util/concurrent/TimeUnit.java

/*
 * 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/publicdomain/zero/1.0/
 */

package java.util.concurrent;

import java.time.Duration;
import java.time.temporal.ChronoUnit;
import java.util.Objects;

/**
 * A {@code 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
 * {@code 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.
 *
 * <p>A {@code 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:
 *
 * <pre> {@code
 * Lock lock = ...;
 * if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...}</pre>
 *
 * while this code will timeout in 50 seconds:
 * <pre> {@code
 * Lock lock = ...;
 * if (lock.tryLock(50L, TimeUnit.SECONDS)) ...}</pre>
 *
 * 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 {@code TimeUnit}.
 *
 * @since 1.5
 * @author Doug Lea
 */
public enum TimeUnit {
    /**
     * Time unit representing one thousandth of a microsecond.
     */
    NANOSECONDS(TimeUnit.NANO_SCALE),
    /**
     * Time unit representing one thousandth of a millisecond.
     */
    MICROSECONDS(TimeUnit.MICRO_SCALE),
    /**
     * Time unit representing one thousandth of a second.
     */
    MILLISECONDS(TimeUnit.MILLI_SCALE),
    /**
     * Time unit representing one second.
     */
    SECONDS(TimeUnit.SECOND_SCALE),
    /**
     * Time unit representing sixty seconds.
     * @since 1.6
     */
    MINUTES(TimeUnit.MINUTE_SCALE),
    /**
     * Time unit representing sixty minutes.
     * @since 1.6
     */
    HOURS(TimeUnit.HOUR_SCALE),
    /**
     * Time unit representing twenty four hours.
     * @since 1.6
     */
    DAYS(TimeUnit.DAY_SCALE);

    // Scales as constants
    private static final long NANO_SCALE   = 1L;
    private static final long MICRO_SCALE  = 1000L * NANO_SCALE;
    private static final long MILLI_SCALE  = 1000L * MICRO_SCALE;
    private static final long SECOND_SCALE = 1000L * MILLI_SCALE;
    private static final long MINUTE_SCALE = 60L * SECOND_SCALE;
    private static final long HOUR_SCALE   = 60L * MINUTE_SCALE;
    private static final long DAY_SCALE    = 24L * HOUR_SCALE;

    /*
     * Instances cache conversion ratios and saturation cutoffs for
     * the units up through SECONDS. Other cases compute them, in
     * method cvt.
     */

    private final long scale;
    private final long maxNanos;
    private final long maxMicros;
    private final long maxMillis;
    private final long maxSecs;
    private final long microRatio;
    private final int milliRatio;   // fits in 32 bits
    private final int secRatio;     // fits in 32 bits

    private TimeUnit(long s) {
        this.scale = s;
        this.maxNanos = Long.MAX_VALUE / s;
        long ur = (s >= MICRO_SCALE) ? (s / MICRO_SCALE) : (MICRO_SCALE / s);
        this.microRatio = ur;
        this.maxMicros = Long.MAX_VALUE / ur;
        long mr = (s >= MILLI_SCALE) ? (s / MILLI_SCALE) : (MILLI_SCALE / s);
        this.milliRatio = (int)mr;
        this.maxMillis = Long.MAX_VALUE / mr;
        long sr = (s >= SECOND_SCALE) ? (s / SECOND_SCALE) : (SECOND_SCALE / s);
        this.secRatio = (int)sr;
        this.maxSecs = Long.MAX_VALUE / sr;
    }

    /**
     * General conversion utility.
     *
     * @param d duration
     * @param dst result unit scale
     * @param src source unit scale
     */
    private static long cvt(long d, long dst, long src) {
        long r, m;
        if (src == dst)
            return d;
        else if (src < dst)
            return d / (dst / src);
        else if (d > (m = Long.MAX_VALUE / (r = src / dst)))
            return Long.MAX_VALUE;
        else if (d < -m)
            return Long.MIN_VALUE;
        else
            return d * r;
    }

