| TimeUnit.java |
1 /*
2 * %W% %E%
3 *
4 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
5 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6 */
7
8 package java.util.concurrent;
9
10 /**
11 * A <tt>TimeUnit</tt> represents time durations at a given unit of
12 * granularity and provides utility methods to convert across units,
13 * and to perform timing and delay operations in these units. A
14 * <tt>TimeUnit</tt> does not maintain time information, but only
15 * helps organize and use time representations that may be maintained
16 * separately across various contexts. A nanosecond is defined as one
17 * thousandth of a microsecond, a microsecond as one thousandth of a
18 * millisecond, a millisecond as one thousandth of a second, a minute
19 * as sixty seconds, an hour as sixty minutes, and a day as twenty four
20 * hours.
21 *
22 * <p>A <tt>TimeUnit</tt> is mainly used to inform time-based methods
23 * how a given timing parameter should be interpreted. For example,
24 * the following code will timeout in 50 milliseconds if the {@link
25 * java.util.concurrent.locks.Lock lock} is not available:
26 *
27 * <pre> Lock lock = ...;
28 * if ( lock.tryLock(50L, TimeUnit.MILLISECONDS) ) ...
29 * </pre>
30 * while this code will timeout in 50 seconds:
31 * <pre>
32 * Lock lock = ...;
33 * if ( lock.tryLock(50L, TimeUnit.SECONDS) ) ...
34 * </pre>
35 *
36 * Note however, that there is no guarantee that a particular timeout
37 * implementation will be able to notice the passage of time at the
38 * same granularity as the given <tt>TimeUnit</tt>.
39 *
40 * @since 1.5
41 * @author Doug Lea
42 */
43 public enum TimeUnit {
44 NANOSECONDS {
45 public long toNanos(long d) { return d; }
46 public long toMicros(long d) { return d/(C1/C0); }
47 public long toMillis(long d) { return d/(C2/C0); }
48 public long toSeconds(long d) { return d/(C3/C0); }
49 public long toMinutes(long d) { return d/(C4/C0); }
50 public long toHours(long d) { return d/(C5/C0); }
51 public long toDays(long d) { return d/(C6/C0); }
52 public long convert(long d, TimeUnit u) { return u.toNanos(d); }
53 int excessNanos(long d, long m) { return (int)(d - (m*C2)); }
54 },
55 MICROSECONDS {
56 public long toNanos(long d) { return x(d, C1/C0, MAX/(C1/C0)); }
57 public long toMicros(long d) { return d; }
58 public long toMillis(long d) { return d/(C2/C1); }
59 public long toSeconds(long d) { return d/(C3/C1); }
60 public long toMinutes(long d) { return d/(C4/C1); }
61 public long toHours(long d) { return d/(C5/C1); }
62 public long toDays(long d) { return d/(C6/C1); }
63 public long convert(long d, TimeUnit u) { return u.toMicros(d); }
64 int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }
65 },
66 MILLISECONDS {
67 public long toNanos(long d) { return x(d, C2/C0, MAX/(C2/C0)); }
68 public long toMicros(long d) { return x(d, C2/C1, MAX/(C2/C1)); }
69 public long toMillis(long d) { return d; }
70 public long toSeconds(long d) { return d/(C3/C2); }
71 public long toMinutes(long d) { return d/(C4/C2); }
72 public long toHours(long d) { return d/(C5/C2); }
73 public long toDays(long d) { return d/(C6/C2); }
74 public long convert(long d, TimeUnit u) { return u.toMillis(d); }
75 int excessNanos(long d, long m) { return 0; }
76 },
77 SECONDS {
78 public long toNanos(long d) { return x(d, C3/C0, MAX/(C3/C0)); }
79 public long toMicros(long d) { return x(d, C3/C1, MAX/(C3/C1)); }
80 public long toMillis(long d) { return x(d, C3/C2, MAX/(C3/C2)); }
81 public long toSeconds(long d) { return d; }
82 public long toMinutes(long d) { return d/(C4/C3); }
83 public long toHours(long d) { return d/(C5/C3); }
84 public long toDays(long d) { return d/(C6/C3); }
85 public long convert(long d, TimeUnit u) { return u.toSeconds(d); }
86 int excessNanos(long d, long m) { return 0; }
87 },
88 MINUTES {
89 public long toNanos(long d) { return x(d, C4/C0, MAX/(C4/C0)); }
90 public long toMicros(long d) { return x(d, C4/C1, MAX/(C4/C1)); }
91 public long toMillis(long d) { return x(d, C4/C2, MAX/(C4/C2)); }
92 public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }
93 public long toMinutes(long d) { return d; }
94 public long toHours(long d) { return d/(C5/C4); }
