1 /*
2 * Copyright 2002-2008 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any 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.util.List;
39 import java.util.ArrayList;
40 import java.util.HashMap;
41 import java.util.Iterator;
42
43 /**
44 * A multi-threaded implementation of Selector for Windows.
45 *
46 * @author Konstantin Kladko
47 * @author Mark Reinhold
48 */
49
50 final class WindowsSelectorImpl extends SelectorImpl {
51 // Initial capacity of the poll array
52 private final int INIT_CAP = 8;
53 // Maximum number of sockets for select().
54 // Should be INIT_CAP times a power of 2
55 private final static int MAX_SELECTABLE_FDS = 1024;
56
57 // The list of SelectableChannels serviced by this Selector. Every mod
58 // MAX_SELECTABLE_FDS entry is bogus, to align this array with the poll
59 // array, where the corresponding entry is occupied by the wakeupSocket
60 private SelectionKeyImpl[] channelArray = new SelectionKeyImpl[INIT_CAP];
61
62 // The global native poll array holds file decriptors and event masks
63 private PollArrayWrapper pollWrapper;
64
65 // The number of valid entries in poll array, including entries occupied
66 // by wakeup socket handle.
67 private int totalChannels = 1;
68
69 // Number of helper threads needed for select. We need one thread per
70 // each additional set of MAX_SELECTABLE_FDS - 1 channels.
71 private int threadsCount = 0;
72
73 // A list of helper threads for select.
74 private final List<SelectThread> threads = new ArrayList<SelectThread>();
75
76 //Pipe used as a wakeup object.
77 private final Pipe wakeupPipe;
78
79 // File descriptors corresponding to source and sink
80 private final int wakeupSourceFd, wakeupSinkFd;
81
82 // Lock for close cleanup
83 private Object closeLock = new Object();
84
85 // Maps file descriptors to their indices in pollArray
86 private final static class FdMap extends HashMap<Integer, MapEntry> {
87 static final long serialVersionUID = 0L;
88 private MapEntry get(int desc) {
89 return get(new Integer(desc));
90 }
91 private MapEntry put(SelectionKeyImpl ski) {
92 return put(new Integer(ski.channel.getFDVal()), new MapEntry(ski));
93 }
94 private MapEntry remove(SelectionKeyImpl ski) {
95 Integer fd = new Integer(ski.channel.getFDVal());
96 MapEntry x = get(fd);
97 if ((x != null) && (x.ski.channel == ski.channel))
98 return remove(fd);
99 return null;
100 }
101 }
102
103 // class for fdMap entries
104 private final static class MapEntry {
105 SelectionKeyImpl ski;
106 long updateCount = 0;
107 long clearedCount = 0;
108 MapEntry(SelectionKeyImpl ski) {
109 this.ski = ski;
110 }
111 }
112 private final FdMap fdMap = new FdMap();
113
114 // SubSelector for the main thread
115 private final SubSelector subSelector = new SubSelector();
116
117 private long timeout; //timeout for poll
118
119 // Lock for interrupt triggering and clearing
120 private final Object interruptLock = new Object();
121 private volatile boolean interruptTriggered = false;
122
123 WindowsSelectorImpl(SelectorProvider sp) throws IOException {
124 super(sp);
125 pollWrapper = new PollArrayWrapper(INIT_CAP);
126 wakeupPipe = Pipe.open();
127 wakeupSourceFd = ((SelChImpl)wakeupPipe.source()).getFDVal();
128
129 // Disable the Nagle algorithm so that the wakeup is more immediate
130 SinkChannelImpl sink = (SinkChannelImpl)wakeupPipe.sink();
131 (sink.sc).socket().setTcpNoDelay(true);
132 wakeupSinkFd = ((SelChImpl)sink).getFDVal();
133
134 pollWrapper.addWakeupSocket(wakeupSourceFd, 0);
135 }
136
137 protected int doSelect(long timeout) throws IOException {
138 if (channelArray == null)
139 throw new ClosedSelectorException();
140 this.timeout = timeout; // set selector timeout
141 processDeregisterQueue();
142 if (interruptTriggered) {
143 resetWakeupSocket();
144 return 0;
145 }
146 // Calculate number of helper threads needed for poll. If necessary
147 // threads are created here and start waiting on startLock
148 adjustThreadsCount();
149 finishLock.reset(); // reset finishLock
150 // Wakeup helper threads, waiting on startLock, so they start polling.
