Marcel Offermans | faaed47 | 2010-09-08 10:07:32 +0000 | [diff] [blame] | 1 | package org.apache.felix.dm.tracker; |
Marcel Offermans | c854d1a | 2009-11-24 15:41:41 +0000 | [diff] [blame] | 2 | |
| 3 | /* |
| 4 | * Copyright (c) OSGi Alliance (2007, 2008). All Rights Reserved. |
| 5 | * |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | * you may not use this file except in compliance with the License. |
| 8 | * You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, software |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | * See the License for the specific language governing permissions and |
| 16 | * limitations under the License. |
| 17 | */ |
| 18 | |
| 19 | import org.osgi.framework.Bundle; |
| 20 | import org.osgi.framework.BundleContext; |
| 21 | import org.osgi.framework.BundleEvent; |
| 22 | import org.osgi.framework.SynchronousBundleListener; |
| 23 | |
| 24 | /** |
| 25 | * The <code>BundleTracker</code> class simplifies tracking bundles much like |
| 26 | * the <code>ServiceTracker</code> simplifies tracking services. |
| 27 | * <p> |
| 28 | * A <code>BundleTracker</code> is constructed with state criteria and a |
| 29 | * <code>BundleTrackerCustomizer</code> object. A <code>BundleTracker</code> can |
| 30 | * use the <code>BundleTrackerCustomizer</code> to select which bundles are |
| 31 | * tracked and to create a customized object to be tracked with the bundle. The |
| 32 | * <code>BundleTracker</code> can then be opened to begin tracking all bundles |
| 33 | * whose state matches the specified state criteria. |
| 34 | * <p> |
| 35 | * The <code>getBundles</code> method can be called to get the |
| 36 | * <code>Bundle</code> objects of the bundles being tracked. The |
| 37 | * <code>getObject</code> method can be called to get the customized object for |
| 38 | * a tracked bundle. |
| 39 | * <p> |
| 40 | * The <code>BundleTracker</code> class is thread-safe. It does not call a |
| 41 | * <code>BundleTrackerCustomizer</code> while holding any locks. |
| 42 | * <code>BundleTrackerCustomizer</code> implementations must also be |
| 43 | * thread-safe. |
| 44 | * |
| 45 | * @ThreadSafe |
| 46 | * @version $Revision: 5894 $ |
| 47 | * @since 1.4 |
| 48 | */ |
| 49 | public class BundleTracker implements BundleTrackerCustomizer { |
| 50 | /* set this to true to compile in debug messages */ |
| 51 | static final boolean DEBUG = false; |
| 52 | |
| 53 | /** |
| 54 | * The Bundle Context used by this <code>BundleTracker</code>. |
| 55 | */ |
| 56 | protected final BundleContext context; |
| 57 | |
| 58 | /** |
| 59 | * The <code>BundleTrackerCustomizer</code> object for this tracker. |
| 60 | */ |
| 61 | final BundleTrackerCustomizer customizer; |
| 62 | |
| 63 | /** |
| 64 | * Tracked bundles: <code>Bundle</code> object -> customized Object and |
| 65 | * <code>BundleListener</code> object |
| 66 | */ |
| 67 | private volatile Tracked tracked; |
| 68 | |
| 69 | /** |
| 70 | * Accessor method for the current Tracked object. This method is only |
| 71 | * intended to be used by the unsynchronized methods which do not modify the |
| 72 | * tracked field. |
| 73 | * |
| 74 | * @return The current Tracked object. |
| 75 | */ |
| 76 | private Tracked tracked() { |
| 77 | return tracked; |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * State mask for bundles being tracked. This field contains the ORed values |
| 82 | * of the bundle states being tracked. |
| 83 | */ |
| 84 | final int mask; |
| 85 | |
| 86 | /** |
| 87 | * Create a <code>BundleTracker</code> for bundles whose state is present in |
| 88 | * the specified state mask. |
| 89 | * |
| 90 | * <p> |
| 91 | * Bundles whose state is present on the specified state mask will be |
