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.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(1L), // (cannot use symbolic scale names here)
    /**
     * Time unit representing one thousandth of a millisecond.
     */
    MICROSECONDS(1000L),
    /**
     * Time unit representing one thousandth of a second.
     */
    MILLISECONDS(1000L * 1000L),
    /**
     * Time unit representing one second.
     */
    SECONDS(1000L * 1000L * 1000L),
    /**
     * Time unit representing sixty seconds.
     * @since 1.6
     */
    MINUTES(1000L * 1000L * 1000L * 60L),
    /**
     * Time unit representing sixty minutes.
     * @since 1.6
     */
    HOURS(1000L * 1000L * 1000L * 60L * 60L),
    /**
     * Time unit representing twenty four hours.
     * @since 1.6
     */
    DAYS(1000L * 1000L * 1000L * 60L * 60L * 24L);

    // 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

    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 = (scale >= 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 scale unit
     * @param src source scale unit
     */
    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);
        }
    }

    /**
     * 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 duration;
        else if (s < MICRO_SCALE)
            return 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 duration;
        else if (s < MILLI_SCALE)
            return 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 duration;
        else if (s < SECOND_SCALE)
            return 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 BlockingQueue.poll})
     * using:
     *
     * <pre> {@code
     * public synchronized Object poll(long timeout, TimeUnit unit)
     *     throws InterruptedException {
     *   while (empty) {
     *     unit.timedWait(this, 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:	1.2
Committed:	Sat Mar 26 12:02:03 2016 UTC (8 years, 2 months ago) by dl
Branch:	MAIN
Changes since 1.1:	+32 -16 lines
Log Message:	use jdk8 @Contended
#	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.temporal.ChronoUnit;
10	import java.util.Objects;
11
12	/**
13	* A {@code TimeUnit} represents time durations at a given unit of
14	* granularity and provides utility methods to convert across units,
15	* and to perform timing and delay operations in these units. A
16	* {@code TimeUnit} does not maintain time information, but only
17	* helps organize and use time representations that may be maintained
18	* separately across various contexts. A nanosecond is defined as one
19	* thousandth of a microsecond, a microsecond as one thousandth of a
20	* millisecond, a millisecond as one thousandth of a second, a minute
21	* as sixty seconds, an hour as sixty minutes, and a day as twenty four
22	* hours.
23	*
24	* <p>A {@code TimeUnit} is mainly used to inform time-based methods
25	* how a given timing parameter should be interpreted. For example,
26	* the following code will timeout in 50 milliseconds if the {@link
27	* java.util.concurrent.locks.Lock lock} is not available:
28	*
29	* <pre> {@code
30	* Lock lock = ...;
31	* if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...}</pre>
32	*
33	* while this code will timeout in 50 seconds:
34	* <pre> {@code
35	* Lock lock = ...;
36	* if (lock.tryLock(50L, TimeUnit.SECONDS)) ...}</pre>
37	*
38	* Note however, that there is no guarantee that a particular timeout
39	* implementation will be able to notice the passage of time at the
40	* same granularity as the given {@code TimeUnit}.
41	*
42	* @since 1.5
43	* @author Doug Lea
44	*/
45	public enum TimeUnit {
46	/**
47	* Time unit representing one thousandth of a microsecond.
48	*/
49	NANOSECONDS(1L), // (cannot use symbolic scale names here)
50	/**
51	* Time unit representing one thousandth of a millisecond.
52	*/
53	MICROSECONDS(1000L),
54	/**
55	* Time unit representing one thousandth of a second.
56	*/
57	MILLISECONDS(1000L * 1000L),
58	/**
59	* Time unit representing one second.
60	*/
61	SECONDS(1000L * 1000L * 1000L),
62	/**
63	* Time unit representing sixty seconds.
64	* @since 1.6
65	*/
66	MINUTES(1000L * 1000L * 1000L * 60L),
67	/**
68	* Time unit representing sixty minutes.
69	* @since 1.6
70	*/
71	HOURS(1000L * 1000L * 1000L * 60L * 60L),
72	/**
73	* Time unit representing twenty four hours.
