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Posted to commits@felix.apache.org by ri...@apache.org on 2006/03/16 16:57:43 UTC
svn commit: r386363 [10/10] - in
/incubator/felix/trunk/org.osgi/src/main/java/org/osgi: framework/
service/condpermadmin/ service/packageadmin/ service/startlevel/
service/url/ util/tracker/
Modified: incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTracker.java
URL: http://svn.apache.org/viewcvs/incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTracker.java?rev=386363&r1=386362&r2=386363&view=diff
==============================================================================
--- incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTracker.java (original)
+++ incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTracker.java Thu Mar 16 07:57:37 2006
@@ -1,982 +1,1139 @@
-/*
- * $Header: /cvshome/build/org.osgi.util.tracker/src/org/osgi/util/tracker/ServiceTracker.java,v 1.13 2005/05/13 20:33:35 hargrave Exp $
- *
- * Copyright (c) OSGi Alliance (2000, 2005). All Rights Reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Public License v1.0 which accompanies this
- * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html.
- */
-
-package org.osgi.util.tracker;
-
-import java.util.*;
-
-import org.osgi.framework.*;
-
-/**
- * The <code>ServiceTracker</code> class simplifies using services from the
- * Framework's service registry.
- * <p>
- * A <code>ServiceTracker</code> object is constructed with search criteria
- * and a <code>ServiceTrackerCustomizer</code> object. A
- * <code>ServiceTracker</code> object can use the
- * <code>ServiceTrackerCustomizer</code> object to customize the service
- * objects to be tracked. The <code>ServiceTracker</code> object can then be
- * opened to begin tracking all services in the Framework's service registry
- * that match the specified search criteria. The <code>ServiceTracker</code>
- * object correctly handles all of the details of listening to
- * <code>ServiceEvent</code> objects and getting and ungetting services.
- * <p>
- * The <code>getServiceReferences</code> method can be called to get
- * references to the services being tracked. The <code>getService</code> and
- * <code>getServices</code> methods can be called to get the service objects
- * for the tracked service.
- *
- * @version $Revision: 1.13 $
- */
-public class ServiceTracker implements ServiceTrackerCustomizer {
- /* set this to true to compile in debug messages */
- static final boolean DEBUG = false;
- /**
- * Bundle context this <code>ServiceTracker</code> object is tracking
- * against.
- */
- 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.
- */
- private 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.
- */
- private 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 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.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 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;
- ServiceReference[] references;
- synchronized (tracked) {
- try {
- context.addServiceListener(tracked, listenerFilter);
- 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);
- }
- }
- }
- catch (InvalidSyntaxException e) {
- throw new RuntimeException(
- "unexpected InvalidSyntaxException: " + e.getMessage()); //$NON-NLS-1$
- }
- }
- /* Call tracked outside of synchronized region */
- if (references != null) {
- int length = references.length;
- for (int i = 0; i < length; i++) {
- ServiceReference reference = references[i];
- /* if the service is still registered */
- if (reference.getBundle() != null) {
- tracked.track(reference);
- }
- }
- }
- }
-
- /**
- * 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 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 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 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 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.
- */
- /*
- * 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.
- */
- private 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.
- *
- */
- class Tracked extends Hashtable implements ServiceListener {
- static final long serialVersionUID = -7420065199791006079L;
- /**
- * List of ServiceReferences in the process of being added.
- */
- private 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;
-
- /**
- * Tracked constructor.
- */
- protected Tracked() {
- super();
- closed = false;
- adding = new ArrayList(6);
- }
-
- /**
- * 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();
- 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.
- */
- protected 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); //$NON-NLS-1$
- }
- /* 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 */
- }
- if (DEBUG) {
- System.out
- .println("ServiceTracker.Tracked.track[adding]: " + reference); //$NON-NLS-1$
- }
- 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 {
- 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();
- }
- }
- else {
- becameUntracked = true;
- }
- }
- }
- /*
- * The service became untracked during the customizer callback.
- */
- if (becameUntracked) {
- if (DEBUG) {
- System.out
- .println("ServiceTracker.Tracked.track[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 (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 isAllServiceTracker returns
- * true.
- *
- * @since 1.3
- */
- class AllTracked extends Tracked implements AllServiceListener {
- static final long serialVersionUID = 4050764875305137716L;
-
- /**
- * Tracked constructor.
- */
- protected AllTracked() {
- super();
- }
- }
+/*
+ * $Header: /cvshome/build/org.osgi.util.tracker/src/org/osgi/util/tracker/ServiceTracker.java,v 1.18 2006/03/14 01:20:01 hargrave Exp $
+ *
+ * Copyright (c) OSGi Alliance (2000, 2005). All Rights Reserved.
