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| 1 | +/* | |
| 2 | + * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package com.sun.jmx.remote.internal; | |
| 27 | + | |
| 28 | +import java.security.AccessController; | |
| 29 | +import java.security.PrivilegedAction; | |
| 30 | +import java.security.PrivilegedActionException; | |
| 31 | +import java.security.PrivilegedExceptionAction; | |
| 32 | +import java.util.ArrayList; | |
| 33 | +import java.util.Collection; | |
| 34 | +import java.util.Collections; | |
| 35 | +import java.util.HashSet; | |
| 36 | +import java.util.List; | |
| 37 | +import java.util.Set; | |
| 38 | +import java.util.HashMap; | |
| 39 | +import java.util.Map; | |
| 40 | + | |
| 41 | +import javax.management.InstanceNotFoundException; | |
| 42 | +import javax.management.MBeanServer; | |
| 43 | +import javax.management.MBeanServerDelegate; | |
| 44 | +import javax.management.MBeanServerNotification; | |
| 45 | +import javax.management.Notification; | |
| 46 | +import javax.management.NotificationBroadcaster; | |
| 47 | +import javax.management.NotificationFilter; | |
| 48 | +import javax.management.NotificationFilterSupport; | |
| 49 | +import javax.management.NotificationListener; | |
| 50 | +import javax.management.ObjectName; | |
| 51 | +import javax.management.QueryEval; | |
| 52 | +import javax.management.QueryExp; | |
| 53 | + | |
| 54 | +import javax.management.remote.NotificationResult; | |
| 55 | +import javax.management.remote.TargetedNotification; | |
| 56 | + | |
| 57 | +import com.sun.jmx.remote.util.EnvHelp; | |
| 58 | +import com.sun.jmx.remote.util.ClassLogger; | |
| 59 | + | |
| 60 | +/** A circular buffer of notifications received from an MBean server. */ | |
| 61 | +/* | |
| 62 | + There is one instance of ArrayNotificationBuffer for every | |
| 63 | + MBeanServer object that has an attached ConnectorServer. Then, for | |
| 64 | + every ConnectorServer attached to a given MBeanServer, there is an | |
| 65 | + instance of the inner class ShareBuffer. So for example with two | |
| 66 | + ConnectorServers it looks like this: | |
| 67 | + | |
| 68 | + ConnectorServer1 -> ShareBuffer1 -\ | |
| 69 | + }-> ArrayNotificationBuffer | |
| 70 | + ConnectorServer2 -> ShareBuffer2 -/ | | |
| 71 | + | | |
| 72 | + v | |
| 73 | + MBeanServer | |
| 74 | + | |
| 75 | + The ArrayNotificationBuffer has a circular buffer of | |
| 76 | + NamedNotification objects. Each ConnectorServer defines a | |
| 77 | + notification buffer size, and this size is recorded by the | |
| 78 | + corresponding ShareBuffer. The buffer size of the | |
| 79 | + ArrayNotificationBuffer is the maximum of all of its ShareBuffers. | |
| 80 | + When a ShareBuffer is added or removed, the ArrayNotificationBuffer | |
| 81 | + size is adjusted accordingly. | |
| 82 | + | |
| 83 | + An ArrayNotificationBuffer also has a BufferListener (which is a | |
| 84 | + NotificationListener) registered on every NotificationBroadcaster | |
| 85 | + MBean in the MBeanServer to which it is attached. The cost of this | |
| 86 | + potentially large set of listeners is the principal motivation for | |
| 87 | + sharing the ArrayNotificationBuffer between ConnectorServers, and | |
| 88 | + also the reason that we are careful to discard the | |
| 89 | + ArrayNotificationBuffer (and its BufferListeners) when there are no | |
| 90 | + longer any ConnectorServers using it. | |
| 91 | + | |
| 92 | + The synchronization of this class is inherently complex. In an attempt | |
| 93 | + to limit the complexity, we use just two locks: | |
| 94 | + | |
| 95 | + - globalLock controls access to the mapping between an MBeanServer | |
| 96 | + and its ArrayNotificationBuffer and to the set of ShareBuffers for | |
| 97 | + each ArrayNotificationBuffer. | |
| 98 | + | |
| 99 | + - the instance lock of each ArrayNotificationBuffer controls access | |
| 100 | + to the array of notifications, including its size, and to the | |
| 101 | + dispose flag of the ArrayNotificationBuffer. The wait/notify | |
| 102 | + mechanism is used to indicate changes to the array. | |
| 103 | + | |
| 104 | + If both locks are held at the same time, the globalLock must be | |
| 105 | + taken first. | |
| 106 | + | |
| 107 | + Since adding or removing a BufferListener to an MBean can involve | |
| 108 | + calling user code, we are careful not to hold any locks while it is | |
