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 import static java.time.LocalTime.NANOS_PER_MILLI;
69 import java.io.Serializable;
70 import java.util.Objects;
71 import java.util.TimeZone;
72 import jdk.internal.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 the same underlying clock
131 * as {@link System#currentTimeMillis()}, but may have a precision finer than
132 * milliseconds if available.
133 * However, little to no guarantee is provided about the accuracy of the
134 * underlying clock. Applications requiring a more accurate clock must implement
135 * this abstract class themselves using a different external clock, such as an
136 * NTP server.
137 *
138 * @since 1.8
139 */
140 public abstract class Clock {
141
142 /**
143 * Obtains a clock that returns the current instant using the best available
144 * system clock, converting to date and time using the UTC time-zone.
145 * <p>
146 * This clock, rather than {@link #systemDefaultZone()}, should be used when
147 * you need the current instant without the date or time.
148 * <p>
149 * This clock is based on the best available system clock.
150 * This may use {@link System#currentTimeMillis()}, or a higher resolution
151 * clock if one is available.
152 * <p>
153 * Conversion from instant to date or time uses the {@linkplain ZoneOffset#UTC UTC time-zone}.
154 * <p>
155 * The returned implementation is immutable, thread-safe and {@code Serializable}.
156 * It is equivalent to {@code system(ZoneOffset.UTC)}.
157 *
158 * @return a clock that uses the best available system clock in the UTC zone, not null
159 */
160 public static Clock systemUTC() {
161 return SystemClock.UTC;
162 }
163
164 /**
165 * Obtains a clock that returns the current instant using the best available
166 * system clock, converting to date and time using the default time-zone.
167 * <p>
168 * This clock is based on the best available system clock.
169 * This may use {@link System#currentTimeMillis()}, or a higher resolution
170 * clock if one is available.
171 * <p>
172 * Using this method hard codes a dependency to the default time-zone into your application.
173 * It is recommended to avoid this and use a specific time-zone whenever possible.
174 * The {@link #systemUTC() UTC clock} should be used when you need the current instant
175 * without the date or time.
176 * <p>
177 * The returned implementation is immutable, thread-safe and {@code Serializable}.
178 * It is equivalent to {@code system(ZoneId.systemDefault())}.
179 *
180 * @return a clock that uses the best available system clock in the default zone, not null
181 * @see ZoneId#systemDefault()
182 */
183 public static Clock systemDefaultZone() {
184 return new SystemClock(ZoneId.systemDefault());
185 }
186
187 /**
188 * Obtains a clock that returns the current instant using the best available
189 * system clock.
190 * <p>
191 * This clock is based on the best available system clock.
192 * This may use {@link System#currentTimeMillis()}, or a higher resolution
193 * clock if one is available.
194 * <p>
195 * Conversion from instant to date or time uses the specified time-zone.
196 * <p>
197 * The returned implementation is immutable, thread-safe and {@code Serializable}.
198 *
199 * @param zone the time-zone to use to convert the instant to date-time, not null
200 * @return a clock that uses the best available system clock in the specified zone, not null
201 */
202 public static Clock system(ZoneId zone) {
203 Objects.requireNonNull(zone, "zone");
204 if (zone == ZoneOffset.UTC) {
205 return SystemClock.UTC;
206 }
207 return new SystemClock(zone);
208 }
209
210 //-------------------------------------------------------------------------
211 /**
212 * Obtains a clock that returns the current instant ticking in whole milliseconds
213 * using the best available system clock.
214 * <p>
215 * This clock will always have the nano-of-second field truncated to milliseconds.
216 * This ensures that the visible time ticks in whole milliseconds.
217 * The underlying clock is the best available system clock, equivalent to
218 * using {@link #system(ZoneId)}.
219 * <p>
220 * Implementations may use a caching strategy for performance reasons.
221 * As such, it is possible that the start of the millisecond observed via this
222 * clock will be later than that observed directly via the underlying clock.
223 * <p>
224 * The returned implementation is immutable, thread-safe and {@code Serializable}.
225 * It is equivalent to {@code tick(system(zone), Duration.ofMillis(1))}.
226 *
227 * @param zone the time-zone to use to convert the instant to date-time, not null
228 * @return a clock that ticks in whole milliseconds using the specified zone, not null
229 * @since 9
230 */
231 public static Clock tickMillis(ZoneId zone) {
232 return new TickClock(system(zone), NANOS_PER_MILLI);
233 }
234
235 //-------------------------------------------------------------------------
236 /**
237 * Obtains a clock that returns the current instant ticking in whole seconds
238 * using the best available system clock.