+ *
+ * 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.osgi.util.tracker;
+
+import java.util.*;
+
+import org.osgi.framework.*;
+
+/**
+ * The <code>ServiceTracker</code> class simplifies using services from the
+ * Framework's service registry.
+ * <p>
+ * A <code>ServiceTracker</code> object is constructed with search criteria
+ * and a <code>ServiceTrackerCustomizer</code> object. A
+ * <code>ServiceTracker</code> object can use the
+ * <code>ServiceTrackerCustomizer</code> object to customize the service
+ * objects to be tracked. The <code>ServiceTracker</code> object can then be
+ * opened to begin tracking all services in the Framework's service registry
+ * that match the specified search criteria. The <code>ServiceTracker</code>
+ * object correctly handles all of the details of listening to
+ * <code>ServiceEvent</code> objects and getting and ungetting services.
+ * <p>
+ * The <code>getServiceReferences</code> method can be called to get
+ * references to the services being tracked. The <code>getService</code> and
+ * <code>getServices</code> methods can be called to get the service objects
+ * for the tracked service.
+ *
+ * @version $Revision: 1.18 $
+ */
+public class ServiceTracker implements ServiceTrackerCustomizer {
+ /* set this to true to compile in debug messages */
+ static final boolean DEBUG = false;
+ /**
+ * Bundle context this <code>ServiceTracker</code> object is tracking
+ * against.
+ */
+ 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 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.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 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 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 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 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.
+ */
+ /*
+ * 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); //$NON-NLS-1$
+ }
+ }
+
+ /**
+ * Finalize. This method no longer performs any function but it kept to
+ * maintain binary compatibility with prior versions of this class.
+ */
+ protected void finalize() throws Throwable {
+ }
+
+ /**
+ * 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.
+ *
+ */
+ 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.
+ */
+ private 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.
+ */
+ private 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.
+ */
+ 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.
+ */
+ protected 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); //$NON-NLS-1$
+ }
+ /* 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 {
+ 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
+ */
+ }
+ }
+ else {
+ becameUntracked = true;
+ }
+ }
+ }
+ /*
+ * 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
+ */
+ class AllTracked extends Tracked implements AllServiceListener {
+ static final long serialVersionUID = 4050764875305137716L;
+
+ /**
+ * AllTracked constructor.
+ */
+ protected AllTracked() {
+ super();
+ }
+ }
}
Modified: incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTrackerCustomizer.java
URL: http://svn.apache.org/viewcvs/incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTrackerCustomizer.java?rev=386363&r1=386362&r2=386363&view=diff
==============================================================================
--- incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTrackerCustomizer.java (original)
+++ incubator/felix/trunk/org.osgi/src/main/java/org/osgi/util/tracker/ServiceTrackerCustomizer.java Thu Mar 16 07:57:37 2006
@@ -1,84 +1,92 @@
-/*
- * $Header: /cvshome/build/org.osgi.util.tracker/src/org/osgi/util/tracker/ServiceTrackerCustomizer.java,v 1.7 2005/05/13 20:33:35 hargrave Exp $
- *
- * Copyright (c) OSGi Alliance (2000, 2005). All Rights Reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Public License v1.0 which accompanies this
- * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html.
- */
-
-package org.osgi.util.tracker;
-
-import org.osgi.framework.ServiceReference;
-
-/**
- * The <code>ServiceTrackerCustomizer</code> interface allows a
- * <code>ServiceTracker</code> object to customize the service objects that are
- * tracked. The <code>ServiceTrackerCustomizer</code> object is called when a
- * service is being added to the <code>ServiceTracker</code> object. The
- * <code>ServiceTrackerCustomizer</code> can then return an object for the tracked
- * service. The <code>ServiceTrackerCustomizer</code> object is also called when a
- * tracked service is modified or has been removed from the
- * <code>ServiceTracker</code> object.
- *
- * <p>
- * The methods in this interface may be called as the result of a
- * <code>ServiceEvent</code> being received by a <code>ServiceTracker</code> object.
- * Since <code>ServiceEvent</code> s are synchronously delivered by the Framework,
- * it is highly recommended that implementations of these methods do not
- * register (<code>BundleContext.registerService</code>), modify (
- * <code>ServiceRegistration.setProperties</code>) or unregister (
- * <code>ServiceRegistration.unregister</code>) a service while being
- * synchronized on any object.
- *
- * @version $Revision: 1.7 $
- */
-public interface ServiceTrackerCustomizer {
- /**
- * A service is being added to the <code>ServiceTracker</code> object.
