| /* |
| * Copyright (c) OSGi Alliance (2007, 2013). 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.HashMap; |
| import java.util.Map; |
| import org.osgi.framework.Bundle; |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.BundleEvent; |
| import org.osgi.framework.SynchronousBundleListener; |
| |
| /** |
| * The {@code BundleTracker} class simplifies tracking bundles much like the |
| * {@code ServiceTracker} simplifies tracking services. |
| * <p> |
| * A {@code BundleTracker} is constructed with state criteria and a |
| * {@code BundleTrackerCustomizer} object. A {@code BundleTracker} can use the |
| * {@code BundleTrackerCustomizer} to select which bundles are tracked and to |
| * create a customized object to be tracked with the bundle. The |
| * {@code BundleTracker} can then be opened to begin tracking all bundles whose |
| * state matches the specified state criteria. |
| * <p> |
| * The {@code getBundles} method can be called to get the {@code Bundle} objects |
| * of the bundles being tracked. The {@code getObject} method can be called to |
| * get the customized object for a tracked bundle. |
| * <p> |
| * The {@code BundleTracker} class is thread-safe. It does not call a |
| * {@code BundleTrackerCustomizer} while holding any locks. |
| * {@code BundleTrackerCustomizer} implementations must also be thread-safe. |
| * |
| * @param <T> The type of the tracked object. |
| * @ThreadSafe |
| * @author $Id: 9a1b57568a8be735292700584f4eb936fc80f2ff $ |
| * @since 1.4 |
| */ |
| public class BundleTracker<T> implements BundleTrackerCustomizer<T> { |
| /* set this to true to compile in debug messages */ |
| static final boolean DEBUG = false; |
| |
| /** |
| * The Bundle Context used by this {@code BundleTracker}. |
| */ |
| protected final BundleContext context; |
| |
| /** |
| * The {@code BundleTrackerCustomizer} object for this tracker. |
| */ |
| final BundleTrackerCustomizer<T> customizer; |
| |
| /** |
| * Tracked bundles: {@code Bundle} object -> customized Object and |
| * {@code BundleListener} object |
| */ |
| private volatile Tracked tracked; |
| |
| /** |
| * Accessor method for the current Tracked object. This method is only |
| * intended to be used by the unsynchronized methods which do not modify the |
| * tracked field. |
| * |
| * @return The current Tracked object. |
| */ |
| private Tracked tracked() { |
| return tracked; |
| } |
| |
| /** |
| * State mask for bundles being tracked. This field contains the ORed values |
| * of the bundle states being tracked. |
| */ |
| final int mask; |
| |
| /** |
| * Create a {@code BundleTracker} for bundles whose state is present in the |
| * specified state mask. |
| * |
| * <p> |
| * Bundles whose state is present on the specified state mask will be |
| * tracked by this {@code BundleTracker}. |
| * |
| * @param context The {@code BundleContext} against which the tracking is |
| * done. |
| * @param stateMask The bit mask of the {@code OR}ing of the bundle states |
| * to be tracked. |
| * @param customizer The customizer object to call when bundles are added, |
| * modified, or removed in this {@code BundleTracker}. If customizer |
| * is {@code null}, then this {@code BundleTracker} will be used as |
| * the {@code BundleTrackerCustomizer} and this {@code BundleTracker} |
| * will call the {@code BundleTrackerCustomizer} methods on itself. |
| * @see Bundle#getState() |
| */ |
| public BundleTracker(BundleContext context, int stateMask, BundleTrackerCustomizer<T> customizer) { |
| this.context = context; |
| this.mask = stateMask; |
| this.customizer = (customizer == null) ? this : customizer; |
| } |
| |
| /** |
| * Open this {@code BundleTracker} and begin tracking bundles. |
| * |
| * <p> |
| * Bundle which match the state criteria specified when this |
| * {@code BundleTracker} was created are now tracked by this |