239 * <p>
240 * This clock will always have the nano-of-second field set to zero.
241 * This ensures that the visible time ticks in whole seconds.
242 * The underlying clock is the best available system clock, equivalent to
243 * using {@link #system(ZoneId)}.
244 * <p>
245 * Implementations may use a caching strategy for performance reasons.
246 * As such, it is possible that the start of the second observed via this
247 * clock will be later than that observed directly via the underlying clock.
248 * <p>
249 * The returned implementation is immutable, thread-safe and {@code Serializable}.
250 * It is equivalent to {@code tick(system(zone), Duration.ofSeconds(1))}.
251 *
252 * @param zone the time-zone to use to convert the instant to date-time, not null
253 * @return a clock that ticks in whole seconds using the specified zone, not null
254 */
255 public static Clock tickSeconds(ZoneId zone) {
256 return new TickClock(system(zone), NANOS_PER_SECOND);
257 }
258
259 /**
260 * Obtains a clock that returns the current instant ticking in whole minutes
261 * using the best available system clock.
262 * <p>
263 * This clock will always have the nano-of-second and second-of-minute fields set to zero.
264 * This ensures that the visible time ticks in whole minutes.
265 * The underlying clock is the best available system clock, equivalent to
266 * using {@link #system(ZoneId)}.
267 * <p>
268 * Implementations may use a caching strategy for performance reasons.
269 * As such, it is possible that the start of the minute observed via this
270 * clock will be later than that observed directly via the underlying clock.
271 * <p>
272 * The returned implementation is immutable, thread-safe and {@code Serializable}.
273 * It is equivalent to {@code tick(system(zone), Duration.ofMinutes(1))}.
274 *
275 * @param zone the time-zone to use to convert the instant to date-time, not null
276 * @return a clock that ticks in whole minutes using the specified zone, not null
277 */
278 public static Clock tickMinutes(ZoneId zone) {
279 return new TickClock(system(zone), NANOS_PER_MINUTE);
280 }
281
282 /**
283 * Obtains a clock that returns instants from the specified clock truncated
284 * to the nearest occurrence of the specified duration.
285 * <p>
286 * This clock will only tick as per the specified duration. Thus, if the duration
287 * is half a second, the clock will return instants truncated to the half second.
288 * <p>
289 * The tick duration must be positive. If it has a part smaller than a whole
290 * millisecond, then the whole duration must divide into one second without
291 * leaving a remainder. All normal tick durations will match these criteria,
292 * including any multiple of hours, minutes, seconds and milliseconds, and
293 * sensible nanosecond durations, such as 20ns, 250,000ns and 500,000ns.
294 * <p>
295 * A duration of zero or one nanosecond would have no truncation effect.
296 * Passing one of these will return the underlying clock.
297 * <p>
298 * Implementations may use a caching strategy for performance reasons.
299 * As such, it is possible that the start of the requested duration observed
300 * via this clock will be later than that observed directly via the underlying clock.
301 * <p>
302 * The returned implementation is immutable, thread-safe and {@code Serializable}
303 * providing that the base clock is.
304 *
305 * @param baseClock the base clock to base the ticking clock on, not null
306 * @param tickDuration the duration of each visible tick, not negative, not null
307 * @return a clock that ticks in whole units of the duration, not null
308 * @throws IllegalArgumentException if the duration is negative, or has a
309 * part smaller than a whole millisecond such that the whole duration is not
310 * divisible into one second
311 * @throws ArithmeticException if the duration is too large to be represented as nanos
312 */
313 public static Clock tick(Clock baseClock, Duration tickDuration) {
314 Objects.requireNonNull(baseClock, "baseClock");
315 Objects.requireNonNull(tickDuration, "tickDuration");
316 if (tickDuration.isNegative()) {
317 throw new IllegalArgumentException("Tick duration must not be negative");
318 }
319 long tickNanos = tickDuration.toNanos();
320 if (tickNanos % 1000_000 == 0) {
321 // ok, no fraction of millisecond
322 } else if (1000_000_000 % tickNanos == 0) {
323 // ok, divides into one second without remainder
324 } else {
325 throw new IllegalArgumentException("Invalid tick duration");
326 }
327 if (tickNanos <= 1) {
328 return baseClock;
329 }
330 return new TickClock(baseClock, tickNanos);
331 }
332
333 //-----------------------------------------------------------------------
334 /**
335 * Obtains a clock that always returns the same instant.
336 * <p>
337 * This clock simply returns the specified instant.
338 * As such, it is not a clock in the conventional sense.
339 * The main use case for this is in testing, where the fixed clock ensures
340 * tests are not dependent on the current clock.