95 public long toDays(long d) { return d/(C6/C4); }
96 public long convert(long d, TimeUnit u) { return u.toMinutes(d); }
97 int excessNanos(long d, long m) { return 0; }
98 },
99 HOURS {
100 public long toNanos(long d) { return x(d, C5/C0, MAX/(C5/C0)); }
101 public long toMicros(long d) { return x(d, C5/C1, MAX/(C5/C1)); }
102 public long toMillis(long d) { return x(d, C5/C2, MAX/(C5/C2)); }
103 public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }
104 public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }
105 public long toHours(long d) { return d; }
106 public long toDays(long d) { return d/(C6/C5); }
107 public long convert(long d, TimeUnit u) { return u.toHours(d); }
108 int excessNanos(long d, long m) { return 0; }
109 },
110 DAYS {
111 public long toNanos(long d) { return x(d, C6/C0, MAX/(C6/C0)); }
112 public long toMicros(long d) { return x(d, C6/C1, MAX/(C6/C1)); }
113 public long toMillis(long d) { return x(d, C6/C2, MAX/(C6/C2)); }
114 public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }
115 public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }
116 public long toHours(long d) { return x(d, C6/C5, MAX/(C6/C5)); }
117 public long toDays(long d) { return d; }
118 public long convert(long d, TimeUnit u) { return u.toDays(d); }
119 int excessNanos(long d, long m) { return 0; }
120 };
121
122 // Handy constants for conversion methods
123 static final long C0 = 1L;
124 static final long C1 = C0 * 1000L;
125 static final long C2 = C1 * 1000L;
126 static final long C3 = C2 * 1000L;
127 static final long C4 = C3 * 60L;
128 static final long C5 = C4 * 60L;
129 static final long C6 = C5 * 24L;
130
131 static final long MAX = Long.MAX_VALUE;
132
133 /**
134 * Scale d by m, checking for overflow.
135 * This has a short name to make above code more readable.
136 */
137 static long x(long d, long m, long over) {
138 if (d > over) return Long.MAX_VALUE;
139 if (d < -over) return Long.MIN_VALUE;
140 return d * m;
141 }
142
143 // To maintain full signature compatibility with 1.5, and to improve the
144 // clarity of the generated javadoc (see 6287639: Abstract methods in
145 // enum classes should not be listed as abstract), method convert
146 // etc. are not declared abstract but otherwise act as abstract methods.
147
148 /**
149 * Convert the given time duration in the given unit to this
150 * unit. Conversions from finer to coarser granularities
151 * truncate, so lose precision. For example converting
152 * <tt>999</tt> milliseconds to seconds results in
153 * <tt>0</tt>. Conversions from coarser to finer granularities
154 * with arguments that would numerically overflow saturate to
155 * <tt>Long.MIN_VALUE</tt> if negative or <tt>Long.MAX_VALUE</tt>
156 * if positive.
157 *
158 * <p>For example, to convert 10 minutes to milliseconds, use:
159 * <tt>TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)</tt>
160 *
161 * @param sourceDuration the time duration in the given <tt>sourceUnit</tt>
162 * @param sourceUnit the unit of the <tt>sourceDuration</tt> argument
163 * @return the converted duration in this unit,
164 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
165 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
166 */
167 public long convert(long sourceDuration, TimeUnit sourceUnit) {
168 throw new AbstractMethodError();
169 }
170
171 /**
172 * Equivalent to <tt>NANOSECONDS.convert(duration, this)</tt>.
173 * @param duration the duration
174 * @return the converted duration,
175 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
176 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
177 * @see #convert
178 */
179 public long toNanos(long duration) {
180 throw new AbstractMethodError();
181 }
182
183 /**
184 * Equivalent to <tt>MICROSECONDS.convert(duration, this)</tt>.
185 * @param duration the duration
186 * @return the converted duration,
187 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
188 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
189 * @see #convert
190 */
191 public long toMicros(long duration) {
192 throw new AbstractMethodError();
193 }
194
195 /**
196 * Equivalent to <tt>MILLISECONDS.convert(duration, this)</tt>.