| 92 | * tracked by this <code>BundleTracker</code>. |
| 93 | * |
| 94 | * @param context The <code>BundleContext</code> against which the tracking |
| 95 | * is done. |
| 96 | * @param stateMask The bit mask of the <code>OR</code>ing of the bundle |
| 97 | * states to be tracked. |
| 98 | * @param customizer The customizer object to call when bundles are added, |
| 99 | * modified, or removed in this <code>BundleTracker</code>. If |
| 100 | * customizer is <code>null</code>, then this |
| 101 | * <code>BundleTracker</code> will be used as the |
| 102 | * <code>BundleTrackerCustomizer</code> and this |
| 103 | * <code>BundleTracker</code> will call the |
| 104 | * <code>BundleTrackerCustomizer</code> methods on itself. |
| 105 | * @see Bundle#getState() |
| 106 | */ |
| 107 | public BundleTracker(BundleContext context, int stateMask, |
| 108 | BundleTrackerCustomizer customizer) { |
| 109 | this.context = context; |
| 110 | this.mask = stateMask; |
| 111 | this.customizer = (customizer == null) ? this : customizer; |
| 112 | } |
| 113 | |
| 114 | /** |
| 115 | * Open this <code>BundleTracker</code> and begin tracking bundles. |
| 116 | * |
| 117 | * <p> |
| 118 | * Bundle which match the state criteria specified when this |
| 119 | * <code>BundleTracker</code> was created are now tracked by this |
| 120 | * <code>BundleTracker</code>. |
| 121 | * |
| 122 | * @throws java.lang.IllegalStateException If the <code>BundleContext</code> |
| 123 | * with which this <code>BundleTracker</code> was created is no |
| 124 | * longer valid. |
| 125 | * @throws java.lang.SecurityException If the caller and this class do not |
| 126 | * have the appropriate |
| 127 | * <code>AdminPermission[context bundle,LISTENER]</code>, and the |
| 128 | * Java Runtime Environment supports permissions. |
| 129 | */ |
| 130 | public void open() { |
| 131 | final Tracked t; |
| 132 | synchronized (this) { |
| 133 | if (tracked != null) { |
| 134 | return; |
| 135 | } |
| 136 | if (DEBUG) { |
| 137 | System.out.println("BundleTracker.open"); //$NON-NLS-1$ |
| 138 | } |
| 139 | t = new Tracked(); |
| 140 | synchronized (t) { |
| 141 | context.addBundleListener(t); |
| 142 | Bundle[] bundles = context.getBundles(); |
| 143 | if (bundles != null) { |
| 144 | int length = bundles.length; |
| 145 | for (int i = 0; i < length; i++) { |
| 146 | int state = bundles[i].getState(); |
| 147 | if ((state & mask) == 0) { |
| 148 | /* null out bundles whose states are not interesting */ |
| 149 | bundles[i] = null; |
| 150 | } |
| 151 | } |
| 152 | /* set tracked with the initial bundles */ |
| 153 | t.setInitial(bundles); |
| 154 | } |
| 155 | } |
| 156 | tracked = t; |
| 157 | } |
| 158 | /* Call tracked outside of synchronized region */ |
| 159 | t.trackInitial(); /* process the initial references */ |
| 160 | } |
| 161 | |
| 162 | /** |
| 163 | * Close this <code>BundleTracker</code>. |
| 164 | * |
| 165 | * <p> |
| 166 | * This method should be called when this <code>BundleTracker</code> should |
| 167 | * end the tracking of bundles. |
| 168 | * |
| 169 | * <p> |
| 170 | * This implementation calls {@link #getBundles()} to get the list of |
| 171 | * tracked bundles to remove. |
| 172 | */ |
| 173 | public void close() { |
| 174 | final Bundle[] bundles; |
| 175 | final Tracked outgoing; |
| 176 | synchronized (this) { |
| 177 | outgoing = tracked; |
| 178 | if (outgoing == null) { |
| 179 | return; |
| 180 | } |
| 181 | if (DEBUG) { |
| 182 | System.out.println("BundleTracker.close"); //$NON-NLS-1$ |
| 183 | } |
| 184 | outgoing.close(); |
| 185 | bundles = getBundles(); |
| 186 | tracked = null; |
| 187 | try { |
| 188 | context.removeBundleListener(outgoing); |
