Line data Source code
1 : // Copyright 2013 the V8 project authors. All rights reserved.
2 : // Use of this source code is governed by a BSD-style license that can be
3 : // found in the LICENSE file.
4 :
5 : #ifndef V8_BASE_PLATFORM_TIME_H_
6 : #define V8_BASE_PLATFORM_TIME_H_
7 :
8 : #include <stdint.h>
9 :
10 : #include <ctime>
11 : #include <iosfwd>
12 : #include <limits>
13 :
14 : #include "src/base/base-export.h"
15 : #include "src/base/bits.h"
16 : #include "src/base/macros.h"
17 : #include "src/base/safe_math.h"
18 : #if V8_OS_WIN
19 : #include "src/base/win32-headers.h"
20 : #endif
21 :
22 : // Forward declarations.
23 : extern "C" {
24 : struct _FILETIME;
25 : struct mach_timespec;
26 : struct timespec;
27 : struct timeval;
28 : }
29 :
30 : namespace v8 {
31 : namespace base {
32 :
33 : class Time;
34 : class TimeDelta;
35 : class TimeTicks;
36 :
37 : namespace time_internal {
38 : template<class TimeClass>
39 : class TimeBase;
40 : }
41 :
42 : class TimeConstants {
43 : public:
44 : static constexpr int64_t kHoursPerDay = 24;
45 : static constexpr int64_t kMillisecondsPerSecond = 1000;
46 : static constexpr int64_t kMillisecondsPerDay =
47 : kMillisecondsPerSecond * 60 * 60 * kHoursPerDay;
48 : static constexpr int64_t kMicrosecondsPerMillisecond = 1000;
49 : static constexpr int64_t kMicrosecondsPerSecond =
50 : kMicrosecondsPerMillisecond * kMillisecondsPerSecond;
51 : static constexpr int64_t kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60;
52 : static constexpr int64_t kMicrosecondsPerHour = kMicrosecondsPerMinute * 60;
53 : static constexpr int64_t kMicrosecondsPerDay =
54 : kMicrosecondsPerHour * kHoursPerDay;
55 : static constexpr int64_t kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;
56 : static constexpr int64_t kNanosecondsPerMicrosecond = 1000;
57 : static constexpr int64_t kNanosecondsPerSecond =
58 : kNanosecondsPerMicrosecond * kMicrosecondsPerSecond;
59 : };
60 :
61 : // -----------------------------------------------------------------------------
62 : // TimeDelta
63 : //
64 : // This class represents a duration of time, internally represented in
65 : // microseonds.
66 :
67 : class V8_BASE_EXPORT TimeDelta final {
68 : public:
69 0 : constexpr TimeDelta() : delta_(0) {}
70 :
71 : // Converts units of time to TimeDeltas.
72 : static constexpr TimeDelta FromDays(int days) {
73 : return TimeDelta(days * TimeConstants::kMicrosecondsPerDay);
74 : }
75 : static constexpr TimeDelta FromHours(int hours) {
76 : return TimeDelta(hours * TimeConstants::kMicrosecondsPerHour);
77 : }
78 : static constexpr TimeDelta FromMinutes(int minutes) {
79 : return TimeDelta(minutes * TimeConstants::kMicrosecondsPerMinute);
80 : }
81 : static constexpr TimeDelta FromSeconds(int64_t seconds) {
82 : return TimeDelta(seconds * TimeConstants::kMicrosecondsPerSecond);
83 : }
84 45 : static constexpr TimeDelta FromMilliseconds(int64_t milliseconds) {
85 50 : return TimeDelta(milliseconds * TimeConstants::kMicrosecondsPerMillisecond);
86 : }
87 : static constexpr TimeDelta FromMicroseconds(int64_t microseconds) {
88 : return TimeDelta(microseconds);
89 : }
90 : static constexpr TimeDelta FromNanoseconds(int64_t nanoseconds) {
91 95 : return TimeDelta(nanoseconds / TimeConstants::kNanosecondsPerMicrosecond);
92 : }
93 :
94 : // Returns the maximum time delta, which should be greater than any reasonable
95 : // time delta we might compare it to. Adding or subtracting the maximum time
96 : // delta to a time or another time delta has an undefined result.
