1 // Copyright (c) 2012 The Chromium 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 // Time represents an absolute point in time, internally represented as 6 // microseconds (s/1,000,000) since the Windows epoch (1601-01-01 00:00:00 UTC) 7 // (See http://crbug.com/14734). System-dependent clock interface routines are 8 // defined in time_PLATFORM.cc. 9 // 10 // TimeDelta represents a duration of time, internally represented in 11 // microseconds. 12 // 13 // TimeTicks represents an abstract time that is most of the time incrementing 14 // for use in measuring time durations. It is internally represented in 15 // microseconds. It can not be converted to a human-readable time, but is 16 // guaranteed not to decrease (if the user changes the computer clock, 17 // Time::Now() may actually decrease or jump). But note that TimeTicks may 18 // "stand still", for example if the computer suspended. 19 // 20 // These classes are represented as only a 64-bit value, so they can be 21 // efficiently passed by value. 22 23 #ifndef BASE_TIME_TIME_H_ 24 #define BASE_TIME_TIME_H_ 25 26 #include <time.h> 27 28 #include "base/atomicops.h" 29 #include "base/base_export.h" 30 #include "base/basictypes.h" 31 32 #if defined(OS_MACOSX) 33 #include <CoreFoundation/CoreFoundation.h> 34 // Avoid Mac system header macro leak. 35 #undef TYPE_BOOL 36 #endif 37 38 #if defined(OS_POSIX) 39 #include <unistd.h> 40 #include <sys/time.h> 41 #endif 42 43 #if defined(OS_WIN) 44 // For FILETIME in FromFileTime, until it moves to a new converter class. 45 // See TODO(iyengar) below. 46 #include <windows.h> 47 #endif 48 49 #include <limits> 50 51 namespace base { 52 53 class Time; 54 class TimeTicks; 55 56 // TimeDelta ------------------------------------------------------------------ 57 58 class BASE_EXPORT TimeDelta { 59 public: 60 TimeDelta() : delta_(0) { 61 } 62 63 // Converts units of time to TimeDeltas. 64 static TimeDelta FromDays(int64 days); 65 static TimeDelta FromHours(int64 hours); 66 static TimeDelta FromMinutes(int64 minutes); 67 static TimeDelta FromSeconds(int64 secs); 68 static TimeDelta FromMilliseconds(int64 ms); 69 static TimeDelta FromMicroseconds(int64 us); 70 #if defined(OS_WIN) 71 static TimeDelta FromQPCValue(LONGLONG qpc_value); 72 #endif 73 74 // Converts an integer value representing TimeDelta to a class. This is used 75 // when deserializing a |TimeDelta| structure, using a value known to be 76 // compatible. It is not provided as a constructor because the integer type 77 // may be unclear from the perspective of a caller. 78 static TimeDelta FromInternalValue(int64 delta) { 79 return TimeDelta(delta); 80 } 81 82 // Returns the internal numeric value of the TimeDelta object. Please don't 83 // use this and do arithmetic on it, as it is more error prone than using the 84 // provided operators. 85 // For serializing, use FromInternalValue to reconstitute. 86 int64 ToInternalValue() const { 87 return delta_; 88 } 89 90 #if defined(OS_POSIX) 91 struct timespec ToTimeSpec() const; 92 #endif 93 94 // Returns the time delta in some unit. The F versions return a floating 95 // point value, the "regular" versions return a rounded-down value. 96 // 97 // InMillisecondsRoundedUp() instead returns an integer that is rounded up 98 // to the next full millisecond. 99 int InDays() const; 100 int InHours() const; 101 int InMinutes() const; 102 double InSecondsF() const; 103 int64 InSeconds() const; 104 double InMillisecondsF() const; 105 int64 InMilliseconds() const; 106 int64 InMillisecondsRoundedUp() const; 107 int64 InMicroseconds() const; 108 109 TimeDelta& operator=(TimeDelta other) { 110 delta_ = other.delta_; 111 return *this; 112 } 113 114 // Computations with other deltas. 