1 /*
2 * Copyright (c) 2011, 2022, 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
118 if (Thread.currentThread().isVirtual()) {
119 numEntries = (timedPoll)
120 ? timedPoll(TimeUnit.MILLISECONDS.toNanos(to))
121 : untimedPoll(blocking);
122 } else {
123 try {
124 begin(blocking);
125 do {
126 long startTime = timedPoll ? System.nanoTime() : 0;
127 numEntries = KQueue.poll(kqfd, pollArrayAddress, MAX_KEVENTS, to);
128 if (numEntries == IOStatus.INTERRUPTED && timedPoll) {
129 // timed poll interrupted so need to adjust timeout
130 long adjust = System.nanoTime() - startTime;
131 to -= TimeUnit.NANOSECONDS.toMillis(adjust);
132 if (to <= 0) {
133 // timeout expired so no retry
134 numEntries = 0;
135 }
136 }
137 } while (numEntries == IOStatus.INTERRUPTED);
138 } finally {
139 end(blocking);
140 }
141 }
142 assert IOStatus.check(numEntries);
143
144 processDeregisterQueue();
145 return processEvents(numEntries, action);
146 }
147
148 /**
149 * If blocking, parks the current virtual thread until a file descriptor is polled
150 * or the thread is interrupted.
151 */
152 private int untimedPoll(boolean block) throws IOException {
153 int numEntries = KQueue.poll(kqfd, pollArrayAddress, MAX_KEVENTS, 0);
154 if (block) {
155 while (numEntries == 0 && !Thread.currentThread().isInterrupted()) {
156 Poller.pollSelector(kqfd, 0);
157 numEntries = KQueue.poll(kqfd, pollArrayAddress, MAX_KEVENTS, 0);
158 }
159 }
160 return numEntries;
161 }
162
163 /**
164 * Parks the current virtual thread until a file descriptor is polled, or the thread
165 * is interrupted, for up to the specified waiting time.
166 */
167 private int timedPoll(long nanos) throws IOException {
168 long startNanos = System.nanoTime();
169 int numEntries = KQueue.poll(kqfd, pollArrayAddress, MAX_KEVENTS, 0);
170 while (numEntries == 0 && !Thread.currentThread().isInterrupted()) {
171 long remainingNanos = nanos - (System.nanoTime() - startNanos);
172 if (remainingNanos <= 0) {
173 // timeout
174 break;
175 }
176 Poller.pollSelector(kqfd, remainingNanos);
177 numEntries = KQueue.poll(kqfd, pollArrayAddress, MAX_KEVENTS, 0);
178 }
179 return numEntries;
180 }
181
182 /**
183 * Process changes to the interest ops.
184 */
185 private void processUpdateQueue() {
186 assert Thread.holdsLock(this);
187
188 synchronized (updateLock) {
189 SelectionKeyImpl ski;
190 while ((ski = updateKeys.pollFirst()) != null) {
191 if (ski.isValid()) {
192 int fd = ski.getFDVal();
193 // add to fdToKey if needed
194 SelectionKeyImpl previous = fdToKey.putIfAbsent(fd, ski);
195 assert (previous == null) || (previous == ski);
196
197 int newEvents = ski.translateInterestOps();
198 int registeredEvents = ski.registeredEvents();
199
200 // DatagramChannelImpl::disconnect has reset socket
201 if (ski.getAndClearReset() && registeredEvents != 0) {
202 KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
203 registeredEvents = 0;
204 }
205
206 if (newEvents != registeredEvents) {
207
208 // add or delete interest in read events
209 if ((registeredEvents & Net.POLLIN) != 0) {
210 if ((newEvents & Net.POLLIN) == 0) {
211 KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
212 }
213 } else if ((newEvents & Net.POLLIN) != 0) {
214 KQueue.register(kqfd, fd, EVFILT_READ, EV_ADD);
215 }
216
217 // add or delete interest in write events
218 if ((registeredEvents & Net.POLLOUT) != 0) {
219 if ((newEvents & Net.POLLOUT) == 0) {
220 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_DELETE);
221 }
222 } else if ((newEvents & Net.POLLOUT) != 0) {
223 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_ADD);
224 }
225
226 ski.registeredEvents(newEvents);
227 }
228 }
229 }
230 }
231 }
232
233 /**
234 * Process the polled events.