97 : static constexpr TimeDelta Max();
98 :
99 : // Returns the minimum time delta, which should be less than than any
100 : // reasonable time delta we might compare it to. Adding or subtracting the
101 : // minimum time delta to a time or another time delta has an undefined result.
102 : static constexpr TimeDelta Min();
103 :
104 : // Returns true if the time delta is zero.
105 : constexpr bool IsZero() const { return delta_ == 0; }
106 :
107 : // Returns true if the time delta is the maximum/minimum time delta.
108 : constexpr bool IsMax() const {
109 7822680 : return delta_ == std::numeric_limits<int64_t>::max();
110 : }
111 : constexpr bool IsMin() const {
112 0 : return delta_ == std::numeric_limits<int64_t>::min();
113 : }
114 :
115 : // Returns the time delta in some unit. The F versions return a floating
116 : // point value, the "regular" versions return a rounded-down value.
117 : //
118 : // InMillisecondsRoundedUp() instead returns an integer that is rounded up
119 : // to the next full millisecond.
120 : int InDays() const;
121 : int InHours() const;
122 : int InMinutes() const;
123 : double InSecondsF() const;
124 : int64_t InSeconds() const;
125 : double InMillisecondsF() const;
126 : int64_t InMilliseconds() const;
127 : int64_t InMillisecondsRoundedUp() const;
128 : int64_t InMicroseconds() const;
129 : int64_t InNanoseconds() const;
130 :
131 : // Converts to/from Mach time specs.
132 : static TimeDelta FromMachTimespec(struct mach_timespec ts);
133 : struct mach_timespec ToMachTimespec() const;
134 :
135 : // Converts to/from POSIX time specs.
136 : static TimeDelta FromTimespec(struct timespec ts);
137 : struct timespec ToTimespec() const;
138 :
139 : TimeDelta& operator=(const TimeDelta& other) = default;
140 :
141 : // Computations with other deltas.
142 : TimeDelta operator+(const TimeDelta& other) const {
143 0 : return TimeDelta(delta_ + other.delta_);
144 : }
145 : TimeDelta operator-(const TimeDelta& other) const {
146 1 : return TimeDelta(delta_ - other.delta_);
147 : }
148 :
149 : TimeDelta& operator+=(const TimeDelta& other) {
150 6191824 : delta_ += other.delta_;
151 : return *this;
152 : }
153 : TimeDelta& operator-=(const TimeDelta& other) {
154 0 : delta_ -= other.delta_;
155 : return *this;
156 : }
157 0 : constexpr TimeDelta operator-() const { return TimeDelta(-delta_); }
158 :
159 : double TimesOf(const TimeDelta& other) const {
160 0 : return static_cast<double>(delta_) / static_cast<double>(other.delta_);
161 : }
162 : double PercentOf(const TimeDelta& other) const {
163 0 : return TimesOf(other) * 100.0;
164 : }
165 :
166 : // Computations with ints, note that we only allow multiplicative operations
167 : // with ints, and additive operations with other deltas.
168 : TimeDelta operator*(int64_t a) const {
169 : return TimeDelta(delta_ * a);
170 : }
171 : TimeDelta operator/(int64_t a) const {
172 : return TimeDelta(delta_ / a);
173 : }
174 : TimeDelta& operator*=(int64_t a) {
175 3 : delta_ *= a;
176 : return *this;
177 : }
178 : TimeDelta& operator/=(int64_t a) {
179 3 : delta_ /= a;
180 : return *this;
181 : }
182 : int64_t operator/(const TimeDelta& other) const {
183 : return delta_ / other.delta_;
184 : }
185 :
186 : // Comparison operators.