| 109 | + done. | |
| 110 | + */ | |
| 111 | +public class ArrayNotificationBuffer implements NotificationBuffer { | |
| 112 | + private boolean disposed = false; | |
| 113 | + | |
| 114 | + // FACTORY STUFF, INCLUDING SHARING | |
| 115 | + | |
| 116 | + private static final Object globalLock = new Object(); | |
| 117 | + private static final | |
| 118 | + HashMap<MBeanServer,ArrayNotificationBuffer> mbsToBuffer = | |
| 119 | + new HashMap<MBeanServer,ArrayNotificationBuffer>(1); | |
| 120 | + private final Collection<ShareBuffer> sharers = new HashSet<ShareBuffer>(1); | |
| 121 | + | |
| 122 | + public static NotificationBuffer getNotificationBuffer( | |
| 123 | + MBeanServer mbs, Map<String, ?> env) { | |
| 124 | + | |
| 125 | + if (env == null) | |
| 126 | + env = Collections.emptyMap(); | |
| 127 | + | |
| 128 | + //Find out queue size | |
| 129 | + int queueSize = EnvHelp.getNotifBufferSize(env); | |
| 130 | + | |
| 131 | + ArrayNotificationBuffer buf; | |
| 132 | + boolean create; | |
| 133 | + NotificationBuffer sharer; | |
| 134 | + synchronized (globalLock) { | |
| 135 | + buf = mbsToBuffer.get(mbs); | |
| 136 | + create = (buf == null); | |
| 137 | + if (create) { | |
| 138 | + buf = new ArrayNotificationBuffer(mbs, queueSize); | |
| 139 | + mbsToBuffer.put(mbs, buf); | |
| 140 | + } | |
| 141 | + sharer = buf.new ShareBuffer(queueSize); | |
| 142 | + } | |
| 143 | + /* We avoid holding any locks while calling createListeners. | |
| 144 | + * This prevents possible deadlocks involving user code, but | |
| 145 | + * does mean that a second ConnectorServer created and started | |
| 146 | + * in this window will return before all the listeners are ready, | |
| 147 | + * which could lead to surprising behaviour. The alternative | |
| 148 | + * would be to block the second ConnectorServer until the first | |
| 149 | + * one has finished adding all the listeners, but that would then | |
| 150 | + * be subject to deadlock. | |
| 151 | + */ | |
| 152 | + if (create) | |
| 153 | + buf.createListeners(); | |
| 154 | + return sharer; | |
| 155 | + } | |
| 156 | + | |
| 157 | + /* Ensure that this buffer is no longer the one that will be returned by | |
| 158 | + * getNotificationBuffer. This method is idempotent - calling it more | |
| 159 | + * than once has no effect beyond that of calling it once. | |
| 160 | + */ | |
| 161 | + static void removeNotificationBuffer(MBeanServer mbs) { | |
| 162 | + synchronized (globalLock) { | |
| 163 | + mbsToBuffer.remove(mbs); | |
| 164 | + } | |
| 165 | + } | |
| 166 | + | |
| 167 | + void addSharer(ShareBuffer sharer) { | |
| 168 | + synchronized (globalLock) { | |
| 169 | + synchronized (this) { | |
| 170 | + if (sharer.getSize() > queueSize) | |
| 171 | + resize(sharer.getSize()); | |
| 172 | + } | |
| 173 | + sharers.add(sharer); | |
| 174 | + } | |
| 175 | + } | |
| 176 | + | |
| 177 | + private void removeSharer(ShareBuffer sharer) { | |
| 178 | + boolean empty; | |
| 179 | + synchronized (globalLock) { | |
| 180 | + sharers.remove(sharer); | |
| 181 | + empty = sharers.isEmpty(); | |
| 182 | + if (empty) | |
| 183 | + removeNotificationBuffer(mBeanServer); | |
| 184 | + else { | |
| 185 | + int max = 0; | |
| 186 | + for (ShareBuffer buf : sharers) { | |
| 187 | + int bufsize = buf.getSize(); | |
| 188 | + if (bufsize > max) | |
| 189 | + max = bufsize; | |
| 190 | + } | |
| 191 | + if (max < queueSize) | |
| 192 | + resize(max); | |
| 193 | + } | |
| 194 | + } | |
| 195 | + if (empty) { | |
| 196 | + synchronized (this) { | |
| 197 | + disposed = true; | |
| 198 | + // Notify potential waiting fetchNotification call | |
| 199 | + notifyAll(); | |
| 200 | + } | |
| 201 | + destroyListeners(); | |
| 202 | + } | |
| 203 | + } | |
| 204 | + | |
| 205 | + private synchronized void resize(int newSize) { | |
| 206 | + if (newSize == queueSize) | |
| 207 | + return; | |
| 208 | + while (queue.size() > newSize) | |
| 209 | + dropNotification(); | |
| 210 | + queue.resize(newSize); | |
| 211 | + queueSize = newSize; | |
| 212 | + } | |
| 213 | + | |
| 214 | + private class ShareBuffer implements NotificationBuffer { | |
| 215 | + ShareBuffer(int size) { | |
| 216 | + this.size = size; | |
| 217 | + addSharer(this); | |
| 218 | + } | |
| 219 | + | |
| 220 | + public NotificationResult | |
| 221 | + fetchNotifications(NotificationBufferFilter filter, | |
| 222 | + long startSequenceNumber, | |