151 // Redundant threads will exit here after wakeup.
152 startLock.startThreads();
153 // do polling in the main thread. Main thread is responsible for
154 // first MAX_SELECTABLE_FDS entries in pollArray.
155 try {
156 begin();
157 try {
158 subSelector.poll();
159 } catch (IOException e) {
160 finishLock.setException(e); // Save this exception
161 }
162 // Main thread is out of poll(). Wakeup others and wait for them
163 if (threads.size() > 0)
164 finishLock.waitForHelperThreads();
165 } finally {
166 end();
167 }
168 // Done with poll(). Set wakeupSocket to nonsignaled for the next run.
169 finishLock.checkForException();
170 processDeregisterQueue();
171 int updated = updateSelectedKeys();
172 // Done with poll(). Set wakeupSocket to nonsignaled for the next run.
173 resetWakeupSocket();
174 return updated;
175 }
176
177 // Helper threads wait on this lock for the next poll.
178 private final StartLock startLock = new StartLock();
179
180 private final class StartLock {
181 // A variable which distinguishes the current run of doSelect from the
182 // previous one. Incrementing runsCounter and notifying threads will
183 // trigger another round of poll.
184 private long runsCounter;
185 // Triggers threads, waiting on this lock to start polling.
186 private synchronized void startThreads() {
187 runsCounter++; // next run
188 notifyAll(); // wake up threads.
189 }
190 // This function is called by a helper thread to wait for the
191 // next round of poll(). It also checks, if this thread became
192 // redundant. If yes, it returns true, notifying the thread
193 // that it should exit.
194 private synchronized boolean waitForStart(SelectThread thread) {
195 while (true) {
196 while (runsCounter == thread.lastRun) {
197 try {
198 startLock.wait();
199 } catch (InterruptedException e) {
200 Thread.currentThread().interrupt();
201 }
202 }
203 if (thread.isZombie()) { // redundant thread
204 return true; // will cause run() to exit.
205 } else {
206 thread.lastRun = runsCounter; // update lastRun
207 return false; // will cause run() to poll.
208 }
209 }
210 }
211 }
212
213 // Main thread waits on this lock, until all helper threads are done
214 // with poll().
215 private final FinishLock finishLock = new FinishLock();
216
217 private final class FinishLock {
218 // Number of helper threads, that did not finish yet.
219 private int threadsToFinish;
220
221 // IOException which occured during the last run.
222 IOException exception = null;
223
224 // Called before polling.
225 private void reset() {
226 threadsToFinish = threads.size(); // helper threads
227 }
228
229 // Each helper thread invokes this function on finishLock, when
230 // the thread is done with poll().
231 private synchronized void threadFinished() {
232 if (threadsToFinish == threads.size()) { // finished poll() first
233 // if finished first, wakeup others
234 wakeup();
235 }
236 threadsToFinish--;
237 if (threadsToFinish == 0) // all helper threads finished poll().
238 notify(); // notify the main thread
239 }
240
241 // The main thread invokes this function on finishLock to wait
242 // for helper threads to finish poll().
243 private synchronized void waitForHelperThreads() {
244 if (threadsToFinish == threads.size()) {
245 // no helper threads finished yet. Wakeup them up.
246 wakeup();
247 }
248 while (threadsToFinish != 0) {
249 try {
250 finishLock.wait();
251 } catch (InterruptedException e) {
252 // Interrupted - set interrupted state.
253 Thread.currentThread().interrupt();
254 }
255 }
256 }
257
258 // sets IOException for this run
259 private synchronized void setException(IOException e) {
260 exception = e;
261 }
262
263 // Checks if there was any exception during the last run.
