1 /*
  2  * Copyright (c) 2011, 2018, 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 sun.nio.ch;
 27 
 28 import java.io.IOException;
 29 import java.nio.channels.ClosedSelectorException;
 30 import java.nio.channels.SelectionKey;
 31 import java.nio.channels.Selector;
 32 import java.nio.channels.spi.SelectorProvider;
 33 import java.util.ArrayDeque;
 34 import java.util.Deque;
 35 import java.util.HashMap;
 36 import java.util.Map;
 37 import java.util.concurrent.TimeUnit;
 38 import java.util.function.Consumer;
 39 
 40 import static sun.nio.ch.KQueue.EVFILT_READ;
 41 import static sun.nio.ch.KQueue.EVFILT_WRITE;
 42 import static sun.nio.ch.KQueue.EV_ADD;
 43 import static sun.nio.ch.KQueue.EV_DELETE;
 44 
 45 /**
 46  * KQueue based Selector implementation for macOS
 47  */
 48 
 49 class KQueueSelectorImpl extends SelectorImpl {
 50 
 51     // maximum number of events to poll in one call to kqueue
 52     private static final int MAX_KEVENTS = 256;
 53 
 54     // kqueue file descriptor
 55     private final int kqfd;
 56 
 57     // address of poll array (event list) when polling for pending events
 58     private final long pollArrayAddress;
 59 
 60     // file descriptors used for interrupt
 61     private final int fd0;
 62     private final int fd1;
 63 
 64     // maps file descriptor to selection key, synchronize on selector
 65     private final Map<Integer, SelectionKeyImpl> fdToKey = new HashMap<>();
 66 
 67     // pending new registrations/updates, queued by setEventOps
 68     private final Object updateLock = new Object();
 69     private final Deque<SelectionKeyImpl> updateKeys = new ArrayDeque<>();
 70 
 71     // interrupt triggering and clearing
 72     private final Object interruptLock = new Object();
 73     private boolean interruptTriggered;
 74 
 75     // used by updateSelectedKeys to handle cases where the same file
 76     // descriptor is polled by more than one filter
 77     private int pollCount;
 78 
 79     KQueueSelectorImpl(SelectorProvider sp) throws IOException {
 80         super(sp);
 81 
 82         this.kqfd = KQueue.create();
 83         this.pollArrayAddress = KQueue.allocatePollArray(MAX_KEVENTS);
 84 
 85         try {
 86             long fds = IOUtil.makePipe(false);
 87             this.fd0 = (int) (fds >>> 32);
 88             this.fd1 = (int) fds;
 89         } catch (IOException ioe) {
 90             KQueue.freePollArray(pollArrayAddress);
 91             FileDispatcherImpl.closeIntFD(kqfd);
 92             throw ioe;
 93         }
 94 
 95         // register one end of the socket pair for wakeups
 96         KQueue.register(kqfd, fd0, EVFILT_READ, EV_ADD);
 97     }
 98 
 99     private void ensureOpen() {
100         if (!isOpen())
101             throw new ClosedSelectorException();
102     }
103 
104     @Override
105     protected int doSelect(Consumer<SelectionKey> action, long timeout)
106         throws IOException
107     {
108         assert Thread.holdsLock(this);
109 
110         long to = Math.min(timeout, Integer.MAX_VALUE);  // max kqueue timeout
111         boolean blocking = (to != 0);
112         boolean timedPoll = (to > 0);
113 
114         int numEntries;
115         processUpdateQueue();
116         processDeregisterQueue();
117         try {
118             begin(blocking);
119 
120             do {
121                 long startTime = timedPoll ? System.nanoTime() : 0;
122                 numEntries = KQueue.poll(kqfd, pollArrayAddress, MAX_KEVENTS, to);
123                 if (numEntries == IOStatus.INTERRUPTED && timedPoll) {
124                     // timed poll interrupted so need to adjust timeout
125                     long adjust = System.nanoTime() - startTime;
126                     to -= TimeUnit.MILLISECONDS.convert(adjust, TimeUnit.NANOSECONDS);
127                     if (to <= 0) {
128                         // timeout expired so no retry
129                         numEntries = 0;
130                     }
131                 }
132             } while (numEntries == IOStatus.INTERRUPTED);
133             assert IOStatus.check(numEntries);
134 
135         } finally {
136             end(blocking);
137         }
138         processDeregisterQueue();
139         return processEvents(numEntries, action);
140     }
141 
142     /**
143      * Process changes to the interest ops.