| 223 | + long timeout, | |
| 224 | + int maxNotifications) | |
| 225 | + throws InterruptedException { | |
| 226 | + NotificationBuffer buf = ArrayNotificationBuffer.this; | |
| 227 | + return buf.fetchNotifications(filter, startSequenceNumber, | |
| 228 | + timeout, maxNotifications); | |
| 229 | + } | |
| 230 | + | |
| 231 | + public void dispose() { | |
| 232 | + ArrayNotificationBuffer.this.removeSharer(this); | |
| 233 | + } | |
| 234 | + | |
| 235 | + int getSize() { | |
| 236 | + return size; | |
| 237 | + } | |
| 238 | + | |
| 239 | + private final int size; | |
| 240 | + } | |
| 241 | + | |
| 242 | + | |
| 243 | + // ARRAYNOTIFICATIONBUFFER IMPLEMENTATION | |
| 244 | + | |
| 245 | + private ArrayNotificationBuffer(MBeanServer mbs, int queueSize) { | |
| 246 | + if (logger.traceOn()) | |
| 247 | + logger.trace("Constructor", "queueSize=" + queueSize); | |
| 248 | + | |
| 249 | + if (mbs == null || queueSize < 1) | |
| 250 | + throw new IllegalArgumentException("Bad args"); | |
| 251 | + | |
| 252 | + this.mBeanServer = mbs; | |
| 253 | + this.queueSize = queueSize; | |
| 254 | + this.queue = new ArrayQueue<NamedNotification>(queueSize); | |
| 255 | + this.earliestSequenceNumber = System.currentTimeMillis(); | |
| 256 | + this.nextSequenceNumber = this.earliestSequenceNumber; | |
| 257 | + | |
| 258 | + logger.trace("Constructor", "ends"); | |
| 259 | + } | |
| 260 | + | |
| 261 | + private synchronized boolean isDisposed() { | |
| 262 | + return disposed; | |
| 263 | + } | |
| 264 | + | |
| 265 | + // We no longer support calling this method from outside. | |
| 266 | + // The JDK doesn't contain any such calls and users are not | |
| 267 | + // supposed to be accessing this class. | |
| 268 | + public void dispose() { | |
| 269 | + throw new UnsupportedOperationException(); | |
| 270 | + } | |
| 271 | + | |
| 272 | + /** | |
| 273 | + * <p>Fetch notifications that match the given listeners.</p> | |
| 274 | + * | |
| 275 | + * <p>The operation only considers notifications with a sequence | |
| 276 | + * number at least <code>startSequenceNumber</code>. It will take | |
| 277 | + * no longer than <code>timeout</code>, and will return no more | |
| 278 | + * than <code>maxNotifications</code> different notifications.</p> | |
| 279 | + * | |
| 280 | + * <p>If there are no notifications matching the criteria, the | |
| 281 | + * operation will block until one arrives, subject to the | |
| 282 | + * timeout.</p> | |
| 283 | + * | |
| 284 | + * @param filter an object that will add notifications to a | |
| 285 | + * {@code List<TargetedNotification>} if they match the current | |
| 286 | + * listeners with their filters. | |
| 287 | + * @param startSequenceNumber the first sequence number to | |
| 288 | + * consider. | |
| 289 | + * @param timeout the maximum time to wait. May be 0 to indicate | |
| 290 | + * not to wait if there are no notifications. | |
| 291 | + * @param maxNotifications the maximum number of notifications to | |
| 292 | + * return. May be 0 to indicate a wait for eligible notifications | |
| 293 | + * that will return a usable <code>nextSequenceNumber</code>. The | |
| 294 | + * {@link TargetedNotification} array in the returned {@link | |
| 295 | + * NotificationResult} may contain more than this number of | |
| 296 | + * elements but will not contain more than this number of | |
| 297 | + * different notifications. | |
| 298 | + */ | |
| 299 | + public NotificationResult | |
| 300 | + fetchNotifications(NotificationBufferFilter filter, | |
| 301 | + long startSequenceNumber, | |
| 302 | + long timeout, | |
| 303 | + int maxNotifications) | |
| 304 | + throws InterruptedException { | |
| 305 | + | |
| 306 | + logger.trace("fetchNotifications", "starts"); | |
| 307 | + | |
| 308 | + if (startSequenceNumber < 0 || isDisposed()) { | |
| 309 | + synchronized(this) { | |
| 310 | + return new NotificationResult(earliestSequenceNumber(), | |
| 311 | + nextSequenceNumber(), | |
| 312 | + new TargetedNotification[0]); | |
| 313 | + } | |
| 314 | + } | |
| 315 | + | |
| 316 | + // Check arg validity | |
| 317 | + if (filter == null | |
| 318 | + || startSequenceNumber < 0 || timeout < 0 | |
| 319 | + || maxNotifications < 0) { | |
| 320 | + logger.trace("fetchNotifications", "Bad args"); | |
| 321 | + throw new IllegalArgumentException("Bad args to fetch"); | |
| 322 | + } | |
| 323 | + | |
