Jake Slack | 03928ae | 2014-05-13 18:41:56 -0700 | [diff] [blame] | 1 | // |
| 2 | // ======================================================================== |
| 3 | // Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd. |
| 4 | // ------------------------------------------------------------------------ |
| 5 | // All rights reserved. This program and the accompanying materials |
| 6 | // are made available under the terms of the Eclipse Public License v1.0 |
| 7 | // and Apache License v2.0 which accompanies this distribution. |
| 8 | // |
| 9 | // The Eclipse Public License is available at |
| 10 | // http://www.eclipse.org/legal/epl-v10.html |
| 11 | // |
| 12 | // The Apache License v2.0 is available at |
| 13 | // http://www.opensource.org/licenses/apache2.0.php |
| 14 | // |
| 15 | // You may elect to redistribute this code under either of these licenses. |
| 16 | // ======================================================================== |
| 17 | // |
| 18 | |
| 19 | package org.eclipse.jetty.util.thread; |
| 20 | |
| 21 | import org.eclipse.jetty.util.log.Log; |
| 22 | import org.eclipse.jetty.util.log.Logger; |
| 23 | |
| 24 | |
| 25 | /* ------------------------------------------------------------ */ |
| 26 | /** Timeout queue. |
| 27 | * This class implements a timeout queue for timers that are at least as likely to be cancelled as they are to expire. |
| 28 | * Unlike the util timeout class, the duration of the timeouts is shared by all scheduled tasks and if the duration |
| 29 | * is changed, this affects all scheduled tasks. |
| 30 | * <p> |
| 31 | * The nested class Task should be extended by users of this class to obtain call back notification of |
| 32 | * expires. |
| 33 | */ |
| 34 | public class Timeout |
| 35 | { |
| 36 | private static final Logger LOG = Log.getLogger(Timeout.class); |
| 37 | private Object _lock; |
| 38 | private long _duration; |
| 39 | private volatile long _now=System.currentTimeMillis(); |
| 40 | private Task _head=new Task(); |
| 41 | |
| 42 | /* ------------------------------------------------------------ */ |
| 43 | public Timeout() |
| 44 | { |
| 45 | _lock=new Object(); |
| 46 | _head._timeout=this; |
| 47 | } |
| 48 | |
| 49 | /* ------------------------------------------------------------ */ |
| 50 | public Timeout(Object lock) |
| 51 | { |
| 52 | _lock=lock; |
| 53 | _head._timeout=this; |
| 54 | } |
| 55 | |
| 56 | /* ------------------------------------------------------------ */ |
| 57 | /** |
| 58 | * @return Returns the duration. |
| 59 | */ |
| 60 | public long getDuration() |
| 61 | { |
| 62 | return _duration; |
| 63 | } |
| 64 | |
| 65 | /* ------------------------------------------------------------ */ |
| 66 | /** |
| 67 | * @param duration The duration to set. |
| 68 | */ |
| 69 | public void setDuration(long duration) |
| 70 | { |
| 71 | _duration = duration; |
| 72 | } |
| 73 | |
| 74 | /* ------------------------------------------------------------ */ |
| 75 | public long setNow() |
| 76 | { |
| 77 | return _now=System.currentTimeMillis(); |
| 78 | } |
| 79 | |
| 80 | /* ------------------------------------------------------------ */ |
| 81 | public long getNow() |
| 82 | { |
| 83 | return _now; |
| 84 | } |
| 85 | |
| 86 | /* ------------------------------------------------------------ */ |
| 87 | public void setNow(long now) |
| 88 | { |
| 89 | _now=now; |
| 90 | } |
| 91 | |
| 92 | /* ------------------------------------------------------------ */ |
| 93 | /** Get an expired tasks. |
| 94 | * This is called instead of {@link #tick()} to obtain the next |
| 95 | * expired Task, but without calling it's {@link Task#expire()} or |
| 96 | * {@link Task#expired()} methods. |
| 97 | * |
| 98 | * @return the next expired task or null. |
| 99 | */ |
| 100 | public Task expired() |
| 101 | { |
| 102 | synchronized (_lock) |
| 103 | { |
| 104 | long _expiry = _now-_duration; |
| 105 | |
| 106 | if (_head._next!=_head) |
| 107 | { |
| 108 | Task task = _head._next; |
| 109 | if (task._timestamp>_expiry) |
