Source for java.util.concurrent.TimeUnit

   1: /*
   2:   * Written by Doug Lea with assistance from members of JCP JSR-166
   3:   * Expert Group and released to the public domain, as explained at
   4:   * http://creativecommons.org/licenses/publicdomain
   5:   */
   6: 
   7: package java.util.concurrent;
   8: 
   9: /**
  10:  * A <tt>TimeUnit</tt> represents time durations at a given unit of
  11:  * granularity and provides utility methods to convert across units,
  12:  * and to perform timing and delay operations in these units.  A
  13:  * <tt>TimeUnit</tt> does not maintain time information, but only
  14:  * helps organize and use time representations that may be maintained
  15:  * separately across various contexts.  A nanosecond is defined as one
  16:  * thousandth of a microsecond, a microsecond as one thousandth of a
  17:  * millisecond, a millisecond as one thousandth of a second, a minute
  18:  * as sixty seconds, an hour as sixty minutes, and a day as twenty four
  19:  * hours.
  20:  *
  21:  * <p>A <tt>TimeUnit</tt> is mainly used to inform time-based methods
  22:  * how a given timing parameter should be interpreted. For example,
  23:  * the following code will timeout in 50 milliseconds if the {@link
  24:  * java.util.concurrent.locks.Lock lock} is not available:
  25:  *
  26:  * <pre>  Lock lock = ...;
  27:  *  if ( lock.tryLock(50L, TimeUnit.MILLISECONDS) ) ...
  28:  * </pre>
  29:  * while this code will timeout in 50 seconds:
  30:  * <pre>
  31:  *  Lock lock = ...;
  32:  *  if ( lock.tryLock(50L, TimeUnit.SECONDS) ) ...
  33:  * </pre>
  34:  *
  35:  * Note however, that there is no guarantee that a particular timeout
  36:  * implementation will be able to notice the passage of time at the
  37:  * same granularity as the given <tt>TimeUnit</tt>.
  38:  *
  39:  * @since 1.5
  40:  * @author Doug Lea
  41:  */
  42: public enum TimeUnit {
  43:     NANOSECONDS {
  44:         public long toNanos(long d)   { return d; }
  45:         public long toMicros(long d)  { return d/(C1/C0); }
  46:         public long toMillis(long d)  { return d/(C2/C0); }
  47:         public long toSeconds(long d) { return d/(C3/C0); }
  48:         public long toMinutes(long d) { return d/(C4/C0); }
  49:         public long toHours(long d)   { return d/(C5/C0); }
  50:         public long toDays(long d)    { return d/(C6/C0); }
  51:         public long convert(long d, TimeUnit u) { return u.toNanos(d); }
  52:         int excessNanos(long d, long m) { return (int)(d - (m*C2)); }
  53:     },
  54:     MICROSECONDS {
  55:         public long toNanos(long d)   { return x(d, C1/C0, MAX/(C1/C0)); }
  56:         public long toMicros(long d)  { return d; }
  57:         public long toMillis(long d)  { return d/(C2/C1); }
  58:         public long toSeconds(long d) { return d/(C3/C1); }
  59:         public long toMinutes(long d) { return d/(C4/C1); }
  60:         public long toHours(long d)   { return d/(C5/C1); }
  61:         public long toDays(long d)    { return d/(C6/C1); }
  62:         public long convert(long d, TimeUnit u) { return u.toMicros(d); }
  63:         int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }
  64:     },
  65:     MILLISECONDS {
  66:         public long toNanos(long d)   { return x(d, C2/C0, MAX/(C2/C0)); }
  67:         public long toMicros(long d)  { return x(d, C2/C1, MAX/(C2/C1)); }
  68:         public long toMillis(long d)  { return d; }
  69:         public long toSeconds(long d) { return d/(C3/C2); }
  70:         public long toMinutes(long d) { return d/(C4/C2); }
  71:         public long toHours(long d)   { return d/(C5/C2); }
  72:         public long toDays(long d)    { return d/(C6/C2); }
  73:         public long convert(long d, TimeUnit u) { return u.toMillis(d); }
  74:         int excessNanos(long d, long m) { return 0; }
  75:     },
  76:     SECONDS {
  77:         public long toNanos(long d)   { return x(d, C3/C0, MAX/(C3/C0)); }
  78:         public long toMicros(long d)  { return x(d, C3/C1, MAX/(C3/C1)); }
  79:         public long toMillis(long d)  { return x(d, C3/C2, MAX/(C3/C2)); }
  80:         public long toSeconds(long d) { return d; }
  81:         public long toMinutes(long d) { return d/(C4/C3); }
  82:         public long toHours(long d)   { return d/(C5/C3); }
  83:         public long toDays(long d)    { return d/(C6/C3); }
  84:         public long convert(long d, TimeUnit u) { return u.toSeconds(d); }
  85:         int excessNanos(long d, long m) { return 0; }
  86:     },
  87:     MINUTES {
  88:         public long toNanos(long d)   { return x(d, C4/C0, MAX/(C4/C0)); }
  89:         public long toMicros(long d)  { return x(d, C4/C1, MAX/(C4/C1)); }
  90:         public long toMillis(long d)  { return x(d, C4/C2, MAX/(C4/C2)); }
  91:         public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }
  92:         public long toMinutes(long d) { return d; }