| 324 | + if (logger.debugOn()) { | |
| 325 | + logger.trace("fetchNotifications", | |
| 326 | + "filter=" + filter + "; startSeq=" + | |
| 327 | + startSequenceNumber + "; timeout=" + timeout + | |
| 328 | + "; max=" + maxNotifications); | |
| 329 | + } | |
| 330 | + | |
| 331 | + if (startSequenceNumber > nextSequenceNumber()) { | |
| 332 | + final String msg = "Start sequence number too big: " + | |
| 333 | + startSequenceNumber + " > " + nextSequenceNumber(); | |
| 334 | + logger.trace("fetchNotifications", msg); | |
| 335 | + throw new IllegalArgumentException(msg); | |
| 336 | + } | |
| 337 | + | |
| 338 | + /* Determine the end time corresponding to the timeout value. | |
| 339 | + Caller may legitimately supply Long.MAX_VALUE to indicate no | |
| 340 | + timeout. In that case the addition will overflow and produce | |
| 341 | + a negative end time. Set end time to Long.MAX_VALUE in that | |
| 342 | + case. We assume System.currentTimeMillis() is positive. */ | |
| 343 | + long endTime = System.currentTimeMillis() + timeout; | |
| 344 | + if (endTime < 0) // overflow | |
| 345 | + endTime = Long.MAX_VALUE; | |
| 346 | + | |
| 347 | + if (logger.debugOn()) | |
| 348 | + logger.debug("fetchNotifications", "endTime=" + endTime); | |
| 349 | + | |
| 350 | + /* We set earliestSeq the first time through the loop. If we | |
| 351 | + set it here, notifications could be dropped before we | |
| 352 | + started examining them, so earliestSeq might not correspond | |
| 353 | + to the earliest notification we examined. */ | |
| 354 | + long earliestSeq = -1; | |
| 355 | + long nextSeq = startSequenceNumber; | |
| 356 | + List<TargetedNotification> notifs = | |
| 357 | + new ArrayList<TargetedNotification>(); | |
| 358 | + | |
| 359 | + /* On exit from this loop, notifs, earliestSeq, and nextSeq must | |
| 360 | + all be correct values for the returned NotificationResult. */ | |
| 361 | + while (true) { | |
| 362 | + logger.debug("fetchNotifications", "main loop starts"); | |
| 363 | + | |
| 364 | + NamedNotification candidate; | |
| 365 | + | |
| 366 | + /* Get the next available notification regardless of filters, | |
| 367 | + or wait for one to arrive if there is none. */ | |
| 368 | + synchronized (this) { | |
| 369 | + | |
| 370 | + /* First time through. The current earliestSequenceNumber | |
| 371 | + is the first one we could have examined. */ | |
| 372 | + if (earliestSeq < 0) { | |
| 373 | + earliestSeq = earliestSequenceNumber(); | |
| 374 | + if (logger.debugOn()) { | |
| 375 | + logger.debug("fetchNotifications", | |
| 376 | + "earliestSeq=" + earliestSeq); | |
| 377 | + } | |
| 378 | + if (nextSeq < earliestSeq) { | |
| 379 | + nextSeq = earliestSeq; | |
| 380 | + logger.debug("fetchNotifications", | |
| 381 | + "nextSeq=earliestSeq"); | |
| 382 | + } | |
| 383 | + } else | |
| 384 | + earliestSeq = earliestSequenceNumber(); | |
| 385 | + | |
| 386 | + /* If many notifications have been dropped since the | |
| 387 | + last time through, nextSeq could now be earlier | |
| 388 | + than the current earliest. If so, notifications | |
| 389 | + may have been lost and we return now so the caller | |
| 390 | + can see this next time it calls. */ | |
| 391 | + if (nextSeq < earliestSeq) { | |
| 392 | + logger.trace("fetchNotifications", | |
| 393 | + "nextSeq=" + nextSeq + " < " + "earliestSeq=" + | |
| 394 | + earliestSeq + " so may have lost notifs"); | |
| 395 | + break; | |
| 396 | + } | |
| 397 | + | |
| 398 | + if (nextSeq < nextSequenceNumber()) { | |
| 399 | + candidate = notificationAt(nextSeq); | |
| 400 | + if (logger.debugOn()) { | |
| 401 | + logger.debug("fetchNotifications", "candidate: " + | |
| 402 | + candidate); | |
| 403 | + logger.debug("fetchNotifications", "nextSeq now " + | |
| 404 | + nextSeq); | |
| 405 | + } | |
| 406 | + } else { | |
| 407 | + /* nextSeq is the largest sequence number. If we | |
| 408 | + already got notifications, return them now. | |
| 409 | + Otherwise wait for some to arrive, with | |
| 410 | + timeout. */ | |
| 411 | + if (notifs.size() > 0) { | |
| 412 | + logger.debug("fetchNotifications", | |
| 413 | + "no more notifs but have some so don't wait"); | |
| 414 | + break; | |
| 415 | + } | |
| 416 | + long toWait = endTime - System.currentTimeMillis(); | |
| 417 | + if (toWait <= 0) { | |
| 418 | + logger.debug("fetchNotifications", "timeout"); | |
| 419 | + break; | |
| 420 | + } | |