| 189 | } |
| 190 | catch (IllegalStateException e) { |
| 191 | /* In case the context was stopped. */ |
| 192 | } |
| 193 | } |
| 194 | if (bundles != null) { |
| 195 | for (int i = 0; i < bundles.length; i++) { |
| 196 | outgoing.untrack(bundles[i], null); |
| 197 | } |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | /** |
| 202 | * Default implementation of the |
| 203 | * <code>BundleTrackerCustomizer.addingBundle</code> method. |
| 204 | * |
| 205 | * <p> |
| 206 | * This method is only called when this <code>BundleTracker</code> has been |
| 207 | * constructed with a <code>null BundleTrackerCustomizer</code> argument. |
| 208 | * |
| 209 | * <p> |
| 210 | * This implementation simply returns the specified <code>Bundle</code>. |
| 211 | * |
| 212 | * <p> |
| 213 | * This method can be overridden in a subclass to customize the object to be |
| 214 | * tracked for the bundle being added. |
| 215 | * |
| 216 | * @param bundle The <code>Bundle</code> being added to this |
| 217 | * <code>BundleTracker</code> object. |
| 218 | * @param event The bundle event which caused this customizer method to be |
| 219 | * called or <code>null</code> if there is no bundle event associated |
| 220 | * with the call to this method. |
| 221 | * @return The specified bundle. |
| 222 | * @see BundleTrackerCustomizer#addingBundle(Bundle, BundleEvent) |
| 223 | */ |
| 224 | public Object addingBundle(Bundle bundle, BundleEvent event) { |
| 225 | return bundle; |
| 226 | } |
| 227 | |
| 228 | public void addedBundle(Bundle bundle, BundleEvent event, Object object) { |
| 229 | /* do nothing */ |
| 230 | } |
| 231 | |
| 232 | /** |
| 233 | * Default implementation of the |
| 234 | * <code>BundleTrackerCustomizer.modifiedBundle</code> method. |
| 235 | * |
| 236 | * <p> |
| 237 | * This method is only called when this <code>BundleTracker</code> has been |
| 238 | * constructed with a <code>null BundleTrackerCustomizer</code> argument. |
| 239 | * |
| 240 | * <p> |
| 241 | * This implementation does nothing. |
| 242 | * |
| 243 | * @param bundle The <code>Bundle</code> whose state has been modified. |
| 244 | * @param event The bundle event which caused this customizer method to be |
| 245 | * called or <code>null</code> if there is no bundle event associated |
| 246 | * with the call to this method. |
| 247 | * @param object The customized object for the specified Bundle. |
| 248 | * @see BundleTrackerCustomizer#modifiedBundle(Bundle, BundleEvent, Object) |
| 249 | */ |
| 250 | public void modifiedBundle(Bundle bundle, BundleEvent event, Object object) { |
| 251 | /* do nothing */ |
| 252 | } |
| 253 | |
| 254 | /** |
| 255 | * Default implementation of the |
| 256 | * <code>BundleTrackerCustomizer.removedBundle</code> method. |
| 257 | * |
| 258 | * <p> |
| 259 | * This method is only called when this <code>BundleTracker</code> has been |
| 260 | * constructed with a <code>null BundleTrackerCustomizer</code> argument. |
| 261 | * |
| 262 | * <p> |
| 263 | * This implementation does nothing. |
| 264 | * |
| 265 | * @param bundle The <code>Bundle</code> being removed. |
| 266 | * @param event The bundle event which caused this customizer method to be |
| 267 | * called or <code>null</code> if there is no bundle event associated |
| 268 | * with the call to this method. |
| 269 | * @param object The customized object for the specified bundle. |
| 270 | * @see BundleTrackerCustomizer#removedBundle(Bundle, BundleEvent, Object) |
| 271 | */ |
| 272 | public void removedBundle(Bundle bundle, BundleEvent event, Object object) { |
| 273 | /* do nothing */ |
| 274 | } |
| 275 | |
| 276 | /** |