115 TimeDelta operator+(TimeDelta other) const { 116 return TimeDelta(delta_ + other.delta_); 117 } 118 TimeDelta operator-(TimeDelta other) const { 119 return TimeDelta(delta_ - other.delta_); 120 } 121 122 TimeDelta& operator+=(TimeDelta other) { 123 delta_ += other.delta_; 124 return *this; 125 } 126 TimeDelta& operator-=(TimeDelta other) { 127 delta_ -= other.delta_; 128 return *this; 129 } 130 TimeDelta operator-() const { 131 return TimeDelta(-delta_); 132 } 133 134 // Computations with ints, note that we only allow multiplicative operations 135 // with ints, and additive operations with other deltas. 136 TimeDelta operator*(int64 a) const { 137 return TimeDelta(delta_ * a); 138 } 139 TimeDelta operator/(int64 a) const { 140 return TimeDelta(delta_ / a); 141 } 142 TimeDelta& operator*=(int64 a) { 143 delta_ *= a; 144 return *this; 145 } 146 TimeDelta& operator/=(int64 a) { 147 delta_ /= a; 148 return *this; 149 } 150 int64 operator/(TimeDelta a) const { 151 return delta_ / a.delta_; 152 } 153 154 // Defined below because it depends on the definition of the other classes. 155 Time operator+(Time t) const; 156 TimeTicks operator+(TimeTicks t) const; 157 158 // Comparison operators. 159 bool operator==(TimeDelta other) const { 160 return delta_ == other.delta_; 161 } 162 bool operator!=(TimeDelta other) const { 163 return delta_ != other.delta_; 164 } 165 bool operator<(TimeDelta other) const { 166 return delta_ < other.delta_; 167 } 168 bool operator<=(TimeDelta other) const { 169 return delta_ <= other.delta_; 170 } 171 bool operator>(TimeDelta other) const { 172 return delta_ > other.delta_; 173 } 174 bool operator>=(TimeDelta other) const { 175 return delta_ >= other.delta_; 176 } 177 178 private: 179 friend class Time; 180 friend class TimeTicks; 181 friend TimeDelta operator*(int64 a, TimeDelta td); 182 183 // Constructs a delta given the duration in microseconds. This is private 184 // to avoid confusion by callers with an integer constructor. Use 185 // FromSeconds, FromMilliseconds, etc. instead. 186 explicit TimeDelta(int64 delta_us) : delta_(delta_us) { 187 } 188 189 // Delta in microseconds. 190 int64 delta_; 191 }; 192 193 inline TimeDelta operator*(int64 a, TimeDelta td) { 194 return TimeDelta(a * td.delta_); 195 } 196 197 // Time ----------------------------------------------------------------------- 198 199 // Represents a wall clock time. 200 class BASE_EXPORT Time { 201 public: 202 static const int64 kMillisecondsPerSecond = 1000; 203 static const int64 kMicrosecondsPerMillisecond = 1000; 204 static const int64 kMicrosecondsPerSecond = kMicrosecondsPerMillisecond * 205 kMillisecondsPerSecond; 206 static const int64 kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60; 207 static const int64 kMicrosecondsPerHour = kMicrosecondsPerMinute * 60; 208 static const int64 kMicrosecondsPerDay = kMicrosecondsPerHour * 24; 209 static const int64 kMicrosecondsPerWeek = kMicrosecondsPerDay * 7; 210 static const int64 kNanosecondsPerMicrosecond = 1000; 211 static const int64 kNanosecondsPerSecond = kNanosecondsPerMicrosecond * 212 kMicrosecondsPerSecond; 213 214 #if !defined(OS_WIN) 215 // On Mac & Linux, this value is the delta from the Windows epoch of 1601 to 216 // the Posix delta of 1970. This is used for migrating between the old 217 // 1970-based epochs to the new 1601-based ones. It should be removed from 218 // this global header and put in the platform-specific ones when we remove the 219 // migration code. 220 static const int64 kWindowsEpochDeltaMicroseconds; 221 #endif 222 223 // Represents an exploded time that can be formatted nicely. This is kind of 224 // like the Win32 SYSTEMTIME structure or the Unix "struct tm" with a few 225 // additions and changes to prevent errors. 226 struct BASE_EXPORT Exploded { 227 int year; // Four digit year "2007" 228 int month; // 1-based month (values 1 = January, etc.) 229 int day_of_week; // 0-based day of week (0 = Sunday, etc.) 230 int day_of_month; // 1-based day of month (1-31) 231 int hour; // Hour within the current day (0-23) 232 int minute; // Minute within the current hour (0-59) 233 int second; // Second within the current minute (0-59 plus leap 234 // seconds which may take it up to 60). 