187 : constexpr bool operator==(const TimeDelta& other) const {
188 17 : return delta_ == other.delta_;
189 : }
190 : constexpr bool operator!=(const TimeDelta& other) const {
191 271904 : return delta_ != other.delta_;
192 : }
193 : constexpr bool operator<(const TimeDelta& other) const {
194 1 : return delta_ < other.delta_;
195 : }
196 : constexpr bool operator<=(const TimeDelta& other) const {
197 2 : return delta_ <= other.delta_;
198 : }
199 : constexpr bool operator>(const TimeDelta& other) const {
200 3 : return delta_ > other.delta_;
201 : }
202 : constexpr bool operator>=(const TimeDelta& other) const {
203 : return delta_ >= other.delta_;
204 : }
205 :
206 : private:
207 : template<class TimeClass> friend class time_internal::TimeBase;
208 : // Constructs a delta given the duration in microseconds. This is private
209 : // to avoid confusion by callers with an integer constructor. Use
210 : // FromSeconds, FromMilliseconds, etc. instead.
211 : explicit constexpr TimeDelta(int64_t delta) : delta_(delta) {}
212 :
213 : // Delta in microseconds.
214 : int64_t delta_;
215 : };
216 :
217 : // static
218 : constexpr TimeDelta TimeDelta::Max() {
219 : return TimeDelta(std::numeric_limits<int64_t>::max());
220 : }
221 :
222 : // static
223 : constexpr TimeDelta TimeDelta::Min() {
224 : return TimeDelta(std::numeric_limits<int64_t>::min());
225 : }
226 :
227 : namespace time_internal {
228 :
229 : // TimeBase--------------------------------------------------------------------
230 :
231 : // Provides value storage and comparison/math operations common to all time
232 : // classes. Each subclass provides for strong type-checking to ensure
233 : // semantically meaningful comparison/math of time values from the same clock
234 : // source or timeline.
235 : template <class TimeClass>
236 : class TimeBase : public TimeConstants {
237 : public:
238 : #if V8_OS_WIN
239 : // To avoid overflow in QPC to Microseconds calculations, since we multiply
240 : // by kMicrosecondsPerSecond, then the QPC value should not exceed
241 : // (2^63 - 1) / 1E6. If it exceeds that threshold, we divide then multiply.
242 : static constexpr int64_t kQPCOverflowThreshold = INT64_C(0x8637BD05AF7);
243 : #endif
244 :
245 : // Returns true if this object has not been initialized.
246 : //
247 : // Warning: Be careful when writing code that performs math on time values,
248 : // since it's possible to produce a valid "zero" result that should not be
249 : // interpreted as a "null" value.
250 197265 : constexpr bool IsNull() const { return us_ == 0; }
251 :
252 : // Returns the maximum/minimum times, which should be greater/less than any
253 : // reasonable time with which we might compare it.
254 : static TimeClass Max() {
255 : return TimeClass(std::numeric_limits<int64_t>::max());
256 : }
257 : static TimeClass Min() {
258 : return TimeClass(std::numeric_limits<int64_t>::min());
259 : }
260 :
261 : // Returns true if this object represents the maximum/minimum time.
262 : constexpr bool IsMax() const {
263 0 : return us_ == std::numeric_limits<int64_t>::max();
264 : }
265 : constexpr bool IsMin() const {
266 : return us_ == std::numeric_limits<int64_t>::min();
267 : }
268 :
269 : // For serializing only. Use FromInternalValue() to reconstitute. Please don't
270 : // use this and do arithmetic on it, as it is more error prone than using the
271 : // provided operators.
272 29045862 : int64_t ToInternalValue() const { return us_; }
273 :
274 : TimeClass& operator=(TimeClass other) {
275 : us_ = other.us_;
276 : return *(static_cast<TimeClass*>(this));
277 : }
278 :
279 : // Compute the difference between two times.
280 : TimeDelta operator-(TimeClass other) const {
281 7391967 : return TimeDelta::FromMicroseconds(us_ - other.us_);
282 : }
283 :
284 : // Return a new time modified by some delta.
285 : TimeClass operator+(TimeDelta delta) const {
286 42101 : return TimeClass(bits::SignedSaturatedAdd64(delta.delta_, us_));
287 : }
288 : TimeClass operator-(TimeDelta delta) const {
289 0 : return TimeClass(-bits::SignedSaturatedSub64(delta.delta_, us_));
290 : }
291 :
292 : // Modify by some time delta.
