1 /*
2 * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 /*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file:
31 *
32 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
33 *
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions are met:
38 *
39 * * Redistributions of source code must retain the above copyright notice,
40 * this list of conditions and the following disclaimer.
41 *
42 * * Redistributions in binary form must reproduce the above copyright notice,
43 * this list of conditions and the following disclaimer in the documentation
44 * and/or other materials provided with the distribution.
45 *
46 * * Neither the name of JSR-310 nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
61 */
62 package java.time;
63
64 import java.io.IOException;
65 import java.io.ObjectInputStream;
66 import static java.time.LocalTime.NANOS_PER_MINUTE;
67 import static java.time.LocalTime.NANOS_PER_SECOND;
68
69 import java.io.Serializable;
70 import java.util.Objects;
71 import java.util.TimeZone;
72 import sun.misc.VM;
73
74 /**
75 * A clock providing access to the current instant, date and time using a time-zone.
76 * <p>
77 * Instances of this class are used to find the current instant, which can be
78 * interpreted using the stored time-zone to find the current date and time.
79 * As such, a clock can be used instead of {@link System#currentTimeMillis()}
80 * and {@link TimeZone#getDefault()}.
81 * <p>
82 * Use of a {@code Clock} is optional. All key date-time classes also have a
83 * {@code now()} factory method that uses the system clock in the default time zone.
84 * The primary purpose of this abstraction is to allow alternate clocks to be
85 * plugged in as and when required. Applications use an object to obtain the
86 * current time rather than a static method. This can simplify testing.
87 * <p>
88 * Best practice for applications is to pass a {@code Clock} into any method
89 * that requires the current instant. A dependency injection framework is one
90 * way to achieve this:
91 * <pre>
92 * public class MyBean {
93 * private Clock clock; // dependency inject
94 * ...
95 * public void process(LocalDate eventDate) {
96 * if (eventDate.isBefore(LocalDate.now(clock)) {
97 * ...
98 * }
99 * }
100 * }
101 * </pre>
102 * This approach allows an alternate clock, such as {@link #fixed(Instant, ZoneId) fixed}
103 * or {@link #offset(Clock, Duration) offset} to be used during testing.
104 * <p>
105 * The {@code system} factory methods provide clocks based on the best available
106 * system clock This may use {@link System#currentTimeMillis()}, or a higher
107 * resolution clock if one is available.
108 *
109 * @implSpec
110 * This abstract class must be implemented with care to ensure other classes operate correctly.
111 * All implementations that can be instantiated must be final, immutable and thread-safe.
112 * <p>
113 * The principal methods are defined to allow the throwing of an exception.
114 * In normal use, no exceptions will be thrown, however one possible implementation would be to
115 * obtain the time from a central time server across the network. Obviously, in this case the
116 * lookup could fail, and so the method is permitted to throw an exception.
117 * <p>
118 * The returned instants from {@code Clock} work on a time-scale that ignores leap seconds,
119 * as described in {@link Instant}. If the implementation wraps a source that provides leap
120 * second information, then a mechanism should be used to "smooth" the leap second.
121 * The Java Time-Scale mandates the use of UTC-SLS, however clock implementations may choose
122 * how accurate they are with the time-scale so long as they document how they work.
123 * Implementations are therefore not required to actually perform the UTC-SLS slew or to
124 * otherwise be aware of leap seconds.
125 * <p>
126 * Implementations should implement {@code Serializable} wherever possible and must
127 * document whether or not they do support serialization.
128 *
129 * @implNote
130 * The clock implementation provided here is based on {@link System#currentTimeMillis()}.
131 * That method provides little to no guarantee about the accuracy of the clock.
132 * Applications requiring a more accurate clock must implement this abstract class
133 * themselves using a different external clock, such as an NTP server.
134 *
135 * @since 1.8
136 */
137 public abstract class Clock {
138
139 /**
140 * Obtains a clock that returns the current instant using the best available
141 * system clock, converting to date and time using the UTC time-zone.
142 * <p>
143 * This clock, rather than {@link #systemDefaultZone()}, should be used when
144 * you need the current instant without the date or time.
145 * <p>
146 * This clock is based on the best available system clock.