235 int millisecond; // Milliseconds within the current second (0-999) 236 237 // A cursory test for whether the data members are within their 238 // respective ranges. A 'true' return value does not guarantee the 239 // Exploded value can be successfully converted to a Time value. 240 bool HasValidValues() const; 241 }; 242 243 // Contains the NULL time. Use Time::Now() to get the current time. 244 Time() : us_(0) { 245 } 246 247 // Returns true if the time object has not been initialized. 248 bool is_null() const { 249 return us_ == 0; 250 } 251 252 // Returns true if the time object is the maximum time. 253 bool is_max() const { 254 return us_ == std::numeric_limits<int64>::max(); 255 } 256 257 // Returns the time for epoch in Unix-like system (Jan 1, 1970). 258 static Time UnixEpoch(); 259 260 // Returns the current time. Watch out, the system might adjust its clock 261 // in which case time will actually go backwards. We don't guarantee that 262 // times are increasing, or that two calls to Now() won't be the same. 263 static Time Now(); 264 265 // Returns the maximum time, which should be greater than any reasonable time 266 // with which we might compare it. 267 static Time Max(); 268 269 // Returns the current time. Same as Now() except that this function always 270 // uses system time so that there are no discrepancies between the returned 271 // time and system time even on virtual environments including our test bot. 272 // For timing sensitive unittests, this function should be used. 273 static Time NowFromSystemTime(); 274 275 // Converts to/from time_t in UTC and a Time class. 276 // TODO(brettw) this should be removed once everybody starts using the |Time| 277 // class. 278 static Time FromTimeT(time_t tt); 279 time_t ToTimeT() const; 280 281 // Converts time to/from a double which is the number of seconds since epoch 282 // (Jan 1, 1970). Webkit uses this format to represent time. 283 // Because WebKit initializes double time value to 0 to indicate "not 284 // initialized", we map it to empty Time object that also means "not 285 // initialized". 286 static Time FromDoubleT(double dt); 287 double ToDoubleT() const; 288 289 #if defined(OS_POSIX) 290 // Converts the timespec structure to time. MacOS X 10.8.3 (and tentatively, 291 // earlier versions) will have the |ts|'s tv_nsec component zeroed out, 292 // having a 1 second resolution, which agrees with 293 // https://developer.apple.com/legacy/library/#technotes/tn/tn1150.html#HFSPlusDates. 294 static Time FromTimeSpec(const timespec& ts); 295 #endif 296 297 // Converts to/from the Javascript convention for times, a number of 298 // milliseconds since the epoch: 299 // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/getTime. 300 static Time FromJsTime(double ms_since_epoch); 301 double ToJsTime() const; 302 303 #if defined(OS_POSIX) 304 static Time FromTimeVal(struct timeval t); 305 struct timeval ToTimeVal() const; 306 #endif 307 308 #if defined(OS_MACOSX) 309 static Time FromCFAbsoluteTime(CFAbsoluteTime t); 310 CFAbsoluteTime ToCFAbsoluteTime() const; 311 #endif 312 313 #if defined(OS_WIN) 314 static Time FromFileTime(FILETIME ft); 315 FILETIME ToFileTime() const; 316 317 // The minimum time of a low resolution timer. This is basically a windows 318 // constant of ~15.6ms. While it does vary on some older OS versions, we'll 319 // treat it as static across all windows versions. 320 static const int kMinLowResolutionThresholdMs = 16; 321 322 // Enable or disable Windows high resolution timer. If the high resolution 323 // timer is not enabled, calls to ActivateHighResolutionTimer will fail. 324 // When disabling the high resolution timer, this function will not cause 325 // the high resolution timer to be deactivated, but will prevent future 326 // activations. 