| * {@code BundleTracker}. |
| * |
| * @throws java.lang.IllegalStateException If the {@code BundleContext} with |
| * which this {@code BundleTracker} was created is no longer valid. |
| * @throws java.lang.SecurityException If the caller and this class do not |
| * have the appropriate |
| * {@code AdminPermission[context bundle,LISTENER]}, and the Java |
| * Runtime Environment supports permissions. |
| */ |
| public void open() { |
| final Tracked t; |
| synchronized (this) { |
| if (tracked != null) { |
| return; |
| } |
| if (DEBUG) { |
| System.out.println("BundleTracker.open"); //$NON-NLS-1$ |
| } |
| t = new Tracked(); |
| synchronized (t) { |
| context.addBundleListener(t); |
| Bundle[] bundles = context.getBundles(); |
| if (bundles != null) { |
| int length = bundles.length; |
| for (int i = 0; i < length; i++) { |
| int state = bundles[i].getState(); |
| if ((state & mask) == 0) { |
| /* null out bundles whose states are not interesting */ |
| bundles[i] = null; |
| } |
| } |
| /* set tracked with the initial bundles */ |
| t.setInitial(bundles); |
| } |
| } |
| tracked = t; |
| } |
| /* Call tracked outside of synchronized region */ |
| t.trackInitial(); /* process the initial references */ |
| } |
| |
| /** |
| * Close this {@code BundleTracker}. |
| * |
| * <p> |
| * This method should be called when this {@code BundleTracker} should end |
| * the tracking of bundles. |
| * |
| * <p> |
| * This implementation calls {@link #getBundles()} to get the list of |
| * tracked bundles to remove. |
| */ |
| public void close() { |
| final Bundle[] bundles; |
| final Tracked outgoing; |
| synchronized (this) { |
| outgoing = tracked; |
| if (outgoing == null) { |
| return; |
| } |
| if (DEBUG) { |
| System.out.println("BundleTracker.close"); //$NON-NLS-1$ |
| } |
| outgoing.close(); |
| bundles = getBundles(); |
| tracked = null; |
| try { |
| context.removeBundleListener(outgoing); |
| } catch (IllegalStateException e) { |
| /* In case the context was stopped. */ |
| } |
| } |
| if (bundles != null) { |
| for (int i = 0; i < bundles.length; i++) { |
| outgoing.untrack(bundles[i], null); |
| } |
| } |
| } |
| |
| /** |
| * Default implementation of the |
| * {@code BundleTrackerCustomizer.addingBundle} method. |
| * |
| * <p> |
| * This method is only called when this {@code BundleTracker} has been |
| * constructed with a {@code null BundleTrackerCustomizer} argument. |
| * |
| * <p> |
| * This implementation simply returns the specified {@code Bundle}. |
| * |
| * <p> |
| * This method can be overridden in a subclass to customize the object to be |
| * tracked for the bundle being added. |
| * |
| * @param bundle The {@code Bundle} being added to this |
| * {@code BundleTracker} object. |
| * @param event The bundle event which caused this customizer method to be |
| * called or {@code null} if there is no bundle event associated with |
| * the call to this method. |
| * @return The specified bundle. |
| * @see BundleTrackerCustomizer#addingBundle(Bundle, BundleEvent) |
| */ |
| public T addingBundle(Bundle bundle, BundleEvent event) { |
| @SuppressWarnings("unchecked") |
| T result = (T) bundle; |
| return result; |
| } |
| |
| /** |
| * Default implementation of the |
| * {@code BundleTrackerCustomizer.modifiedBundle} method. |
| * |
| * <p> |
| * This method is only called when this {@code BundleTracker} has been |
| * constructed with a {@code null BundleTrackerCustomizer} argument. |
| * |
| * <p> |
| * This implementation does nothing. |
| * |
| * @param bundle The {@code Bundle} whose state has been modified. |
| * @param event The bundle event which caused this customizer method to be |
| * called or {@code null} if there is no bundle event associated with |
| * the call to this method. |
| * @param object The customized object for the specified Bundle. |