147 * This may use {@link System#currentTimeMillis()}, or a higher resolution
148 * clock if one is available.
149 * <p>
150 * Conversion from instant to date or time uses the {@linkplain ZoneOffset#UTC UTC time-zone}.
151 * <p>
152 * The returned implementation is immutable, thread-safe and {@code Serializable}.
153 * It is equivalent to {@code system(ZoneOffset.UTC)}.
154 *
155 * @return a clock that uses the best available system clock in the UTC zone, not null
156 */
157 public static Clock systemUTC() {
158 return SystemClock.UTC;
159 }
160
161 /**
162 * Obtains a clock that returns the current instant using the best available
163 * system clock, converting to date and time using the default time-zone.
164 * <p>
165 * This clock is based on the best available system clock.
166 * This may use {@link System#currentTimeMillis()}, or a higher resolution
167 * clock if one is available.
168 * <p>
169 * Using this method hard codes a dependency to the default time-zone into your application.
170 * It is recommended to avoid this and use a specific time-zone whenever possible.
171 * The {@link #systemUTC() UTC clock} should be used when you need the current instant
172 * without the date or time.
173 * <p>
174 * The returned implementation is immutable, thread-safe and {@code Serializable}.
175 * It is equivalent to {@code system(ZoneId.systemDefault())}.
176 *
177 * @return a clock that uses the best available system clock in the default zone, not null
178 * @see ZoneId#systemDefault()
179 */
180 public static Clock systemDefaultZone() {
181 return new SystemClock(ZoneId.systemDefault());
182 }
183
184 /**
185 * Obtains a clock that returns the current instant using best available
186 * system clock.
187 * <p>
188 * This clock is based on the best available system clock.
189 * This may use {@link System#currentTimeMillis()}, or a higher resolution
190 * clock if one is available.
191 * <p>
192 * Conversion from instant to date or time uses the specified time-zone.
193 * <p>
194 * The returned implementation is immutable, thread-safe and {@code Serializable}.
195 *
196 * @param zone the time-zone to use to convert the instant to date-time, not null
197 * @return a clock that uses the best available system clock in the specified zone, not null
198 */
199 public static Clock system(ZoneId zone) {
200 Objects.requireNonNull(zone, "zone");
201 if (zone == ZoneOffset.UTC) {
202 return SystemClock.UTC;
203 }
204 return new SystemClock(zone);
205 }
206
207 //-------------------------------------------------------------------------
208 /**
209 * Obtains a clock that returns the current instant ticking in whole seconds
210 * using best available system clock.
211 * <p>
212 * This clock will always have the nano-of-second field set to zero.
213 * This ensures that the visible time ticks in whole seconds.
214 * The underlying clock is the best available system clock, equivalent to
215 * using {@link #system(ZoneId)}.
216 * <p>
217 * Implementations may use a caching strategy for performance reasons.
218 * As such, it is possible that the start of the second observed via this
219 * clock will be later than that observed directly via the underlying clock.
220 * <p>
221 * The returned implementation is immutable, thread-safe and {@code Serializable}.
222 * It is equivalent to {@code tick(system(zone), Duration.ofSeconds(1))}.
223 *
224 * @param zone the time-zone to use to convert the instant to date-time, not null
225 * @return a clock that ticks in whole seconds using the specified zone, not null
226 */
227 public static Clock tickSeconds(ZoneId zone) {
228 return new TickClock(system(zone), NANOS_PER_SECOND);
229 }
230
231 /**
232 * Obtains a clock that returns the current instant ticking in whole minutes
233 * using best available system clock.
234 * <p>
235 * This clock will always have the nano-of-second and second-of-minute fields set to zero.
236 * This ensures that the visible time ticks in whole minutes.
237 * The underlying clock is the best available system clock, equivalent to
238 * using {@link #system(ZoneId)}.
239 * <p>
240 * Implementations may use a caching strategy for performance reasons.
241 * As such, it is possible that the start of the minute observed via this
242 * clock will be later than that observed directly via the underlying clock.
243 * <p>
244 * The returned implementation is immutable, thread-safe and {@code Serializable}.
245 * It is equivalent to {@code tick(system(zone), Duration.ofMinutes(1))}.
