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: * *
{@code
* Lock lock = ...;
* if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...}
*
* while this code will timeout in 50 seconds:
* {@code
* 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 {
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 {
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 {
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 {
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 {
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 {
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 {
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; }
};
// Handy constants for conversion methods
static final long C0 = 1L;
static final long C1 = C0 * 1000L;
static final long C2 = C1 * 1000L;
static final long C3 = C2 * 1000L;
static final long C4 = C3 * 60L;
static final long C5 = C4 * 60L;
static final long C6 = C5 * 24L;
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;
}
// To maintain full signature compatibility with 1.5, and to improve the
// clarity of the generated javadoc (see 6287639: Abstract methods in
// enum classes should not be listed as abstract), method convert
// etc. are not declared abstract but otherwise act as abstract methods.
/**
* 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.
*
* For example, to convert 10 minutes to milliseconds, use: * TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES) * * @param sourceDuration the time duration in the given sourceUnit * @param sourceUnit the unit of the sourceDuration 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 long convert(long sourceDuration, TimeUnit sourceUnit) { throw new AbstractMethodError(); } /** * 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 long toNanos(long duration) { throw new AbstractMethodError(); } /** * 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 long toMicros(long duration) { throw new AbstractMethodError(); } /** * 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 long toMillis(long duration) { throw new AbstractMethodError(); } /** * Equivalent to SECONDS.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 long toSeconds(long duration) { throw new AbstractMethodError(); } /** * Equivalent to MINUTES.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 * @since 1.6 */ public long toMinutes(long duration) { throw new AbstractMethodError(); } /** * Equivalent to HOURS.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 * @since 1.6 */ public long toHours(long duration) { throw new AbstractMethodError(); } /** * Equivalent to DAYS.convert(duration, this). * @param duration the duration * @return the converted duration * @see #convert * @since 1.6 */ public long toDays(long duration) { throw new AbstractMethodError(); } /** * Utility to compute the excess-nanosecond argument to wait, * sleep, join. * @param d the duration * @param m the number of milliseconds * @return the number of nanoseconds */ abstract int excessNanos(long d, long m); /** * Performs a timed {@link Object#wait(long, int) 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: * *
{@code
* 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. If less than
* or equal to zero, do not wait at all.
* @throws InterruptedException if interrupted while waiting
*/
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);
}
}
/**
* Performs a timed {@link Thread#join(long, int) 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. If less than
* or equal to zero, do not wait at all.
* @throws InterruptedException if interrupted while waiting
*/
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);
}
}
/**
* Performs a {@link Thread#sleep(long, int) Thread.sleep} using
* this time 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. If less than
* or equal to zero, do not sleep at all.
* @throws InterruptedException if interrupted while sleeping
*/
public void sleep(long timeout) throws InterruptedException {
if (timeout > 0) {
long ms = toMillis(timeout);
int ns = excessNanos(timeout, ms);
Thread.sleep(ms, ns);
}
}
}