327 // Must be called from the main thread. 328 // For more details see comments in time_win.cc. 329 static void EnableHighResolutionTimer(bool enable); 330 331 // Activates or deactivates the high resolution timer based on the |activate| 332 // flag. If the HighResolutionTimer is not Enabled (see 333 // EnableHighResolutionTimer), this function will return false. Otherwise 334 // returns true. Each successful activate call must be paired with a 335 // subsequent deactivate call. 336 // All callers to activate the high resolution timer must eventually call 337 // this function to deactivate the high resolution timer. 338 static bool ActivateHighResolutionTimer(bool activate); 339 340 // Returns true if the high resolution timer is both enabled and activated. 341 // This is provided for testing only, and is not tracked in a thread-safe 342 // way. 343 static bool IsHighResolutionTimerInUse(); 344 #endif 345 346 // Converts an exploded structure representing either the local time or UTC 347 // into a Time class. 348 static Time FromUTCExploded(const Exploded& exploded) { 349 return FromExploded(false, exploded); 350 } 351 static Time FromLocalExploded(const Exploded& exploded) { 352 return FromExploded(true, exploded); 353 } 354 355 // Converts an integer value representing Time to a class. This is used 356 // when deserializing a |Time| structure, using a value known to be 357 // compatible. It is not provided as a constructor because the integer type 358 // may be unclear from the perspective of a caller. 359 static Time FromInternalValue(int64 us) { 360 return Time(us); 361 } 362 363 // Converts a string representation of time to a Time object. 364 // An example of a time string which is converted is as below:- 365 // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified 366 // in the input string, FromString assumes local time and FromUTCString 367 // assumes UTC. A timezone that cannot be parsed (e.g. "UTC" which is not 368 // specified in RFC822) is treated as if the timezone is not specified. 369 // TODO(iyengar) Move the FromString/FromTimeT/ToTimeT/FromFileTime to 370 // a new time converter class. 371 static bool FromString(const char* time_string, Time* parsed_time) { 372 return FromStringInternal(time_string, true, parsed_time); 373 } 374 static bool FromUTCString(const char* time_string, Time* parsed_time) { 375 return FromStringInternal(time_string, false, parsed_time); 376 } 377 378 // For serializing, use FromInternalValue to reconstitute. Please don't use 379 // this and do arithmetic on it, as it is more error prone than using the 380 // provided operators. 381 int64 ToInternalValue() const { 382 return us_; 383 } 384 385 // Fills the given exploded structure with either the local time or UTC from 386 // this time structure (containing UTC). 387 void UTCExplode(Exploded* exploded) const { 388 return Explode(false, exploded); 389 } 390 void LocalExplode(Exploded* exploded) const { 391 return Explode(true, exploded); 392 } 393 394 // Rounds this time down to the nearest day in local time. It will represent 395 // midnight on that day. 396 Time LocalMidnight() const; 397 398 Time& operator=(Time other) { 399 us_ = other.us_; 400 return *this; 401 } 402 403 // Compute the difference between two times. 404 TimeDelta operator-(Time other) const { 405 return TimeDelta(us_ - other.us_); 406 } 407 408 // Modify by some time delta. 409 Time& operator+=(TimeDelta delta) { 410 us_ += delta.delta_; 411 return *this; 412 } 413 Time& operator-=(TimeDelta delta) { 414 us_ -= delta.delta_; 415 return *this; 416 } 417 418 // Return a new time modified by some delta. 419 Time operator+(TimeDelta delta) const { 420 return Time(us_ + delta.delta_); 421 } 422 Time operator-(TimeDelta delta) const { 423 return Time(us_ - delta.delta_); 424 } 425 426 // Comparison operators 427 bool operator==(Time other) const { 428 return us_ == other.us_; 429 } 430 bool operator!