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
7package java.util.concurrent;
8
9import java.util.Objects;
10
11// BEGIN android-note
12// removed java 9 ChronoUnit related code
13// END android-note
14
15/**
16 * A {@code TimeUnit} represents time durations at a given unit of
17 * granularity and provides utility methods to convert across units,
18 * and to perform timing and delay operations in these units.  A
19 * {@code TimeUnit} does not maintain time information, but only
20 * helps organize and use time representations that may be maintained
21 * separately across various contexts.  A nanosecond is defined as one
22 * thousandth of a microsecond, a microsecond as one thousandth of a
23 * millisecond, a millisecond as one thousandth of a second, a minute
24 * as sixty seconds, an hour as sixty minutes, and a day as twenty four
25 * hours.
26 *
27 * <p>A {@code TimeUnit} is mainly used to inform time-based methods
28 * how a given timing parameter should be interpreted. For example,
29 * the following code will timeout in 50 milliseconds if the {@link
30 * java.util.concurrent.locks.Lock lock} is not available:
31 *
32 * <pre> {@code
33 * Lock lock = ...;
34 * if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...}</pre>
35 *
36 * while this code will timeout in 50 seconds:
37 * <pre> {@code
38 * Lock lock = ...;
39 * if (lock.tryLock(50L, TimeUnit.SECONDS)) ...}</pre>
40 *
41 * Note however, that there is no guarantee that a particular timeout
42 * implementation will be able to notice the passage of time at the
43 * same granularity as the given {@code TimeUnit}.
44 *
45 * @since 1.5
46 * @author Doug Lea
47 */
48public enum TimeUnit {
49    /**
50     * Time unit representing one thousandth of a microsecond.
51     */
52    NANOSECONDS {
53        public long toNanos(long d)   { return d; }
54        public long toMicros(long d)  { return d/(C1/C0); }
55        public long toMillis(long d)  { return d/(C2/C0); }
56        public long toSeconds(long d) { return d/(C3/C0); }
57        public long toMinutes(long d) { return d/(C4/C0); }
58        public long toHours(long d)   { return d/(C5/C0); }
59        public long toDays(long d)    { return d/(C6/C0); }
60        public long convert(long d, TimeUnit u) { return u.toNanos(d); }
61        int excessNanos(long d, long m) { return (int)(d - (m*C2)); }
62    },
63
64    /**
65     * Time unit representing one thousandth of a millisecond.
66     */
67    MICROSECONDS {
68        public long toNanos(long d)   { return x(d, C1/C0, MAX/(C1/C0)); }
69        public long toMicros(long d)  { return d; }
70        public long toMillis(long d)  { return d/(C2/C1); }
71        public long toSeconds(long d) { return d/(C3/C1); }
72        public long toMinutes(long d) { return d/(C4/C1); }
73        public long toHours(long d)   { return d/(C5/C1); }
74        public long toDays(long d)    { return d/(C6/C1); }
75        public long convert(long d, TimeUnit u) { return u.toMicros(d); }
76        int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }
77    },
78
79    /**
80     * Time unit representing one thousandth of a second.
81     */
82    MILLISECONDS {
83        public long toNanos(long d)   { return x(d, C2/C0, MAX/(C2/C0)); }
84        public long toMicros(long d)  { return x(d, C2/C1, MAX/(C2/C1)); }
85        public long toMillis(long d)  { return d; }
86        public long toSeconds(long d) { return d/(C3/C2); }
87        public long toMinutes(long d) { return d/(C4/C2); }
88        public long toHours(long d)   { return d/(C5/C2); }
89        public long toDays(long d)    { return d/(C6/C2); }
90        public long convert(long d, TimeUnit u) { return u.toMillis(d); }
91        int excessNanos(long d, long m) { return 0; }
92    },
93
94    /**
95     * Time unit representing one second.
96     */
97    SECONDS {
98        public long toNanos(long d)   { return x(d, C3/C0, MAX/(C3/C0)); }
99        public long toMicros(long d)  { return x(d, C3/C1, MAX/(C3/C1)); }
100        public long toMillis(long d)  { return x(d, C3/C2, MAX/(C3/C2)); }
101        public long toSeconds(long d) { return d; }
102        public long toMinutes(long d) { return d/(C4/C3); }
103        public long toHours(long d)   { return d/(C5/C3); }
104        public long toDays(long d)    { return d/(C6/C3); }
105        public long convert(long d, TimeUnit u) { return u.toSeconds(d); }
106        int excessNanos(long d, long m) { return 0; }
107    },
108
109    /**
110     * Time unit representing sixty seconds.
