1 /* 2 * Copyright (c) 2002, 2013, 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 /* 27 */ 28 29 30 package sun.nio.ch; 31 32 import java.nio.channels.spi.SelectorProvider; 33 import java.nio.channels.Selector; 34 import java.nio.channels.ClosedSelectorException; 35 import java.nio.channels.Pipe; 36 import java.nio.channels.SelectableChannel; 37 import java.io.IOException; 38 import java.nio.channels.CancelledKeyException; 39 import java.util.List; 40 import java.util.ArrayList; 41 import java.util.HashMap; 42 import java.util.Iterator; 43 44 /** 45 * A multi-threaded implementation of Selector for Windows. 46 * 47 * @author Konstantin Kladko 48 * @author Mark Reinhold 49 */ 50 51 final class WindowsSelectorImpl extends SelectorImpl { 52 // Initial capacity of the poll array 53 private final int INIT_CAP = 8; 54 // Maximum number of sockets for select(). 55 // Should be INIT_CAP times a power of 2 56 private static final int MAX_SELECTABLE_FDS = 1024; 57 58 // The list of SelectableChannels serviced by this Selector. Every mod 59 // MAX_SELECTABLE_FDS entry is bogus, to align this array with the poll 60 // array, where the corresponding entry is occupied by the wakeupSocket 61 private SelectionKeyImpl[] channelArray = new SelectionKeyImpl[INIT_CAP]; 62 63 // The global native poll array holds file decriptors and event masks 64 private PollArrayWrapper pollWrapper; 65 66 // The number of valid entries in poll array, including entries occupied 67 // by wakeup socket handle. 68 private int totalChannels = 1; 69 70 // Number of helper threads needed for select. We need one thread per 71 // each additional set of MAX_SELECTABLE_FDS - 1 channels. 72 private int threadsCount = 0; 73 74 // A list of helper threads for select. 75 private final List<SelectThread> threads = new ArrayList<SelectThread>(); 76 77 //Pipe used as a wakeup object. 78 private final Pipe wakeupPipe; 79 80 // File descriptors corresponding to source and sink 81 private final int wakeupSourceFd, wakeupSinkFd; 82 83 // Lock for close cleanup 84 private Object closeLock = new Object(); 85 86 // Maps file descriptors to their indices in pollArray 87 private static final class FdMap extends HashMap<Integer, MapEntry> { 88 static final long serialVersionUID = 0L; 89 private MapEntry get(int desc) { 90 return get(new Integer(desc)); 91 } 92 private MapEntry put(SelectionKeyImpl ski) { 93 return put(new Integer(ski.channel.getFDVal()), new MapEntry(ski)); 94 } 95 private MapEntry remove(SelectionKeyImpl ski) { 96 Integer fd = new Integer(ski.channel.getFDVal()); 97 MapEntry x = get(fd); 98 if ((x != null) && (x.ski.channel == ski.channel)) 99 return remove(fd); 100 return null; 101 } 102 } 103 104 // class for fdMap entries 105 private static final class MapEntry { 106 SelectionKeyImpl ski; 107 long updateCount = 0; 108 long clearedCount = 0; 109 MapEntry(SelectionKeyImpl ski) { 110 this.ski = ski; 111 } 112 } 113 private final FdMap fdMap = new FdMap(); 114 115 // SubSelector for the main thread 116 private final SubSelector subSelector = new SubSelector(); 117 118 private long timeout; //timeout for poll 119 120 // Lock for interrupt triggering and clearing 121 private final Object interruptLock = new Object(); 122 private volatile boolean interruptTriggered = false; 123 124 WindowsSelectorImpl(SelectorProvider sp) throws IOException { 125 super(sp); 126 pollWrapper = new PollArrayWrapper(INIT_CAP); 127 wakeupPipe = Pipe.open(); 128 wakeupSourceFd = ((SelChImpl)wakeupPipe.source()).getFDVal(); 129 130 // Disable the Nagle algorithm so that the wakeup is more immediate 131 SinkChannelImpl sink = (SinkChannelImpl)wakeupPipe.sink(); 132 (sink.sc).socket().setTcpNoDelay(true); 133 wakeupSinkFd = ((SelChImpl)sink).getFDVal(); 134 135 pollWrapper.addWakeupSocket(wakeupSourceFd, 0); 136 } 137 138 protected int doSelect(long timeout) throws IOException { 139 if (channelArray == null) 140 throw new ClosedSelectorException(); 141 this.timeout = timeout; // set selector timeout 142 processDeregisterQueue(); 143 if (interruptTriggered) { 144 resetWakeupSocket(); 145 return 0; 146 } 147 // Calculate number of helper threads needed for poll. If necessary 148 // threads are created here and start waiting on startLock 149 adjustThreadsCount(); 150 finishLock.reset(); // reset finishLock 151 // Wakeup helper threads, waiting on startLock, so they start polling. 