    /**
     * Converts the given time duration in the given unit to this unit.
     * Conversions from finer to coarser granularities truncate, so
     * lose precision. For example, converting {@code 999} milliseconds
     * to seconds results in {@code 0}. Conversions from coarser to
     * finer granularities with arguments that would numerically
     * overflow saturate to {@code Long.MIN_VALUE} if negative or
     * {@code Long.MAX_VALUE} if positive.
     *
     * <p>For example, to convert 10 minutes to milliseconds, use:
     * {@code TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)}
     *
     * @param sourceDuration the time duration in the given {@code sourceUnit}
     * @param sourceUnit the unit of the {@code sourceDuration} argument
     * @return the converted duration in this unit,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long convert(long sourceDuration, TimeUnit sourceUnit) {
        switch (this) {
        case NANOSECONDS:  return sourceUnit.toNanos(sourceDuration);
        case MICROSECONDS: return sourceUnit.toMicros(sourceDuration);
        case MILLISECONDS: return sourceUnit.toMillis(sourceDuration);
        case SECONDS:      return sourceUnit.toSeconds(sourceDuration);
        default: return cvt(sourceDuration, scale, sourceUnit.scale);
        }
    }

    /**
     * Converts the given time duration to this unit.
     *
     * <p>For any TimeUnit {@code unit},
     * {@code unit.convert(Duration.ofNanos(n))}
     * is equivalent to
     * {@code unit.convert(n, NANOSECONDS)}, and
     * {@code unit.convert(Duration.of(n, unit.toChronoUnit()))}
     * is equivalent to {@code n} (in the absence of overflow).
     *
     * @param duration the time duration
     * @return the converted duration in this unit,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     * @throws NullPointerException if {@code duration} is null
     * @see Duration#of(long,TemporalUnit)
     * @since 11
     */
    public long convert(Duration duration) {
        long secs = duration.getSeconds();
        int nano = duration.getNano();
        if (secs < 0 && nano > 0) {
            // use representation compatible with integer division
            secs++;
            nano -= SECOND_SCALE;
        }
        final long s, nanoVal;
        // Optimize for the common case - NANOSECONDS without overflow
        if (this == NANOSECONDS)
            nanoVal = nano;
        else if ((s = scale) < SECOND_SCALE)
            nanoVal = nano / s;
        else if (this == SECONDS)
            return secs;
        else
            return secs / secRatio;
        long val = secs * secRatio + nanoVal;
        return ((secs < maxSecs && secs > -maxSecs) ||
                (secs == maxSecs && val > 0) ||
                (secs == -maxSecs && val < 0))
            ? val
            : (secs > 0) ? Long.MAX_VALUE : Long.MIN_VALUE;
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) NANOSECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toNanos(long duration) {
        long s, m;
        if ((s = scale) == NANO_SCALE)
            return duration;
        else if (duration > (m = maxNanos))
            return Long.MAX_VALUE;
        else if (duration < -m)
            return Long.MIN_VALUE;
        else
            return duration * s;
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) MICROSECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toMicros(long duration) {
        long s, m;
        if ((s = scale) <= MICRO_SCALE)
            return (s == MICRO_SCALE) ? duration : duration / microRatio;
        else if (duration > (m = maxMicros))
            return Long.MAX_VALUE;
        else if (duration < -m)
            return Long.MIN_VALUE;
        else
            return duration * microRatio;
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) MILLISECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toMillis(long duration) {
        long s, m;
        if ((s = scale) <= MILLI_SCALE)
            return (s == MILLI_SCALE) ? duration : duration / milliRatio;
        else if (duration > (m = maxMillis))
            return Long.MAX_VALUE;
        else if (duration < -m)
            return Long.MIN_VALUE;
        else
            return duration * milliRatio;
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) SECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toSeconds(long duration) {
        long s, m;
        if ((s = scale) <= SECOND_SCALE)
            return (s == SECOND_SCALE) ? duration : duration / secRatio;
        else if (duration > (m = maxSecs))
            return Long.MAX_VALUE;
        else if (duration < -m)
            return Long.MIN_VALUE;
        else
            return duration * secRatio;
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) MINUTES.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     * @since 1.6
     */
    public long toMinutes(long duration) {
        return cvt(duration, MINUTE_SCALE, scale);
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) HOURS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively overflow,
     * or {@code Long.MAX_VALUE} if it would positively overflow.
     * @since 1.6
     */
    public long toHours(long duration) {
        return cvt(duration, HOUR_SCALE, scale);
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) DAYS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration
     * @since 1.6
     */
    public long toDays(long duration) {
        return cvt(duration, DAY_SCALE, scale);
    }

