the |
| * tracking is done. |
| * @param filter <code>Filter</code> object to select the services to be |
| * tracked. |
| * @param customizer The customizer object to call when services are added, |
| * modified, or removed in this <code>ServiceTracker</code> object. |
| * If customizer is null, then this <code>ServiceTracker</code> |
| * object will be used as the <code>ServiceTrackerCustomizer</code> |
| * object and the <code>ServiceTracker</code> object will call the |
| * <code>ServiceTrackerCustomizer</code> methods on itself. |
| * @since 1.1 |
| */ |
| public ServiceTracker(BundleContext context, Filter filter, |
| ServiceTrackerCustomizer customizer) { |
| this.context = context; |
| this.trackReference = null; |
| this.trackClass = null; |
| this.listenerFilter = null; |
| this.filter = filter; |
| this.customizer = (customizer == null) ? this : customizer; |
| if ((context == null) || (filter == null)) { // we throw a NPE here |
| // to |
| // be consistent with the |
| // other constructors |
| throw new NullPointerException(); |
| } |
| } |
| |
| /** |
| * Open this <code>ServiceTracker</code> object and begin tracking |
| * services. |
| * |
| * <p> |
| * This method calls <code>open(false)</code>. |
| * |
| * @throws java.lang.IllegalStateException if the <code>BundleContext</code> |
| * object with which this <code>ServiceTracker</code> object was |
| * created is no longer valid. |
| * @see #open(boolean) |
| */ |
| public void open() { |
| open(false); |
| } |
| |
| /** |
| * Open this <code>ServiceTracker</code> object and begin tracking |
| * services. |
| * |
| * <p> |
| * Services which match the search criteria specified when this |
| * <code>ServiceTracker</code> object was created are now tracked by this |
| * <code>ServiceTracker</code> object. |
| * |
| * @param trackAllServices If <code>true</code>, then this |
| * <code>ServiceTracker</code> will track all matching services |
| * regardless of class loader accessibility. If <code>false</code>, |
| * then this <code>ServiceTracker</code> will only track matching |
| * services which are class loader accessibile to the bundle whose |
| * <code>BundleContext</code> is used by this |
| * <code>ServiceTracker</code>. |
| * @throws java.lang.IllegalStateException if the <code>BundleContext</code> |
| * object with which this <code>ServiceTracker</code> object was |
| * created is no longer valid. |
| * @since 1.3 |
| */ |
| public synchronized void open(boolean trackAllServices) { |
| if (tracked != null) { |
| return; |
| } |
| if (DEBUG) { |
| System.out.println("ServiceTracker.open: " + filter); //$NON-NLS-1$ |
| } |
| tracked = trackAllServices ? new AllTracked() : new Tracked(); |
| trackingCount = 0; |
| synchronized (tracked) { |
| try { |
| context.addServiceListener(tracked, listenerFilter); |
| ServiceReference[] references; |
| if (listenerFilter == null) { // user supplied filter |
| references = getInitialReferences(trackAllServices, null, |
| filter.toString()); |
| } |
| else { // constructor supplied filter |
| if (trackClass == null) { |
| references = new ServiceReference[] {trackReference}; |
| } |
| else { |
| references = getInitialReferences(trackAllServices, |
| trackClass, null); |
| } |
| } |
| |
| tracked.setInitialServices(references); // set tracked with |
| // the initial |
| // references |
| } |
| catch (InvalidSyntaxException e) { |
| throw new RuntimeException( |
| "unexpected InvalidSyntaxException: " + e.getMessage()); //$NON-NLS-1$ |
| } |
| } |
| /* Call tracked outside of synchronized region */ |
| tracked.trackInitialServices(); // process the initial references |
| } |
| |
| /** |
| * Returns the list of initial <code>ServiceReference</code> objects that |
| * will be tracked by this <code>ServiceTracker</code> object. |
| * |
| * @param trackAllServices If true, use getAllServiceReferences. |
| * @param trackClass the class name with which the service was registered, |
| * or null for all services. |
| * @param filterString the filter criteria or null for all services. |
| * @return the list of initial <code>ServiceReference</code> objects. |
| * @throws InvalidSyntaxException if the filter uses an invalid syntax. |
| */ |
| private ServiceReference[] getInitialReferences(boolean trackAllServices, |
| String trackClass, String filterString) |