152 // Redundant threads will exit here after wakeup. 153 startLock.startThreads(); 154 // do polling in the main thread. Main thread is responsible for 155 // first MAX_SELECTABLE_FDS entries in pollArray. 156 try { 157 begin(); 158 try { 159 subSelector.poll(); 160 } catch (IOException e) { 161 finishLock.setException(e); // Save this exception 162 } 163 // Main thread is out of poll(). Wakeup others and wait for them 164 if (threads.size() > 0) 165 finishLock.waitForHelperThreads(); 166 } finally { 167 end(); 168 } 169 // Done with poll(). Set wakeupSocket to nonsignaled for the next run. 170 finishLock.checkForException(); 171 processDeregisterQueue(); 172 int updated = updateSelectedKeys(); 173 // Done with poll(). Set wakeupSocket to nonsignaled for the next run. 174 resetWakeupSocket(); 175 return updated; 176 } 177 178 // Helper threads wait on this lock for the next poll. 179 private final StartLock startLock = new StartLock(); 180 181 private final class StartLock { 182 // A variable which distinguishes the current run of doSelect from the 183 // previous one. Incrementing runsCounter and notifying threads will 184 // trigger another round of poll. 185 private long runsCounter; 186 // Triggers threads, waiting on this lock to start polling. 187 private synchronized void startThreads() { 188 runsCounter++; // next run 189 notifyAll(); // wake up threads. 190 } 191 // This function is called by a helper thread to wait for the 192 // next round of poll(). It also checks, if this thread became 193 // redundant. If yes, it returns true, notifying the thread 194 // that it should exit. 195 private synchronized boolean waitForStart(SelectThread thread) { 196 while (true) { 197 while (runsCounter == thread.lastRun) { 198 try { 199 startLock.wait(); 200 } catch (InterruptedException e) { 201 Thread.currentThread().interrupt(); 202 } 203 } 204 if (thread.isZombie()) { // redundant thread 205 return true; // will cause run() to exit. 206 } else { 207 thread.lastRun = runsCounter; // update lastRun 208 return false; // will cause run() to poll. 209 } 210 } 211 } 212 } 213 214 // Main thread waits on this lock, until all helper threads are done 215 // with poll(). 216 private final FinishLock finishLock = new FinishLock(); 217 218 private final class FinishLock { 219 // Number of helper threads, that did not finish yet. 220 private int threadsToFinish; 221 222 // IOException which occurred during the last run. 223 IOException exception = null; 224 225 // Called before polling. 226 private void reset() { 227 threadsToFinish = threads.size(); // helper threads 228 } 229 230 // Each helper thread invokes this function on finishLock, when 231 // the thread is done with poll(). 232 private synchronized void threadFinished() { 233 if (threadsToFinish == threads.size()) { // finished poll() first 234 // if finished first, wakeup others 235 wakeup(); 236 } 237 threadsToFinish--; 238 if (threadsToFinish == 0) // all helper threads finished poll(). 239 notify(); // notify the main thread 240 } 241 242 // The main thread invokes this function on finishLock to wait 243 // for helper threads to finish poll(). 244 private synchronized void waitForHelperThreads() { 245 if (threadsToFinish == threads.size()) { 246 // no helper threads finished yet. Wakeup them up. 247 wakeup(); 248 } 249 while (threadsToFinish != 0) { 250 try { 251 finishLock.wait(); 252 } catch (InterruptedException e) { 253 // Interrupted - set interrupted state. 