246 *
247 * @param zone the time-zone to use to convert the instant to date-time, not null
248 * @return a clock that ticks in whole minutes using the specified zone, not null
249 */
250 public static Clock tickMinutes(ZoneId zone) {
251 return new TickClock(system(zone), NANOS_PER_MINUTE);
252 }
253
254 /**
255 * Obtains a clock that returns instants from the specified clock truncated
256 * to the nearest occurrence of the specified duration.
257 * <p>
258 * This clock will only tick as per the specified duration. Thus, if the duration
259 * is half a second, the clock will return instants truncated to the half second.
260 * <p>
261 * The tick duration must be positive. If it has a part smaller than a whole
262 * millisecond, then the whole duration must divide into one second without
263 * leaving a remainder. All normal tick durations will match these criteria,
264 * including any multiple of hours, minutes, seconds and milliseconds, and
265 * sensible nanosecond durations, such as 20ns, 250,000ns and 500,000ns.
266 * <p>
267 * A duration of zero or one nanosecond would have no truncation effect.
268 * Passing one of these will return the underlying clock.
269 * <p>
270 * Implementations may use a caching strategy for performance reasons.
271 * As such, it is possible that the start of the requested duration observed
272 * via this clock will be later than that observed directly via the underlying clock.
273 * <p>
274 * The returned implementation is immutable, thread-safe and {@code Serializable}
275 * providing that the base clock is.
276 *
277 * @param baseClock the base clock to base the ticking clock on, not null
278 * @param tickDuration the duration of each visible tick, not negative, not null
279 * @return a clock that ticks in whole units of the duration, not null
280 * @throws IllegalArgumentException if the duration is negative, or has a
281 * part smaller than a whole millisecond such that the whole duration is not
282 * divisible into one second
283 * @throws ArithmeticException if the duration is too large to be represented as nanos
284 */
285 public static Clock tick(Clock baseClock, Duration tickDuration) {
286 Objects.requireNonNull(baseClock, "baseClock");
287 Objects.requireNonNull(tickDuration, "tickDuration");
288 if (tickDuration.isNegative()) {
289 throw new IllegalArgumentException("Tick duration must not be negative");
290 }
291 long tickNanos = tickDuration.toNanos();
292 if (tickNanos % 1000_000 == 0) {
293 // ok, no fraction of millisecond
294 } else if (1000_000_000 % tickNanos == 0) {
295 // ok, divides into one second without remainder
296 } else {
297 throw new IllegalArgumentException("Invalid tick duration");
298 }
299 if (tickNanos <= 1) {
300 return baseClock;
301 }
302 return new TickClock(baseClock, tickNanos);
303 }
304
305 //-----------------------------------------------------------------------
306 /**
307 * Obtains a clock that always returns the same instant.
308 * <p>
309 * This clock simply returns the specified instant.
310 * As such, it is not a clock in the conventional sense.
311 * The main use case for this is in testing, where the fixed clock ensures
312 * tests are not dependent on the current clock.
313 * <p>
314 * The returned implementation is immutable, thread-safe and {@code Serializable}.
315 *
316 * @param fixedInstant the instant to use as the clock, not null
317 * @param zone the time-zone to use to convert the instant to date-time, not null
318 * @return a clock that always returns the same instant, not null
319 */
320 public static Clock fixed(Instant fixedInstant, ZoneId zone) {
321 Objects.requireNonNull(fixedInstant, "fixedInstant");
322 Objects.requireNonNull(zone, "zone");
323 return new FixedClock(fixedInstant, zone);
324 }
325
326 //-------------------------------------------------------------------------
327 /**
328 * Obtains a clock that returns instants from the specified clock with the
329 * specified duration added
330 * <p>
331 * This clock wraps another clock, returning instants that are later by the
332 * specified duration. If the duration is negative, the instants will be
333 * earlier than the current date and time.
334 * The main use case for this is to simulate running in the future or in the past.
335 * <p>
336 * A duration of zero would have no offsetting effect.
337 * Passing zero will return the underlying clock.
338 * <p>
339 * The returned implementation is immutable, thread-safe and {@code Serializable}
340 * providing that the base clock is.