| throws InvalidSyntaxException { |
| if (trackAllServices) { |
| return context.getAllServiceReferences(trackClass, filterString); |
| } |
| else { |
| return context.getServiceReferences(trackClass, filterString); |
| } |
| } |
| |
| /** |
| * Close this <code>ServiceTracker</code> object. |
| * |
| * <p> |
| * This method should be called when this <code>ServiceTracker</code> |
| * object should end the tracking of services. |
| */ |
| public synchronized void close() { |
| if (tracked == null) { |
| return; |
| } |
| if (DEBUG) { |
| System.out.println("ServiceTracker.close: " + filter); //$NON-NLS-1$ |
| } |
| tracked.close(); |
| ServiceReference[] references = getServiceReferences(); |
| Tracked outgoing = tracked; |
| tracked = null; |
| try { |
| context.removeServiceListener(outgoing); |
| } |
| catch (IllegalStateException e) { |
| /* In case the context was stopped. */ |
| } |
| if (references != null) { |
| for (int i = 0; i < references.length; i++) { |
| outgoing.untrack(references[i]); |
| } |
| } |
| trackingCount = -1; |
| if (DEBUG) { |
| if ((cachedReference == null) && (cachedService == null)) { |
| System.out |
| .println("ServiceTracker.close[cached cleared]: " + filter); //$NON-NLS-1$ |
| } |
| } |
| } |
| |
| /** |
| * Default implementation of the |
| * <code>ServiceTrackerCustomizer.addingService</code> method. |
| * |
| * <p> |
| * This method is only called when this <code>ServiceTracker</code> object |
| * has been constructed with a <code>null ServiceTrackerCustomizer</code> |
| * argument. |
| * |
| * The default implementation returns the result of calling |
| * <code>getService</code>, on the <code>BundleContext</code> object |
| * with which this <code>ServiceTracker</code> object was created, passing |
| * the specified <code>ServiceReference</code> object. |
| * <p> |
| * This method can be overridden in a subclass to customize the service |
| * object to be tracked for the service being added. In that case, take care |
| * not to rely on the default implementation of removedService that will |
| * unget the service. |
| * |
| * @param reference Reference to service being added to this |
| * <code>ServiceTracker</code> object. |
| * @return The service object to be tracked for the service added to this |
| * <code>ServiceTracker</code> object. |
| * @see ServiceTrackerCustomizer |
| */ |
| public Object addingService(ServiceReference reference) { |
| return context.getService(reference); |
| } |
| |
| /** |
| * Default implementation of the |
| * <code>ServiceTrackerCustomizer.modifiedService</code> method. |
| * |
| * <p> |
| * This method is only called when this <code>ServiceTracker</code> object |
| * has been constructed with a <code>null ServiceTrackerCustomizer</code> |
| * argument. |
| * |
| * The default implementation does nothing. |
| * |
| * @param reference Reference to modified service. |
| * @param service The service object for the modified service. |
| * @see ServiceTrackerCustomizer |
| */ |
| public void modifiedService(ServiceReference reference, Object service) { |
| } |
| |
| /** |
| * Default implementation of the |
| * <code>ServiceTrackerCustomizer.removedService</code> method. |
| * |
| * <p> |
| * This method is only called when this <code>ServiceTracker</code> object |
| * has been constructed with a <code>null ServiceTrackerCustomizer</code> |
| * argument. |
| * |
| * The default implementation calls <code>ungetService</code>, on the |
| * <code>BundleContext</code> object with which this |
| * <code>ServiceTracker</code> object was created, passing the specified |
| * <code>ServiceReference</code> object. |
| * <p> |
| * This method can be overridden in a subclass. If the default |
| * implementation of <code>addingService</code> method was used, this |
| * method must unget the service. |
| * |
| * @param reference Reference to removed service. |
| * @param service The service object for the removed service. |
| * @see ServiceTrackerCustomizer |
| */ |
| public void removedService(ServiceReference reference, Object service) { |
| context.ungetService(reference); |
| } |
| |
| /** |
| * Wait for at least one service to be tracked by this |
| * <code>ServiceTracker</code> object. |
| * <p> |
| * It is strongly recommended that <code>waitForService</code> is not used |