254 Thread.currentThread().interrupt(); 255 } 256 } 257 } 258 259 // sets IOException for this run 260 private synchronized void setException(IOException e) { 261 exception = e; 262 } 263 264 // Checks if there was any exception during the last run. 265 // If yes, throws it 266 private void checkForException() throws IOException { 267 if (exception == null) 268 return; 269 StringBuffer message = new StringBuffer("An exception occurred" + 270 " during the execution of select(): \n"); 271 message.append(exception); 272 message.append('\n'); 273 exception = null; 274 throw new IOException(message.toString()); 275 } 276 } 277 278 private final class SubSelector { 279 private final int pollArrayIndex; // starting index in pollArray to poll 280 // These arrays will hold result of native select(). 281 // The first element of each array is the number of selected sockets. 282 // Other elements are file descriptors of selected sockets. 283 private final int[] readFds = new int [MAX_SELECTABLE_FDS + 1]; 284 private final int[] writeFds = new int [MAX_SELECTABLE_FDS + 1]; 285 private final int[] exceptFds = new int [MAX_SELECTABLE_FDS + 1]; 286 287 private SubSelector() { 288 this.pollArrayIndex = 0; // main thread 289 } 290 291 private SubSelector(int threadIndex) { // helper threads 292 this.pollArrayIndex = (threadIndex + 1) * MAX_SELECTABLE_FDS; 293 } 294 295 private int poll() throws IOException{ // poll for the main thread 296 return poll0(pollWrapper.pollArrayAddress, 297 Math.min(totalChannels, MAX_SELECTABLE_FDS), 298 readFds, writeFds, exceptFds, timeout); 299 } 300 301 private int poll(int index) throws IOException { 302 // poll for helper threads 303 return poll0(pollWrapper.pollArrayAddress + 304 (pollArrayIndex * PollArrayWrapper.SIZE_POLLFD), 305 Math.min(MAX_SELECTABLE_FDS, 306 totalChannels - (index + 1) * MAX_SELECTABLE_FDS), 307 readFds, writeFds, exceptFds, timeout); 308 } 309 310 private native int poll0(long pollAddress, int numfds, 311 int[] readFds, int[] writeFds, int[] exceptFds, long timeout); 312 313 private int processSelectedKeys(long updateCount) { 314 int numKeysUpdated = 0; 315 numKeysUpdated += processFDSet(updateCount, readFds, 316 Net.POLLIN, 317 false); 318 numKeysUpdated += processFDSet(updateCount, writeFds, 319 Net.POLLCONN | 320 Net.POLLOUT, 321 false); 322 numKeysUpdated += processFDSet(updateCount, exceptFds, 323 Net.POLLIN | 324 Net.POLLCONN | 325 Net.POLLOUT, 326 true); 327 return numKeysUpdated; 328 } 329 330 /** 331 * Note, clearedCount is used to determine if the readyOps have 332 * been reset in this select operation. updateCount is used to 333 * tell if a key has been counted as updated in this select 334 * operation. 335 * 336 * me.updateCount <= me.clearedCount <= updateCount 337 */ 338 private int processFDSet(long updateCount, int[] fds, int rOps, 339 boolean isExceptFds) 340 { 341 int numKeysUpdated = 0; 342 for (int i = 1; i <= fds[0]; i++) { 343 int desc = fds[i]; 344 if (desc == wakeupSourceFd) { 345 synchronized (interruptLock) { 346 interruptTriggered = true; 347 } 348 continue; 349 } 350 MapEntry me = fdMap.get(desc); 351 // If me is null, the key was deregistered in the previous 352 // processDeregisterQueue. 