341 *
342 * @param baseClock the base clock to add the duration to, not null
343 * @param offsetDuration the duration to add, not null
344 * @return a clock based on the base clock with the duration added, not null
345 */
346 public static Clock offset(Clock baseClock, Duration offsetDuration) {
347 Objects.requireNonNull(baseClock, "baseClock");
348 Objects.requireNonNull(offsetDuration, "offsetDuration");
349 if (offsetDuration.equals(Duration.ZERO)) {
350 return baseClock;
351 }
352 return new OffsetClock(baseClock, offsetDuration);
353 }
354
355 //-----------------------------------------------------------------------
356 /**
357 * Constructor accessible by subclasses.
358 */
359 protected Clock() {
360 }
361
362 //-----------------------------------------------------------------------
363 /**
364 * Gets the time-zone being used to create dates and times.
365 * <p>
366 * A clock will typically obtain the current instant and then convert that
367 * to a date or time using a time-zone. This method returns the time-zone used.
368 *
369 * @return the time-zone being used to interpret instants, not null
370 */
371 public abstract ZoneId getZone();
372
373 /**
374 * Returns a copy of this clock with a different time-zone.
375 * <p>
376 * A clock will typically obtain the current instant and then convert that
377 * to a date or time using a time-zone. This method returns a clock with
378 * similar properties but using a different time-zone.
379 *
380 * @param zone the time-zone to change to, not null
381 * @return a clock based on this clock with the specified time-zone, not null
382 */
383 public abstract Clock withZone(ZoneId zone);
384
385 //-------------------------------------------------------------------------
386 /**
387 * Gets the current millisecond instant of the clock.
388 * <p>
389 * This returns the millisecond-based instant, measured from 1970-01-01T00:00Z (UTC).
390 * This is equivalent to the definition of {@link System#currentTimeMillis()}.
391 * <p>
392 * Most applications should avoid this method and use {@link Instant} to represent
393 * an instant on the time-line rather than a raw millisecond value.
394 * This method is provided to allow the use of the clock in high performance use cases
395 * where the creation of an object would be unacceptable.
396 * <p>
397 * The default implementation currently calls {@link #instant}.
398 *
399 * @return the current millisecond instant from this clock, measured from
400 * the Java epoch of 1970-01-01T00:00Z (UTC), not null
401 * @throws DateTimeException if the instant cannot be obtained, not thrown by most implementations
402 */
403 public long millis() {
404 return instant().toEpochMilli();
405 }
406
407 //-----------------------------------------------------------------------
408 /**
409 * Gets the current instant of the clock.
410 * <p>
411 * This returns an instant representing the current instant as defined by the clock.
412 *
413 * @return the current instant from this clock, not null
414 * @throws DateTimeException if the instant cannot be obtained, not thrown by most implementations
415 */
416 public abstract Instant instant();
417
418 //-----------------------------------------------------------------------
419 /**
420 * Checks if this clock is equal to another clock.
421 * <p>
422 * Clocks should override this method to compare equals based on
423 * their state and to meet the contract of {@link Object#equals}.
424 * If not overridden, the behavior is defined by {@link Object#equals}
425 *
426 * @param obj the object to check, null returns false
427 * @return true if this is equal to the other clock
428 */
429 @Override
430 public boolean equals(Object obj) {
431 return super.equals(obj);
432 }
433
434 /**
435 * A hash code for this clock.
436 * <p>
437 * Clocks should override this method based on
438 * their state and to meet the contract of {@link Object#hashCode}.
439 * If not overridden, the behavior is defined by {@link Object#hashCode}
440 *
441 * @return a suitable hash code
442 */
443 @Override
444 public int hashCode() {
445 return super.hashCode();
446 }
447
448 //-----------------------------------------------------------------------
449 /**
450 * Implementation of a clock that always returns the latest time from
451 * {@link System#currentTimeMillis()}.
452 */
453 static final class SystemClock extends Clock implements Serializable {
454 private static final long serialVersionUID = 6740630888130243051L;
455 private static final long OFFSET_SEED =
456 System.currentTimeMillis()/1000 - 1024; // initial offest
457 static final SystemClock UTC = new SystemClock(ZoneOffset.UTC);
458
459 private final ZoneId zone;
460 // We don't actually need a volatile here.
