Shubham Ajmera | e318a0e | 2016-04-08 15:32:00 +0100 | [diff] [blame] | 1 | /* |
Shubham Ajmera | 519adb2 | 2016-06-29 15:13:16 +0100 | [diff] [blame^] | 2 | * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved. |
Shubham Ajmera | e318a0e | 2016-04-08 15:32:00 +0100 | [diff] [blame] | 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.nio.channels.spi.AsynchronousChannelProvider; |
| 29 | import java.io.IOException; |
| 30 | import java.util.concurrent.ArrayBlockingQueue; |
| 31 | import java.util.concurrent.RejectedExecutionException; |
| 32 | import java.util.concurrent.atomic.AtomicInteger; |
| 33 | import static sun.nio.ch.EPoll.*; |
| 34 | |
| 35 | /** |
| 36 | * AsynchronousChannelGroup implementation based on the Linux epoll facility. |
| 37 | */ |
| 38 | |
| 39 | final class EPollPort |
| 40 | extends Port |
| 41 | { |
| 42 | // maximum number of events to poll at a time |
| 43 | private static final int MAX_EPOLL_EVENTS = 512; |
| 44 | |
| 45 | // errors |
| 46 | private static final int ENOENT = 2; |
| 47 | |
| 48 | // epoll file descriptor |
| 49 | private final int epfd; |
| 50 | |
| 51 | // true if epoll closed |
| 52 | private boolean closed; |
| 53 | |
| 54 | // socket pair used for wakeup |
| 55 | private final int sp[]; |
| 56 | |
| 57 | // number of wakeups pending |
| 58 | private final AtomicInteger wakeupCount = new AtomicInteger(); |
| 59 | |
| 60 | // address of the poll array passed to epoll_wait |
| 61 | private final long address; |
| 62 | |
| 63 | // encapsulates an event for a channel |
| 64 | static class Event { |
| 65 | final PollableChannel channel; |
| 66 | final int events; |
| 67 | |
| 68 | Event(PollableChannel channel, int events) { |
| 69 | this.channel = channel; |
| 70 | this.events = events; |
| 71 | } |
| 72 | |
| 73 | PollableChannel channel() { return channel; } |
| 74 | int events() { return events; } |
| 75 | } |
| 76 | |
| 77 | // queue of events for cases that a polling thread dequeues more than one |
| 78 | // event |
| 79 | private final ArrayBlockingQueue<Event> queue; |
| 80 | private final Event NEED_TO_POLL = new Event(null, 0); |
| 81 | private final Event EXECUTE_TASK_OR_SHUTDOWN = new Event(null, 0); |
| 82 | |
| 83 | EPollPort(AsynchronousChannelProvider provider, ThreadPool pool) |
| 84 | throws IOException |
| 85 | { |
| 86 | super(provider, pool); |
| 87 | |
| 88 | // open epoll |
| 89 | this.epfd = epollCreate(); |
| 90 | |
| 91 | // create socket pair for wakeup mechanism |
| 92 | int[] sv = new int[2]; |
| 93 | try { |
| 94 | socketpair(sv); |
| 95 | // register one end with epoll |
Shubham Ajmera | 519adb2 | 2016-06-29 15:13:16 +0100 | [diff] [blame^] | 96 | epollCtl(epfd, EPOLL_CTL_ADD, sv[0], Net.POLLIN); |
Shubham Ajmera | e318a0e | 2016-04-08 15:32:00 +0100 | [diff] [blame] | 97 | } catch (IOException x) { |
| 98 | close0(epfd); |
| 99 | throw x; |
| 100 | } |
| 101 | this.sp = sv; |
| 102 | |
| 103 | // allocate the poll array |
| 104 | this.address = allocatePollArray(MAX_EPOLL_EVENTS); |
| 105 | |
| 106 | // create the queue and offer the special event to ensure that the first |
| 107 | // threads polls |
| 108 | this.queue = new ArrayBlockingQueue<Event>(MAX_EPOLL_EVENTS); |
| 109 | this.queue.offer(NEED_TO_POLL); |
| 110 | } |
| 111 | |