| 110 | return null; |
| 111 | |
| 112 | task.unlink(); |
| 113 | task._expired=true; |
| 114 | return task; |
| 115 | } |
| 116 | return null; |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | /* ------------------------------------------------------------ */ |
| 121 | public void tick() |
| 122 | { |
| 123 | final long expiry = _now-_duration; |
| 124 | |
| 125 | Task task=null; |
| 126 | while (true) |
| 127 | { |
| 128 | try |
| 129 | { |
| 130 | synchronized (_lock) |
| 131 | { |
| 132 | task= _head._next; |
| 133 | if (task==_head || task._timestamp>expiry) |
| 134 | break; |
| 135 | task.unlink(); |
| 136 | task._expired=true; |
| 137 | task.expire(); |
| 138 | } |
| 139 | |
| 140 | task.expired(); |
| 141 | } |
| 142 | catch(Throwable th) |
| 143 | { |
| 144 | LOG.warn(Log.EXCEPTION,th); |
| 145 | } |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | /* ------------------------------------------------------------ */ |
| 150 | public void tick(long now) |
| 151 | { |
| 152 | _now=now; |
| 153 | tick(); |
| 154 | } |
| 155 | |
| 156 | /* ------------------------------------------------------------ */ |
| 157 | public void schedule(Task task) |
| 158 | { |
| 159 | schedule(task,0L); |
| 160 | } |
| 161 | |
| 162 | /* ------------------------------------------------------------ */ |
| 163 | /** |
| 164 | * @param task |
| 165 | * @param delay A delay in addition to the default duration of the timeout |
| 166 | */ |
| 167 | public void schedule(Task task,long delay) |
| 168 | { |
| 169 | synchronized (_lock) |
| 170 | { |
| 171 | if (task._timestamp!=0) |
| 172 | { |
| 173 | task.unlink(); |
| 174 | task._timestamp=0; |
| 175 | } |
| 176 | task._timeout=this; |
| 177 | task._expired=false; |
| 178 | task._delay=delay; |
| 179 | task._timestamp = _now+delay; |
| 180 | |
| 181 | Task last=_head._prev; |
| 182 | while (last!=_head) |
| 183 | { |
| 184 | if (last._timestamp <= task._timestamp) |
| 185 | break; |
| 186 | last=last._prev; |
| 187 | } |
| 188 | last.link(task); |
| 189 | } |
| 190 | } |
| 191 | |
| 192 | |
| 193 | /* ------------------------------------------------------------ */ |
| 194 | public void cancelAll() |
| 195 | { |
| 196 | synchronized (_lock) |
| 197 | { |
| 198 | _head._next=_head._prev=_head; |
| 199 | } |
| 200 | } |
| 201 | |
| 202 | /* ------------------------------------------------------------ */ |
| 203 | public boolean isEmpty() |
| 204 | { |
| 205 | synchronized (_lock) |
| 206 | { |
| 207 | return _head._next==_head; |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | /* ------------------------------------------------------------ */ |
| 212 | public long getTimeToNext() |
| 213 | { |
| 214 | synchronized (_lock) |
| 215 | { |
| 216 | if (_head._next==_head) |
| 217 | return -1; |
| 218 | long to_next = _duration+_head._next._timestamp-_now; |
| 219 | return to_next<0?0:to_next; |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | /* ------------------------------------------------------------ */ |
| 224 | @Override |
| 225 | public String toString() |
| 226 | { |
| 227 | StringBuffer buf = new StringBuffer(); |
| 228 | buf.append(super.toString()); |
| 229 | |
| 230 | Task task = _head._next; |
| 231 | while (task!=_head) |
| 232 | { |
| 233 | buf.append("-->"); |
| 234 | buf.append(task); |
| 235 | task=task._next; |
| 236 | } |
| 237 | |
| 238 | return buf.toString(); |
| 239 | } |
| 240 | |
| 241 | /* ------------------------------------------------------------ */ |
| 242 | /* ------------------------------------------------------------ */ |
| 243 | /* ------------------------------------------------------------ */ |
| 244 | /* ------------------------------------------------------------ */ |
| 245 | /** Task. |
| 246 | * The base class for scheduled timeouts. This class should be |
| 247 | * extended to implement the expire() method, which is called if the |
| 248 | * timeout expires. |
| 249 | * |
| 250 | * |
| 251 | * |
| 252 | */ |
| 253 | public static class Task |
| 254 | { |
| 255 | Task _next; |