=(Time other) const { 431 return us_ != other.us_; 432 } 433 bool operator<(Time other) const { 434 return us_ < other.us_; 435 } 436 bool operator<=(Time other) const { 437 return us_ <= other.us_; 438 } 439 bool operator>(Time other) const { 440 return us_ > other.us_; 441 } 442 bool operator>=(Time other) const { 443 return us_ >= other.us_; 444 } 445 446 private: 447 friend class TimeDelta; 448 449 explicit Time(int64 us) : us_(us) { 450 } 451 452 // Explodes the given time to either local time |is_local = true| or UTC 453 // |is_local = false|. 454 void Explode(bool is_local, Exploded* exploded) const; 455 456 // Unexplodes a given time assuming the source is either local time 457 // |is_local = true| or UTC |is_local = false|. 458 static Time FromExploded(bool is_local, const Exploded& exploded); 459 460 // Converts a string representation of time to a Time object. 461 // An example of a time string which is converted is as below:- 462 // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified 463 // in the input string, local time |is_local = true| or 464 // UTC |is_local = false| is assumed. A timezone that cannot be parsed 465 // (e.g. "UTC" which is not specified in RFC822) is treated as if the 466 // timezone is not specified. 467 static bool FromStringInternal(const char* time_string, 468 bool is_local, 469 Time* parsed_time); 470 471 // The representation of Jan 1, 1970 UTC in microseconds since the 472 // platform-dependent epoch. 473 static const int64 kTimeTToMicrosecondsOffset; 474 475 #if defined(OS_WIN) 476 // Indicates whether fast timers are usable right now. For instance, 477 // when using battery power, we might elect to prevent high speed timers 478 // which would draw more power. 479 static bool high_resolution_timer_enabled_; 480 // Count of activations on the high resolution timer. Only use in tests 481 // which are single threaded. 482 static int high_resolution_timer_activated_; 483 #endif 484 485 // Time in microseconds in UTC. 486 int64 us_; 487 }; 488 489 // Inline the TimeDelta factory methods, for fast TimeDelta construction. 490 491 // static 492 inline TimeDelta TimeDelta::FromDays(int64 days) { 493 return TimeDelta(days * Time::kMicrosecondsPerDay); 494 } 495 496 // static 497 inline TimeDelta TimeDelta::FromHours(int64 hours) { 498 return TimeDelta(hours * Time::kMicrosecondsPerHour); 499 } 500 501 // static 502 inline TimeDelta TimeDelta::FromMinutes(int64 minutes) { 503 return TimeDelta(minutes * Time::kMicrosecondsPerMinute); 504 } 505 506 // static 507 inline TimeDelta TimeDelta::FromSeconds(int64 secs) { 508 return TimeDelta(secs * Time::kMicrosecondsPerSecond); 509 } 510 511 // static 512 inline TimeDelta TimeDelta::FromMilliseconds(int64 ms) { 513 return TimeDelta(ms * Time::kMicrosecondsPerMillisecond); 514 } 515 516 // static 517 inline TimeDelta TimeDelta::FromMicroseconds(int64 us) { 518 return TimeDelta(us); 519 } 520 521 inline Time TimeDelta::operator+(Time t) const { 522 return Time(t.us_ + delta_); 523 } 524 525 // TimeTicks ------------------------------------------------------------------ 526 527 class BASE_EXPORT TimeTicks { 528 public: 529 TimeTicks() : ticks_(0) { 530 } 531 532 // Platform-dependent tick count representing "right now." 533 // The resolution of this clock is ~1-15ms. Resolution varies depending 534 // on hardware/operating system configuration. 535 static TimeTicks Now(); 536 537 // Returns a platform-dependent high-resolution tick count. Implementation 538 // is hardware dependent and may or may not return sub-millisecond 539 // resolution. THIS CALL IS GENERALLY MUCH MORE EXPENSIVE THAN Now() AND 540 // SHOULD ONLY BE USED WHEN IT IS REALLY NEEDED. 541 static TimeTicks HighResNow(); 542 543 // Returns true if ThreadNow() is supported on this system. 