/* * Written by Doug Lea with assistance from members of JCP JSR-166 * Expert Group and released to the public domain, as explained at * http://creativecommons.org/licenses/publicdomain */ package java.util.concurrent; /** * A TimeUnit represents time durations at a given unit of * granularity and provides utility methods to convert across units, * and to perform timing and delay operations in these units. A * TimeUnit does not maintain time information, but only * helps organize and use time representations that may be maintained * separately across various contexts. A nanosecond is defined as one * thousandth of a microsecond, a microsecond as one thousandth of a * millisecond, a millisecond as one thousandth of a second, a minute * as sixty seconds, an hour as sixty minutes, and a day as twenty four * hours. * *

A TimeUnit is mainly used to inform time-based methods * how a given timing parameter should be interpreted. For example, * the following code will timeout in 50 milliseconds if the {@link * java.util.concurrent.locks.Lock lock} is not available: * * 

  Lock lock = ...;
  *  if ( lock.tryLock(50L, TimeUnit.MILLISECONDS) ) ...
  *
* while this code will timeout in 50 seconds: * 
  *  Lock lock = ...;
  *  if ( lock.tryLock(50L, TimeUnit.SECONDS) ) ...
  *
* * Note however, that there is no guarantee that a particular timeout * implementation will be able to notice the passage of time at the * same granularity as the given TimeUnit. * * @since 1.5 * @author Doug Lea */ public enum TimeUnit { NANOSECONDS (0) { public long toNanos(long d) { return d; } public long toMicros(long d) { return d/(C1/C0); } public long toMillis(long d) { return d/(C2/C0); } public long toSeconds(long d) { return d/(C3/C0); } public long toMinutes(long d) { return d/(C4/C0); } public long toHours(long d) { return d/(C5/C0); } public long toDays(long d) { return d/(C6/C0); } public long convert(long d, TimeUnit u) { return u.toNanos(d); } int excessNanos(long d, long m) { return (int)(d - (m*C2)); } }, MICROSECONDS (1) { public long toNanos(long d) { return x(d, C1/C0, MAX/(C1/C0)); } public long toMicros(long d) { return d; } public long toMillis(long d) { return d/(C2/C1); } public long toSeconds(long d) { return d/(C3/C1); } public long toMinutes(long d) { return d/(C4/C1); } public long toHours(long d) { return d/(C5/C1); } public long toDays(long d) { return d/(C6/C1); } public long convert(long d, TimeUnit u) { return u.toMicros(d); } int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); } }, MILLISECONDS (2) { public long toNanos(long d) { return x(d, C2/C0, MAX/(C2/C0)); } public long toMicros(long d) { return x(d, C2/C1, MAX/(C2/C1)); } public long toMillis(long d) { return d; } public long toSeconds(long d) { return d/(C3/C2); } public long toMinutes(long d) { return d/(C4/C2); } public long toHours(long d) { return d/(C5/C2); } public long toDays(long d) { return d/(C6/C2); } public long convert(long d, TimeUnit u) { return u.toMillis(d); } int excessNanos(long d, long m) { return 0; } }, SECONDS (3) { public long toNanos(long d) { return x(d, C3/C0, MAX/(C3/C0)); } public long toMicros(long d) { return x(d, C3/C1, MAX/(C3/C1)); } public long toMillis(long d) { return x(d, C3/C2, MAX/(C3/C2)); } public long toSeconds(long d) { return d; } public long toMinutes(long d) { return d/(C4/C3); } public long toHours(long d) { return d/(C5/C3); } public long toDays(long d) { return d/(C6/C3); } public long convert(long d, TimeUnit u) { return u.toSeconds(d); } int excessNanos(long d, long m) { return 0; } }, MINUTES (4) { public long toNanos(long d) { return x(d, C4/C0, MAX/(C4/C0)); } public long toMicros(long d) { return x(d, C4/C1, MAX/(C4/C1)); } public long toMillis(long d) { return x(d, C4/C2, MAX/(C4/C2)); } public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); } public long toMinutes(long d) { return d; } public long toHours(long d) { return d/(C5/C4); } public long toDays(long d) { return d/(C6/C4); } public long convert(long d, TimeUnit u) { return u.toMinutes(d); } int excessNanos(long d, long m) { return 0; } }, HOURS (5) { public long toNanos(long d) { return x(d, C5/C0, MAX/(C5/C0)); } public long toMicros(long d) { return x(d, C5/C1, MAX/(C5/C1)); } public long toMillis(long d) { return x(d, C5/C2, MAX/(C5/C2)); } public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); } public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); } public long toHours(long d) { return d; } public long toDays(long d) { return d/(C6/C5); } public long convert(long d, TimeUnit u) { return u.toHours(d); } int excessNanos(long d, long m) { return 0; } }, DAYS (6) { public long toNanos(long d) { return x(d, C6/C0, MAX/(C6/C0)); } public long toMicros(long d) { return x(d, C6/C1, MAX/(C6/C1)); } public long toMillis(long d) { return x(d, C6/C2, MAX/(C6/C2)); } public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); } public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); } public long toHours(long d) { return x(d, C6/C5, MAX/(C6/C5)); } public long toDays(long d) { return d; } public long convert(long d, TimeUnit u) { return u.toDays(d); } int excessNanos(long d, long m) { return 0; } }; /** * The index of this unit. This value is no longer used in this * version of this class, but is retained for serialization * compatibility with previous version. */ private final int index; /** Internal constructor */ TimeUnit(int index) { this.index = index; } // Handy constants for conversion methods static final long C0 = 1; static final long C1 = C0 * 1000; static final long C2 = C1 * 1000; static final long C3 = C2 * 1000; static final long C4 = C3 * 60; static final long C5 = C4 * 60; static final long C6 = C5 * 24; static final long MAX = Long.MAX_VALUE; /** * Scale d by m, checking for overflow. * This has a short name to make above code more readable. */ static long x(long d, long m, long over) { if (d > over) return Long.MAX_VALUE; if (d < -over) return Long.MIN_VALUE; return d * m; } /** * Convert the given time duration in the given unit to this * unit. Conversions from finer to coarser granularities * truncate, so lose precision. For example converting * 999 milliseconds to seconds results in * 0. Conversions from coarser to finer granularities * with arguments that would numerically overflow saturate to * Long.MIN_VALUE if negative or Long.MAX_VALUE * if positive. * * @param duration the time duration in the given unit * @param unit the unit of the duration argument * @return the converted duration in this unit, * or Long.MIN_VALUE if conversion would negatively * overflow, or Long.MAX_VALUE if it would positively overflow. */ public abstract long convert(long duration, TimeUnit unit); /** * Equivalent to NANOSECONDS.convert(duration, this). * @param duration the duration * @return the converted duration, * or Long.MIN_VALUE if conversion would negatively * overflow, or Long.MAX_VALUE if it would positively overflow. * @see #convert */ public abstract long toNanos(long duration); /** * Equivalent to MICROSECONDS.convert(duration, this). * @param duration the duration * @return the converted duration, * or Long.MIN_VALUE if conversion would negatively * overflow, or Long.MAX_VALUE if it would positively overflow. * @see #convert */ public abstract long toMicros(long duration); /** * Equivalent to MILLISECONDS.convert(duration, this). * @param duration the duration * @return the converted duration, * or Long.MIN_VALUE if conversion would negatively * overflow, or Long.MAX_VALUE if it would positively overflow. * @see #convert */ public abstract long toMillis(long duration); /** * Equivalent to SECONDS.convert(duration, this). * @param duration the duration * @return the converted duration. * @see #convert */ public abstract long toSeconds(long duration); /** * Equivalent to MINUTES.convert(duration, this). * @param duration the duration * @return the converted duration. * @see #convert */ public abstract long toMinutes(long duration); /** * Equivalent to HOURS.convert(duration, this). * @param duration the duration * @return the converted duration. * @see #convert */ public abstract long toHours(long duration); /** * Equivalent to DAYS.convert(duration, this). * @param duration the duration * @return the converted duration. * @see #convert */ public abstract long toDays(long duration); /** * Utility to compute the excess-nanosecond argument to wait, * sleep, join. * @param d the duration * @param m the number of millisecondss * @return the number of nanoseconds */ abstract int excessNanos(long d, long m); /** * Perform a timed Object.wait using this time unit. * This is a convenience method that converts timeout arguments * into the form required by the Object.wait method. * *