| 256 | Task _prev; |
| 257 | Timeout _timeout; |
| 258 | long _delay; |
| 259 | long _timestamp=0; |
| 260 | boolean _expired=false; |
| 261 | |
| 262 | /* ------------------------------------------------------------ */ |
| 263 | protected Task() |
| 264 | { |
| 265 | _next=_prev=this; |
| 266 | } |
| 267 | |
| 268 | /* ------------------------------------------------------------ */ |
| 269 | public long getTimestamp() |
| 270 | { |
| 271 | return _timestamp; |
| 272 | } |
| 273 | |
| 274 | /* ------------------------------------------------------------ */ |
| 275 | public long getAge() |
| 276 | { |
| 277 | final Timeout t = _timeout; |
| 278 | if (t!=null) |
| 279 | { |
| 280 | final long now=t._now; |
| 281 | if (now!=0 && _timestamp!=0) |
| 282 | return now-_timestamp; |
| 283 | } |
| 284 | return 0; |
| 285 | } |
| 286 | |
| 287 | /* ------------------------------------------------------------ */ |
| 288 | private void unlink() |
| 289 | { |
| 290 | _next._prev=_prev; |
| 291 | _prev._next=_next; |
| 292 | _next=_prev=this; |
| 293 | _expired=false; |
| 294 | } |
| 295 | |
| 296 | /* ------------------------------------------------------------ */ |
| 297 | private void link(Task task) |
| 298 | { |
| 299 | Task next_next = _next; |
| 300 | _next._prev=task; |
| 301 | _next=task; |
| 302 | _next._next=next_next; |
| 303 | _next._prev=this; |
| 304 | } |
| 305 | |
| 306 | /* ------------------------------------------------------------ */ |
| 307 | /** Schedule the task on the given timeout. |
| 308 | * The task exiry will be called after the timeout duration. |
| 309 | * @param timer |
| 310 | */ |
| 311 | public void schedule(Timeout timer) |
| 312 | { |
| 313 | timer.schedule(this); |
| 314 | } |
| 315 | |
| 316 | /* ------------------------------------------------------------ */ |
| 317 | /** Schedule the task on the given timeout. |
| 318 | * The task exiry will be called after the timeout duration. |
| 319 | * @param timer |
| 320 | */ |
| 321 | public void schedule(Timeout timer, long delay) |
| 322 | { |
| 323 | timer.schedule(this,delay); |
| 324 | } |
| 325 | |
| 326 | /* ------------------------------------------------------------ */ |
| 327 | /** Reschedule the task on the current timeout. |
| 328 | * The task timeout is rescheduled as if it had been cancelled and |
| 329 | * scheduled on the current timeout. |
| 330 | */ |
| 331 | public void reschedule() |
| 332 | { |
| 333 | Timeout timeout = _timeout; |
| 334 | if (timeout!=null) |
| 335 | timeout.schedule(this,_delay); |
| 336 | } |
| 337 | |
| 338 | /* ------------------------------------------------------------ */ |
| 339 | /** Cancel the task. |
| 340 | * Remove the task from the timeout. |
| 341 | */ |
| 342 | public void cancel() |
| 343 | { |
| 344 | Timeout timeout = _timeout; |
| 345 | if (timeout!=null) |
| 346 | { |
| 347 | synchronized (timeout._lock) |
| 348 | { |
| 349 | unlink(); |
| 350 | _timestamp=0; |
| 351 | } |
| 352 | } |
| 353 | } |
| 354 | |
| 355 | /* ------------------------------------------------------------ */ |
| 356 | public boolean isExpired() { return _expired; } |
| 357 | |
| 358 | /* ------------------------------------------------------------ */ |
| 359 | public boolean isScheduled() { return _next!=this; } |
| 360 | |
| 361 | /* ------------------------------------------------------------ */ |
| 362 | /** Expire task. |
| 363 | * This method is called when the timeout expires. It is called |
| 364 | * in the scope of the synchronize block (on this) that sets |
| 365 | * the {@link #isExpired()} state to true. |
| 366 | * @see #expired() For an unsynchronized callback. |
| 367 | */ |
| 368 | protected void expire(){} |
| 369 | |
| 370 | /* ------------------------------------------------------------ */ |
| 371 | /** Expire task. |
| 372 | * This method is called when the timeout expires. It is called |
| 373 | * outside of any synchronization scope and may be delayed. |
| 374 | * |
| 375 | */ |
| 376 | public void expired(){} |
| 377 | |
| 378 | } |
| 379 | |
| 380 | } |