    /**
     * 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
     */
    private int excessNanos(long d, long m) {
        long s;
        if ((s = scale) == NANO_SCALE)
            return (int)(d - (m * MILLI_SCALE));
        else if (s == MICRO_SCALE)
            return (int)((d * 1000L) - (m * MILLI_SCALE));
        else
            return 0;
    }

    /**
     * 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 {@code Object.wait} method.
     *
     * <p>For example, you could implement a blocking {@code poll} method
     * (see {@link BlockingQueue#poll(long, TimeUnit) BlockingQueue.poll})
     * using:
     *
     * <pre> {@code
     * public E poll(long timeout, TimeUnit unit)
     *     throws InterruptedException {
     *   synchronized (lock) {
     *     while (isEmpty()) {
     *       unit.timedWait(lock, timeout);
     *       ...
     *     }
     *   }
     * }}</pre>
     *
     * @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 {@code 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 {@code 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);
        }
    }

    /**
     * Converts this {@code TimeUnit} to the equivalent {@code ChronoUnit}.
     *
     * @return the converted equivalent ChronoUnit
     * @since 9
     */
    public ChronoUnit toChronoUnit() {
        switch (this) {
        case NANOSECONDS:  return ChronoUnit.NANOS;
        case MICROSECONDS: return ChronoUnit.MICROS;
        case MILLISECONDS: return ChronoUnit.MILLIS;
        case SECONDS:      return ChronoUnit.SECONDS;
        case MINUTES:      return ChronoUnit.MINUTES;
        case HOURS:        return ChronoUnit.HOURS;
        case DAYS:         return ChronoUnit.DAYS;
        default: throw new AssertionError();
        }
    }

    /**
     * Converts a {@code ChronoUnit} to the equivalent {@code TimeUnit}.
     *
     * @param chronoUnit the ChronoUnit to convert
     * @return the converted equivalent TimeUnit
     * @throws IllegalArgumentException if {@code chronoUnit} has no
     *         equivalent TimeUnit
     * @throws NullPointerException if {@code chronoUnit} is null
     * @since 9
     */
    public static TimeUnit of(ChronoUnit chronoUnit) {
        switch (Objects.requireNonNull(chronoUnit, "chronoUnit")) {
        case NANOS:   return TimeUnit.NANOSECONDS;
        case MICROS:  return TimeUnit.MICROSECONDS;
        case MILLIS:  return TimeUnit.MILLISECONDS;
        case SECONDS: return TimeUnit.SECONDS;
        case MINUTES: return TimeUnit.MINUTES;
        case HOURS:   return TimeUnit.HOURS;
        case DAYS:    return TimeUnit.DAYS;
        default:
            throw new IllegalArgumentException(
                "No TimeUnit equivalent for " + chronoUnit);
        }
    }