293 : TimeClass& operator+=(TimeDelta delta) {
294 : return static_cast<TimeClass&>(*this = (*this + delta));
295 : }
296 : TimeClass& operator-=(TimeDelta delta) {
297 : return static_cast<TimeClass&>(*this = (*this - delta));
298 : }
299 :
300 : // Comparison operators
301 : bool operator==(TimeClass other) const {
302 12 : return us_ == other.us_;
303 : }
304 : bool operator!=(TimeClass other) const {
305 27450 : return us_ != other.us_;
306 : }
307 : bool operator<(TimeClass other) const {
308 : return us_ < other.us_;
309 : }
310 : bool operator<=(TimeClass other) const {
311 : return us_ <= other.us_;
312 : }
313 : bool operator>(TimeClass other) const {
314 4 : return us_ > other.us_;
315 : }
316 : bool operator>=(TimeClass other) const {
317 738558 : return us_ >= other.us_;
318 : }
319 :
320 : // Converts an integer value representing TimeClass to a class. This is used
321 : // when deserializing a |TimeClass| structure, using a value known to be
322 : // compatible. It is not provided as a constructor because the integer type
323 : // may be unclear from the perspective of a caller.
324 : static TimeClass FromInternalValue(int64_t us) { return TimeClass(us); }
325 :
326 : protected:
327 2 : explicit constexpr TimeBase(int64_t us) : us_(us) {}
328 :
329 : // Time value in a microsecond timebase.
330 : int64_t us_;
331 : };
332 :
333 : } // namespace time_internal
334 :
335 :
336 : // -----------------------------------------------------------------------------
337 : // Time
338 : //
339 : // This class represents an absolute point in time, internally represented as
340 : // microseconds (s/1,000,000) since 00:00:00 UTC, January 1, 1970.
341 :
342 : class V8_BASE_EXPORT Time final : public time_internal::TimeBase<Time> {
343 : public:
344 : // Contains the nullptr time. Use Time::Now() to get the current time.
345 : constexpr Time() : TimeBase(0) {}
346 :
347 : // Returns the current time. Watch out, the system might adjust its clock
348 : // in which case time will actually go backwards. We don't guarantee that
349 : // times are increasing, or that two calls to Now() won't be the same.
350 : static Time Now();
351 :
352 : // Returns the current time. Same as Now() except that this function always
353 : // uses system time so that there are no discrepancies between the returned
354 : // time and system time even on virtual environments including our test bot.
355 : // For timing sensitive unittests, this function should be used.
356 : static Time NowFromSystemTime();
357 :
358 : // Returns the time for epoch in Unix-like system (Jan 1, 1970).
359 : static Time UnixEpoch() { return Time(0); }
360 :
361 : // Converts to/from POSIX time specs.
362 : static Time FromTimespec(struct timespec ts);
363 : struct timespec ToTimespec() const;
364 :
365 : // Converts to/from POSIX time values.
366 : static Time FromTimeval(struct timeval tv);
367 : struct timeval ToTimeval() const;
368 :
369 : // Converts to/from Windows file times.
370 : static Time FromFiletime(struct _FILETIME ft);
371 : struct _FILETIME ToFiletime() const;
372 :
373 : // Converts to/from the Javascript convention for times, a number of
374 : // milliseconds since the epoch:
375 : static Time FromJsTime(double ms_since_epoch);
376 : double ToJsTime() const;
377 :
378 : private:
379 : friend class time_internal::TimeBase<Time>;
380 : explicit constexpr Time(int64_t us) : TimeBase(us) {}
381 : };
382 :
383 : V8_BASE_EXPORT std::ostream& operator<<(std::ostream&, const Time&);
384 :
385 : inline Time operator+(const TimeDelta& delta, const Time& time) {
386 : return time + delta;
387 : }
388 :
389 :
390 : // -----------------------------------------------------------------------------
391 : // TimeTicks
392 : //
393 : // This class represents an abstract time that is most of the time incrementing
394 : // for use in measuring time durations. It is internally represented in
395 : // microseconds. It can not be converted to a human-readable time, but is
396 : // guaranteed not to decrease (if the user changes the computer clock,
397 : // Time::Now() may actually decrease or jump). But note that TimeTicks may
398 : // "stand still", for example if the computer suspended.