353 if (me == null) 354 continue; 355 SelectionKeyImpl sk = me.ski; 356 357 // The descriptor may be in the exceptfds set because there is 358 // OOB data queued to the socket. If there is OOB data then it 359 // is discarded and the key is not added to the selected set. 360 if (isExceptFds && 361 (sk.channel() instanceof SocketChannelImpl) && 362 discardUrgentData(desc)) 363 { 364 continue; 365 } 366 367 if (selectedKeys.contains(sk)) { // Key in selected set 368 if (me.clearedCount != updateCount) { 369 if (sk.channel.translateAndSetReadyOps(rOps, sk) && 370 (me.updateCount != updateCount)) { 371 me.updateCount = updateCount; 372 numKeysUpdated++; 373 } 374 } else { // The readyOps have been set; now add 375 if (sk.channel.translateAndUpdateReadyOps(rOps, sk) && 376 (me.updateCount != updateCount)) { 377 me.updateCount = updateCount; 378 numKeysUpdated++; 379 } 380 } 381 me.clearedCount = updateCount; 382 } else { // Key is not in selected set yet 383 if (me.clearedCount != updateCount) { 384 sk.channel.translateAndSetReadyOps(rOps, sk); 385 if ((sk.nioReadyOps() & sk.nioInterestOps()) != 0) { 386 selectedKeys.add(sk); 387 me.updateCount = updateCount; 388 numKeysUpdated++; 389 } 390 } else { // The readyOps have been set; now add 391 sk.channel.translateAndUpdateReadyOps(rOps, sk); 392 if ((sk.nioReadyOps() & sk.nioInterestOps()) != 0) { 393 selectedKeys.add(sk); 394 me.updateCount = updateCount; 395 numKeysUpdated++; 396 } 397 } 398 me.clearedCount = updateCount; 399 } 400 } 401 return numKeysUpdated; 402 } 403 } 404 405 // Represents a helper thread used for select. 406 private final class SelectThread extends Thread { 407 private final int index; // index of this thread 408 final SubSelector subSelector; 409 private long lastRun = 0; // last run number 410 private volatile boolean zombie; 411 // Creates a new thread 412 private SelectThread(int i) { 413 super(null, null, "SelectorHelper", 0, false); 414 this.index = i; 415 this.subSelector = new SubSelector(i); 416 //make sure we wait for next round of poll 417 this.lastRun = startLock.runsCounter; 418 } 419 void makeZombie() { 420 zombie = true; 421 } 422 boolean isZombie() { 423 return zombie; 424 } 425 public void run() { 426 while (true) { // poll loop 427 // wait for the start of poll. If this thread has become 428 // redundant, then exit. 429 if (startLock.waitForStart(this)) 430 return; 431 // call poll() 432 try { 433 subSelector.poll(index); 434 } catch (IOException e) { 435 // Save this exception and let other threads finish. 436 finishLock.setException(e); 437 } 438 // notify main thread, that this thread has finished, and 439 // wakeup others, if this thread is the first to finish. 440 finishLock.threadFinished(); 441 } 442 } 443 } 444 445 // After some channels registered/deregistered, the number of required 446 // helper threads may have changed. Adjust this number. 447 private void adjustThreadsCount() { 448 if (threadsCount > threads.size()) { 449 // More threads needed. Start more threads. 450 for (int i = threads.size(); i < threadsCount; i++) { 451 SelectThread newThread = new SelectThread(i); 452 threads.add(newThread); 453 newThread.setDaemon(true); 454 newThread.start(); 455 } 456 } else if (threadsCount < threads.size()) { 457 // Some threads become redundant. Remove them from the threads List. 458 for (int i = threads.size() - 1 ; i >= threadsCount; i--) 459 threads.remove(i).makeZombie(); 460 } 461 } 462 463 // Sets Windows wakeup socket to a signaled state. 464 private void setWakeupSocket() { 465 setWakeupSocket0(wakeupSinkFd); 466 } 467 private native void setWakeupSocket0(int wakeupSinkFd); 468 469 // Sets Windows wakeup socket to a non-signaled state. 470 private void resetWakeupSocket() { 471 synchronized (interruptLock) { 472 if (interruptTriggered == false) 473 return; 474 resetWakeupSocket0(wakeupSourceFd); 475 interruptTriggered = false; 476 } 477 } 478 479 private native void resetWakeupSocket0(int wakeupSourceFd); 480 481 private native boolean discardUrgentData(int fd); 482 483 // We increment this counter on each call to updateSelectedKeys() 484 // each entry in SubSelector.fdsMap has a memorized value of 485 // updateCount. When we increment numKeysUpdated we set updateCount 486 // for the corresponding entry to its current value. This is used to 487 // avoid counting the same key more than once - the same key can 488 // appear in readfds and writefds. 