197 * @param duration the duration
198 * @return the converted duration,
199 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
200 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
201 * @see #convert
202 */
203 public long toMillis(long duration) {
204 throw new AbstractMethodError();
205 }
206
207 /**
208 * Equivalent to <tt>SECONDS.convert(duration, this)</tt>.
209 * @param duration the duration
210 * @return the converted duration,
211 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
212 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
213 * @see #convert
214 */
215 public long toSeconds(long duration) {
216 throw new AbstractMethodError();
217 }
218
219 /**
220 * Equivalent to <tt>MINUTES.convert(duration, this)</tt>.
221 * @param duration the duration
222 * @return the converted duration,
223 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
224 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
225 * @see #convert
226 * @since 1.6
227 */
228 public long toMinutes(long duration) {
229 throw new AbstractMethodError();
230 }
231
232 /**
233 * Equivalent to <tt>HOURS.convert(duration, this)</tt>.
234 * @param duration the duration
235 * @return the converted duration,
236 * or <tt>Long.MIN_VALUE</tt> if conversion would negatively
237 * overflow, or <tt>Long.MAX_VALUE</tt> if it would positively overflow.
238 * @see #convert
239 * @since 1.6
240 */
241 public long toHours(long duration) {
242 throw new AbstractMethodError();
243 }
244
245 /**
246 * Equivalent to <tt>DAYS.convert(duration, this)</tt>.
247 * @param duration the duration
248 * @return the converted duration
249 * @see #convert
250 * @since 1.6
251 */
252 public long toDays(long duration) {
253 throw new AbstractMethodError();
254 }
255
256 /**
257 * Utility to compute the excess-nanosecond argument to wait,
258 * sleep, join.
259 * @param d the duration
260 * @param m the number of milliseconds
261 * @return the number of nanoseconds
262 */
263 abstract int excessNanos(long d, long m);
264
265 /**
266 * Performs a timed <tt>Object.wait</tt> using this time unit.
267 * This is a convenience method that converts timeout arguments
268 * into the form required by the <tt>Object.wait</tt> method.
269 *
270 * <p>For example, you could implement a blocking <tt>poll</tt>
271 * method (see {@link BlockingQueue#poll BlockingQueue.poll})
272 * using:
273 *
274 * <pre> public synchronized Object poll(long timeout, TimeUnit unit) throws InterruptedException {
275 * while (empty) {
276 * unit.timedWait(this, timeout);
277 * ...
278 * }
279 * }</pre>
280 *
281 * @param obj the object to wait on
282 * @param timeout the maximum time to wait. If less than
283 * or equal to zero, do not wait at all.
284 * @throws InterruptedException if interrupted while waiting.
285 * @see Object#wait(long, int)
286 */
287 public void timedWait(Object obj, long timeout)
288 throws InterruptedException {
289 if (timeout > 0) {
290 long ms = toMillis(timeout);
291 int ns = excessNanos(timeout, ms);
292 obj.wait(ms, ns);
293 }
294 }
295
296 /**
297 * Performs a timed <tt>Thread.join</tt> using this time unit.
298 * This is a convenience method that converts time arguments into the
299 * form required by the <tt>Thread.join</tt> method.
300 * @param thread the thread to wait for
301 * @param timeout the maximum time to wait. If less than
302 * or equal to zero, do not wait at all.
303 * @throws InterruptedException if interrupted while waiting.
304 * @see Thread#join(long, int)
305 */
306 public void timedJoin(Thread thread, long timeout)
307 throws InterruptedException {
308 if (timeout > 0) {
309 long ms = toMillis(timeout);
310 int ns = excessNanos(timeout, ms);
311 thread.join(ms, ns);
312 }
313 }
314
315 /**
316 * Performs a <tt>Thread.sleep</tt> using this unit.
317 * This is a convenience method that converts time arguments into the
318 * form required by the <tt>Thread.sleep</tt> method.
319 * @param timeout the minimum time to sleep. If less than
320 * or equal to zero, do not sleep at all.
321 * @throws InterruptedException if interrupted while sleeping.
322 * @see Thread#sleep
323 */
324 public void sleep(long timeout) throws InterruptedException {
325 if (timeout > 0) {
326 long ms = toMillis(timeout);
327 int ns = excessNanos(timeout, ms);
328 Thread.sleep(ms, ns);
329 }
330 }
331
332 }
333