| * during the calling of the <code>BundleActivator</code> methods. |
| * <code>BundleActivator</code> methods are expected to complete in a |
| * short period of time. |
| * |
| * @param timeout time interval in milliseconds to wait. If zero, the method |
| * will wait indefinately. |
| * @return Returns the result of <code>getService()</code>. |
| * @throws InterruptedException If another thread has interrupted the |
| * current thread. |
| * @throws IllegalArgumentException If the value of timeout is negative. |
| */ |
| public Object waitForService(long timeout) throws InterruptedException { |
| if (timeout < 0) { |
| throw new IllegalArgumentException("timeout value is negative"); //$NON-NLS-1$ |
| } |
| Object object = getService(); |
| while (object == null) { |
| Tracked tracked = this.tracked; /* |
| * use local var since we are not |
| * synchronized |
| */ |
| if (tracked == null) { /* if ServiceTracker is not open */ |
| return null; |
| } |
| synchronized (tracked) { |
| if (tracked.size() == 0) { |
| tracked.wait(timeout); |
| } |
| } |
| object = getService(); |
| if (timeout > 0) { |
| return object; |
| } |
| } |
| return object; |
| } |
| |
| /** |
| * Return an array of <code>ServiceReference</code> objects for all |
| * services being tracked by this <code>ServiceTracker</code> object. |
| * |
| * @return Array of <code>ServiceReference</code> objects or |
| * <code>null</code> if no service are being tracked. |
| */ |
| public ServiceReference[] getServiceReferences() { |
| Tracked tracked = this.tracked; /* |
| * use local var since we are not |
| * synchronized |
| */ |
| if (tracked == null) { /* if ServiceTracker is not open */ |
| return null; |
| } |
| synchronized (tracked) { |
| int length = tracked.size(); |
| if (length == 0) { |
| return null; |
| } |
| ServiceReference[] references = new ServiceReference[length]; |
| Enumeration keys = tracked.keys(); |
| for (int i = 0; i < length; i++) { |
| references[i] = (ServiceReference) keys.nextElement(); |
| } |
| return references; |
| } |
| } |
| |
| /** |
| * Returns a <code>ServiceReference</code> object for one of the services |
| * being tracked by this <code>ServiceTracker</code> object. |
| * |
| * <p> |
| * If multiple services are being tracked, the service with the highest |
| * ranking (as specified in its <code>service.ranking</code> property) is |
| * returned. |
| * |
| * <p> |
| * If there is a tie in ranking, the service with the lowest service ID (as |
| * specified in its <code>service.id</code> property); that is, the |
| * service that was registered first is returned. |
| * <p> |
| * This is the same algorithm used by |
| * <code>BundleContext.getServiceReference</code>. |
| * |
| * @return <code>ServiceReference</code> object or <code>null</code> if |
| * no service is being tracked. |
| * @since 1.1 |
| */ |
| public ServiceReference getServiceReference() { |
| ServiceReference reference = cachedReference; |
| if (reference != null) { |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.getServiceReference[cached]: " + filter); //$NON-NLS-1$ |
| } |
| return reference; |
| } |
| if (DEBUG) { |
| System.out.println("ServiceTracker.getServiceReference: " + filter); //$NON-NLS-1$ |
| } |
| ServiceReference[] references = getServiceReferences(); |
| int length = (references == null) ? 0 : references.length; |
| if (length == 0) /* if no service is being tracked */ |
| { |
| return null; |
| } |
| int index = 0; |
| if (length > 1) /* if more than one service, select highest ranking */ |
| { |
| int rankings[] = new int[length]; |
| int count = 0; |
| int maxRanking = Integer.MIN_VALUE; |
| for (int i = 0; i < length; i++) { |
| Object property = references[i] |
| .getProperty(Constants.SERVICE_RANKING); |
| int ranking = (property instanceof Integer) ? ((Integer) property) |
| .intValue() |
| : 0; |
| rankings[i] = ranking; |
| if (ranking > maxRanking) { |
| index = i; |
| maxRanking = ranking; |
| count = 1; |
| } |
| else { |
| if (ranking == maxRanking) { |
| count++; |
| } |
| } |
| } |
| if (count > 1) /* if still more than one service, select lowest id */ |
| { |
| long minId = Long.MAX_VALUE; |
| for (int i = 0; i < length; i++) { |
| if (rankings[i] == maxRanking) { |
| long id = ((Long) (references[i] |
| .getProperty(Constants.SERVICE_ID))) |