| 421 | + | |
| 422 | + /* dispose called */ | |
| 423 | + if (isDisposed()) { | |
| 424 | + if (logger.debugOn()) | |
| 425 | + logger.debug("fetchNotifications", | |
| 426 | + "dispose callled, no wait"); | |
| 427 | + return new NotificationResult(earliestSequenceNumber(), | |
| 428 | + nextSequenceNumber(), | |
| 429 | + new TargetedNotification[0]); | |
| 430 | + } | |
| 431 | + | |
| 432 | + if (logger.debugOn()) | |
| 433 | + logger.debug("fetchNotifications", | |
| 434 | + "wait(" + toWait + ")"); | |
| 435 | + wait(toWait); | |
| 436 | + | |
| 437 | + continue; | |
| 438 | + } | |
| 439 | + } | |
| 440 | + | |
| 441 | + /* We have a candidate notification. See if it matches | |
| 442 | + our filters. We do this outside the synchronized block | |
| 443 | + so we don't hold up everyone accessing the buffer | |
| 444 | + (including notification senders) while we evaluate | |
| 445 | + potentially slow filters. */ | |
| 446 | + ObjectName name = candidate.getObjectName(); | |
| 447 | + Notification notif = candidate.getNotification(); | |
| 448 | + List<TargetedNotification> matchedNotifs = | |
| 449 | + new ArrayList<TargetedNotification>(); | |
| 450 | + logger.debug("fetchNotifications", | |
| 451 | + "applying filter to candidate"); | |
| 452 | + filter.apply(matchedNotifs, name, notif); | |
| 453 | + | |
| 454 | + if (matchedNotifs.size() > 0) { | |
| 455 | + /* We only check the max size now, so that our | |
| 456 | + returned nextSeq is as large as possible. This | |
| 457 | + prevents the caller from thinking it missed | |
| 458 | + interesting notifications when in fact we knew they | |
| 459 | + weren't. */ | |
| 460 | + if (maxNotifications <= 0) { | |
| 461 | + logger.debug("fetchNotifications", | |
| 462 | + "reached maxNotifications"); | |
| 463 | + break; | |
| 464 | + } | |
| 465 | + --maxNotifications; | |
| 466 | + if (logger.debugOn()) | |
| 467 | + logger.debug("fetchNotifications", "add: " + | |
| 468 | + matchedNotifs); | |
| 469 | + notifs.addAll(matchedNotifs); | |
| 470 | + } | |
| 471 | + | |
| 472 | + ++nextSeq; | |
| 473 | + } // end while | |
| 474 | + | |
| 475 | + /* Construct and return the result. */ | |
| 476 | + int nnotifs = notifs.size(); | |
| 477 | + TargetedNotification[] resultNotifs = | |
| 478 | + new TargetedNotification[nnotifs]; | |
| 479 | + notifs.toArray(resultNotifs); | |
| 480 | + NotificationResult nr = | |
| 481 | + new NotificationResult(earliestSeq, nextSeq, resultNotifs); | |
| 482 | + if (logger.debugOn()) | |
| 483 | + logger.debug("fetchNotifications", nr.toString()); | |
| 484 | + logger.trace("fetchNotifications", "ends"); | |
| 485 | + | |
| 486 | + return nr; | |
| 487 | + } | |
| 488 | + | |
| 489 | + synchronized long earliestSequenceNumber() { | |
| 490 | + return earliestSequenceNumber; | |
| 491 | + } | |
| 492 | + | |
| 493 | + synchronized long nextSequenceNumber() { | |
| 494 | + return nextSequenceNumber; | |
| 495 | + } | |
| 496 | + | |
| 497 | + synchronized void addNotification(NamedNotification notif) { | |
| 498 | + if (logger.traceOn()) | |
| 499 | + logger.trace("addNotification", notif.toString()); | |
| 500 | + | |
| 501 | + while (queue.size() >= queueSize) { | |
| 502 | + dropNotification(); | |
| 503 | + if (logger.debugOn()) { | |
| 504 | + logger.debug("addNotification", | |
| 505 | + "dropped oldest notif, earliestSeq=" + | |
| 506 | + earliestSequenceNumber); | |
| 507 | + } | |
| 508 | + } | |
| 509 | + queue.add(notif); | |
| 510 | + nextSequenceNumber++; | |
| 511 | + if (logger.debugOn()) | |
| 512 | + logger.debug("addNotification", "nextSeq=" + nextSequenceNumber); | |
| 513 | + notifyAll(); | |
| 514 | + } | |
| 515 | + | |
| 516 | + private void dropNotification() { | |
| 517 | + queue.remove(0); | |
| 518 | + earliestSequenceNumber++; | |
| 519 | + } | |
| 520 | + | |
| 521 | + synchronized NamedNotification notificationAt(long seqNo) { | |
| 522 | + long index = seqNo - earliestSequenceNumber; | |
| 523 | + if (index < 0 || index > Integer.MAX_VALUE) { | |
| 524 | + final String msg = "Bad sequence number: " + seqNo + " (earliest " | |
| 525 | + + earliestSequenceNumber + ")"; | |
| 526 | + logger.trace("notificationAt", msg); | |
| 527 | + throw new IllegalArgumentException(msg); | |
| 528 | + } | |
| 529 | + return queue.get((int) index); | |
| 530 | + } | |
| 531 | + | |
| 532 | + private static class NamedNotification { | |