}
Revision:	1.5
Committed:	Fri Jun 8 02:20:22 2018 UTC (5 years, 11 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.4:	+59 -18 lines
Log Message:	sync from src/main
#	Content
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/publicdomain/zero/1.0/
5	*/
6
7	package java.util.concurrent;
8
9	import java.time.Duration;
10	import java.time.temporal.ChronoUnit;
11	import java.util.Objects;
12
13	/**
14	* A {@code TimeUnit} represents time durations at a given unit of
15	* granularity and provides utility methods to convert across units,
16	* and to perform timing and delay operations in these units. A
17	* {@code TimeUnit} does not maintain time information, but only
18	* helps organize and use time representations that may be maintained
19	* separately across various contexts. A nanosecond is defined as one
20	* thousandth of a microsecond, a microsecond as one thousandth of a
21	* millisecond, a millisecond as one thousandth of a second, a minute
22	* as sixty seconds, an hour as sixty minutes, and a day as twenty four
23	* hours.
24	*
25	* <p>A {@code TimeUnit} is mainly used to inform time-based methods
26	* how a given timing parameter should be interpreted. For example,
27	* the following code will timeout in 50 milliseconds if the {@link
28	* java.util.concurrent.locks.Lock lock} is not available:
29	*
30	* <pre> {@code
31	* Lock lock = ...;
32	* if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...}</pre>
33	*
34	* while this code will timeout in 50 seconds:
35	* <pre> {@code
36	* Lock lock = ...;
37	* if (lock.tryLock(50L, TimeUnit.SECONDS)) ...}</pre>
38	*
39	* Note however, that there is no guarantee that a particular timeout
40	* implementation will be able to notice the passage of time at the
41	* same granularity as the given {@code TimeUnit}.
42	*
43	* @since 1.5
44	* @author Doug Lea
45	*/
46	public enum TimeUnit {
47	/**
48	* Time unit representing one thousandth of a microsecond.
49	*/
50	NANOSECONDS(TimeUnit.NANO_SCALE),
51	/**
52	* Time unit representing one thousandth of a millisecond.
53	*/
54	MICROSECONDS(TimeUnit.MICRO_SCALE),
55	/**
56	* Time unit representing one thousandth of a second.
57	*/
58	MILLISECONDS(TimeUnit.MILLI_SCALE),
59	/**
60	* Time unit representing one second.
61	*/
62	SECONDS(TimeUnit.SECOND_SCALE),
63	/**
64	* Time unit representing sixty seconds.
65	* @since 1.6
66	*/
67	MINUTES(TimeUnit.MINUTE_SCALE),
68	/**
69	* Time unit representing sixty minutes.
70	* @since 1.6
71	*/
72	HOURS(TimeUnit.HOUR_SCALE),
73	/**
74	* Time unit representing twenty four hours.
75	* @since 1.6
76	*/
77	DAYS(TimeUnit.DAY_SCALE);
78
79	// Scales as constants
80	private static final long NANO_SCALE = 1L;
81	private static final long MICRO_SCALE = 1000L * NANO_SCALE;
82	private static final long MILLI_SCALE = 1000L * MICRO_SCALE;
83	private static final long SECOND_SCALE = 1000L * MILLI_SCALE;
84	private static final long MINUTE_SCALE = 60L * SECOND_SCALE;
85	private static final long HOUR_SCALE = 60L * MINUTE_SCALE;
86	private static final long DAY_SCALE = 24L * HOUR_SCALE;
87
88	/*
89	* Instances cache conversion ratios and saturation cutoffs for
90	* the units up through SECONDS. Other cases compute them, in
91	* method cvt.
92	*/
93
94	private final long scale;
95	private final long maxNanos;
96	private final long maxMicros;
97	private final long maxMillis;
98	private final long maxSecs;
99	private final long microRatio;
100	private final int milliRatio; // fits in 32 bits
101	private final int secRatio; // fits in 32 bits
102
103	private TimeUnit(long s) {
104	this.scale = s;
105	this.maxNanos = Long.MAX_VALUE / s;
106	long ur = (s >= MICRO_SCALE) ? (s / MICRO_SCALE) : (MICRO_SCALE / s);
107	this.microRatio = ur;
108	this.maxMicros = Long.MAX_VALUE / ur;
109	long mr = (s >= MILLI_SCALE) ? (s / MILLI_SCALE) : (MILLI_SCALE / s);