| .longValue(); |
| if (id < minId) { |
| index = i; |
| minId = id; |
| } |
| } |
| } |
| } |
| } |
| return cachedReference = references[index]; |
| } |
| |
| /** |
| * Returns the service object for the specified |
| * <code>ServiceReference</code> object if the referenced service is being |
| * tracked by this <code>ServiceTracker</code> object. |
| * |
| * @param reference Reference to the desired service. |
| * @return Service object or <code>null</code> if the service referenced |
| * by the specified <code>ServiceReference</code> object is not |
| * being tracked. |
| */ |
| public Object getService(ServiceReference reference) { |
| Tracked tracked = this.tracked; /* |
| * use local var since we are not |
| * synchronized |
| */ |
| if (tracked == null) { /* if ServiceTracker is not open */ |
| return null; |
| } |
| synchronized (tracked) { |
| return tracked.get(reference); |
| } |
| } |
| |
| /** |
| * Return an array of service objects for all services being tracked by this |
| * <code>ServiceTracker</code> object. |
| * |
| * @return Array of service objects or <code>null</code> if no service are |
| * being tracked. |
| */ |
| public Object[] getServices() { |
| Tracked tracked = this.tracked; /* |
| * use local var since we are not |
| * synchronized |
| */ |
| if (tracked == null) { /* if ServiceTracker is not open */ |
| return null; |
| } |
| synchronized (tracked) { |
| ServiceReference[] references = getServiceReferences(); |
| int length = (references == null) ? 0 : references.length; |
| if (length == 0) { |
| return null; |
| } |
| Object[] objects = new Object[length]; |
| for (int i = 0; i < length; i++) { |
| objects[i] = getService(references[i]); |
| } |
| return objects; |
| } |
| } |
| |
| /** |
| * Returns a service object for one of the services being tracked by this |
| * <code>ServiceTracker</code> object. |
| * |
| * <p> |
| * If any services are being tracked, this method returns the result of |
| * calling <code>getService(getServiceReference())</code>. |
| * |
| * @return Service object or <code>null</code> if no service is being |
| * tracked. |
| */ |
| public Object getService() { |
| Object service = cachedService; |
| if (service != null) { |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.getService[cached]: " + filter); //$NON-NLS-1$ |
| } |
| return service; |
| } |
| if (DEBUG) { |
| System.out.println("ServiceTracker.getService: " + filter); //$NON-NLS-1$ |
| } |
| ServiceReference reference = getServiceReference(); |
| if (reference == null) { |
| return null; |
| } |
| return cachedService = getService(reference); |
| } |
| |
| /** |
| * Remove a service from this <code>ServiceTracker</code> object. |
| * |
| * The specified service will be removed from this |
| * <code>ServiceTracker</code> object. If the specified service was being |
| * tracked then the <code>ServiceTrackerCustomizer.removedService</code> |
| * method will be called for that service. |
| * |
| * @param reference Reference to the service to be removed. |
| */ |
| public void remove(ServiceReference reference) { |
| Tracked tracked = this.tracked; /* |
| * use local var since we are not |
| * synchronized |
| */ |
| if (tracked == null) { /* if ServiceTracker is not open */ |
| return; |
| } |
| tracked.untrack(reference); |
| } |
| |
| /** |
| * Return the number of services being tracked by this |
| * <code>ServiceTracker</code> object. |
| * |
| * @return Number of services being tracked. |
| */ |
| public int size() { |
| Tracked tracked = this.tracked; /* |
| * use local var since we are not |
| * synchronized |
| */ |
| if (tracked == null) { /* if ServiceTracker is not open */ |
| return 0; |
| } |
| return tracked.size(); |
| } |
| |
| /** |
| * Returns the tracking count for this <code>ServiceTracker</code> object. |
| * |
| * The tracking count is initialized to 0 when this |
| * <code>ServiceTracker</code> object is opened. Every time a service is |
| * added, modified or removed from this <code>ServiceTracker</code> object |
| * the tracking count is incremented. |
| * |
| * <p> |
| * The tracking count can be used to determine if this |
| * <code>ServiceTracker</code> object has added, modified or removed a |
| * service by comparing a tracking count value previously collected with the |