74	* @since 1.6
75	*/
76	DAYS(1000L * 1000L * 1000L * 60L * 60L * 24L);
77
78	// Scales as constants
79	private static final long NANO_SCALE = 1L;
80	private static final long MICRO_SCALE = 1000L * NANO_SCALE;
81	private static final long MILLI_SCALE = 1000L * MICRO_SCALE;
82	private static final long SECOND_SCALE = 1000L * MILLI_SCALE;
83	private static final long MINUTE_SCALE = 60L * SECOND_SCALE;
84	private static final long HOUR_SCALE = 60L * MINUTE_SCALE;
85	private static final long DAY_SCALE = 24L * HOUR_SCALE;
86
87	/*
88	* Instances cache conversion ratios and saturation cutoffs for
89	* the units up through SECONDS. Other cases compute them, in
90	* method cvt.
91	*/
92
93	private final long scale;
94	private final long maxNanos;
95	private final long maxMicros;
96	private final long maxMillis;
97	private final long maxSecs;
98	private final long microRatio;
99	private final int milliRatio; // fits in 32 bits
100	private final int secRatio; // fits in 32 bits
101
102	TimeUnit(long s) {
103	this.scale = s;
104	this.maxNanos = Long.MAX_VALUE / s;
105	long ur = (s >= MICRO_SCALE) ? (s / MICRO_SCALE) : (MICRO_SCALE / s);
106	this.microRatio = ur;
107	this.maxMicros = Long.MAX_VALUE / ur;
108	long mr = (scale >= MILLI_SCALE) ? (s / MILLI_SCALE) : (MILLI_SCALE / s);
109	this.milliRatio = (int)mr;
110	this.maxMillis = Long.MAX_VALUE / mr;
111	long sr = (s >= SECOND_SCALE) ? (s / SECOND_SCALE) : (SECOND_SCALE / s);
112	this.secRatio = (int)sr;
113	this.maxSecs = Long.MAX_VALUE / sr;
114	}
115
116	/**
117	* General conversion utility.
118	*
119	* @param d duration
120	* @param dst result scale unit
121	* @param src source scale unit
122	*/
123	private static long cvt(long d, long dst, long src) {
124	long r, m;
125	if (src == dst)
126	return d;
127	else if (src < dst)
128	return d / (dst / src);
129	else if (d > (m = Long.MAX_VALUE / (r = src / dst)))
130	return Long.MAX_VALUE;
131	else if (d < -m)
132	return Long.MIN_VALUE;
133	else
134	return d * r;
135	}
136
137	/**
138	* Converts the given time duration in the given unit to this unit.
139	* Conversions from finer to coarser granularities truncate, so
140	* lose precision. For example, converting {@code 999} milliseconds
141	* to seconds results in {@code 0}. Conversions from coarser to
142	* finer granularities with arguments that would numerically
143	* overflow saturate to {@code Long.MIN_VALUE} if negative or
144	* {@code Long.MAX_VALUE} if positive.
145	*
146	* <p>For example, to convert 10 minutes to milliseconds, use:
147	* {@code TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)}
148	*
149	* @param sourceDuration the time duration in the given {@code sourceUnit}
150	* @param sourceUnit the unit of the {@code sourceDuration} argument
151	* @return the converted duration in this unit,
152	* or {@code Long.MIN_VALUE} if conversion would negatively
153	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
154	*/
155	public long convert(long sourceDuration, TimeUnit sourceUnit) {
156	switch (this) {
157	case NANOSECONDS: return sourceUnit.toNanos(sourceDuration);
158	case MICROSECONDS: return sourceUnit.toMicros(sourceDuration);
159	case MILLISECONDS: return sourceUnit.toMillis(sourceDuration);
160	case SECONDS: return sourceUnit.toSeconds(sourceDuration);
161	default: return cvt(sourceDuration, scale, sourceUnit.scale);
162	}
163	}
164
165	/**
166	* Equivalent to
167	* {@link #convert(long, TimeUnit) NANOSECONDS.convert(duration, this)}.