489 private long updateCount = 0; 490 491 // Update ops of the corresponding Channels. Add the ready keys to the 492 // ready queue. 493 private int updateSelectedKeys() { 494 updateCount++; 495 int numKeysUpdated = 0; 496 numKeysUpdated += subSelector.processSelectedKeys(updateCount); 497 for (SelectThread t: threads) { 498 numKeysUpdated += t.subSelector.processSelectedKeys(updateCount); 499 } 500 return numKeysUpdated; 501 } 502 503 protected void implClose() throws IOException { 504 synchronized (closeLock) { 505 if (channelArray != null) { 506 if (pollWrapper != null) { 507 // prevent further wakeup 508 synchronized (interruptLock) { 509 interruptTriggered = true; 510 } 511 wakeupPipe.sink().close(); 512 wakeupPipe.source().close(); 513 for(int i = 1; i < totalChannels; i++) { // Deregister channels 514 if (i % MAX_SELECTABLE_FDS != 0) { // skip wakeupEvent 515 deregister(channelArray[i]); 516 SelectableChannel selch = channelArray[i].channel(); 517 if (!selch.isOpen() && !selch.isRegistered()) 518 ((SelChImpl)selch).kill(); 519 } 520 } 521 pollWrapper.free(); 522 pollWrapper = null; 523 selectedKeys = null; 524 channelArray = null; 525 // Make all remaining helper threads exit 526 for (SelectThread t: threads) 527 t.makeZombie(); 528 startLock.startThreads(); 529 } 530 } 531 } 532 } 533 534 protected void implRegister(SelectionKeyImpl ski) { 535 synchronized (closeLock) { 536 if (pollWrapper == null) 537 throw new ClosedSelectorException(); 538 growIfNeeded(); 539 channelArray[totalChannels] = ski; 540 ski.setIndex(totalChannels); 541 fdMap.put(ski); 542 keys.add(ski); 543 pollWrapper.addEntry(totalChannels, ski); 544 totalChannels++; 545 } 546 } 547 548 private void growIfNeeded() { 549 if (channelArray.length == totalChannels) { 550 int newSize = totalChannels * 2; // Make a larger array 551 SelectionKeyImpl temp[] = new SelectionKeyImpl[newSize]; 552 System.arraycopy(channelArray, 1, temp, 1, totalChannels - 1); 553 channelArray = temp; 554 pollWrapper.grow(newSize); 555 } 556 if (totalChannels % MAX_SELECTABLE_FDS == 0) { // more threads needed 557 pollWrapper.addWakeupSocket(wakeupSourceFd, totalChannels); 558 totalChannels++; 559 threadsCount++; 560 } 561 } 562 563 protected void implDereg(SelectionKeyImpl ski) throws IOException{ 564 int i = ski.getIndex(); 565 assert (i >= 0); 566 synchronized (closeLock) { 567 if (i != totalChannels - 1) { 568 // Copy end one over it 569 SelectionKeyImpl endChannel = channelArray[totalChannels-1]; 570 channelArray[i] = endChannel; 571 endChannel.setIndex(i); 572 pollWrapper.replaceEntry(pollWrapper, totalChannels - 1, 573 pollWrapper, i); 574 } 575 ski.setIndex(-1); 576 } 577 channelArray[totalChannels - 1] = null; 578 totalChannels--; 579 if ( totalChannels != 1 && totalChannels % MAX_SELECTABLE_FDS == 1) { 580 totalChannels--; 581 threadsCount--; // The last thread has become redundant. 582 } 583 fdMap.remove(ski); // Remove the key from fdMap, keys and selectedKeys 584 keys.remove(ski); 585 selectedKeys.remove(ski); 586 deregister(ski); 587 SelectableChannel selch = ski.channel(); 588 if (!selch.isOpen() && !selch.isRegistered()) 589 ((SelChImpl)selch).kill(); 590 } 591 592 public void putEventOps(SelectionKeyImpl sk, int ops) { 593 synchronized (closeLock) { 594 if (pollWrapper == null) 595 throw new ClosedSelectorException(); 596 // make sure this sk has not been removed yet 597 int index = sk.getIndex(); 598 if (index == -1) 599 throw new CancelledKeyException(); 600 pollWrapper.putEventOps(index, ops); 601 } 602 } 603 604 public Selector wakeup() { 605 synchronized (interruptLock) { 606 if (!interruptTriggered) { 607 setWakeupSocket(); 608 interruptTriggered = true; 609 } 610 } 611 return this; 612 } 613 614 static { 615 IOUtil.load(); 616 } 617 } --- EOF ---