264 // If yes, throws it
265 private void checkForException() throws IOException {
266 if (exception == null)
267 return;
268 StringBuffer message = new StringBuffer("An exception occured" +
269 " during the execution of select(): \n");
270 message.append(exception);
271 message.append('\n');
272 exception = null;
273 throw new IOException(message.toString());
274 }
275 }
276
277 private final class SubSelector {
278 private final int pollArrayIndex; // starting index in pollArray to poll
279 // These arrays will hold result of native select().
280 // The first element of each array is the number of selected sockets.
281 // Other elements are file descriptors of selected sockets.
282 private final int[] readFds = new int [MAX_SELECTABLE_FDS + 1];
283 private final int[] writeFds = new int [MAX_SELECTABLE_FDS + 1];
284 private final int[] exceptFds = new int [MAX_SELECTABLE_FDS + 1];
285
286 private SubSelector() {
287 this.pollArrayIndex = 0; // main thread
288 }
289
290 private SubSelector(int threadIndex) { // helper threads
291 this.pollArrayIndex = (threadIndex + 1) * MAX_SELECTABLE_FDS;
292 }
293
294 private int poll() throws IOException{ // poll for the main thread
295 return poll0(pollWrapper.pollArrayAddress,
296 Math.min(totalChannels, MAX_SELECTABLE_FDS),
297 readFds, writeFds, exceptFds, timeout);
298 }
299
300 private int poll(int index) throws IOException {
301 // poll for helper threads
302 return poll0(pollWrapper.pollArrayAddress +
303 (pollArrayIndex * PollArrayWrapper.SIZE_POLLFD),
304 Math.min(MAX_SELECTABLE_FDS,
305 totalChannels - (index + 1) * MAX_SELECTABLE_FDS),
306 readFds, writeFds, exceptFds, timeout);
307 }
308
309 private native int poll0(long pollAddress, int numfds,
310 int[] readFds, int[] writeFds, int[] exceptFds, long timeout);
311
312 private int processSelectedKeys(long updateCount) {
313 int numKeysUpdated = 0;
314 numKeysUpdated += processFDSet(updateCount, readFds,
315 PollArrayWrapper.POLLIN);
316 numKeysUpdated += processFDSet(updateCount, writeFds,
317 PollArrayWrapper.POLLCONN |
318 PollArrayWrapper.POLLOUT);
319 numKeysUpdated += processFDSet(updateCount, exceptFds,
320 PollArrayWrapper.POLLIN |
321 PollArrayWrapper.POLLCONN |
322 PollArrayWrapper.POLLOUT);
323 return numKeysUpdated;
324 }
325
326 /**
327 * Note, clearedCount is used to determine if the readyOps have
328 * been reset in this select operation. updateCount is used to
329 * tell if a key has been counted as updated in this select
330 * operation.
331 *
332 * me.updateCount <= me.clearedCount <= updateCount
333 */
334 private int processFDSet(long updateCount, int[] fds, int rOps) {
335 int numKeysUpdated = 0;
336 for (int i = 1; i <= fds[0]; i++) {
337 int desc = fds[i];
338 if (desc == wakeupSourceFd) {
339 synchronized (interruptLock) {
340 interruptTriggered = true;
341 }
342 continue;
343 }
344 MapEntry me = fdMap.get(desc);
345 // If me is null, the key was deregistered in the previous
346 // processDeregisterQueue.