168	* @param duration the duration
169	* @return the converted duration,
170	* or {@code Long.MIN_VALUE} if conversion would negatively
171	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
172	*/
173	public long toNanos(long duration) {
174	long s, m;
175	if ((s = scale) == NANO_SCALE)
176	return duration;
177	else if (duration > (m = maxNanos))
178	return Long.MAX_VALUE;
179	else if (duration < -m)
180	return Long.MIN_VALUE;
181	else
182	return duration * s;
183	}
184
185	/**
186	* Equivalent to
187	* {@link #convert(long, TimeUnit) MICROSECONDS.convert(duration, this)}.
188	* @param duration the duration
189	* @return the converted duration,
190	* or {@code Long.MIN_VALUE} if conversion would negatively
191	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
192	*/
193	public long toMicros(long duration) {
194	long s, m;
195	if ((s = scale) == MICRO_SCALE)
196	return duration;
197	else if (s < MICRO_SCALE)
198	return duration / microRatio;
199	else if (duration > (m = maxMicros))
200	return Long.MAX_VALUE;
201	else if (duration < -m)
202	return Long.MIN_VALUE;
203	else
204	return duration * microRatio;
205	}
206
207	/**
208	* Equivalent to
209	* {@link #convert(long, TimeUnit) MILLISECONDS.convert(duration, this)}.
210	* @param duration the duration
211	* @return the converted duration,
212	* or {@code Long.MIN_VALUE} if conversion would negatively
213	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
214	*/
215	public long toMillis(long duration) {
216	long s, m;
217	if ((s = scale) == MILLI_SCALE)
218	return duration;
219	else if (s < MILLI_SCALE)
220	return duration / milliRatio;
221	else if (duration > (m = maxMillis))
222	return Long.MAX_VALUE;
223	else if (duration < -m)
224	return Long.MIN_VALUE;
225	else
226	return duration * milliRatio;
227	}
228
229	/**
230	* Equivalent to
231	* {@link #convert(long, TimeUnit) SECONDS.convert(duration, this)}.
232	* @param duration the duration
233	* @return the converted duration,
234	* or {@code Long.MIN_VALUE} if conversion would negatively
235	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
236	*/
237	public long toSeconds(long duration) {
238	long s, m;
239	if ((s = scale) == SECOND_SCALE)
240	return duration;
241	else if (s < SECOND_SCALE)
242	return duration / secRatio;
243	else if (duration > (m = maxSecs))
244	return Long.MAX_VALUE;
245	else if (duration < -m)
246	return Long.MIN_VALUE;
247	else
248	return duration * secRatio;
249	}
250
251	/**
252	* Equivalent to
253	* {@link #convert(long, TimeUnit) MINUTES.convert(duration, this)}.
254	* @param duration the duration
255	* @return the converted duration,
256	* or {@code Long.MIN_VALUE} if conversion would negatively
257	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
258	* @since 1.6
259	*/
260	public long toMinutes(long duration) {
261	return cvt(duration, MINUTE_SCALE, scale);
262	}
263
264	/**
265	* Equivalent to
266	* {@link #convert(long, TimeUnit) HOURS.convert(duration, this)}.
267	* @param duration the duration
268	* @return the converted duration,
269	* or {@code Long.MIN_VALUE} if conversion would negatively
270	* overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
271	* @since 1.6
272	*/
273	public long toHours(long duration) {
274	return cvt(duration, HOUR_SCALE, scale);
275	}
276
277	/**
278	* Equivalent to
279	* {@link #convert(long, TimeUnit) DAYS.convert(duration, this)}.
280	* @param duration the duration
281	* @return the converted duration
282	* @since 1.6
283	*/
284	public long toDays(long duration) {
285	return cvt(duration, DAY_SCALE, scale);
286	}
287
288	/**
289	* Utility to compute the excess-nanosecond argument to wait,
290	* sleep, join.
291	* @param d the duration
292	* @param m the number of milliseconds
293	* @return the number of nanoseconds
294	*/
295	private int excessNanos(long d, long m) {
296	long s;
297	if ((s = scale) == NANO_SCALE)
298	return (int)(d - (m * MILLI_SCALE));
299	else if (s == MICRO_SCALE)
300	return (int)((d * 1000L) - (m * MILLI_SCALE));
301	else
302	return 0;
303	}
304
305	/**
306	* Performs a timed {@link Object#wait(long, int) Object.wait}
307	* using this time unit.
308	* This is a convenience method that converts timeout arguments
309	* into the form required by the {@code Object.wait} method.