110	this.milliRatio = (int)mr;
111	this.maxMillis = Long.MAX_VALUE / mr;
112	long sr = (s >= SECOND_SCALE) ? (s / SECOND_SCALE) : (SECOND_SCALE / s);
113	this.secRatio = (int)sr;
114	this.maxSecs = Long.MAX_VALUE / sr;
115	}
116
117	/**
118	* General conversion utility.
119	*
120	* @param d duration
121	* @param dst result unit scale
122	* @param src source unit scale
123	*/
124	private static long cvt(long d, long dst, long src) {
125	long r, m;
126	if (src == dst)
127	return d;
128	else if (src < dst)
129	return d / (dst / src);
130	else if (d > (m = Long.MAX_VALUE / (r = src / dst)))
131	return Long.MAX_VALUE;
132	else if (d < -m)
133	return Long.MIN_VALUE;
134	else
135	return d * r;
136	}
137
138	/**
139	* Converts the given time duration in the given unit to this unit.
140	* Conversions from finer to coarser granularities truncate, so
141	* lose precision. For example, converting {@code 999} milliseconds
142	* to seconds results in {@code 0}. Conversions from coarser to
143	* finer granularities with arguments that would numerically
144	* overflow saturate to {@code Long.MIN_VALUE} if negative or
145	* {@code Long.MAX_VALUE} if positive.
146	*
147	* <p>For example, to convert 10 minutes to milliseconds, use:
148	* {@code TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)}
149	*
150	* @param sourceDuration the time duration in the given {@code sourceUnit}
151	* @param sourceUnit the unit of the {@code sourceDuration} argument
152	* @return the converted duration in this unit,
153	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
154	* or {@code Long.MAX_VALUE} if it would positively overflow.
155	*/
156	public long convert(long sourceDuration, TimeUnit sourceUnit) {
157	switch (this) {
158	case NANOSECONDS: return sourceUnit.toNanos(sourceDuration);
159	case MICROSECONDS: return sourceUnit.toMicros(sourceDuration);
160	case MILLISECONDS: return sourceUnit.toMillis(sourceDuration);
161	case SECONDS: return sourceUnit.toSeconds(sourceDuration);
162	default: return cvt(sourceDuration, scale, sourceUnit.scale);
163	}
164	}
165
166	/**
167	* Converts the given time duration to this unit.
168	*
169	* <p>For any TimeUnit {@code unit},
170	* {@code unit.convert(Duration.ofNanos(n))}
171	* is equivalent to
172	* {@code unit.convert(n, NANOSECONDS)}, and
173	* {@code unit.convert(Duration.of(n, unit.toChronoUnit()))}
174	* is equivalent to {@code n} (in the absence of overflow).
175	*
176	* @param duration the time duration
177	* @return the converted duration in this unit,
178	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
179	* or {@code Long.MAX_VALUE} if it would positively overflow.
180	* @throws NullPointerException if {@code duration} is null
181	* @see Duration#of(long,TemporalUnit)
182	* @since 11
183	*/
184	public long convert(Duration duration) {
185	long secs = duration.getSeconds();
186	int nano = duration.getNano();
187	if (secs < 0 && nano > 0) {
188	// use representation compatible with integer division
189	secs++;
190	nano -= SECOND_SCALE;
191	}
192	final long s, nanoVal;
193	// Optimize for the common case - NANOSECONDS without overflow
194	if (this == NANOSECONDS)
195	nanoVal = nano;
196	else if ((s = scale) < SECOND_SCALE)
197	nanoVal = nano / s;
198	else if (this == SECONDS)
199	return secs;
200	else
201	return secs / secRatio;
202	long val = secs * secRatio + nanoVal;
203	return ((secs < maxSecs && secs > -maxSecs) \|\|
204	(secs == maxSecs && val > 0) \|\|
205	(secs == -maxSecs && val < 0))
206	? val
207	: (secs > 0) ? Long.MAX_VALUE : Long.MIN_VALUE;
208	}
209
210	/**
211	* Equivalent to
212	* {@link #convert(long, TimeUnit) NANOSECONDS.convert(duration, this)}.
213	* @param duration the duration
214	* @return the converted duration,
215	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
216	* or {@code Long.MAX_VALUE} if it would positively overflow.