235 * If the interrupt fd has been selected, drain it and clear the interrupt.
236 */
237 private int processEvents(int numEntries, Consumer<SelectionKey> action)
238 throws IOException
239 {
240 assert Thread.holdsLock(this);
241
242 int numKeysUpdated = 0;
243 boolean interrupted = false;
244
245 // A file descriptor may be registered with kqueue with more than one
246 // filter and so there may be more than one event for a fd. The poll
247 // count is incremented here and compared against the SelectionKey's
248 // "lastPolled" field. This ensures that the ready ops is updated rather
249 // than replaced when a file descriptor is polled by both the read and
250 // write filter.
251 pollCount++;
252
253 for (int i = 0; i < numEntries; i++) {
254 long kevent = KQueue.getEvent(pollArrayAddress, i);
255 int fd = KQueue.getDescriptor(kevent);
256 if (fd == fd0) {
257 interrupted = true;
258 } else {
259 SelectionKeyImpl ski = fdToKey.get(fd);
260 if (ski != null) {
261 int rOps = 0;
262 short filter = KQueue.getFilter(kevent);
263 if (filter == EVFILT_READ) {
264 rOps |= Net.POLLIN;
265 } else if (filter == EVFILT_WRITE) {
266 rOps |= Net.POLLOUT;
267 }
268 int updated = processReadyEvents(rOps, ski, action);
269 if (updated > 0 && ski.lastPolled != pollCount) {
270 numKeysUpdated++;
271 ski.lastPolled = pollCount;
272 }
273 }
274 }
275 }
276
277 if (interrupted) {
278 clearInterrupt();
279 }
280 return numKeysUpdated;
281 }
282
283 @Override
284 protected void implClose() throws IOException {
285 assert !isOpen();
286 assert Thread.holdsLock(this);
287
288 // prevent further wakeup
289 synchronized (interruptLock) {
290 interruptTriggered = true;
291 }
292
293 FileDispatcherImpl.closeIntFD(kqfd);
294 KQueue.freePollArray(pollArrayAddress);
295
296 FileDispatcherImpl.closeIntFD(fd0);
297 FileDispatcherImpl.closeIntFD(fd1);
298 }
299
300 @Override
301 protected void implDereg(SelectionKeyImpl ski) throws IOException {
302 assert !ski.isValid();
303 assert Thread.holdsLock(this);
304
305 int fd = ski.getFDVal();
306 int registeredEvents = ski.registeredEvents();
307 if (fdToKey.remove(fd) != null) {
308 if (registeredEvents != 0) {
309 if ((registeredEvents & Net.POLLIN) != 0)
310 KQueue.register(kqfd, fd, EVFILT_READ, EV_DELETE);
311 if ((registeredEvents & Net.POLLOUT) != 0)
312 KQueue.register(kqfd, fd, EVFILT_WRITE, EV_DELETE);
313 ski.registeredEvents(0);
314 }
315 } else {
316 assert registeredEvents == 0;
317 }
318 }
319
320 @Override
321 public void setEventOps(SelectionKeyImpl ski) {
322 ensureOpen();
323 synchronized (updateLock) {
324 updateKeys.addLast(ski);
325 }
326 }
327
328 @Override
329 public Selector wakeup() {
330 synchronized (interruptLock) {
331 if (!interruptTriggered) {
332 try {
333 IOUtil.write1(fd1, (byte)0);
334 } catch (IOException ioe) {
335 throw new InternalError(ioe);
336 }
337 interruptTriggered = true;
338 }
339 }
340 return this;
341 }
342
343 private void clearInterrupt() throws IOException {
344 synchronized (interruptLock) {
345 IOUtil.drain(fd0);
346 interruptTriggered = false;
347 }
348 }
349 }