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| 1 | +/* | |
| 2 | + * Copyright (c) 2008, 2011, 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.fs; | |
| 27 | + | |
| 28 | +import java.nio.file.*; | |
| 29 | +import java.security.AccessController; | |
| 30 | +import java.security.PrivilegedAction; | |
| 31 | +import java.io.IOException; | |
| 32 | +import java.util.*; | |
| 33 | + | |
| 34 | +/** | |
| 35 | + * Base implementation of background poller thread used in watch service | |
| 36 | + * implementations. A poller thread waits on events from the file system and | |
| 37 | + * also services "requests" from clients to register for new events or cancel | |
| 38 | + * existing registrations. | |
| 39 | + */ | |
| 40 | + | |
| 41 | +abstract class AbstractPoller implements Runnable { | |
| 42 | + | |
| 43 | + // list of requests pending to the poller thread | |
| 44 | + private final LinkedList<Request> requestList; | |
| 45 | + | |
| 46 | + // set to true when shutdown | |
| 47 | + private boolean shutdown; | |
| 48 | + | |
| 49 | + protected AbstractPoller() { | |
| 50 | + this.requestList = new LinkedList<Request>(); | |
| 51 | + this.shutdown = false; | |
| 52 | + } | |
| 53 | + | |
| 54 | + /** | |
| 55 | + * Starts the poller thread | |
| 56 | + */ | |
| 57 | + public void start() { | |
| 58 | + final Runnable thisRunnable = this; | |
| 59 | + AccessController.doPrivileged(new PrivilegedAction<Object>() { | |
| 60 | + @Override | |
| 61 | + public Object run() { | |
| 62 | + Thread thr = new Thread(thisRunnable); | |
| 63 | + thr.setDaemon(true); | |
| 64 | + thr.start(); | |
| 65 | + return null; | |
| 66 | + } | |
| 67 | + }); | |
| 68 | + } | |
| 69 | + | |
| 70 | + /** | |
| 71 | + * Wakeup poller thread so that it can service pending requests | |
| 72 | + */ | |
| 73 | + abstract void wakeup() throws IOException; | |
| 74 | + | |
| 75 | + /** | |
| 76 | + * Executed by poller thread to register directory for changes | |
| 77 | + */ | |
| 78 | + abstract Object implRegister(Path path, | |
| 79 | + Set<? extends WatchEvent.Kind<?>> events, | |
| 80 | + WatchEvent.Modifier... modifiers); | |
| 81 | + | |
| 82 | + /** | |
| 83 | + * Executed by poller thread to cancel key | |
| 84 | + */ | |
| 85 | + abstract void implCancelKey(WatchKey key); | |
| 86 | + | |
| 87 | + /** | |
| 88 | + * Executed by poller thread to shutdown and cancel all keys | |
| 89 | + */ | |
| 90 | + abstract void implCloseAll(); | |
| 91 | + | |
| 92 | + /** | |
| 93 | + * Requests, and waits on, poller thread to register given file. | |
| 94 | + */ | |
| 95 | + final WatchKey register(Path dir, | |
| 96 | + WatchEvent.Kind<?>[] events, | |
| 97 | + WatchEvent.Modifier... modifiers) | |
| 98 | + throws IOException | |
| 99 | + { | |
| 100 | + // validate arguments before request to poller | |
| 101 | + if (dir == null) | |
| 102 | + throw new NullPointerException(); | |
| 103 | + if (events.length == 0) | |
| 104 | + throw new IllegalArgumentException("No events to register"); | |
| 105 | + Set<WatchEvent.Kind<?>> eventSet = new HashSet<>(events.length); | |
| 106 | + for (WatchEvent.Kind<?> event: events) { | |
| 107 | + // standard events | |
| 108 | + if (event == StandardWatchEventKinds.ENTRY_CREATE || | |
| 109 | + event == StandardWatchEventKinds.ENTRY_MODIFY || | |
| 110 | + event == StandardWatchEventKinds.ENTRY_DELETE) | |
| 111 | + { | |
| 112 | + eventSet.add(event); | |
| 113 | + continue; | |
| 114 | + } | |
| 115 | + | |
| 116 | + // OVERFLOW is ignored | |
| 117 | + if (event == StandardWatchEventKinds.OVERFLOW) { | |
| 118 | + if (events.length == 1) | |
| 119 | + throw new IllegalArgumentException("No events to register"); | |
| 120 | + continue; | |
| 121 | + } | |
| 122 | + | |
| 123 | + // null/unsupported | |
| 124 | + if (event == null) | |
| 125 | + throw new NullPointerException("An element in event set is 'null'"); | |
| 126 | + throw new UnsupportedOperationException(event.name()); | |
| 127 | + } | |
| 128 | + return (WatchKey)invoke(RequestType.REGISTER, dir, eventSet, modifiers); | |
| 129 | + } | |
| 130 | + | |
| 131 | + /** | |
| 132 | + * Cancels, and waits on, poller thread to cancel given key. | |
| 133 | + */ | |
| 134 | + final void cancel(WatchKey key) { | |
| 135 | + try { | |
| 136 | + invoke(RequestType.CANCEL, key); | |
| 137 | + } catch (IOException x) { | |
| 138 | + // should not happen | |
| 139 | + throw new AssertionError(x.getMessage()); | |
| 140 | + } | |
| 141 | + } | |
| 142 | + | |
| 143 | + /** | |
| 144 | + * Shutdown poller thread | |
| 145 | + */ | |