341 * <p>
342 * The returned implementation is immutable, thread-safe and {@code Serializable}.
343 *
344 * @param fixedInstant the instant to use as the clock, not null
345 * @param zone the time-zone to use to convert the instant to date-time, not null
346 * @return a clock that always returns the same instant, not null
347 */
348 public static Clock fixed(Instant fixedInstant, ZoneId zone) {
349 Objects.requireNonNull(fixedInstant, "fixedInstant");
350 Objects.requireNonNull(zone, "zone");
351 return new FixedClock(fixedInstant, zone);
352 }
353
354 //-------------------------------------------------------------------------
355 /**
356 * Obtains a clock that returns instants from the specified clock with the
357 * specified duration added
358 * <p>
359 * This clock wraps another clock, returning instants that are later by the
360 * specified duration. If the duration is negative, the instants will be
361 * earlier than the current date and time.
362 * The main use case for this is to simulate running in the future or in the past.
363 * <p>
364 * A duration of zero would have no offsetting effect.
365 * Passing zero will return the underlying clock.
366 * <p>
367 * The returned implementation is immutable, thread-safe and {@code Serializable}
368 * providing that the base clock is.
369 *
370 * @param baseClock the base clock to add the duration to, not null
371 * @param offsetDuration the duration to add, not null
372 * @return a clock based on the base clock with the duration added, not null
373 */
374 public static Clock offset(Clock baseClock, Duration offsetDuration) {
375 Objects.requireNonNull(baseClock, "baseClock");
376 Objects.requireNonNull(offsetDuration, "offsetDuration");
377 if (offsetDuration.equals(Duration.ZERO)) {
378 return baseClock;
379 }
380 return new OffsetClock(baseClock, offsetDuration);
381 }
382
383 //-----------------------------------------------------------------------
384 /**
385 * Constructor accessible by subclasses.
386 */
387 protected Clock() {
388 }
389
390 //-----------------------------------------------------------------------
391 /**
392 * Gets the time-zone being used to create dates and times.
393 * <p>
394 * A clock will typically obtain the current instant and then convert that
395 * to a date or time using a time-zone. This method returns the time-zone used.
396 *
397 * @return the time-zone being used to interpret instants, not null
398 */
399 public abstract ZoneId getZone();
400
401 /**
402 * Returns a copy of this clock with a different time-zone.
403 * <p>
404 * A clock will typically obtain the current instant and then convert that
405 * to a date or time using a time-zone. This method returns a clock with
406 * similar properties but using a different time-zone.
407 *
408 * @param zone the time-zone to change to, not null
409 * @return a clock based on this clock with the specified time-zone, not null
410 */
411 public abstract Clock withZone(ZoneId zone);
412
413 //-------------------------------------------------------------------------
414 /**
415 * Gets the current millisecond instant of the clock.
416 * <p>
417 * This returns the millisecond-based instant, measured from 1970-01-01T00:00Z (UTC).
418 * This is equivalent to the definition of {@link System#currentTimeMillis()}.
419 * <p>
420 * Most applications should avoid this method and use {@link Instant} to represent
421 * an instant on the time-line rather than a raw millisecond value.
422 * This method is provided to allow the use of the clock in high performance use cases
423 * where the creation of an object would be unacceptable.
424 * <p>
425 * The default implementation currently calls {@link #instant}.
426 *
427 * @return the current millisecond instant from this clock, measured from
428 * the Java epoch of 1970-01-01T00:00Z (UTC), not null
429 * @throws DateTimeException if the instant cannot be obtained, not thrown by most implementations
430 */
431 public long millis() {
432 return instant().toEpochMilli();
433 }
434
435 //-----------------------------------------------------------------------
436 /**
437 * Gets the current instant of the clock.
438 * <p>
439 * This returns an instant representing the current instant as defined by the clock.
440 *
441 * @return the current instant from this clock, not null
442 * @throws DateTimeException if the instant cannot be obtained, not thrown by most implementations
443 */
444 public abstract Instant instant();
445
446 //-----------------------------------------------------------------------
447 /**
448 * Checks if this clock is equal to another clock.
449 * <p>
450 * Clocks should override this method to compare equals based on
451 * their state and to meet the contract of {@link Object#equals}.
452 * If not overridden, the behavior is defined by {@link Object#equals}
453 *
454 * @param obj the object to check, null returns false
455 * @return true if this is equal to the other clock
456 */
457 @Override
458 public boolean equals(Object obj) {
459 return super.equals(obj);
460 }
461
462 /**
463 * A hash code for this clock.