| 533 | + NamedNotification(ObjectName sender, Notification notif) { | |
| 534 | + this.sender = sender; | |
| 535 | + this.notification = notif; | |
| 536 | + } | |
| 537 | + | |
| 538 | + ObjectName getObjectName() { | |
| 539 | + return sender; | |
| 540 | + } | |
| 541 | + | |
| 542 | + Notification getNotification() { | |
| 543 | + return notification; | |
| 544 | + } | |
| 545 | + | |
| 546 | + public String toString() { | |
| 547 | + return "NamedNotification(" + sender + ", " + notification + ")"; | |
| 548 | + } | |
| 549 | + | |
| 550 | + private final ObjectName sender; | |
| 551 | + private final Notification notification; | |
| 552 | + } | |
| 553 | + | |
| 554 | + /* | |
| 555 | + * Add our listener to every NotificationBroadcaster MBean | |
| 556 | + * currently in the MBean server and to every | |
| 557 | + * NotificationBroadcaster later created. | |
| 558 | + * | |
| 559 | + * It would be really nice if we could just do | |
| 560 | + * mbs.addNotificationListener(new ObjectName("*:*"), ...); | |
| 561 | + * Definitely something for the next version of JMX. | |
| 562 | + * | |
| 563 | + * There is a nasty race condition that we must handle. We | |
| 564 | + * first register for MBean-creation notifications so we can add | |
| 565 | + * listeners to new MBeans, then we query the existing MBeans to | |
| 566 | + * add listeners to them. The problem is that a new MBean could | |
| 567 | + * arrive after we register for creations but before the query has | |
| 568 | + * completed. Then we could see the MBean both in the query and | |
| 569 | + * in an MBean-creation notification, and we would end up | |
| 570 | + * registering our listener twice. | |
| 571 | + * | |
| 572 | + * To solve this problem, we arrange for new MBeans that arrive | |
| 573 | + * while the query is being done to be added to the Set createdDuringQuery | |
| 574 | + * and we do not add a listener immediately. When the query is done, | |
| 575 | + * we atomically turn off the addition of new names to createdDuringQuery | |
| 576 | + * and add all the names that were there to the result of the query. | |
| 577 | + * Since we are dealing with Sets, the result is the same whether or not | |
| 578 | + * the newly-created MBean was included in the query result. | |
| 579 | + * | |
| 580 | + * It is important not to hold any locks during the operation of adding | |
| 581 | + * listeners to MBeans. An MBean's addNotificationListener can be | |
| 582 | + * arbitrary user code, and this could deadlock with any locks we hold | |
| 583 | + * (see bug 6239400). The corollary is that we must not do any operations | |
| 584 | + * in this method or the methods it calls that require locks. | |
| 585 | + */ | |
| 586 | + private void createListeners() { | |
| 587 | + logger.debug("createListeners", "starts"); | |
| 588 | + | |
| 589 | + synchronized (this) { | |
| 590 | + createdDuringQuery = new HashSet<ObjectName>(); | |
| 591 | + } | |
| 592 | + | |
| 593 | + try { | |
| 594 | + addNotificationListener(MBeanServerDelegate.DELEGATE_NAME, | |
| 595 | + creationListener, creationFilter, null); | |
| 596 | + logger.debug("createListeners", "added creationListener"); | |
| 597 | + } catch (Exception e) { | |
| 598 | + final String msg = "Can't add listener to MBean server delegate: "; | |
| 599 | + RuntimeException re = new IllegalArgumentException(msg + e); | |
| 600 | + EnvHelp.initCause(re, e); | |
| 601 | + logger.fine("createListeners", msg + e); | |
| 602 | + logger.debug("createListeners", e); | |
| 603 | + throw re; | |
| 604 | + } | |
| 605 | + | |
| 606 | + /* Spec doesn't say whether Set returned by QueryNames can be modified | |
| 607 | + so we clone it. */ | |
| 608 | + Set<ObjectName> names = queryNames(null, broadcasterQuery); | |
| 609 | + names = new HashSet<ObjectName>(names); | |
| 610 | + | |
| 611 | + synchronized (this) { | |
| 612 | + names.addAll(createdDuringQuery); | |
| 613 | + createdDuringQuery = null; | |
| 614 | + } | |
| 615 | + | |
| 616 | + for (ObjectName name : names) | |
| 617 | + addBufferListener(name); | |
| 618 | + logger.debug("createListeners", "ends"); | |
| 619 | + } | |
| 620 | + | |
| 621 | + private void addBufferListener(ObjectName name) { | |
| 622 | + checkNoLocks(); | |
| 623 | + if (logger.debugOn()) | |
| 624 | + logger.debug("addBufferListener", name.toString()); | |
| 625 | + try { | |