544 static bool IsThreadNowSupported() { 545 #if defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0) 546 return true; 547 #else 548 return false; 549 #endif 550 } 551 552 // Returns thread-specific CPU-time on systems that support this feature. 553 // Needs to be guarded with a call to IsThreadNowSupported(). Use this timer 554 // to (approximately) measure how much time the calling thread spent doing 555 // actual work vs. being de-scheduled. May return bogus results if the thread 556 // migrates to another CPU between two calls. 557 static TimeTicks ThreadNow(); 558 559 // Returns the current system trace time or, if none is defined, the current 560 // high-res time (i.e. HighResNow()). On systems where a global trace clock 561 // is defined, timestamping TraceEvents's with this value guarantees 562 // synchronization between events collected inside chrome and events 563 // collected outside (e.g. kernel, X server). 564 static TimeTicks NowFromSystemTraceTime(); 565 566 #if defined(OS_WIN) 567 // Get the absolute value of QPC time drift. For testing. 568 static int64 GetQPCDriftMicroseconds(); 569 570 static TimeTicks FromQPCValue(LONGLONG qpc_value); 571 572 // Returns true if the high resolution clock is working on this system. 573 // This is only for testing. 574 static bool IsHighResClockWorking(); 575 #endif 576 577 // Returns true if this object has not been initialized. 578 bool is_null() const { 579 return ticks_ == 0; 580 } 581 582 // Converts an integer value representing TimeTicks to a class. This is used 583 // when deserializing a |TimeTicks| structure, using a value known to be 584 // compatible. It is not provided as a constructor because the integer type 585 // may be unclear from the perspective of a caller. 586 static TimeTicks FromInternalValue(int64 ticks) { 587 return TimeTicks(ticks); 588 } 589 590 // Returns the internal numeric value of the TimeTicks object. 591 // For serializing, use FromInternalValue to reconstitute. 592 int64 ToInternalValue() const { 593 return ticks_; 594 } 595 596 TimeTicks& operator=(TimeTicks other) { 597 ticks_ = other.ticks_; 598 return *this; 599 } 600 601 // Compute the difference between two times. 602 TimeDelta operator-(TimeTicks other) const { 603 return TimeDelta(ticks_ - other.ticks_); 604 } 605 606 // Modify by some time delta. 607 TimeTicks& operator+=(TimeDelta delta) { 608 ticks_ += delta.delta_; 609 return *this; 610 } 611 TimeTicks& operator-=(TimeDelta delta) { 612 ticks_ -= delta.delta_; 613 return *this; 614 } 615 616 // Return a new TimeTicks modified by some delta. 617 TimeTicks operator+(TimeDelta delta) const { 618 return TimeTicks(ticks_ + delta.delta_); 619 } 620 TimeTicks operator-(TimeDelta delta) const { 621 return TimeTicks(ticks_ - delta.delta_); 622 } 623 624 // Comparison operators 625 bool operator==(TimeTicks other) const { 626 return ticks_ == other.ticks_; 627 } 628 bool operator!=(TimeTicks other) const { 629 return ticks_ != other.ticks_; 630 } 631 bool operator<(TimeTicks other) const { 632 return ticks_ < other.ticks_; 633 } 634 bool operator<=(TimeTicks other) const { 635 return ticks_ <= other.ticks_; 636 } 637 bool operator>(TimeTicks other) const { 638 return ticks_ > other.ticks_; 639 } 640 bool operator>=(TimeTicks other) const { 641 return ticks_ >= other.ticks_; 642 } 643 644 protected: 645 friend class TimeDelta; 646 647 // Please use Now() to create a new object. This is for internal use 648 // and testing. Ticks is in microseconds. 649 explicit TimeTicks(int64 ticks) : ticks_(ticks) { 650 } 651 652 // Tick count in microseconds. 653 int64 ticks_; 654 655 #if defined(OS_WIN) 656 typedef DWORD (*TickFunctionType)(void); 657 static TickFunctionType SetMockTickFunction(TickFunctionType ticker); 658 #endif 659 }; 660 661 inline TimeTicks TimeDelta::operator+(TimeTicks t) const { 662 return TimeTicks(t.ticks_ + delta_); 663 } 664 665 } // namespace base 666 667 #endif // BASE_TIME_TIME_H_ 668