| 146 | + final void close() throws IOException { | |
| 147 | + invoke(RequestType.CLOSE); | |
| 148 | + } | |
| 149 | + | |
| 150 | + /** | |
| 151 | + * Types of request that the poller thread must handle | |
| 152 | + */ | |
| 153 | + private static enum RequestType { | |
| 154 | + REGISTER, | |
| 155 | + CANCEL, | |
| 156 | + CLOSE; | |
| 157 | + } | |
| 158 | + | |
| 159 | + /** | |
| 160 | + * Encapsulates a request (command) to the poller thread. | |
| 161 | + */ | |
| 162 | + private static class Request { | |
| 163 | + private final RequestType type; | |
| 164 | + private final Object[] params; | |
| 165 | + | |
| 166 | + private boolean completed = false; | |
| 167 | + private Object result = null; | |
| 168 | + | |
| 169 | + Request(RequestType type, Object... params) { | |
| 170 | + this.type = type; | |
| 171 | + this.params = params; | |
| 172 | + } | |
| 173 | + | |
| 174 | + RequestType type() { | |
| 175 | + return type; | |
| 176 | + } | |
| 177 | + | |
| 178 | + Object[] parameters() { | |
| 179 | + return params; | |
| 180 | + } | |
| 181 | + | |
| 182 | + void release(Object result) { | |
| 183 | + synchronized (this) { | |
| 184 | + this.completed = true; | |
| 185 | + this.result = result; | |
| 186 | + notifyAll(); | |
| 187 | + } | |
| 188 | + } | |
| 189 | + | |
| 190 | + /** | |
| 191 | + * Await completion of the request. The return value is the result of | |
| 192 | + * the request. | |
| 193 | + */ | |
| 194 | + Object awaitResult() { | |
| 195 | + synchronized (this) { | |
| 196 | + while (!completed) { | |
| 197 | + try { | |
| 198 | + wait(); | |
| 199 | + } catch (InterruptedException x) { | |
| 200 | + // ignore | |
| 201 | + } | |
| 202 | + } | |
| 203 | + return result; | |
| 204 | + } | |
| 205 | + } | |
| 206 | + } | |
| 207 | + | |
| 208 | + /** | |
| 209 | + * Enqueues request to poller thread and waits for result | |
| 210 | + */ | |
| 211 | + private Object invoke(RequestType type, Object... params) throws IOException { | |
| 212 | + // submit request | |
| 213 | + Request req = new Request(type, params); | |
| 214 | + synchronized (requestList) { | |
| 215 | + if (shutdown) { | |
| 216 | + throw new ClosedWatchServiceException(); | |
| 217 | + } | |
| 218 | + requestList.add(req); | |
| 219 | + } | |
| 220 | + | |
| 221 | + // wakeup thread | |
| 222 | + wakeup(); | |
| 223 | + | |
| 224 | + // wait for result | |
| 225 | + Object result = req.awaitResult(); | |
| 226 | + | |
| 227 | + if (result instanceof RuntimeException) | |
| 228 | + throw (RuntimeException)result; | |
| 229 | + if (result instanceof IOException ) | |
| 230 | + throw (IOException)result; | |
| 231 | + return result; | |
| 232 | + } | |
| 233 | + | |
| 234 | + /** | |
| 235 | + * Invoked by poller thread to process all pending requests | |
| 236 | + * | |
| 237 | + * @return true if poller thread should shutdown | |
| 238 | + */ | |
| 239 | + @SuppressWarnings("unchecked") | |
| 240 | + boolean processRequests() { | |
| 241 | + synchronized (requestList) { | |
| 242 | + Request req; | |
| 243 | + while ((req = requestList.poll()) != null) { | |
| 244 | + // if in process of shutdown then reject request | |
| 245 | + if (shutdown) { | |
| 246 | + req.release(new ClosedWatchServiceException()); | |
| 247 | + } | |
| 248 | + | |
| 249 | + switch (req.type()) { | |
| 250 | + /** | |
| 251 | + * Register directory | |
| 252 | + */ | |
| 253 | + case REGISTER: { | |
| 254 | + Object[] params = req.parameters(); | |
| 255 | + Path path = (Path)params[0]; | |
| 256 | + Set<? extends WatchEvent.Kind<?>> events = | |
| 257 | + (Set<? extends WatchEvent.Kind<?>>)params[1]; | |
| 258 | + WatchEvent.Modifier[] modifiers = | |
| 259 | + (WatchEvent.Modifier[])params[2]; | |
| 260 | + req.release(implRegister(path, events, modifiers)); | |
| 261 | + break; | |
| 262 | + } | |
| 263 | + /** | |
| 264 | + * Cancel existing key | |
| 265 | + */ | |
| 266 | + case CANCEL : { | |
| 267 | + Object[] params = req.parameters(); | |
| 268 | + WatchKey key = (WatchKey)params[0]; | |
| 269 | + implCancelKey(key); | |
| 270 | + req.release(null); | |
| 271 | + break; | |
| 272 | + } | |
| 273 | + /** | |
| 274 | + * Close watch service | |
| 275 | + */ | |
| 276 | + case CLOSE: { | |
| 277 | + implCloseAll(); | |
| 278 | + req.release(null); | |
| 279 | + shutdown = true; | |
| 280 | + break; | |
| 281 | + } | |
| 282 | + | |
| 283 | + default: | |
| 284 | + req.release(new IOException("request not recognized")); | |
| 285 | + } | |
| 286 | + } | |
| 287 | + } | |
| 288 | + return shutdown; | |
| 289 | + } | |
| 290 | +} | |