111     * @since 1.6
112     */
113    MINUTES {
114        public long toNanos(long d)   { return x(d, C4/C0, MAX/(C4/C0)); }
115        public long toMicros(long d)  { return x(d, C4/C1, MAX/(C4/C1)); }
116        public long toMillis(long d)  { return x(d, C4/C2, MAX/(C4/C2)); }
117        public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }
118        public long toMinutes(long d) { return d; }
119        public long toHours(long d)   { return d/(C5/C4); }
120        public long toDays(long d)    { return d/(C6/C4); }
121        public long convert(long d, TimeUnit u) { return u.toMinutes(d); }
122        int excessNanos(long d, long m) { return 0; }
123    },
124
125    /**
126     * Time unit representing sixty minutes.
127     * @since 1.6
128     */
129    HOURS {
130        public long toNanos(long d)   { return x(d, C5/C0, MAX/(C5/C0)); }
131        public long toMicros(long d)  { return x(d, C5/C1, MAX/(C5/C1)); }
132        public long toMillis(long d)  { return x(d, C5/C2, MAX/(C5/C2)); }
133        public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }
134        public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }
135        public long toHours(long d)   { return d; }
136        public long toDays(long d)    { return d/(C6/C5); }
137        public long convert(long d, TimeUnit u) { return u.toHours(d); }
138        int excessNanos(long d, long m) { return 0; }
139    },
140
141    /**
142     * Time unit representing twenty four hours.
143     * @since 1.6
144     */
145    DAYS {
146        public long toNanos(long d)   { return x(d, C6/C0, MAX/(C6/C0)); }
147        public long toMicros(long d)  { return x(d, C6/C1, MAX/(C6/C1)); }
148        public long toMillis(long d)  { return x(d, C6/C2, MAX/(C6/C2)); }
149        public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }
150        public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }
151        public long toHours(long d)   { return x(d, C6/C5, MAX/(C6/C5)); }
152        public long toDays(long d)    { return d; }
153        public long convert(long d, TimeUnit u) { return u.toDays(d); }
154        int excessNanos(long d, long m) { return 0; }
155    };
156
157    // Handy constants for conversion methods
158    static final long C0 = 1L;
159    static final long C1 = C0 * 1000L;
160    static final long C2 = C1 * 1000L;
161    static final long C3 = C2 * 1000L;
162    static final long C4 = C3 * 60L;
163    static final long C5 = C4 * 60L;
164    static final long C6 = C5 * 24L;
165
166    static final long MAX = Long.MAX_VALUE;
167
168    /**
169     * Scale d by m, checking for overflow.
170     * This has a short name to make above code more readable.
171     */
172    static long x(long d, long m, long over) {
173        if (d > +over) return Long.MAX_VALUE;
174        if (d < -over) return Long.MIN_VALUE;
175        return d * m;
176    }
177
178    // To maintain full signature compatibility with 1.5, and to improve the
179    // clarity of the generated javadoc (see 6287639: Abstract methods in
180    // enum classes should not be listed as abstract), method convert
181    // etc. are not declared abstract but otherwise act as abstract methods.
182
183    /**
184     * Converts the given time duration in the given unit to this unit.
185     * Conversions from finer to coarser granularities truncate, so
186     * lose precision. For example, converting {@code 999} milliseconds
187     * to seconds results in {@code 0}. Conversions from coarser to
188     * finer granularities with arguments that would numerically
189     * overflow saturate to {@code Long.MIN_VALUE} if negative or
190     * {@code Long.MAX_VALUE} if positive.
191     *
192     * <p>For example, to convert 10 minutes to milliseconds, use:
193     * {@code TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)}
194     *
195     * @param sourceDuration the time duration in the given {@code sourceUnit}
196     * @param sourceUnit the unit of the {@code sourceDuration} argument
197     * @return the converted duration in this unit,
198     * or {@code Long.MIN_VALUE} if conversion would negatively
199     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
200     */
201    public long convert(long sourceDuration, TimeUnit sourceUnit) {
202        throw new AbstractMethodError();
203    }
204
205    /**
206     * Equivalent to
207     * {@link #convert(long, TimeUnit) NANOSECONDS.convert(duration, this)}.
208     * @param duration the duration
209     * @return the converted duration,
210     * or {@code Long.MIN_VALUE} if conversion would negatively
211     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
212     */
213    public long toNanos(long duration) {
214        throw new AbstractMethodError();
215    }
216
217    /**
218     * Equivalent to
219     * {@link #convert(long, TimeUnit) MICROSECONDS.convert(duration, this)}.