464 * <p>
465 * Clocks should override this method based on
466 * their state and to meet the contract of {@link Object#hashCode}.
467 * If not overridden, the behavior is defined by {@link Object#hashCode}
468 *
469 * @return a suitable hash code
470 */
471 @Override
472 public int hashCode() {
473 return super.hashCode();
474 }
475
476 //-----------------------------------------------------------------------
477 /**
478 * Implementation of a clock that always returns the latest time from
479 * {@link System#currentTimeMillis()}.
480 */
481 static final class SystemClock extends Clock implements Serializable {
482 private static final long serialVersionUID = 6740630888130243051L;
483 private static final long OFFSET_SEED =
484 System.currentTimeMillis()/1000 - 1024; // initial offest
485 static final SystemClock UTC = new SystemClock(ZoneOffset.UTC);
486
487 private final ZoneId zone;
488 // We don't actually need a volatile here.
489 // We don't care if offset is set or read concurrently by multiple
490 // threads - we just need a value which is 'recent enough' - in other
491 // words something that has been updated at least once in the last
492 // 2^32 secs (~136 years). And even if we by chance see an invalid
493 // offset, the worst that can happen is that we will get a -1 value
494 // from getNanoTimeAdjustment, forcing us to update the offset
495 // once again.
496 private transient long offset;
497
498 SystemClock(ZoneId zone) {
499 this.zone = zone;
500 this.offset = OFFSET_SEED;
501 }
502 @Override
503 public ZoneId getZone() {
504 return zone;
505 }
506 @Override
507 public Clock withZone(ZoneId zone) {
508 if (zone.equals(this.zone)) { // intentional NPE
509 return this;
510 }
511 return new SystemClock(zone);
512 }
513 @Override
514 public long millis() {
515 // System.currentTimeMillis() and VM.getNanoTimeAdjustment(offset)
516 // use the same time source - System.currentTimeMillis() simply
517 // limits the resolution to milliseconds.
518 // So we take the faster path and call System.currentTimeMillis()
519 // directly - in order to avoid the performance penalty of
520 // VM.getNanoTimeAdjustment(offset) which is less efficient.
521 return System.currentTimeMillis();
522 }
523 @Override
524 public Instant instant() {
525 // Take a local copy of offset. offset can be updated concurrently
526 // by other threads (even if we haven't made it volatile) so we will
527 // work with a local copy.
528 long localOffset = offset;
529 long adjustment = VM.getNanoTimeAdjustment(localOffset);
530
531 if (adjustment == -1) {
532 // -1 is a sentinel value returned by VM.getNanoTimeAdjustment
533 // when the offset it is given is too far off the current UTC
534 // time. In principle, this should not happen unless the
535 // JVM has run for more than ~136 years (not likely) or
536 // someone is fiddling with the system time, or the offset is
537 // by chance at 1ns in the future (very unlikely).
538 // We can easily recover from all these conditions by bringing
539 // back the offset in range and retry.
540
541 // bring back the offset in range. We use -1024 to make
542 // it more unlikely to hit the 1ns in the future condition.
543 localOffset = System.currentTimeMillis()/1000 - 1024;
544
545 // retry
546 adjustment = VM.getNanoTimeAdjustment(localOffset);
547
548 if (adjustment == -1) {
549 // Should not happen: we just recomputed a new offset.
550 // It should have fixed the issue.
551 throw new InternalError("Offset " + localOffset + " is not in range");
552 } else {
553 // OK - recovery succeeded. Update the offset for the
554 // next call...
555 offset = localOffset;
556 }
557 }
558 return Instant.ofEpochSecond(localOffset, adjustment);
559 }
560 @Override
561 public boolean equals(Object obj) {
562 if (obj instanceof SystemClock) {
563 return zone.equals(((SystemClock) obj).zone);
564 }
565 return false;
566 }
567 @Override
568 public int hashCode() {
569 return zone.hashCode() + 1;
570 }
571 @Override
572 public String toString() {
573 return "SystemClock[" + zone + "]";
574 }
575 private void readObject(ObjectInputStream is)
576 throws IOException, ClassNotFoundException {
577 // ensure that offset is initialized
578 is.defaultReadObject();
579 offset = OFFSET_SEED;
580 }
581 }
582
583 //-----------------------------------------------------------------------
584 /**
585 * Implementation of a clock that always returns the same instant.
586 * This is typically used for testing.