347 if (me == null)
348 continue;
349 SelectionKeyImpl sk = me.ski;
350 if (selectedKeys.contains(sk)) { // Key in selected set
351 if (me.clearedCount != updateCount) {
352 if (sk.channel.translateAndSetReadyOps(rOps, sk) &&
353 (me.updateCount != updateCount)) {
354 me.updateCount = updateCount;
355 numKeysUpdated++;
356 }
357 } else { // The readyOps have been set; now add
358 if (sk.channel.translateAndUpdateReadyOps(rOps, sk) &&
359 (me.updateCount != updateCount)) {
360 me.updateCount = updateCount;
361 numKeysUpdated++;
362 }
363 }
364 me.clearedCount = updateCount;
365 } else { // Key is not in selected set yet
366 if (me.clearedCount != updateCount) {
367 sk.channel.translateAndSetReadyOps(rOps, sk);
368 if ((sk.nioReadyOps() & sk.nioInterestOps()) != 0) {
369 selectedKeys.add(sk);
370 me.updateCount = updateCount;
371 numKeysUpdated++;
372 }
373 } else { // The readyOps have been set; now add
374 sk.channel.translateAndUpdateReadyOps(rOps, sk);
375 if ((sk.nioReadyOps() & sk.nioInterestOps()) != 0) {
376 selectedKeys.add(sk);
377 me.updateCount = updateCount;
378 numKeysUpdated++;
379 }
380 }
381 me.clearedCount = updateCount;
382 }
383 }
384 return numKeysUpdated;
385 }
386 }
387
388 // Represents a helper thread used for select.
389 private final class SelectThread extends Thread {
390 private final int index; // index of this thread
391 final SubSelector subSelector;
392 private long lastRun = 0; // last run number
393 private volatile boolean zombie;
394 // Creates a new thread
395 private SelectThread(int i) {
396 this.index = i;
397 this.subSelector = new SubSelector(i);
398 //make sure we wait for next round of poll
399 this.lastRun = startLock.runsCounter;
400 }
401 void makeZombie() {
402 zombie = true;
403 }
404 boolean isZombie() {
405 return zombie;
406 }
407 public void run() {
408 while (true) { // poll loop
409 // wait for the start of poll. If this thread has become
410 // redundant, then exit.
411 if (startLock.waitForStart(this))
412 return;
413 // call poll()
414 try {
415 subSelector.poll(index);
416 } catch (IOException e) {
417 // Save this exception and let other threads finish.
418 finishLock.setException(e);
419 }
420 // notify main thread, that this thread has finished, and
421 // wakeup others, if this thread is the first to finish.
422 finishLock.threadFinished();
423 }
424 }
425 }
426
427 // After some channels registered/deregistered, the number of required
428 // helper threads may have changed. Adjust this number.
429 private void adjustThreadsCount() {
430 if (threadsCount > threads.size()) {
431 // More threads needed. Start more threads.
432 for (int i = threads.size(); i < threadsCount; i++) {
433 SelectThread newThread = new SelectThread(i);
434 threads.add(newThread);
435 newThread.setDaemon(true);
436 newThread.start();
437 }
438 } else if (threadsCount < threads.size()) {
439 // Some threads become redundant. Remove them from the threads List.
440 for (int i = threads.size() - 1 ; i >= threadsCount; i--)
441 threads.remove(i).makeZombie();
442 }
443 }
444
445 // Sets Windows wakeup socket to a signaled state.
446 private void setWakeupSocket() {
447 setWakeupSocket0(wakeupSinkFd);
448 }
449 private native void setWakeupSocket0(int wakeupSinkFd);
450
451 // Sets Windows wakeup socket to a non-signaled state.
452 private void resetWakeupSocket() {
453 synchronized (interruptLock) {
454 if (interruptTriggered == false)
455 return;
456 resetWakeupSocket0(wakeupSourceFd);
457 interruptTriggered = false;
458 }
459 }
460
461 private native void resetWakeupSocket0(int wakeupSourceFd);
462
463 // We increment this counter on each call to updateSelectedKeys()
464 // each entry in SubSelector.fdsMap has a memorized value of
465 // updateCount. When we increment numKeysUpdated we set updateCount
466 // for the corresponding entry to its current value. This is used to
467 // avoid counting the same key more than once - the same key can
468 // appear in readfds and writefds.
469 private long updateCount = 0;
470
471 // Update ops of the corresponding Channels. Add the ready keys to the
472 // ready queue.