217	*/
218	public long toNanos(long duration) {
219	long s, m;
220	if ((s = scale) == NANO_SCALE)
221	return duration;
222	else if (duration > (m = maxNanos))
223	return Long.MAX_VALUE;
224	else if (duration < -m)
225	return Long.MIN_VALUE;
226	else
227	return duration * s;
228	}
229
230	/**
231	* Equivalent to
232	* {@link #convert(long, TimeUnit) MICROSECONDS.convert(duration, this)}.
233	* @param duration the duration
234	* @return the converted duration,
235	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
236	* or {@code Long.MAX_VALUE} if it would positively overflow.
237	*/
238	public long toMicros(long duration) {
239	long s, m;
240	if ((s = scale) <= MICRO_SCALE)
241	return (s == MICRO_SCALE) ? duration : duration / microRatio;
242	else if (duration > (m = maxMicros))
243	return Long.MAX_VALUE;
244	else if (duration < -m)
245	return Long.MIN_VALUE;
246	else
247	return duration * microRatio;
248	}
249
250	/**
251	* Equivalent to
252	* {@link #convert(long, TimeUnit) MILLISECONDS.convert(duration, this)}.
253	* @param duration the duration
254	* @return the converted duration,
255	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
256	* or {@code Long.MAX_VALUE} if it would positively overflow.
257	*/
258	public long toMillis(long duration) {
259	long s, m;
260	if ((s = scale) <= MILLI_SCALE)
261	return (s == MILLI_SCALE) ? duration : duration / milliRatio;
262	else if (duration > (m = maxMillis))
263	return Long.MAX_VALUE;
264	else if (duration < -m)
265	return Long.MIN_VALUE;
266	else
267	return duration * milliRatio;
268	}
269
270	/**
271	* Equivalent to
272	* {@link #convert(long, TimeUnit) SECONDS.convert(duration, this)}.
273	* @param duration the duration
274	* @return the converted duration,
275	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
276	* or {@code Long.MAX_VALUE} if it would positively overflow.
277	*/
278	public long toSeconds(long duration) {
279	long s, m;
280	if ((s = scale) <= SECOND_SCALE)
281	return (s == SECOND_SCALE) ? duration : duration / secRatio;
282	else if (duration > (m = maxSecs))
283	return Long.MAX_VALUE;
284	else if (duration < -m)
285	return Long.MIN_VALUE;
286	else
287	return duration * secRatio;
288	}
289
290	/**
291	* Equivalent to
292	* {@link #convert(long, TimeUnit) MINUTES.convert(duration, this)}.
293	* @param duration the duration
294	* @return the converted duration,
295	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
296	* or {@code Long.MAX_VALUE} if it would positively overflow.
297	* @since 1.6
298	*/
299	public long toMinutes(long duration) {
300	return cvt(duration, MINUTE_SCALE, scale);
301	}
302
303	/**
304	* Equivalent to
305	* {@link #convert(long, TimeUnit) HOURS.convert(duration, this)}.
306	* @param duration the duration
307	* @return the converted duration,
308	* or {@code Long.MIN_VALUE} if conversion would negatively overflow,
309	* or {@code Long.MAX_VALUE} if it would positively overflow.
310	* @since 1.6
311	*/
312	public long toHours(long duration) {
313	return cvt(duration, HOUR_SCALE, scale);
314	}
315
316	/**
317	* Equivalent to
318	* {@link #convert(long, TimeUnit) DAYS.convert(duration, this)}.
319	* @param duration the duration
320	* @return the converted duration
321	* @since 1.6
322	*/
323	public long toDays(long duration) {
324	return cvt(duration, DAY_SCALE, scale);
325	}
326
327	/**
328	* Utility to compute the excess-nanosecond argument to wait,
329	* sleep, join.
330	* @param d the duration
331	* @param m the number of milliseconds
332	* @return the number of nanoseconds
333	*/
334	private int excessNanos(long d, long m) {
335	long s;
336	if ((s = scale) == NANO_SCALE)
337	return (int)(d - (m * MILLI_SCALE));
338	else if (s == MICRO_SCALE)
339	return (int)((d * 1000L) - (m * MILLI_SCALE));
340	else
341	return 0;
342	}
343
344	/**