| * @see BundleTrackerCustomizer#modifiedBundle(Bundle, BundleEvent, Object) |
| */ |
| public void modifiedBundle(Bundle bundle, BundleEvent event, T object) { |
| /* do nothing */ |
| } |
| |
| /** |
| * Default implementation of the |
| * {@code BundleTrackerCustomizer.removedBundle} method. |
| * |
| * <p> |
| * This method is only called when this {@code BundleTracker} has been |
| * constructed with a {@code null BundleTrackerCustomizer} argument. |
| * |
| * <p> |
| * This implementation does nothing. |
| * |
| * @param bundle The {@code Bundle} being removed. |
| * @param event The bundle event which caused this customizer method to be |
| * called or {@code null} if there is no bundle event associated with |
| * the call to this method. |
| * @param object The customized object for the specified bundle. |
| * @see BundleTrackerCustomizer#removedBundle(Bundle, BundleEvent, Object) |
| */ |
| public void removedBundle(Bundle bundle, BundleEvent event, T object) { |
| /* do nothing */ |
| } |
| |
| /** |
| * Return an array of {@code Bundle}s for all bundles being tracked by this |
| * {@code BundleTracker}. |
| * |
| * @return An array of {@code Bundle}s or {@code null} if no bundles are |
| * being tracked. |
| */ |
| public Bundle[] getBundles() { |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return null; |
| } |
| synchronized (t) { |
| int length = t.size(); |
| if (length == 0) { |
| return null; |
| } |
| return t.copyKeys(new Bundle[length]); |
| } |
| } |
| |
| /** |
| * Returns the customized object for the specified {@code Bundle} if the |
| * specified bundle is being tracked by this {@code BundleTracker}. |
| * |
| * @param bundle The {@code Bundle} being tracked. |
| * @return The customized object for the specified {@code Bundle} or |
| * {@code null} if the specified {@code Bundle} is not being |
| * tracked. |
| */ |
| public T getObject(Bundle bundle) { |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return null; |
| } |
| synchronized (t) { |
| return t.getCustomizedObject(bundle); |
| } |
| } |
| |
| /** |
| * Remove a bundle from this {@code BundleTracker}. |
| * |
| * The specified bundle will be removed from this {@code BundleTracker} . If |
| * the specified bundle was being tracked then the |
| * {@code BundleTrackerCustomizer.removedBundle} method will be called for |
| * that bundle. |
| * |
| * @param bundle The {@code Bundle} to be removed. |
| */ |
| public void remove(Bundle bundle) { |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return; |
| } |
| t.untrack(bundle, null); |
| } |
| |
| /** |
| * Return the number of bundles being tracked by this {@code BundleTracker}. |
| * |
| * @return The number of bundles being tracked. |
| */ |
| public int size() { |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return 0; |
| } |
| synchronized (t) { |
| return t.size(); |
| } |
| } |
| |
| /** |
| * Returns the tracking count for this {@code BundleTracker}. |
| * |
| * The tracking count is initialized to 0 when this {@code BundleTracker} is |
| * opened. Every time a bundle is added, modified or removed from this |
| * {@code BundleTracker} the tracking count is incremented. |
| * |
| * <p> |
| * The tracking count can be used to determine if this {@code BundleTracker} |
| * has added, modified or removed a bundle by comparing a tracking count |
| * value previously collected with the current tracking count value. If the |
| * value has not changed, then no bundle has been added, modified or removed |
| * from this {@code BundleTracker} since the previous tracking count was |
| * collected. |
| * |
| * @return The tracking count for this {@code BundleTracker} or -1 if this |
| * {@code BundleTracker} is not open. |
| */ |
| public int getTrackingCount() { |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return -1; |