| 112 | EPollPort start() { |
| 113 | startThreads(new EventHandlerTask()); |
| 114 | return this; |
| 115 | } |
| 116 | |
| 117 | /** |
| 118 | * Release all resources |
| 119 | */ |
| 120 | private void implClose() { |
| 121 | synchronized (this) { |
| 122 | if (closed) |
| 123 | return; |
| 124 | closed = true; |
| 125 | } |
| 126 | freePollArray(address); |
| 127 | close0(sp[0]); |
| 128 | close0(sp[1]); |
| 129 | close0(epfd); |
| 130 | } |
| 131 | |
| 132 | private void wakeup() { |
| 133 | if (wakeupCount.incrementAndGet() == 1) { |
| 134 | // write byte to socketpair to force wakeup |
| 135 | try { |
| 136 | interrupt(sp[1]); |
| 137 | } catch (IOException x) { |
| 138 | throw new AssertionError(x); |
| 139 | } |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | @Override |
| 144 | void executeOnHandlerTask(Runnable task) { |
| 145 | synchronized (this) { |
| 146 | if (closed) |
| 147 | throw new RejectedExecutionException(); |
| 148 | offerTask(task); |
| 149 | wakeup(); |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | @Override |
| 154 | void shutdownHandlerTasks() { |
| 155 | /* |
| 156 | * If no tasks are running then just release resources; otherwise |
| 157 | * write to the one end of the socketpair to wakeup any polling threads. |
| 158 | */ |
| 159 | int nThreads = threadCount(); |
| 160 | if (nThreads == 0) { |
| 161 | implClose(); |
| 162 | } else { |
| 163 | // send interrupt to each thread |
| 164 | while (nThreads-- > 0) { |
| 165 | wakeup(); |
| 166 | } |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | // invoke by clients to register a file descriptor |
| 171 | @Override |
| 172 | void startPoll(int fd, int events) { |
| 173 | // update events (or add to epoll on first usage) |
| 174 | int err = epollCtl(epfd, EPOLL_CTL_MOD, fd, (events | EPOLLONESHOT)); |
| 175 | if (err == ENOENT) |
| 176 | err = epollCtl(epfd, EPOLL_CTL_ADD, fd, (events | EPOLLONESHOT)); |
| 177 | if (err != 0) |
| 178 | throw new AssertionError(); // should not happen |
| 179 | } |
| 180 | |
| 181 | /* |
| 182 | * Task to process events from epoll and dispatch to the channel's |
| 183 | * onEvent handler. |
| 184 | * |
| 185 | * Events are retreived from epoll in batch and offered to a BlockingQueue |
| 186 | * where they are consumed by handler threads. A special "NEED_TO_POLL" |
| 187 | * event is used to signal one consumer to re-poll when all events have |
| 188 | * been consumed. |
| 189 | */ |
| 190 | private class EventHandlerTask implements Runnable { |
| 191 | private Event poll() throws IOException { |
| 192 | try { |
| 193 | for (;;) { |
| 194 | int n = epollWait(epfd, address, MAX_EPOLL_EVENTS); |
| 195 | /* |
| 196 | * 'n' events have been read. Here we map them to their |
| 197 | * corresponding channel in batch and queue n-1 so that |
| 198 | * they can be handled by other handler threads. The last |
| 199 | * event is handled by this thread (and so is not queued). |
| 200 | */ |
| 201 | fdToChannelLock.readLock().lock(); |
| 202 | try { |
| 203 | while (n-- > 0) { |
| 204 | long eventAddress = getEvent(address, n); |
| 205 | int fd = getDescriptor(eventAddress); |
| 206 | |
| 207 | // wakeup |
| 208 | if (fd == sp[0]) { |
| 209 | if (wakeupCount.decrementAndGet() == 0) { |