310	*
311	* <p>For example, you could implement a blocking {@code poll}
312	* method (see {@link BlockingQueue#poll BlockingQueue.poll})
313	* using:
314	*
315	* <pre> {@code
316	* public synchronized Object poll(long timeout, TimeUnit unit)
317	* throws InterruptedException {
318	* while (empty) {
319	* unit.timedWait(this, timeout);
320	* ...
321	* }
322	* }}</pre>
323	*
324	* @param obj the object to wait on
325	* @param timeout the maximum time to wait. If less than
326	* or equal to zero, do not wait at all.
327	* @throws InterruptedException if interrupted while waiting
328	*/
329	public void timedWait(Object obj, long timeout)
330	throws InterruptedException {
331	if (timeout > 0) {
332	long ms = toMillis(timeout);
333	int ns = excessNanos(timeout, ms);
334	obj.wait(ms, ns);
335	}
336	}
337
338	/**
339	* Performs a timed {@link Thread#join(long, int) Thread.join}
340	* using this time unit.
341	* This is a convenience method that converts time arguments into the
342	* form required by the {@code Thread.join} method.
343	*
344	* @param thread the thread to wait for
345	* @param timeout the maximum time to wait. If less than
346	* or equal to zero, do not wait at all.
347	* @throws InterruptedException if interrupted while waiting
348	*/
349	public void timedJoin(Thread thread, long timeout)
350	throws InterruptedException {
351	if (timeout > 0) {
352	long ms = toMillis(timeout);
353	int ns = excessNanos(timeout, ms);
354	thread.join(ms, ns);
355	}
356	}
357
358	/**
359	* Performs a {@link Thread#sleep(long, int) Thread.sleep} using
360	* this time unit.
361	* This is a convenience method that converts time arguments into the
362	* form required by the {@code Thread.sleep} method.
363	*
364	* @param timeout the minimum time to sleep. If less than
365	* or equal to zero, do not sleep at all.
366	* @throws InterruptedException if interrupted while sleeping
367	*/
368	public void sleep(long timeout) throws InterruptedException {
369	if (timeout > 0) {
370	long ms = toMillis(timeout);
371	int ns = excessNanos(timeout, ms);
372	Thread.sleep(ms, ns);
373	}
374	}
375
376	/**
377	* Converts this {@code TimeUnit} to the equivalent {@code ChronoUnit}.
378	*
379	* @return the converted equivalent ChronoUnit
380	* @since 9
381	*/
382	public ChronoUnit toChronoUnit() {
383	switch (this) {
384	case NANOSECONDS: return ChronoUnit.NANOS;
385	case MICROSECONDS: return ChronoUnit.MICROS;
386	case MILLISECONDS: return ChronoUnit.MILLIS;
387	case SECONDS: return ChronoUnit.SECONDS;
388	case MINUTES: return ChronoUnit.MINUTES;
389	case HOURS: return ChronoUnit.HOURS;
390	case DAYS: return ChronoUnit.DAYS;
391	default: throw new AssertionError();
392	}
393	}
394
395	/**
396	* Converts a {@code ChronoUnit} to the equivalent {@code TimeUnit}.
397	*
398	* @param chronoUnit the ChronoUnit to convert
399	* @return the converted equivalent TimeUnit
400	* @throws IllegalArgumentException if {@code chronoUnit} has no
401	* equivalent TimeUnit
402	* @throws NullPointerException if {@code chronoUnit} is null
403	* @since 9
404	*/
405	public static TimeUnit of(ChronoUnit chronoUnit) {
406	switch (Objects.requireNonNull(chronoUnit, "chronoUnit")) {
407	case NANOS: return TimeUnit.NANOSECONDS;
408	case MICROS: return TimeUnit.MICROSECONDS;
409	case MILLIS: return TimeUnit.MILLISECONDS;
410	case SECONDS: return TimeUnit.SECONDS;
411	case MINUTES: return TimeUnit.MINUTES;
412	case HOURS: return TimeUnit.HOURS;
413	case DAYS: return TimeUnit.DAYS;
414	default:
415	throw new IllegalArgumentException(
416	"No TimeUnit equivalent for " + chronoUnit);
417	}
418	}
419
420	}