345	* Performs a timed {@link Object#wait(long, int) Object.wait}
346	* using this time unit.
347	* This is a convenience method that converts timeout arguments
348	* into the form required by the {@code Object.wait} method.
349	*
350	* <p>For example, you could implement a blocking {@code poll} method
351	* (see {@link BlockingQueue#poll(long, TimeUnit) BlockingQueue.poll})
352	* using:
353	*
354	* <pre> {@code
355	* public E poll(long timeout, TimeUnit unit)
356	* throws InterruptedException {
357	* synchronized (lock) {
358	* while (isEmpty()) {
359	* unit.timedWait(lock, timeout);
360	* ...
361	* }
362	* }
363	* }}</pre>
364	*
365	* @param obj the object to wait on
366	* @param timeout the maximum time to wait. If less than
367	* or equal to zero, do not wait at all.
368	* @throws InterruptedException if interrupted while waiting
369	*/
370	public void timedWait(Object obj, long timeout)
371	throws InterruptedException {
372	if (timeout > 0) {
373	long ms = toMillis(timeout);
374	int ns = excessNanos(timeout, ms);
375	obj.wait(ms, ns);
376	}
377	}
378
379	/**
380	* Performs a timed {@link Thread#join(long, int) Thread.join}
381	* using this time unit.
382	* This is a convenience method that converts time arguments into the
383	* form required by the {@code Thread.join} method.
384	*
385	* @param thread the thread to wait for
386	* @param timeout the maximum time to wait. If less than
387	* or equal to zero, do not wait at all.
388	* @throws InterruptedException if interrupted while waiting
389	*/
390	public void timedJoin(Thread thread, long timeout)
391	throws InterruptedException {
392	if (timeout > 0) {
393	long ms = toMillis(timeout);
394	int ns = excessNanos(timeout, ms);
395	thread.join(ms, ns);
396	}
397	}
398
399	/**
400	* Performs a {@link Thread#sleep(long, int) Thread.sleep} using
401	* this time unit.
402	* This is a convenience method that converts time arguments into the
403	* form required by the {@code Thread.sleep} method.
404	*
405	* @param timeout the minimum time to sleep. If less than
406	* or equal to zero, do not sleep at all.
407	* @throws InterruptedException if interrupted while sleeping
408	*/
409	public void sleep(long timeout) throws InterruptedException {
410	if (timeout > 0) {
411	long ms = toMillis(timeout);
412	int ns = excessNanos(timeout, ms);
413	Thread.sleep(ms, ns);
414	}
415	}
416
417	/**
418	* Converts this {@code TimeUnit} to the equivalent {@code ChronoUnit}.
419	*
420	* @return the converted equivalent ChronoUnit
421	* @since 9
422	*/
423	public ChronoUnit toChronoUnit() {
424	switch (this) {
425	case NANOSECONDS: return ChronoUnit.NANOS;
426	case MICROSECONDS: return ChronoUnit.MICROS;
427	case MILLISECONDS: return ChronoUnit.MILLIS;
428	case SECONDS: return ChronoUnit.SECONDS;
429	case MINUTES: return ChronoUnit.MINUTES;
430	case HOURS: return ChronoUnit.HOURS;
431	case DAYS: return ChronoUnit.DAYS;
432	default: throw new AssertionError();
433	}
434	}
435
436	/**
437	* Converts a {@code ChronoUnit} to the equivalent {@code TimeUnit}.
438	*
439	* @param chronoUnit the ChronoUnit to convert
440	* @return the converted equivalent TimeUnit
441	* @throws IllegalArgumentException if {@code chronoUnit} has no
442	* equivalent TimeUnit
443	* @throws NullPointerException if {@code chronoUnit} is null
444	* @since 9
445	*/
446	public static TimeUnit of(ChronoUnit chronoUnit) {
447	switch (Objects.requireNonNull(chronoUnit, "chronoUnit")) {
448	case NANOS: return TimeUnit.NANOSECONDS;
449	case MICROS: return TimeUnit.MICROSECONDS;
450	case MILLIS: return TimeUnit.MILLISECONDS;
451	case SECONDS: return TimeUnit.SECONDS;
452	case MINUTES: return TimeUnit.MINUTES;
453	case HOURS: return TimeUnit.HOURS;
454	case DAYS: return TimeUnit.DAYS;
455	default:
456	throw new IllegalArgumentException(
457	"No TimeUnit equivalent for " + chronoUnit);
458	}
459	}
460
461	}