399 :
400 : class V8_BASE_EXPORT TimeTicks final
401 : : public time_internal::TimeBase<TimeTicks> {
402 : public:
403 : constexpr TimeTicks() : TimeBase(0) {}
404 :
405 : // Platform-dependent tick count representing "right now." When
406 : // IsHighResolution() returns false, the resolution of the clock could be as
407 : // coarse as ~15.6ms. Otherwise, the resolution should be no worse than one
408 : // microsecond.
409 : // This method never returns a null TimeTicks.
410 : static TimeTicks Now();
411 :
412 : // This is equivalent to Now() but DCHECKs that IsHighResolution(). Useful for
413 : // test frameworks that rely on high resolution clocks (in practice all
414 : // platforms but low-end Windows devices have high resolution clocks).
415 : static TimeTicks HighResolutionNow();
416 :
417 : // Returns true if the high-resolution clock is working on this system.
418 : static bool IsHighResolution();
419 :
420 : private:
421 : friend class time_internal::TimeBase<TimeTicks>;
422 :
423 : // Please use Now() to create a new object. This is for internal use
424 : // and testing. Ticks are in microseconds.
425 : explicit constexpr TimeTicks(int64_t ticks) : TimeBase(ticks) {}
426 : };
427 :
428 : inline TimeTicks operator+(const TimeDelta& delta, const TimeTicks& ticks) {
429 : return ticks + delta;
430 : }
431 :
432 :
433 : // ThreadTicks ----------------------------------------------------------------
434 :
435 : // Represents a clock, specific to a particular thread, than runs only while the
436 : // thread is running.
437 : class V8_BASE_EXPORT ThreadTicks final
438 : : public time_internal::TimeBase<ThreadTicks> {
439 : public:
440 : constexpr ThreadTicks() : TimeBase(0) {}
441 :
442 : // Returns true if ThreadTicks::Now() is supported on this system.
443 : static bool IsSupported();
444 :
445 : // Waits until the initialization is completed. Needs to be guarded with a
446 : // call to IsSupported().
447 : static void WaitUntilInitialized() {
448 : #if V8_OS_WIN
449 : WaitUntilInitializedWin();
450 : #endif
451 : }
452 :
453 : // Returns thread-specific CPU-time on systems that support this feature.
454 : // Needs to be guarded with a call to IsSupported(). Use this timer
455 : // to (approximately) measure how much time the calling thread spent doing
456 : // actual work vs. being de-scheduled. May return bogus results if the thread
457 : // migrates to another CPU between two calls. Returns an empty ThreadTicks
458 : // object until the initialization is completed. If a clock reading is
459 : // absolutely needed, call WaitUntilInitialized() before this method.
460 : static ThreadTicks Now();
461 :
462 : #if V8_OS_WIN
463 : // Similar to Now() above except this returns thread-specific CPU time for an
464 : // arbitrary thread. All comments for Now() method above apply apply to this
465 : // method as well.
466 : static ThreadTicks GetForThread(const HANDLE& thread_handle);
467 : #endif
468 :
469 : private:
470 : template <class TimeClass>
471 : friend class time_internal::TimeBase;
472 :
473 : // Please use Now() or GetForThread() to create a new object. This is for
474 : // internal use and testing. Ticks are in microseconds.
475 : explicit constexpr ThreadTicks(int64_t ticks) : TimeBase(ticks) {}
476 :
477 : #if V8_OS_WIN
478 : // Returns the frequency of the TSC in ticks per second, or 0 if it hasn't
479 : // been measured yet. Needs to be guarded with a call to IsSupported().
480 : static double TSCTicksPerSecond();
481 : static bool IsSupportedWin();
482 : static void WaitUntilInitializedWin();
483 : #endif
484 : };
485 :
486 : } // namespace base
487 : } // namespace v8
488 :
489 : #endif // V8_BASE_PLATFORM_TIME_H_
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