| 210 | // no more wakeups so drain pipe |
| 211 | drain1(sp[0]); |
| 212 | } |
| 213 | |
| 214 | // queue special event if there are more events |
| 215 | // to handle. |
| 216 | if (n > 0) { |
| 217 | queue.offer(EXECUTE_TASK_OR_SHUTDOWN); |
| 218 | continue; |
| 219 | } |
| 220 | return EXECUTE_TASK_OR_SHUTDOWN; |
| 221 | } |
| 222 | |
| 223 | PollableChannel channel = fdToChannel.get(fd); |
| 224 | if (channel != null) { |
| 225 | int events = getEvents(eventAddress); |
| 226 | Event ev = new Event(channel, events); |
| 227 | |
| 228 | // n-1 events are queued; This thread handles |
| 229 | // the last one except for the wakeup |
| 230 | if (n > 0) { |
| 231 | queue.offer(ev); |
| 232 | } else { |
| 233 | return ev; |
| 234 | } |
| 235 | } |
| 236 | } |
| 237 | } finally { |
| 238 | fdToChannelLock.readLock().unlock(); |
| 239 | } |
| 240 | } |
| 241 | } finally { |
| 242 | // to ensure that some thread will poll when all events have |
| 243 | // been consumed |
| 244 | queue.offer(NEED_TO_POLL); |
| 245 | } |
| 246 | } |
| 247 | |
| 248 | public void run() { |
| 249 | Invoker.GroupAndInvokeCount myGroupAndInvokeCount = |
| 250 | Invoker.getGroupAndInvokeCount(); |
| 251 | final boolean isPooledThread = (myGroupAndInvokeCount != null); |
| 252 | boolean replaceMe = false; |
| 253 | Event ev; |
| 254 | try { |
| 255 | for (;;) { |
| 256 | // reset invoke count |
| 257 | if (isPooledThread) |
| 258 | myGroupAndInvokeCount.resetInvokeCount(); |
| 259 | |
| 260 | try { |
| 261 | replaceMe = false; |
| 262 | ev = queue.take(); |
| 263 | |
| 264 | // no events and this thread has been "selected" to |
| 265 | // poll for more. |
| 266 | if (ev == NEED_TO_POLL) { |
| 267 | try { |
| 268 | ev = poll(); |
| 269 | } catch (IOException x) { |
| 270 | x.printStackTrace(); |
| 271 | return; |
| 272 | } |
| 273 | } |
| 274 | } catch (InterruptedException x) { |
| 275 | continue; |
| 276 | } |
| 277 | |
| 278 | // handle wakeup to execute task or shutdown |
| 279 | if (ev == EXECUTE_TASK_OR_SHUTDOWN) { |
| 280 | Runnable task = pollTask(); |
| 281 | if (task == null) { |
| 282 | // shutdown request |
| 283 | return; |
| 284 | } |
| 285 | // run task (may throw error/exception) |
| 286 | replaceMe = true; |
| 287 | task.run(); |
| 288 | continue; |
| 289 | } |
| 290 | |
| 291 | // process event |
| 292 | try { |
| 293 | ev.channel().onEvent(ev.events(), isPooledThread); |
| 294 | } catch (Error x) { |
| 295 | replaceMe = true; throw x; |
| 296 | } catch (RuntimeException x) { |
| 297 | replaceMe = true; throw x; |
| 298 | } |
| 299 | } |
| 300 | } finally { |
| 301 | // last handler to exit when shutdown releases resources |
| 302 | int remaining = threadExit(this, replaceMe); |
| 303 | if (remaining == 0 && isShutdown()) { |
| 304 | implClose(); |
| 305 | } |
| 306 | } |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | // -- Native methods -- |
| 311 | |
| 312 | private static native void socketpair(int[] sv) throws IOException; |
| 313 | |
| 314 | private static native void interrupt(int fd) throws IOException; |
| 315 | |
| 316 | private static native void drain1(int fd) throws IOException; |
| 317 | |
| 318 | private static native void close0(int fd); |
Shubham Ajmera | e318a0e | 2016-04-08 15:32:00 +0100 | [diff] [blame] | 319 | } |