473 private int updateSelectedKeys() {
474 updateCount++;
475 int numKeysUpdated = 0;
476 numKeysUpdated += subSelector.processSelectedKeys(updateCount);
477 for (SelectThread t: threads) {
478 numKeysUpdated += t.subSelector.processSelectedKeys(updateCount);
479 }
480 return numKeysUpdated;
481 }
482
483 protected void implClose() throws IOException {
484 synchronized (closeLock) {
485 if (channelArray != null) {
486 if (pollWrapper != null) {
487 // prevent further wakeup
488 synchronized (interruptLock) {
489 interruptTriggered = true;
490 }
491 wakeupPipe.sink().close();
492 wakeupPipe.source().close();
493 for(int i = 1; i < totalChannels; i++) { // Deregister channels
494 if (i % MAX_SELECTABLE_FDS != 0) { // skip wakeupEvent
495 deregister(channelArray[i]);
496 SelectableChannel selch = channelArray[i].channel();
497 if (!selch.isOpen() && !selch.isRegistered())
498 ((SelChImpl)selch).kill();
499 }
500 }
501 pollWrapper.free();
502 pollWrapper = null;
503 selectedKeys = null;
504 channelArray = null;
505 // Make all remaining helper threads exit
506 for (SelectThread t: threads)
507 t.makeZombie();
508 startLock.startThreads();
509 }
510 }
511 }
512 }
513
514 protected void implRegister(SelectionKeyImpl ski) {
515 synchronized (closeLock) {
516 if (pollWrapper == null)
517 throw new ClosedSelectorException();
518 growIfNeeded();
519 channelArray[totalChannels] = ski;
520 ski.setIndex(totalChannels);
521 fdMap.put(ski);
522 keys.add(ski);
523 pollWrapper.addEntry(totalChannels, ski);
524 totalChannels++;
525 }
526 }
527
528 private void growIfNeeded() {
529 if (channelArray.length == totalChannels) {
530 int newSize = totalChannels * 2; // Make a larger array
531 SelectionKeyImpl temp[] = new SelectionKeyImpl[newSize];
532 System.arraycopy(channelArray, 1, temp, 1, totalChannels - 1);
533 channelArray = temp;
534 pollWrapper.grow(newSize);
535 }
536 if (totalChannels % MAX_SELECTABLE_FDS == 0) { // more threads needed
537 pollWrapper.addWakeupSocket(wakeupSourceFd, totalChannels);
538 totalChannels++;
539 threadsCount++;
540 }
541 }
542
543 protected void implDereg(SelectionKeyImpl ski) throws IOException{
544 int i = ski.getIndex();
545 assert (i >= 0);
546 if (i != totalChannels - 1) {
547 // Copy end one over it
548 SelectionKeyImpl endChannel = channelArray[totalChannels-1];
549 channelArray[i] = endChannel;
550 endChannel.setIndex(i);
551 pollWrapper.replaceEntry(pollWrapper, totalChannels - 1,
552 pollWrapper, i);
553 }
554 channelArray[totalChannels - 1] = null;
555 totalChannels--;
556 ski.setIndex(-1);
557 if ( totalChannels != 1 && totalChannels % MAX_SELECTABLE_FDS == 1) {
558 totalChannels--;
559 threadsCount--; // The last thread has become redundant.
560 }
561 fdMap.remove(ski); // Remove the key from fdMap, keys and selectedKeys
562 keys.remove(ski);
563 selectedKeys.remove(ski);
564 deregister(ski);
565 SelectableChannel selch = ski.channel();
566 if (!selch.isOpen() && !selch.isRegistered())
567 ((SelChImpl)selch).kill();
568 }
569
570 void putEventOps(SelectionKeyImpl sk, int ops) {
571 synchronized (closeLock) {
572 if (pollWrapper == null)
573 throw new ClosedSelectorException();
574 pollWrapper.putEventOps(sk.getIndex(), ops);
575 }
576 }
577
578 public Selector wakeup() {
579 synchronized (interruptLock) {
580 if (!interruptTriggered) {
581 setWakeupSocket();
582 interruptTriggered = true;
583 }
584 }
585 return this;
586 }
587
588 static {
589 Util.load();
590 }
591 }