| * current tracking count value. If the value has not changed, then no |
| * service has been added, modified or removed from this |
| * <code>ServiceTracker</code> object since the previous tracking count |
| * was collected. |
| * |
| * @since 1.2 |
| * @return The tracking count for this <code>ServiceTracker</code> object |
| * or -1 if this <code>ServiceTracker</code> object is not open. |
| */ |
| public int getTrackingCount() { |
| return trackingCount; |
| } |
| |
| /** |
| * Called by the Tracked object whenever the set of tracked services is |
| * modified. Increments the tracking count and clears the cache. |
| * |
| * @GuardedBy tracked |
| */ |
| /* |
| * This method must not be synchronized since it is called by Tracked while |
| * Tracked is synchronized. We don't want synchronization interactions |
| * between the ServiceListener thread and the user thread. |
| */ |
| void modified() { |
| trackingCount++; /* increment modification count */ |
| cachedReference = null; /* clear cached value */ |
| cachedService = null; /* clear cached value */ |
| if (DEBUG) { |
| System.out.println("ServiceTracker.modified: " + filter); //$NON-NLS-1$ |
| } |
| } |
| |
| /** |
| * Inner class to track services. If a <code>ServiceTracker</code> object |
| * is reused (closed then reopened), then a new Tracked object is used. This |
| * class is a hashtable mapping <code>ServiceReference</code> object -> |
| * customized Object. This class is the <code>ServiceListener</code> |
| * object for the tracker. This class is used to synchronize access to the |
| * tracked services. This is not a public class. It is only for use by the |
| * implementation of the <code>ServiceTracker</code> class. |
| * |
| * @ThreadSafe |
| */ |
| class Tracked extends Hashtable implements ServiceListener { |
| static final long serialVersionUID = -7420065199791006079L; |
| /** |
| * List of ServiceReferences in the process of being added. This is used |
| * to deal with nesting of ServiceEvents. Since ServiceEvents are |
| * synchronously delivered, ServiceEvents can be nested. For example, |
| * when processing the adding of a service and the customizer causes the |
| * service to be unregistered, notification to the nested call to |
| * untrack that the service was unregistered can be made to the track |
| * method. |
| * |
| * Since the ArrayList implementation is not synchronized, all access to |
| * this list must be protected by the same synchronized object for |
| * thread-safety. |
| * |
| * @GuardedBy this |
| */ |
| private final ArrayList adding; |
| |
| /** |
| * true if the tracked object is closed. |
| * |
| * This field is volatile because it is set by one thread and read by |
| * another. |
| */ |
| private volatile boolean closed; |
| |
| /** |
| * Initial list of ServiceReferences for the tracker. This is used to |
| * correctly process the initial services which could become |
| * unregistered before they are tracked. This is necessary since the |
| * initial set of tracked services are not "announced" by ServiceEvents |
| * and therefore the ServiceEvent for unregistration could be delivered |
| * before we track the service. |
| * |
| * A service must not be in both the initial and adding lists at the |
| * same time. A service must be moved from the initial list to the |
| * adding list "atomically" before we begin tracking it. |
| * |
| * Since the LinkedList implementation is not synchronized, all access |
| * to this list must be protected by the same synchronized object for |
| * thread-safety. |
| * |
| * @GuardedBy this |
| */ |
| private final LinkedList initial; |
| |
| /** |
| * Tracked constructor. |
| */ |
| protected Tracked() { |
| super(); |
| closed = false; |
| adding = new ArrayList(6); |
| initial = new LinkedList(); |
| } |
| |
| /** |
| * Set initial list of services into tracker before ServiceEvents begin |
| * to be received. |
| * |
| * This method must be called from ServiceTracker.open while |
| * synchronized on this object in the same synchronized block as the |
| * addServiceListener call. |
| * |
| * @param references The initial list of services to be tracked. |
| * @GuardedBy this |
| */ |
| protected void setInitialServices(ServiceReference[] references) { |
| if (references == null) { |
| return; |
| } |
| int size = references.length; |