220     * @param duration the duration
221     * @return the converted duration,
222     * or {@code Long.MIN_VALUE} if conversion would negatively
223     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
224     */
225    public long toMicros(long duration) {
226        throw new AbstractMethodError();
227    }
228
229    /**
230     * Equivalent to
231     * {@link #convert(long, TimeUnit) MILLISECONDS.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 toMillis(long duration) {
238        throw new AbstractMethodError();
239    }
240
241    /**
242     * Equivalent to
243     * {@link #convert(long, TimeUnit) SECONDS.convert(duration, this)}.
244     * @param duration the duration
245     * @return the converted duration,
246     * or {@code Long.MIN_VALUE} if conversion would negatively
247     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
248     */
249    public long toSeconds(long duration) {
250        throw new AbstractMethodError();
251    }
252
253    /**
254     * Equivalent to
255     * {@link #convert(long, TimeUnit) MINUTES.convert(duration, this)}.
256     * @param duration the duration
257     * @return the converted duration,
258     * or {@code Long.MIN_VALUE} if conversion would negatively
259     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
260     * @since 1.6
261     */
262    public long toMinutes(long duration) {
263        throw new AbstractMethodError();
264    }
265
266    /**
267     * Equivalent to
268     * {@link #convert(long, TimeUnit) HOURS.convert(duration, this)}.
269     * @param duration the duration
270     * @return the converted duration,
271     * or {@code Long.MIN_VALUE} if conversion would negatively
272     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
273     * @since 1.6
274     */
275    public long toHours(long duration) {
276        throw new AbstractMethodError();
277    }
278
279    /**
280     * Equivalent to
281     * {@link #convert(long, TimeUnit) DAYS.convert(duration, this)}.
282     * @param duration the duration
283     * @return the converted duration
284     * @since 1.6
285     */
286    public long toDays(long duration) {
287        throw new AbstractMethodError();
288    }
289
290    /**
291     * Utility to compute the excess-nanosecond argument to wait,
292     * sleep, join.
293     * @param d the duration
294     * @param m the number of milliseconds
295     * @return the number of nanoseconds
296     */
297    abstract int excessNanos(long d, long m);
298
299    /**
300     * Performs a timed {@link Object#wait(long, int) Object.wait}
301     * using this time unit.
302     * This is a convenience method that converts timeout arguments
303     * into the form required by the {@code Object.wait} method.
304     *
305     * <p>For example, you could implement a blocking {@code poll}
306     * method (see {@link BlockingQueue#poll BlockingQueue.poll})
307     * using:
308     *
309     * <pre> {@code
310     * public synchronized Object poll(long timeout, TimeUnit unit)
311     *     throws InterruptedException {
312     *   while (empty) {
313     *     unit.timedWait(this, timeout);
314     *     ...
315     *   }
316     * }}</pre>
317     *
318     * @param obj the object to wait on
319     * @param timeout the maximum time to wait. If less than
320     * or equal to zero, do not wait at all.
321     * @throws InterruptedException if interrupted while waiting
322     */
323    public void timedWait(Object obj, long timeout)
324            throws InterruptedException {
325        if (timeout > 0) {
326            long ms = toMillis(timeout);
327            int ns = excessNanos(timeout, ms);
328            obj.wait(ms, ns);
329        }
330    }
331
332    /**
333     * Performs a timed {@link Thread#join(long, int) Thread.join}
334     * using this time unit.
335     * This is a convenience method that converts time arguments into the
336     * form required by the {@code Thread.join} method.
337     *
338     * @param thread the thread to wait for
339     * @param timeout the maximum time to wait. If less than
340     * or equal to zero, do not wait at all.
341     * @throws InterruptedException if interrupted while waiting
342     */
343    public void timedJoin(Thread thread, long timeout)
344            throws InterruptedException {
345        if (timeout > 0) {
346            long ms = toMillis(timeout);
347            int ns = excessNanos(timeout, ms);
348            thread.join(ms, ns);
349        }
350    }
351
352    /**
353     * Performs a {@link Thread#sleep(long, int) Thread.sleep} using
354     * this time unit.
355     * This is a convenience method that converts time arguments into the
356     * form required by the {@code Thread.sleep} method.
357     *
358     * @param timeout the minimum time to sleep. If less than
359     * or equal to zero, do not sleep at all.
360     * @throws InterruptedException if interrupted while sleeping
361     */
362    public void sleep(long timeout) throws InterruptedException {
363        if (timeout > 0) {
364            long ms = toMillis(timeout);
365            int ns = excessNanos(timeout, ms);
366            Thread.sleep(ms, ns);
367        }
368    }
369}
370