| 277 | * Return an array of <code>Bundle</code>s for all bundles being tracked by |
| 278 | * this <code>BundleTracker</code>. |
| 279 | * |
| 280 | * @return An array of <code>Bundle</code>s or <code>null</code> if no |
| 281 | * bundles are being tracked. |
| 282 | */ |
| 283 | public Bundle[] getBundles() { |
| 284 | final Tracked t = tracked(); |
| 285 | if (t == null) { /* if BundleTracker is not open */ |
| 286 | return null; |
| 287 | } |
| 288 | synchronized (t) { |
| 289 | int length = t.size(); |
| 290 | if (length == 0) { |
| 291 | return null; |
| 292 | } |
| 293 | return (Bundle[]) t.getTracked(new Bundle[length]); |
| 294 | } |
| 295 | } |
| 296 | |
| 297 | /** |
| 298 | * Returns the customized object for the specified <code>Bundle</code> if |
| 299 | * the specified bundle is being tracked by this <code>BundleTracker</code>. |
| 300 | * |
| 301 | * @param bundle The <code>Bundle</code> being tracked. |
| 302 | * @return The customized object for the specified <code>Bundle</code> or |
| 303 | * <code>null</code> if the specified <code>Bundle</code> is not |
| 304 | * being tracked. |
| 305 | */ |
| 306 | public Object getObject(Bundle bundle) { |
| 307 | final Tracked t = tracked(); |
| 308 | if (t == null) { /* if BundleTracker is not open */ |
| 309 | return null; |
| 310 | } |
| 311 | synchronized (t) { |
| 312 | return t.getCustomizedObject(bundle); |
| 313 | } |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * Remove a bundle from this <code>BundleTracker</code>. |
| 318 | * |
| 319 | * The specified bundle will be removed from this <code>BundleTracker</code> |
| 320 | * . If the specified bundle was being tracked then the |
| 321 | * <code>BundleTrackerCustomizer.removedBundle</code> method will be called |
| 322 | * for that bundle. |
| 323 | * |
| 324 | * @param bundle The <code>Bundle</code> to be removed. |
| 325 | */ |
| 326 | public void remove(Bundle bundle) { |
| 327 | final Tracked t = tracked(); |
| 328 | if (t == null) { /* if BundleTracker is not open */ |
| 329 | return; |
| 330 | } |
| 331 | t.untrack(bundle, null); |
| 332 | } |
| 333 | |
| 334 | /** |
| 335 | * Return the number of bundles being tracked by this |
| 336 | * <code>BundleTracker</code>. |
| 337 | * |
| 338 | * @return The number of bundles being tracked. |
| 339 | */ |
| 340 | public int size() { |
| 341 | final Tracked t = tracked(); |
| 342 | if (t == null) { /* if BundleTracker is not open */ |
| 343 | return 0; |
| 344 | } |
| 345 | synchronized (t) { |
| 346 | return t.size(); |
| 347 | } |
| 348 | } |
| 349 | |
| 350 | /** |
| 351 | * Returns the tracking count for this <code>BundleTracker</code>. |
| 352 | * |
| 353 | * The tracking count is initialized to 0 when this |
| 354 | * <code>BundleTracker</code> is opened. Every time a bundle is added, |
| 355 | * modified or removed from this <code>BundleTracker</code> the tracking |
| 356 | * count is incremented. |
| 357 | * |
| 358 | * <p> |
| 359 | * The tracking count can be used to determine if this |
| 360 | * <code>BundleTracker</code> has added, modified or removed a bundle by |
| 361 | * comparing a tracking count value previously collected with the current |
| 362 | * tracking count value. If the value has not changed, then no bundle has |
| 363 | * been added, modified or removed from this <code>BundleTracker</code> |
| 364 | * since the previous tracking count was collected. |
| 365 | * |
| 366 | * @return The tracking count for this <code>BundleTracker</code> or -1 if |
| 367 | * this <code>BundleTracker</code> is not open. |
| 368 | */ |
| 369 | public int getTrackingCount() { |
| 370 | final Tracked t = tracked(); |
| 371 | if (t == null) { /* if BundleTracker is not open */ |
| 372 | return -1; |