| for (int i = 0; i < size; i++) { |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.setInitialServices: " + references[i]); //$NON-NLS-1$ |
| } |
| initial.add(references[i]); |
| } |
| } |
| |
| /** |
| * Track the initial list of services. This is called after |
| * ServiceEvents can begin to be received. |
| * |
| * This method must be called from ServiceTracker.open while not |
| * synchronized on this object after the addServiceListener call. |
| * |
| */ |
| protected void trackInitialServices() { |
| while (true) { |
| ServiceReference reference; |
| synchronized (this) { |
| if (initial.size() == 0) { |
| /* |
| * if there are no more inital services |
| */ |
| return; /* we are done */ |
| } |
| /* |
| * move the first service from the initial list to the |
| * adding list within this synchronized block. |
| */ |
| reference = (ServiceReference) initial.removeFirst(); |
| if (this.get(reference) != null) { |
| /* if we are already tracking this service */ |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.trackInitialServices[already tracked]: " + reference); //$NON-NLS-1$ |
| } |
| continue; /* skip this service */ |
| } |
| if (adding.contains(reference)) { |
| /* |
| * if this service is already in the process of being |
| * added. |
| */ |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.trackInitialServices[already adding]: " + reference); //$NON-NLS-1$ |
| } |
| continue; /* skip this service */ |
| } |
| adding.add(reference); |
| } |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.trackInitialServices: " + reference); //$NON-NLS-1$ |
| } |
| trackAdding(reference); /* |
| * Begin tracking it. We call |
| * trackAdding since we have already put |
| * the reference in the adding list. |
| */ |
| } |
| } |
| |
| /** |
| * Called by the owning <code>ServiceTracker</code> object when it is |
| * closed. |
| */ |
| protected void close() { |
| closed = true; |
| } |
| |
| /** |
| * <code>ServiceListener</code> method for the |
| * <code>ServiceTracker</code> class. This method must NOT be |
| * synchronized to avoid deadlock potential. |
| * |
| * @param event <code>ServiceEvent</code> object from the framework. |
| */ |
| public void serviceChanged(ServiceEvent event) { |
| /* |
| * Check if we had a delayed call (which could happen when we |
| * close). |
| */ |
| if (closed) { |
| return; |
| } |
| ServiceReference reference = event.getServiceReference(); |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.serviceChanged[" + event.getType() + "]: " + reference); //$NON-NLS-1$ //$NON-NLS-2$ |
| } |
| |
| switch (event.getType()) { |
| case ServiceEvent.REGISTERED : |
| case ServiceEvent.MODIFIED : |
| if (listenerFilter != null) { // constructor supplied |
| // filter |
| track(reference); |
| /* |
| * If the customizer throws an unchecked exception, it |
| * is safe to let it propagate |
| */ |
| } |
| else { // user supplied filter |
| if (filter.match(reference)) { |
| track(reference); |
| /* |
| * If the customizer throws an unchecked exception, |
| * it is safe to let it propagate |
| */ |
| } |
| else { |
| untrack(reference); |
| /* |
| * If the customizer throws an unchecked exception, |
| * it is safe to let it propagate |
| */ |
| } |
| } |
| break; |
| case ServiceEvent.UNREGISTERING : |
| untrack(reference); |
| /* |
| * If the customizer throws an unchecked exception, it is |
| * safe to let it propagate |
| */ |
| break; |
| } |
| } |
| |
| /** |
| * Begin to track the referenced service. |
| * |
| * @param reference Reference to a service to be tracked. |
| */ |
| private void track(ServiceReference reference) { |
| Object object; |
| synchronized (this) { |
| object = this.get(reference); |
| } |
| if (object != null) /* we are already tracking the service */ |
| { |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.track[modified]: " + reference); //$NON-NLS-1$ |
| } |
| synchronized (this) { |
| modified(); /* increment modification count */ |
| } |
| /* Call customizer outside of synchronized region */ |
| customizer.modifiedService(reference, object); |
| /* |
| * If the customizer throws an unchecked exception, it is safe |
| * to let it propagate |
| */ |
| return; |
| } |
| synchronized (this) { |
| if (adding.contains(reference)) { /* |
| * if this service is |