  93:         public long toHours(long d)   { return d/(C5/C4); }
  94:         public long toDays(long d)    { return d/(C6/C4); }
  95:         public long convert(long d, TimeUnit u) { return u.toMinutes(d); }
  96:         int excessNanos(long d, long m) { return 0; }
  97:     },
  98:     HOURS {
  99:         public long toNanos(long d)   { return x(d, C5/C0, MAX/(C5/C0)); }
 100:         public long toMicros(long d)  { return x(d, C5/C1, MAX/(C5/C1)); }
 101:         public long toMillis(long d)  { return x(d, C5/C2, MAX/(C5/C2)); }
 102:         public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }
 103:         public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }
 104:         public long toHours(long d)   { return d; }
 105:         public long toDays(long d)    { return d/(C6/C5); }
 106:         public long convert(long d, TimeUnit u) { return u.toHours(d); }
 107:         int excessNanos(long d, long m) { return 0; }
 108:     },
 109:     DAYS {
 110:         public long toNanos(long d)   { return x(d, C6/C0, MAX/(C6/C0)); }
 111:         public long toMicros(long d)  { return x(d, C6/C1, MAX/(C6/C1)); }
 112:         public long toMillis(long d)  { return x(d, C6/C2, MAX/(C6/C2)); }
 113:         public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }
 114:         public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }
 115:         public long toHours(long d)   { return x(d, C6/C5, MAX/(C6/C5)); }
 116:         public long toDays(long d)    { return d; }
 117:         public long convert(long d, TimeUnit u) { return u.toDays(d); }
 118:         int excessNanos(long d, long m) { return 0; }
 119:     };
 120: 
 121:     // Handy constants for conversion methods
 122:     static final long C0 = 1L;
 123:     static final long C1 = C0 * 1000L;
 124:     static final long C2 = C1 * 1000L;
 125:     static final long C3 = C2 * 1000L;
 126:     static final long C4 = C3 * 60L;
 127:     static final long C5 = C4 * 60L;
 128:     static final long C6 = C5 * 24L;
 129: 
 130:     static final long MAX = Long.MAX_VALUE;
 131: 
 132:     /**
 133:      * Scale d by m, checking for overflow.
 134:      * This has a short name to make above code more readable.
 135:      */
 136:     static long x(long d, long m, long over) {
 137:         if (d >  over) return Long.MAX_VALUE;
 138:         if (d < -over) return Long.MIN_VALUE;
 139:         return d * m;
 140:     }
 141: 
 142:     // To maintain full signature compatibility with 1.5, and to improve the
 143:     // clarity of the generated javadoc (see 6287639: Abstract methods in
 144:     // enum classes should not be listed as abstract), method convert
 145:     // etc. are not declared abstract but otherwise act as abstract methods.
 146: 
 147:     /**
 148:      * Convert the given time duration in the given unit to this
 149:      * unit.  Conversions from finer to coarser granularities
 150:      * truncate, so lose precision. For example converting
 151:      * <tt>999</tt> milliseconds to seconds results in
 152:      * <tt>0</tt>. Conversions from coarser to finer granularities
 153:      * with arguments that would numerically overflow saturate to
 154:      * <tt>Long.MIN_VALUE</tt> if negative or <tt>Long.MAX_VALUE</tt>
 155:      * if positive.
 156:      *
 157:      * <p>For example, to convert 10 minutes to milliseconds, use:
 158:      * <tt>TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)</tt>
 159:      *
 160:      * @param sourceDuration the time duration in the given <tt>sourceUnit</tt>
 161:      * @param sourceUnit the unit of the <tt>sourceDuration</tt> argument
 162:      * @return the converted duration in this unit,
 163:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 164:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 165:      */
 166:     public long convert(long sourceDuration, TimeUnit sourceUnit) {
 167:         throw new AbstractMethodError();
 168:     }
 169: 
 170:     /**
 171:      * Equivalent to <tt>NANOSECONDS.convert(duration, this)</tt>.
 172:      * @param duration the duration
 173:      * @return the converted duration,
 174:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 175:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 176:      * @see #convert
 177:      */
 178:     public long toNanos(long duration) {
 179:         throw new AbstractMethodError();
 180:     }
 181: 
 182:     /**
 183:      * Equivalent to <tt>MICROSECONDS.convert(duration, this)</tt>.
 184:      * @param duration the duration
 185:      * @return the converted duration,
 186:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 187:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 188:      * @see #convert
 189:      */
 190:     public long toMicros(long duration) {
 191:         throw new AbstractMethodError();
 192:     }
 193: 
 194:     /**
 195:      * Equivalent to <tt>MILLISECONDS.convert(duration, this)</tt>.