- *
- * <p>
- * This method is called before a service which matched the search
- * parameters of the <code>ServiceTracker</code> object is added to it. This
- * method should return the service object to be tracked for this
- * <code>ServiceReference</code> object. The returned service object is stored
- * in the <code>ServiceTracker</code> object and is available from the
- * <code>getService</code> and <code>getServices</code> methods.
- *
- * @param reference Reference to service being added to the
- * <code>ServiceTracker</code> object.
- * @return The service object to be tracked for the
- * <code>ServiceReference</code> object or <code>null</code> if the
- * <code>ServiceReference</code> object should not be tracked.
- */
- public abstract Object addingService(ServiceReference reference);
-
- /**
- * A service tracked by the <code>ServiceTracker</code> object has been
- * modified.
- *
- * <p>
- * This method is called when a service being tracked by the
- * <code>ServiceTracker</code> object has had it properties modified.
- *
- * @param reference Reference to service that has been modified.
- * @param service The service object for the modified service.
- */
- public abstract void modifiedService(ServiceReference reference,
- Object service);
-
- /**
- * A service tracked by the <code>ServiceTracker</code> object has been
- * removed.
- *
- * <p>
- * This method is called after a service is no longer being tracked by the
- * <code>ServiceTracker</code> object.
- *
- * @param reference Reference to service that has been removed.
- * @param service The service object for the removed service.
- */
- public abstract void removedService(ServiceReference reference,
- Object service);
+/*
+ * $Header: /cvshome/build/org.osgi.util.tracker/src/org/osgi/util/tracker/ServiceTrackerCustomizer.java,v 1.9 2006/03/14 01:20:01 hargrave Exp $
+ *
+ * Copyright (c) OSGi Alliance (2000, 2005). All Rights Reserved.
+ *
+ * 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.osgi.util.tracker;
+
+import org.osgi.framework.ServiceReference;
+
+/**
+ * The <code>ServiceTrackerCustomizer</code> interface allows a
+ * <code>ServiceTracker</code> object to customize the service objects that are
+ * tracked. The <code>ServiceTrackerCustomizer</code> object is called when a
+ * service is being added to the <code>ServiceTracker</code> object. The
+ * <code>ServiceTrackerCustomizer</code> can then return an object for the tracked
+ * service. The <code>ServiceTrackerCustomizer</code> object is also called when a
+ * tracked service is modified or has been removed from the
+ * <code>ServiceTracker</code> object.
+ *
+ * <p>
+ * The methods in this interface may be called as the result of a
+ * <code>ServiceEvent</code> being received by a <code>ServiceTracker</code> object.
+ * Since <code>ServiceEvent</code> s are synchronously delivered by the Framework,
+ * it is highly recommended that implementations of these methods do not
+ * register (<code>BundleContext.registerService</code>), modify (
+ * <code>ServiceRegistration.setProperties</code>) or unregister (
+ * <code>ServiceRegistration.unregister</code>) a service while being
+ * synchronized on any object.
+ *
+ * @version $Revision: 1.9 $
+ */
+public interface ServiceTrackerCustomizer {
+ /**
+ * A service is being added to the <code>ServiceTracker</code> object.
+ *
+ * <p>
+ * This method is called before a service which matched the search
+ * parameters of the <code>ServiceTracker</code> object is added to it. This
+ * method should return the service object to be tracked for this
+ * <code>ServiceReference</code> object. The returned service object is stored
+ * in the <code>ServiceTracker</code> object and is available from the
+ * <code>getService</code> and <code>getServices</code> methods.
+ *
+ * @param reference Reference to service being added to the
+ * <code>ServiceTracker</code> object.
+ * @return The service object to be tracked for the
+ * <code>ServiceReference</code> object or <code>null</code> if the
+ * <code>ServiceReference</code> object should not be tracked.
+ */
+ public Object addingService(ServiceReference reference);
+
+ /**
+ * A service tracked by the <code>ServiceTracker</code> object has been
+ * modified.
+ *
+ * <p>
+ * This method is called when a service being tracked by the
+ * <code>ServiceTracker</code> object has had it properties modified.
+ *
+ * @param reference Reference to service that has been modified.
+ * @param service The service object for the modified service.
+ */
+ public void modifiedService(ServiceReference reference,
+ Object service);
+
+ /**
+ * A service tracked by the <code>ServiceTracker</code> object has been
+ * removed.
+ *
+ * <p>
+ * This method is called after a service is no longer being tracked by the
+ * <code>ServiceTracker</code> object.
+ *
+ * @param reference Reference to service that has been removed.
+ * @param service The service object for the removed service.
+ */
+ public void removedService(ServiceReference reference,
+ Object service);
}