461 // We don't care if offset is set or read concurrently by multiple
462 // threads - we just need a value which is 'recent enough' - in other
463 // words something that has been updated at least once in the last
464 // 2^32 secs (~136 years). And even if we by chance see an invalid
465 // offset, the worst that can happen is that we will get a -1 value
466 // from getNanoTimeAdjustment, forcing us to update the offset
467 // once again.
468 private transient long offset;
469
470 SystemClock(ZoneId zone) {
471 this.zone = zone;
472 this.offset = OFFSET_SEED;
473 }
474 @Override
475 public ZoneId getZone() {
476 return zone;
477 }
478 @Override
479 public Clock withZone(ZoneId zone) {
480 if (zone.equals(this.zone)) { // intentional NPE
481 return this;
482 }
483 return new SystemClock(zone);
484 }
485 @Override
486 public long millis() {
487 // System.currentTimeMillis() and VM.getNanoTimeAdjustment(offset)
488 // use the same time source - System.currentTimeMillis() simply
489 // limits the resolution to milliseconds.
490 // So we take the faster path and call System.currentTimeMillis()
491 // directly - in order to avoid the performance penalty of
492 // VM.getNanoTimeAdjustment(offset) which is less efficient.
493 return System.currentTimeMillis();
494 }
495 @Override
496 public Instant instant() {
497 // Take a local copy of offset. offset can be updated concurrently
498 // by other threads (even if we haven't made it volatile) so we will
499 // work with a local copy.
500 long localOffset = offset;
501 long adjustment = VM.getNanoTimeAdjustment(localOffset);
502
503 if (adjustment == -1) {
504 // -1 is a sentinel value returned by VM.getNanoTimeAdjustment
505 // when the offset it is given is too far off the current UTC
506 // time. In principle, this should not happen unless the
507 // JVM has run for more than ~136 years (not likely) or
508 // someone is fiddling with the system time, or the offset is
509 // by chance at 1ns in the future (very unlikely).
510 // We can easily recover from all these conditions by bringing
511 // back the offset in range and retry.
512
513 // bring back the offset in range. We use -1024 to make
514 // it more unlikely to hit the 1ns in the future condition.
515 localOffset = System.currentTimeMillis()/1000 - 1024;
516
517 // retry
518 adjustment = VM.getNanoTimeAdjustment(localOffset);
519
520 if (adjustment == -1) {
521 // Should not happen: we just recomputed a new offset.
522 // It should have fixed the issue.
523 throw new InternalError("Offset " + localOffset + " is not in range");
524 } else {
525 // OK - recovery succeeded. Update the offset for the
526 // next call...
527 offset = localOffset;
528 }
529 }
530 return Instant.ofEpochSecond(localOffset, adjustment);
531 }
532 @Override
533 public boolean equals(Object obj) {
534 if (obj instanceof SystemClock) {
535 return zone.equals(((SystemClock) obj).zone);
536 }
537 return false;
538 }
539 @Override
540 public int hashCode() {
541 return zone.hashCode() + 1;
542 }
543 @Override
544 public String toString() {
545 return "SystemClock[" + zone + "]";
546 }
547 private void readObject(ObjectInputStream is)
548 throws IOException, ClassNotFoundException {
549 // ensure that offset is initialized
550 is.defaultReadObject();
551 offset = OFFSET_SEED;
552 }
553 }
554
555 //-----------------------------------------------------------------------
556 /**
557 * Implementation of a clock that always returns the same instant.
558 * This is typically used for testing.