| 373 | } |
| 374 | synchronized (t) { |
| 375 | return t.getTrackingCount(); |
| 376 | } |
| 377 | } |
| 378 | |
| 379 | /** |
| 380 | * Inner class which subclasses AbstractTracked. This class is the |
| 381 | * <code>SynchronousBundleListener</code> object for the tracker. |
| 382 | * |
| 383 | * @ThreadSafe |
| 384 | * @since 1.4 |
| 385 | */ |
| 386 | class Tracked extends AbstractTracked implements SynchronousBundleListener { |
| 387 | /** |
| 388 | * Tracked constructor. |
| 389 | */ |
| 390 | Tracked() { |
| 391 | super(); |
| 392 | } |
| 393 | |
| 394 | /** |
| 395 | * <code>BundleListener</code> method for the <code>BundleTracker</code> |
| 396 | * class. This method must NOT be synchronized to avoid deadlock |
| 397 | * potential. |
| 398 | * |
| 399 | * @param event <code>BundleEvent</code> object from the framework. |
| 400 | */ |
| 401 | public void bundleChanged(final BundleEvent event) { |
| 402 | /* |
| 403 | * Check if we had a delayed call (which could happen when we |
| 404 | * close). |
| 405 | */ |
| 406 | if (closed) { |
| 407 | return; |
| 408 | } |
| 409 | final Bundle bundle = event.getBundle(); |
| 410 | final int state = bundle.getState(); |
| 411 | if (DEBUG) { |
| 412 | System.out |
| 413 | .println("BundleTracker.Tracked.bundleChanged[" + state + "]: " + bundle); //$NON-NLS-1$ //$NON-NLS-2$ |
| 414 | } |
| 415 | |
| 416 | if ((state & mask) != 0) { |
| 417 | track(bundle, event); |
| 418 | /* |
| 419 | * If the customizer throws an unchecked exception, it is safe |
| 420 | * to let it propagate |
| 421 | */ |
| 422 | } |
| 423 | else { |
| 424 | untrack(bundle, event); |
| 425 | /* |
| 426 | * If the customizer throws an unchecked exception, it is safe |
| 427 | * to let it propagate |
| 428 | */ |
| 429 | } |
| 430 | } |
| 431 | |
| 432 | /** |
| 433 | * Call the specific customizer adding method. This method must not be |
| 434 | * called while synchronized on this object. |
| 435 | * |
| 436 | * @param item Item to be tracked. |
| 437 | * @param related Action related object. |
| 438 | * @return Customized object for the tracked item or <code>null</code> |
| 439 | * if the item is not to be tracked. |
| 440 | */ |
| 441 | Object customizerAdding(final Object item, |
| 442 | final Object related) { |
| 443 | return customizer |
| 444 | .addingBundle((Bundle) item, (BundleEvent) related); |
| 445 | } |
| 446 | |
| 447 | void customizerAdded(final Object item, final Object related, final Object object) { |
| 448 | customizer.addedBundle((Bundle) item, (BundleEvent) related, object); |
| 449 | } |
| 450 | |
| 451 | /** |
| 452 | * Call the specific customizer modified method. This method must not be |
| 453 | * called while synchronized on this object. |
| 454 | * |
| 455 | * @param item Tracked item. |
| 456 | * @param related Action related object. |
| 457 | * @param object Customized object for the tracked item. |
| 458 | */ |
| 459 | void customizerModified(final Object item, |
| 460 | final Object related, final Object object) { |
| 461 | customizer.modifiedBundle((Bundle) item, (BundleEvent) related, |
| 462 | object); |
| 463 | } |
| 464 | |
| 465 | /** |
| 466 | * Call the specific customizer removed method. This method must not be |
| 467 | * called while synchronized on this object. |
| 468 | * |
| 469 | * @param item Tracked item. |
| 470 | * @param related Action related object. |
| 471 | * @param object Customized object for the tracked item. |
| 472 | */ |
| 473 | void customizerRemoved(final Object item, |
| 474 | final Object related, final Object object) { |
| 475 | customizer.removedBundle((Bundle) item, (BundleEvent) related, |
| 476 | object); |
| 477 | } |
| 478 | } |
| 479 | } |