For example, you could implement a blocking poll * method (see {@link BlockingQueue#poll BlockingQueue.poll}) * using: * * 

  public synchronized  Object poll(long timeout, TimeUnit unit) throws InterruptedException {
      *    while (empty) {
      *      unit.timedWait(this, timeout);
      *      ...
      *    }
      *  }
* * @param obj the object to wait on * @param timeout the maximum time to wait. * @throws InterruptedException if interrupted while waiting. * @see Object#wait(long, int) */ public void timedWait(Object obj, long timeout) throws InterruptedException { if (timeout > 0) { long ms = toMillis(timeout); int ns = excessNanos(timeout, ms); obj.wait(ms, ns); } } /** * Perform a timed Thread.join using this time unit. * This is a convenience method that converts time arguments into the * form required by the Thread.join method. * @param thread the thread to wait for * @param timeout the maximum time to wait * @throws InterruptedException if interrupted while waiting. * @see Thread#join(long, int) */ public void timedJoin(Thread thread, long timeout) throws InterruptedException { if (timeout > 0) { long ms = toMillis(timeout); int ns = excessNanos(timeout, ms); thread.join(ms, ns); } } /** * Perform a Thread.sleep using this unit. * This is a convenience method that converts time arguments into the * form required by the Thread.sleep method. * @param timeout the minimum time to sleep * @throws InterruptedException if interrupted while sleeping. * @see Thread#sleep */ public void sleep(long timeout) throws InterruptedException { if (timeout > 0) { long ms = toMillis(timeout); int ns = excessNanos(timeout, ms); Thread.sleep(ms, ns); } } }