587 */
588 static final class FixedClock extends Clock implements Serializable {
589 private static final long serialVersionUID = 7430389292664866958L;
590 private final Instant instant;
591 private final ZoneId zone;
592
593 FixedClock(Instant fixedInstant, ZoneId zone) {
594 this.instant = fixedInstant;
595 this.zone = zone;
596 }
597 @Override
598 public ZoneId getZone() {
599 return zone;
600 }
601 @Override
602 public Clock withZone(ZoneId zone) {
603 if (zone.equals(this.zone)) { // intentional NPE
604 return this;
605 }
606 return new FixedClock(instant, zone);
607 }
608 @Override
609 public long millis() {
610 return instant.toEpochMilli();
611 }
612 @Override
613 public Instant instant() {
614 return instant;
615 }
616 @Override
617 public boolean equals(Object obj) {
618 if (obj instanceof FixedClock) {
619 FixedClock other = (FixedClock) obj;
620 return instant.equals(other.instant) && zone.equals(other.zone);
621 }
622 return false;
623 }
624 @Override
625 public int hashCode() {
626 return instant.hashCode() ^ zone.hashCode();
627 }
628 @Override
629 public String toString() {
630 return "FixedClock[" + instant + "," + zone + "]";
631 }
632 }
633
634 //-----------------------------------------------------------------------
635 /**
636 * Implementation of a clock that adds an offset to an underlying clock.
637 */
638 static final class OffsetClock extends Clock implements Serializable {
639 private static final long serialVersionUID = 2007484719125426256L;
640 private final Clock baseClock;
641 private final Duration offset;
642
643 OffsetClock(Clock baseClock, Duration offset) {
644 this.baseClock = baseClock;
645 this.offset = offset;
646 }
647 @Override
648 public ZoneId getZone() {
649 return baseClock.getZone();
650 }
651 @Override
652 public Clock withZone(ZoneId zone) {
653 if (zone.equals(baseClock.getZone())) { // intentional NPE
654 return this;
655 }
656 return new OffsetClock(baseClock.withZone(zone), offset);
657 }
658 @Override
659 public long millis() {
660 return Math.addExact(baseClock.millis(), offset.toMillis());
661 }
662 @Override
663 public Instant instant() {
664 return baseClock.instant().plus(offset);
665 }
666 @Override
667 public boolean equals(Object obj) {
668 if (obj instanceof OffsetClock) {
669 OffsetClock other = (OffsetClock) obj;
670 return baseClock.equals(other.baseClock) && offset.equals(other.offset);
671 }
672 return false;
673 }
674 @Override
675 public int hashCode() {
676 return baseClock.hashCode() ^ offset.hashCode();
677 }
678 @Override
679 public String toString() {
680 return "OffsetClock[" + baseClock + "," + offset + "]";
681 }
682 }
683
684 //-----------------------------------------------------------------------
685 /**
686 * Implementation of a clock that adds an offset to an underlying clock.
687 */
688 static final class TickClock extends Clock implements Serializable {
689 private static final long serialVersionUID = 6504659149906368850L;
690 private final Clock baseClock;
691 private final long tickNanos;
692
693 TickClock(Clock baseClock, long tickNanos) {
694 this.baseClock = baseClock;
695 this.tickNanos = tickNanos;
696 }
697 @Override
698 public ZoneId getZone() {
699 return baseClock.getZone();
700 }
701 @Override
702 public Clock withZone(ZoneId zone) {
703 if (zone.equals(baseClock.getZone())) { // intentional NPE
704 return this;
705 }
706 return new TickClock(baseClock.withZone(zone), tickNanos);
707 }
708 @Override
709 public long millis() {
710 long millis = baseClock.millis();
711 return millis - Math.floorMod(millis, tickNanos / 1000_000L);
712 }
713 @Override
714 public Instant instant() {
715 if ((tickNanos % 1000_000) == 0) {
716 long millis = baseClock.millis();
717 return Instant.ofEpochMilli(millis - Math.floorMod(millis, tickNanos / 1000_000L));
718 }
719 Instant instant = baseClock.instant();
720 long nanos = instant.getNano();
721 long adjust = Math.floorMod(nanos, tickNanos);
722 return instant.minusNanos(adjust);
723 }
724 @Override
725 public boolean equals(Object obj) {
726 if (obj instanceof TickClock) {
727 TickClock other = (TickClock) obj;
728 return baseClock.equals(other.baseClock) && tickNanos == other.tickNanos;
729 }
730 return false;
731 }
732 @Override
733 public int hashCode() {
734 return baseClock.hashCode() ^ ((int) (tickNanos ^ (tickNanos >>> 32)));
735 }
736 @Override
737 public String toString() {
738 return "TickClock[" + baseClock + "," + Duration.ofNanos(tickNanos) + "]";
739 }
740 }
741
742 }
743