| 626 | + addNotificationListener(name, bufferListener, null, name); | |
| 627 | + } catch (Exception e) { | |
| 628 | + logger.trace("addBufferListener", e); | |
| 629 | + /* This can happen if the MBean was unregistered just | |
| 630 | + after the query. Or user NotificationBroadcaster might | |
| 631 | + throw unexpected exception. */ | |
| 632 | + } | |
| 633 | + } | |
| 634 | + | |
| 635 | + private void removeBufferListener(ObjectName name) { | |
| 636 | + checkNoLocks(); | |
| 637 | + if (logger.debugOn()) | |
| 638 | + logger.debug("removeBufferListener", name.toString()); | |
| 639 | + try { | |
| 640 | + removeNotificationListener(name, bufferListener); | |
| 641 | + } catch (Exception e) { | |
| 642 | + logger.trace("removeBufferListener", e); | |
| 643 | + } | |
| 644 | + } | |
| 645 | + | |
| 646 | + private void addNotificationListener(final ObjectName name, | |
| 647 | + final NotificationListener listener, | |
| 648 | + final NotificationFilter filter, | |
| 649 | + final Object handback) | |
| 650 | + throws Exception { | |
| 651 | + try { | |
| 652 | + AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() { | |
| 653 | + public Void run() throws InstanceNotFoundException { | |
| 654 | + mBeanServer.addNotificationListener(name, | |
| 655 | + listener, | |
| 656 | + filter, | |
| 657 | + handback); | |
| 658 | + return null; | |
| 659 | + } | |
| 660 | + }); | |
| 661 | + } catch (Exception e) { | |
| 662 | + throw extractException(e); | |
| 663 | + } | |
| 664 | + } | |
| 665 | + | |
| 666 | + private void removeNotificationListener(final ObjectName name, | |
| 667 | + final NotificationListener listener) | |
| 668 | + throws Exception { | |
| 669 | + try { | |
| 670 | + AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() { | |
| 671 | + public Void run() throws Exception { | |
| 672 | + mBeanServer.removeNotificationListener(name, listener); | |
| 673 | + return null; | |
| 674 | + } | |
| 675 | + }); | |
| 676 | + } catch (Exception e) { | |
| 677 | + throw extractException(e); | |
| 678 | + } | |
| 679 | + } | |
| 680 | + | |
| 681 | + private Set<ObjectName> queryNames(final ObjectName name, | |
| 682 | + final QueryExp query) { | |
| 683 | + PrivilegedAction<Set<ObjectName>> act = | |
| 684 | + new PrivilegedAction<Set<ObjectName>>() { | |
| 685 | + public Set<ObjectName> run() { | |
| 686 | + return mBeanServer.queryNames(name, query); | |
| 687 | + } | |
| 688 | + }; | |
| 689 | + try { | |
| 690 | + return AccessController.doPrivileged(act); | |
| 691 | + } catch (RuntimeException e) { | |
| 692 | + logger.fine("queryNames", "Failed to query names: " + e); | |
| 693 | + logger.debug("queryNames", e); | |
| 694 | + throw e; | |
| 695 | + } | |
| 696 | + } | |
| 697 | + | |
| 698 | + private static boolean isInstanceOf(final MBeanServer mbs, | |
| 699 | + final ObjectName name, | |
| 700 | + final String className) { | |
| 701 | + PrivilegedExceptionAction<Boolean> act = | |
| 702 | + new PrivilegedExceptionAction<Boolean>() { | |
| 703 | + public Boolean run() throws InstanceNotFoundException { | |
| 704 | + return mbs.isInstanceOf(name, className); | |
| 705 | + } | |
| 706 | + }; | |
| 707 | + try { | |
| 708 | + return AccessController.doPrivileged(act); | |
| 709 | + } catch (Exception e) { | |
| 710 | + logger.fine("isInstanceOf", "failed: " + e); | |
| 711 | + logger.debug("isInstanceOf", e); | |
| 712 | + return false; | |
| 713 | + } | |
| 714 | + } | |
| 715 | + | |
| 716 | + /* This method must not be synchronized. See the comment on the | |
| 717 | + * createListeners method. | |
| 718 | + * | |
| 719 | + * The notification could arrive after our buffer has been destroyed | |
| 720 | + * or even during its destruction. So we always add our listener | |
| 721 | + * (without synchronization), then we check if the buffer has been | |
| 722 | + * destroyed and if so remove the listener we just added. | |
| 723 | + */ | |
| 724 | + private void createdNotification(MBeanServerNotification n) { | |
| 725 | + final String shouldEqual = | |
| 726 | + MBeanServerNotification.REGISTRATION_NOTIFICATION; | |
| 727 | + if (!n.getType().equals(shouldEqual)) { | |
| 728 | + logger.warning("createNotification", "bad type: " + n.getType()); | |
| 729 | + return; | |
| 730 | + } | |
| 731 | + | |
| 732 | + ObjectName name = n.getMBeanName(); | |
| 733 | + if (logger.debugOn()) | |
