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 { + 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);
+ Object o = new Object();
+ synchronized (o) {
+ o.wait(ms, ns);
+ }
+ }
+ }
+
+}