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 if (newEvents != registeredEvents) {
160
161 // add or delete interest in read events
162 if ((registeredEvents & Net.POLLIN) != 0) {
163 if ((newEvents & Net.POLLIN) == 0) {
164 KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
165 }
166 } else if ((newEvents & Net.POLLIN) != 0) {
167 KQueue.register(kqfd, fd, EVFILT_READ, EV_ADD);
168 }
169
170 // add or delete interest in write events
171 if ((registeredEvents & Net.POLLOUT) != 0) {
172 if ((newEvents & Net.POLLOUT) == 0) {
173 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_DELETE);
174 }
175 } else if ((newEvents & Net.POLLOUT) != 0) {
176 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_ADD);
177 }
178
179 ski.registeredEvents(newEvents);
180 }
181 }
182 }
183 }
184 }
185
186 /**
187 * Process the polled events.
188 * If the interrupt fd has been selected, drain it and clear the interrupt.
189 */
190 private int processEvents(int numEntries, Consumer<SelectionKey> action)
191 throws IOException
192 {
193 assert Thread.holdsLock(this);
194
195 int numKeysUpdated = 0;
196 boolean interrupted = false;
197
198 // A file descriptor may be registered with kqueue with more than one
199 // filter and so there may be more than one event for a fd. The poll
200 // count is incremented here and compared against the SelectionKey's
201 // "lastPolled" field. This ensures that the ready ops is updated rather
202 // than replaced when a file descriptor is polled by both the read and
203 // write filter.
204 pollCount++;
205
206 for (int i = 0; i < numEntries; i++) {
207 long kevent = KQueue.getEvent(pollArrayAddress, i);
208 int fd = KQueue.getDescriptor(kevent);
209 if (fd == fd0) {
210 interrupted = true;
211 } else {
212 SelectionKeyImpl ski = fdToKey.get(fd);
213 if (ski != null) {
214 int rOps = 0;
215 short filter = KQueue.getFilter(kevent);
216 if (filter == EVFILT_READ) {
217 rOps |= Net.POLLIN;
218 } else if (filter == EVFILT_WRITE) {
219 rOps |= Net.POLLOUT;
220 }
221 int updated = processReadyEvents(rOps, ski, action);
222 if (updated > 0 && ski.lastPolled != pollCount) {
223 numKeysUpdated++;
224 ski.lastPolled = pollCount;
225 }
226 }
227 }
228 }
229
230 if (interrupted) {
231 clearInterrupt();
232 }
233 return numKeysUpdated;
234 }
235
236 @Override
237 protected void implClose() throws IOException {
238 assert !isOpen();
239 assert Thread.holdsLock(this);
240
241 // prevent further wakeup
242 synchronized (interruptLock) {
243 interruptTriggered = true;
244 }
245
246 FileDispatcherImpl.closeIntFD(kqfd);
247 KQueue.freePollArray(pollArrayAddress);
248
249 FileDispatcherImpl.closeIntFD(fd0);
250 FileDispatcherImpl.closeIntFD(fd1);
251 }
252
253 @Override
254 protected void implDereg(SelectionKeyImpl ski) throws IOException {
255 assert !ski.isValid();
256 assert Thread.holdsLock(this);
257
258 int fd = ski.getFDVal();
259 int registeredEvents = ski.registeredEvents();
260 if (fdToKey.remove(fd) != null) {
261 if (registeredEvents != 0) {
262 if ((registeredEvents & Net.POLLIN) != 0)
263 KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
264 if ((registeredEvents & Net.POLLOUT) != 0)
265 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_DELETE);
266 ski.registeredEvents(0);
267 }
268 } else {
269 assert registeredEvents == 0;
270 }
271 }
272
273 @Override
274 public void setEventOps(SelectionKeyImpl ski) {
275 ensureOpen();
276 synchronized (updateLock) {
277 updateKeys.addLast(ski);
278 }
279 }
280
281 @Override
282 public Selector wakeup() {
283 synchronized (interruptLock) {
284 if (!interruptTriggered) {
285 try {
286 IOUtil.write1(fd1, (byte)0);
287 } catch (IOException ioe) {
288 throw new InternalError(ioe);
289 }
290 interruptTriggered = true;
291 }
292 }
293 return this;
294 }
295
296 private void clearInterrupt() throws IOException {
297 synchronized (interruptLock) {
298 IOUtil.drain(fd0);
299 interruptTriggered = false;
300 }
301 }
302 }