| * already in the process of |
| * being added. |
| */ |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.track[already adding]: " + reference); //$NON-NLS-1$ |
| } |
| return; |
| } |
| adding.add(reference); /* mark this service is being added */ |
| } |
| |
| trackAdding(reference); /* |
| * call trackAdding now that we have put the |
| * reference in the adding list |
| */ |
| } |
| |
| /** |
| * Common logic to add a service to the tracker used by track and |
| * trackInitialServices. The specified reference must have been placed |
| * in the adding list before calling this method. |
| * |
| * @param reference Reference to a service to be tracked. |
| */ |
| private void trackAdding(ServiceReference reference) { |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.trackAdding: " + reference); //$NON-NLS-1$ |
| } |
| Object object = null; |
| boolean becameUntracked = false; |
| /* Call customizer outside of synchronized region */ |
| try { |
| object = customizer.addingService(reference); |
| /* |
| * If the customizer throws an unchecked exception, it will |
| * propagate after the finally |
| */ |
| } |
| finally { |
| boolean needToCallback = false; |
| synchronized (this) { |
| if (adding.remove(reference)) { /* |
| * if the service was not |
| * untracked during the |
| * customizer callback |
| */ |
| if (object != null) { |
| this.put(reference, object); |
| modified(); /* increment modification count */ |
| notifyAll(); /* |
| * notify any waiters in |
| * waitForService |
| */ |
| // marrs: extra callback added, will be invoked after |
| // the synchronized block |
| needToCallback = true; |
| } |
| } |
| else { |
| becameUntracked = true; |
| } |
| } |
| if (needToCallback) { |
| customizer.addedService(reference, object); |
| } |
| } |
| /* |
| * The service became untracked during the customizer callback. |
| */ |
| if (becameUntracked) { |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.trackAdding[removed]: " + reference); //$NON-NLS-1$ |
| } |
| /* Call customizer outside of synchronized region */ |
| customizer.removedService(reference, object); |
| /* |
| * If the customizer throws an unchecked exception, it is safe |
| * to let it propagate |
| */ |
| } |
| } |
| |
| /** |
| * Discontinue tracking the referenced service. |
| * |
| * @param reference Reference to the tracked service. |
| */ |
| protected void untrack(ServiceReference reference) { |
| Object object; |
| synchronized (this) { |
| if (initial.remove(reference)) { /* |
| * if this service is |
| * already in the list of |
| * initial references to |
| * process |
| */ |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.untrack[removed from initial]: " + reference); //$NON-NLS-1$ |
| } |
| return; /* |
| * we have removed it from the list and it will not |
| * be processed |
| */ |
| } |
| |
| if (adding.remove(reference)) { /* |
| * if the service is in the |
| * process of being added |
| */ |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.untrack[being added]: " + reference); //$NON-NLS-1$ |
| } |
| return; /* |
| * in case the service is untracked while in the |
| * process of adding |
| */ |
| } |
| object = this.remove(reference); /* |
| * must remove from tracker |
| * before calling customizer |
| * callback |
| */ |
| if (object == null) { /* are we actually tracking the service */ |
| return; |
| } |
| modified(); /* increment modification count */ |
| } |
| if (DEBUG) { |
| System.out |
| .println("ServiceTracker.Tracked.untrack[removed]: " + reference); //$NON-NLS-1$ |
| } |
| /* Call customizer outside of synchronized region */ |
| customizer.removedService(reference, object); |
| /* |
| * If the customizer throws an unchecked exception, it is safe to |
| * let it propagate |
| */ |
| } |
| } |
| |
| /** |
| * Subclass of Tracked which implements the AllServiceListener interface. |
| * This class is used by the ServiceTracker if open is called with true. |
| * |
| * @since 1.3 |
| * @ThreadSafe |
| */ |
| class AllTracked extends Tracked implements AllServiceListener { |
| static final long serialVersionUID = 4050764875305137716L; |
| |
| /** |
| * AllTracked constructor. |
| */ |
| protected AllTracked() { |
| super(); |
| } |
| } |
| |
| public void addedService(ServiceReference ref, Object service) { |
| // do nothing |
| } |
| } |