559 */
560 static final class FixedClock extends Clock implements Serializable {
561 private static final long serialVersionUID = 7430389292664866958L;
562 private final Instant instant;
563 private final ZoneId zone;
564
565 FixedClock(Instant fixedInstant, ZoneId zone) {
566 this.instant = fixedInstant;
567 this.zone = zone;
568 }
569 @Override
570 public ZoneId getZone() {
571 return zone;
572 }
573 @Override
574 public Clock withZone(ZoneId zone) {
575 if (zone.equals(this.zone)) { // intentional NPE
576 return this;
577 }
578 return new FixedClock(instant, zone);
579 }
580 @Override
581 public long millis() {
582 return instant.toEpochMilli();
583 }
584 @Override
585 public Instant instant() {
586 return instant;
587 }
588 @Override
589 public boolean equals(Object obj) {
590 if (obj instanceof FixedClock) {
591 FixedClock other = (FixedClock) obj;
592 return instant.equals(other.instant) && zone.equals(other.zone);
593 }
594 return false;
595 }
596 @Override
597 public int hashCode() {
598 return instant.hashCode() ^ zone.hashCode();
599 }
600 @Override
601 public String toString() {
602 return "FixedClock[" + instant + "," + zone + "]";
603 }
604 }
605
606 //-----------------------------------------------------------------------
607 /**
608 * Implementation of a clock that adds an offset to an underlying clock.
609 */
610 static final class OffsetClock extends Clock implements Serializable {
611 private static final long serialVersionUID = 2007484719125426256L;
612 private final Clock baseClock;
613 private final Duration offset;
614
615 OffsetClock(Clock baseClock, Duration offset) {
616 this.baseClock = baseClock;
617 this.offset = offset;
618 }
619 @Override
620 public ZoneId getZone() {
621 return baseClock.getZone();
622 }
623 @Override
624 public Clock withZone(ZoneId zone) {
625 if (zone.equals(baseClock.getZone())) { // intentional NPE
626 return this;
627 }
628 return new OffsetClock(baseClock.withZone(zone), offset);
629 }
630 @Override
631 public long millis() {
632 return Math.addExact(baseClock.millis(), offset.toMillis());
633 }
634 @Override
635 public Instant instant() {
636 return baseClock.instant().plus(offset);
637 }
638 @Override
639 public boolean equals(Object obj) {
640 if (obj instanceof OffsetClock) {
641 OffsetClock other = (OffsetClock) obj;
642 return baseClock.equals(other.baseClock) && offset.equals(other.offset);
643 }
644 return false;
645 }
646 @Override
647 public int hashCode() {
648 return baseClock.hashCode() ^ offset.hashCode();
649 }
650 @Override
651 public String toString() {
652 return "OffsetClock[" + baseClock + "," + offset + "]";
653 }
654 }
655
656 //-----------------------------------------------------------------------
657 /**
658 * Implementation of a clock that adds an offset to an underlying clock.
659 */
660 static final class TickClock extends Clock implements Serializable {
661 private static final long serialVersionUID = 6504659149906368850L;
662 private final Clock baseClock;
663 private final long tickNanos;
664
665 TickClock(Clock baseClock, long tickNanos) {
666 this.baseClock = baseClock;
667 this.tickNanos = tickNanos;
668 }
669 @Override
670 public ZoneId getZone() {
671 return baseClock.getZone();
672 }
673 @Override
674 public Clock withZone(ZoneId zone) {
675 if (zone.equals(baseClock.getZone())) { // intentional NPE
676 return this;
677 }
678 return new TickClock(baseClock.withZone(zone), tickNanos);
679 }
680 @Override
681 public long millis() {
682 long millis = baseClock.millis();
683 return millis - Math.floorMod(millis, tickNanos / 1000_000L);
684 }
685 @Override
686 public Instant instant() {
687 if ((tickNanos % 1000_000) == 0) {
688 long millis = baseClock.millis();
689 return Instant.ofEpochMilli(millis - Math.floorMod(millis, tickNanos / 1000_000L));
690 }
691 Instant instant = baseClock.instant();
692 long nanos = instant.getNano();
693 long adjust = Math.floorMod(nanos, tickNanos);
694 return instant.minusNanos(adjust);
695 }
696 @Override
697 public boolean equals(Object obj) {
698 if (obj instanceof TickClock) {
699 TickClock other = (TickClock) obj;
700 return baseClock.equals(other.baseClock) && tickNanos == other.tickNanos;
701 }
702 return false;
703 }
704 @Override
705 public int hashCode() {
706 return baseClock.hashCode() ^ ((int) (tickNanos ^ (tickNanos >>> 32)));
707 }
708 @Override
709 public String toString() {
710 return "TickClock[" + baseClock + "," + Duration.ofNanos(tickNanos) + "]";
711 }
712 }
713
714 }