| 734 | + logger.debug("createdNotification", "for: " + name); | |
| 735 | + | |
| 736 | + synchronized (this) { | |
| 737 | + if (createdDuringQuery != null) { | |
| 738 | + createdDuringQuery.add(name); | |
| 739 | + return; | |
| 740 | + } | |
| 741 | + } | |
| 742 | + | |
| 743 | + if (isInstanceOf(mBeanServer, name, broadcasterClass)) { | |
| 744 | + addBufferListener(name); | |
| 745 | + if (isDisposed()) | |
| 746 | + removeBufferListener(name); | |
| 747 | + } | |
| 748 | + } | |
| 749 | + | |
| 750 | + private class BufferListener implements NotificationListener { | |
| 751 | + public void handleNotification(Notification notif, Object handback) { | |
| 752 | + if (logger.debugOn()) { | |
| 753 | + logger.debug("BufferListener.handleNotification", | |
| 754 | + "notif=" + notif + "; handback=" + handback); | |
| 755 | + } | |
| 756 | + ObjectName name = (ObjectName) handback; | |
| 757 | + addNotification(new NamedNotification(name, notif)); | |
| 758 | + } | |
| 759 | + } | |
| 760 | + | |
| 761 | + private final NotificationListener bufferListener = new BufferListener(); | |
| 762 | + | |
| 763 | + private static class BroadcasterQuery | |
| 764 | + extends QueryEval implements QueryExp { | |
| 765 | + private static final long serialVersionUID = 7378487660587592048L; | |
| 766 | + | |
| 767 | + public boolean apply(final ObjectName name) { | |
| 768 | + final MBeanServer mbs = QueryEval.getMBeanServer(); | |
| 769 | + return isInstanceOf(mbs, name, broadcasterClass); | |
| 770 | + } | |
| 771 | + } | |
| 772 | + private static final QueryExp broadcasterQuery = new BroadcasterQuery(); | |
| 773 | + | |
| 774 | + private static final NotificationFilter creationFilter; | |
| 775 | + static { | |
| 776 | + NotificationFilterSupport nfs = new NotificationFilterSupport(); | |
| 777 | + nfs.enableType(MBeanServerNotification.REGISTRATION_NOTIFICATION); | |
| 778 | + creationFilter = nfs; | |
| 779 | + } | |
| 780 | + | |
| 781 | + private final NotificationListener creationListener = | |
| 782 | + new NotificationListener() { | |
| 783 | + public void handleNotification(Notification notif, | |
| 784 | + Object handback) { | |
| 785 | + logger.debug("creationListener", "handleNotification called"); | |
| 786 | + createdNotification((MBeanServerNotification) notif); | |
| 787 | + } | |
| 788 | + }; | |
| 789 | + | |
| 790 | + private void destroyListeners() { | |
| 791 | + checkNoLocks(); | |
| 792 | + logger.debug("destroyListeners", "starts"); | |
| 793 | + try { | |
| 794 | + removeNotificationListener(MBeanServerDelegate.DELEGATE_NAME, | |
| 795 | + creationListener); | |
| 796 | + } catch (Exception e) { | |
| 797 | + logger.warning("remove listener from MBeanServer delegate", e); | |
| 798 | + } | |
| 799 | + Set<ObjectName> names = queryNames(null, broadcasterQuery); | |
| 800 | + for (final ObjectName name : names) { | |
| 801 | + if (logger.debugOn()) | |
| 802 | + logger.debug("destroyListeners", | |
| 803 | + "remove listener from " + name); | |
| 804 | + removeBufferListener(name); | |
| 805 | + } | |
| 806 | + logger.debug("destroyListeners", "ends"); | |
| 807 | + } | |
| 808 | + | |
| 809 | + private void checkNoLocks() { | |
| 810 | + if (Thread.holdsLock(this) || Thread.holdsLock(globalLock)) | |
| 811 | + logger.warning("checkNoLocks", "lock protocol violation"); | |
| 812 | + } | |
| 813 | + | |
| 814 | + /** | |
| 815 | + * Iterate until we extract the real exception | |
| 816 | + * from a stack of PrivilegedActionExceptions. | |
| 817 | + */ | |
| 818 | + private static Exception extractException(Exception e) { | |
| 819 | + while (e instanceof PrivilegedActionException) { | |
| 820 | + e = ((PrivilegedActionException)e).getException(); | |
| 821 | + } | |
| 822 | + return e; | |
| 823 | + } | |
| 824 | + | |
| 825 | + private static final ClassLogger logger = | |
| 826 | + new ClassLogger("javax.management.remote.misc", | |
| 827 | + "ArrayNotificationBuffer"); | |
| 828 | + | |
| 829 | + private final MBeanServer mBeanServer; | |
| 830 | + private final ArrayQueue<NamedNotification> queue; | |
| 831 | + private int queueSize; | |
| 832 | + private long earliestSequenceNumber; | |
| 833 | + private long nextSequenceNumber; | |
| 834 | + private Set<ObjectName> createdDuringQuery; | |
| 835 | + | |
| 836 | + static final String broadcasterClass = | |
| 837 | + NotificationBroadcaster.class.getName(); | |
| 838 | +} | |