| } |
| synchronized (t) { |
| return t.getTrackingCount(); |
| } |
| } |
| |
| /** |
| * Return a {@code Map} with the {@code Bundle}s and customized objects for |
| * all bundles being tracked by this {@code BundleTracker}. |
| * |
| * @return A {@code Map} with the {@code Bundle}s and customized objects for |
| * all services being tracked by this {@code BundleTracker}. If no |
| * bundles are being tracked, then the returned map is empty. |
| * @since 1.5 |
| */ |
| public Map<Bundle, T> getTracked() { |
| Map<Bundle, T> map = new HashMap<Bundle, T>(); |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return map; |
| } |
| synchronized (t) { |
| return t.copyEntries(map); |
| } |
| } |
| |
| /** |
| * Return if this {@code BundleTracker} is empty. |
| * |
| * @return {@code true} if this {@code BundleTracker} is not tracking any |
| * bundles. |
| * @since 1.5 |
| */ |
| public boolean isEmpty() { |
| final Tracked t = tracked(); |
| if (t == null) { /* if BundleTracker is not open */ |
| return true; |
| } |
| synchronized (t) { |
| return t.isEmpty(); |
| } |
| } |
| |
| /** |
| * Inner class which subclasses AbstractTracked. This class is the |
| * {@code SynchronousBundleListener} object for the tracker. |
| * |
| * @ThreadSafe |
| * @since 1.4 |
| */ |
| private final class Tracked extends AbstractTracked<Bundle, T, BundleEvent> implements SynchronousBundleListener { |
| /** |
| * Tracked constructor. |
| */ |
| Tracked() { |
| super(); |
| } |
| |
| /** |
| * {@code BundleListener} method for the {@code BundleTracker} class. |
| * This method must NOT be synchronized to avoid deadlock potential. |
| * |
| * @param event {@code BundleEvent} object from the framework. |
| */ |
| public void bundleChanged(final BundleEvent event) { |
| /* |
| * Check if we had a delayed call (which could happen when we |
| * close). |
| */ |
| if (closed) { |
| return; |
| } |
| final Bundle bundle = event.getBundle(); |
| final int state = bundle.getState(); |
| if (DEBUG) { |
| System.out.println("BundleTracker.Tracked.bundleChanged[" + state + "]: " + bundle); //$NON-NLS-1$ //$NON-NLS-2$ |
| } |
| |
| if ((state & mask) != 0) { |
| track(bundle, event); |
| /* |
| * If the customizer throws an unchecked exception, it is safe |
| * to let it propagate |
| */ |
| } else { |
| untrack(bundle, event); |
| /* |
| * If the customizer throws an unchecked exception, it is safe |
| * to let it propagate |
| */ |
| } |
| } |
| |
| /** |
| * Call the specific customizer adding method. This method must not be |
| * called while synchronized on this object. |
| * |
| * @param item Item to be tracked. |
| * @param related Action related object. |
| * @return Customized object for the tracked item or {@code null} if the |
| * item is not to be tracked. |
| */ |
| @Override |
| T customizerAdding(final Bundle item, final BundleEvent related) { |
| return customizer.addingBundle(item, related); |
| } |
| |
| /** |
| * Call the specific customizer modified method. This method must not be |
| * called while synchronized on this object. |
| * |
| * @param item Tracked item. |
| * @param related Action related object. |
| * @param object Customized object for the tracked item. |
| */ |
| @Override |
| void customizerModified(final Bundle item, final BundleEvent related, final T object) { |
| customizer.modifiedBundle(item, related, object); |
| } |
| |
| /** |
| * Call the specific customizer removed method. This method must not be |
| * called while synchronized on this object. |
| * |
| * @param item Tracked item. |
| * @param related Action related object. |
| * @param object Customized object for the tracked item. |
| */ |
| @Override |
| void customizerRemoved(final Bundle item, final BundleEvent related, final T object) { |
| customizer.removedBundle(item, related, object); |
| } |
| } |
| } |