144      */
145     private void processUpdateQueue() {
146         assert Thread.holdsLock(this);
147 
148         synchronized (updateLock) {
149             SelectionKeyImpl ski;
150             while ((ski = updateKeys.pollFirst()) != null) {
151                 if (ski.isValid()) {
152                     int fd = ski.getFDVal();
153                     // add to fdToKey if needed
154                     SelectionKeyImpl previous = fdToKey.putIfAbsent(fd, ski);
155                     assert (previous == null) || (previous == ski);
156 
157                     int newEvents = ski.translateInterestOps();
158                     int registeredEvents = ski.registeredEvents();
159 
160                     // DatagramChannelImpl::disconnect has reset socket
161                     if (ski.getAndClearReset() && registeredEvents != 0) {
162                         KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
163                         registeredEvents = 0;
164                     }
165 
166                     if (newEvents != registeredEvents) {
167 
168                         // add or delete interest in read events
169                         if ((registeredEvents & Net.POLLIN) != 0) {
170                             if ((newEvents & Net.POLLIN) == 0) {
171                                 KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
172                             }
173                         } else if ((newEvents & Net.POLLIN) != 0) {
174                             KQueue.register(kqfd, fd, EVFILT_READ, EV_ADD);
175                         }
176 
177                         // add or delete interest in write events
178                         if ((registeredEvents & Net.POLLOUT) != 0) {
179                             if ((newEvents & Net.POLLOUT) == 0) {
180                                 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_DELETE);
181                             }
182                         } else if ((newEvents & Net.POLLOUT) != 0) {
183                             KQueue.register(kqfd, fd, EVFILT_WRITE, EV_ADD);
184                         }
185 
186                         ski.registeredEvents(newEvents);
187                     }
188                 }
189             }
190         }
191     }
192 
193     /**
194      * Process the polled events.
195      * If the interrupt fd has been selected, drain it and clear the interrupt.
196      */
197     private int processEvents(int numEntries, Consumer<SelectionKey> action)
198         throws IOException
199     {
200         assert Thread.holdsLock(this);
201 
202         int numKeysUpdated = 0;
203         boolean interrupted = false;
204 
205         // A file descriptor may be registered with kqueue with more than one
206         // filter and so there may be more than one event for a fd. The poll
207         // count is incremented here and compared against the SelectionKey's
208         // "lastPolled" field. This ensures that the ready ops is updated rather
209         // than replaced when a file descriptor is polled by both the read and
210         // write filter.
211         pollCount++;
212 
213         for (int i = 0; i < numEntries; i++) {
214             long kevent = KQueue.getEvent(pollArrayAddress, i);
215             int fd = KQueue.getDescriptor(kevent);
216             if (fd == fd0) {
217                 interrupted = true;
218             } else {
219                 SelectionKeyImpl ski = fdToKey.get(fd);
220                 if (ski != null) {
221                     int rOps = 0;
222                     short filter = KQueue.getFilter(kevent);
223                     if (filter == EVFILT_READ) {
224                         rOps |= Net.POLLIN;
225                     } else if (filter == EVFILT_WRITE) {
226                         rOps |= Net.POLLOUT;
227                     }
228                     int updated = processReadyEvents(rOps, ski, action);
229                     if (updated > 0 && ski.lastPolled != pollCount) {
230                         numKeysUpdated++;
231                         ski.lastPolled = pollCount;
232                     }
233                 }
234             }
235         }
236 
237         if (interrupted) {
238             clearInterrupt();
239         }
240         return numKeysUpdated;
241     }
242 
243     @Override
244     protected void implClose() throws IOException {
245         assert !isOpen();
246         assert Thread.holdsLock(this);
247 
248         // prevent further wakeup
249         synchronized (interruptLock) {
250             interruptTriggered = true;
251         }
252 
253         FileDispatcherImpl.closeIntFD(kqfd);
254         KQueue.freePollArray(pollArrayAddress);
255 
256         FileDispatcherImpl.closeIntFD(fd0);
257         FileDispatcherImpl.closeIntFD(fd1);
258     }
259 
260     @Override
261     protected void implDereg(SelectionKeyImpl ski) throws IOException {
262         assert !ski.isValid();
263         assert Thread.holdsLock(this);
264 
265         int fd = ski.getFDVal();
266         int registeredEvents = ski.registeredEvents();
267         if (fdToKey.remove(fd) != null) {
268             if (registeredEvents != 0) {
269                 if ((registeredEvents & Net.POLLIN) != 0)
270                     KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
271                 if ((registeredEvents & Net.POLLOUT) != 0)
272                     KQueue.register(kqfd, fd, EVFILT_WRITE, EV_DELETE);
273                 ski.registeredEvents(0);
274             }
275         } else {
276             assert registeredEvents == 0;
277         }
278     }
279 
280     @Override
281     public void setEventOps(SelectionKeyImpl ski) {
282         ensureOpen();
283         synchronized (updateLock) {
284             updateKeys.addLast(ski);
285         }
286     }
287 
288     @Override
289     public Selector wakeup() {
290         synchronized (interruptLock) {
291             if (!interruptTriggered) {
292                 try {
293                     IOUtil.write1(fd1, (byte)0);
294                 } catch (IOException ioe) {
295                     throw new InternalError(ioe);
296                 }
297                 interruptTriggered = true;
298             }
299         }
300         return this;
301     }
302 
303     private void clearInterrupt() throws IOException {
304         synchronized (interruptLock) {
305             IOUtil.drain(fd0);
306             interruptTriggered = false;
307         }
308     }
309 }