 196:      * @param duration the duration
 197:      * @return the converted duration,
 198:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 199:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 200:      * @see #convert
 201:      */
 202:     public long toMillis(long duration) {
 203:         throw new AbstractMethodError();
 204:     }
 205: 
 206:     /**
 207:      * Equivalent to <tt>SECONDS.convert(duration, this)</tt>.
 208:      * @param duration the duration
 209:      * @return the converted duration,
 210:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 211:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 212:      * @see #convert
 213:      */
 214:     public long toSeconds(long duration) {
 215:         throw new AbstractMethodError();
 216:     }
 217: 
 218:     /**
 219:      * Equivalent to <tt>MINUTES.convert(duration, this)</tt>.
 220:      * @param duration the duration
 221:      * @return the converted duration,
 222:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 223:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 224:      * @see #convert
 225:      * @since 1.6
 226:      */
 227:     public long toMinutes(long duration) {
 228:         throw new AbstractMethodError();
 229:     }
 230: 
 231:     /**
 232:      * Equivalent to <tt>HOURS.convert(duration, this)</tt>.
 233:      * @param duration the duration
 234:      * @return the converted duration,
 235:      * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
 236:      * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
 237:      * @see #convert
 238:      * @since 1.6
 239:      */
 240:     public long toHours(long duration) {
 241:         throw new AbstractMethodError();
 242:     }
 243: 
 244:     /**
 245:      * Equivalent to <tt>DAYS.convert(duration, this)</tt>.
 246:      * @param duration the duration
 247:      * @return the converted duration
 248:      * @see #convert
 249:      * @since 1.6
 250:      */
 251:     public long toDays(long duration) {
 252:         throw new AbstractMethodError();
 253:     }
 254: 
 255:     /**
 256:      * Utility to compute the excess-nanosecond argument to wait,
 257:      * sleep, join.
 258:      * @param d the duration
 259:      * @param m the number of milliseconds
 260:      * @return the number of nanoseconds
 261:      */
 262:     abstract int excessNanos(long d, long m);
 263: 
 264:     /**
 265:      * Performs a timed <tt>Object.wait</tt> using this time unit.
 266:      * This is a convenience method that converts timeout arguments
 267:      * into the form required by the <tt>Object.wait</tt> method.
 268:      *
 269:      * <p>For example, you could implement a blocking <tt>poll</tt>
 270:      * method (see {@link BlockingQueue#poll BlockingQueue.poll})
 271:      * using:
 272:      *
 273:      * <pre>  public synchronized Object poll(long timeout, TimeUnit unit) throws InterruptedException {
 274:      *    while (empty) {
 275:      *      unit.timedWait(this, timeout);
 276:      *      ...
 277:      *    }
 278:      *  }</pre>
 279:      *
 280:      * @param obj the object to wait on
 281:      * @param timeout the maximum time to wait. If less than
 282:      * or equal to zero, do not wait at all.
 283:      * @throws InterruptedException if interrupted while waiting.
 284:      * @see Object#wait(long, int)
 285:      */
 286:     public void timedWait(Object obj, long timeout)
 287:     throws InterruptedException {
 288:         if (timeout > 0) {
 289:             long ms = toMillis(timeout);
 290:             int ns = excessNanos(timeout, ms);
 291:             obj.wait(ms, ns);
 292:         }
 293:     }
 294: 
 295:     /**
 296:      * Performs a timed <tt>Thread.join</tt> using this time unit.
 297:      * This is a convenience method that converts time arguments into the
 298:      * form required by the <tt>Thread.join</tt> method.
 299:      * @param thread the thread to wait for
 300:      * @param timeout the maximum time to wait. If less than
 301:      * or equal to zero, do not wait at all.
 302:      * @throws InterruptedException if interrupted while waiting.
 303:      * @see Thread#join(long, int)
 304:      */
 305:     public void timedJoin(Thread thread, long timeout)
 306:     throws InterruptedException {
 307:         if (timeout > 0) {
 308:             long ms = toMillis(timeout);
 309:             int ns = excessNanos(timeout, ms);
 310:             thread.join(ms, ns);
 311:         }
 312:     }
 313: 
 314:     /**
 315:      * Performs a <tt>Thread.sleep</tt> using this unit.
 316:      * This is a convenience method that converts time arguments into the
 317:      * form required by the <tt>Thread.sleep</tt> method.
 318:      * @param timeout the minimum time to sleep. If less than
 319:      * or equal to zero, do not sleep at all.
 320:      * @throws InterruptedException if interrupted while sleeping.
 321:      * @see Thread#sleep
 322:      */
 323:     public void sleep(long timeout) throws InterruptedException {
 324:         if (timeout > 0) {
 325:             long ms = toMillis(timeout);
 326:             int ns = excessNanos(timeout, ms);
 327:             Thread.sleep(ms, ns);
 328:         }
 329:     }
 330: 
 331: }