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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 | } | ||