| // Copyright 2013 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/base/platform/time.h" |
| |
| #if V8_OS_POSIX |
| #include <fcntl.h> // for O_RDONLY |
| #include <sys/time.h> |
| #include <unistd.h> |
| #endif |
| #if V8_OS_MACOSX |
| #include <mach/mach.h> |
| #include <mach/mach_time.h> |
| #include <pthread.h> |
| #endif |
| |
| #include <cstring> |
| #include <ostream> |
| |
| #if V8_OS_WIN |
| #include "src/base/atomicops.h" |
| #include "src/base/lazy-instance.h" |
| #include "src/base/win32-headers.h" |
| #endif |
| #include "src/base/cpu.h" |
| #include "src/base/logging.h" |
| #include "src/base/platform/platform.h" |
| |
| #if V8_OS_STARBOARD |
| #include "starboard/time.h" |
| #endif |
| |
| namespace { |
| |
| #if V8_OS_MACOSX |
| int64_t ComputeThreadTicks() { |
| mach_msg_type_number_t thread_info_count = THREAD_BASIC_INFO_COUNT; |
| thread_basic_info_data_t thread_info_data; |
| kern_return_t kr = thread_info( |
| pthread_mach_thread_np(pthread_self()), |
| THREAD_BASIC_INFO, |
| reinterpret_cast<thread_info_t>(&thread_info_data), |
| &thread_info_count); |
| CHECK_EQ(kr, KERN_SUCCESS); |
| |
| v8::base::CheckedNumeric<int64_t> absolute_micros( |
| thread_info_data.user_time.seconds + |
| thread_info_data.system_time.seconds); |
| absolute_micros *= v8::base::Time::kMicrosecondsPerSecond; |
| absolute_micros += (thread_info_data.user_time.microseconds + |
| thread_info_data.system_time.microseconds); |
| return absolute_micros.ValueOrDie(); |
| } |
| #elif V8_OS_POSIX |
| // Helper function to get results from clock_gettime() and convert to a |
| // microsecond timebase. Minimum requirement is MONOTONIC_CLOCK to be supported |
| // on the system. FreeBSD 6 has CLOCK_MONOTONIC but defines |
| // _POSIX_MONOTONIC_CLOCK to -1. |
| V8_INLINE int64_t ClockNow(clockid_t clk_id) { |
| #if (defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0) || \ |
| defined(V8_OS_BSD) || defined(V8_OS_ANDROID) |
| // On AIX clock_gettime for CLOCK_THREAD_CPUTIME_ID outputs time with |
| // resolution of 10ms. thread_cputime API provides the time in ns |
| #if defined(V8_OS_AIX) |
| thread_cputime_t tc; |
| if (clk_id == CLOCK_THREAD_CPUTIME_ID) { |
| if (thread_cputime(-1, &tc) != 0) { |
| UNREACHABLE(); |
| } |
| } |
| #endif |
| struct timespec ts; |
| if (clock_gettime(clk_id, &ts) != 0) { |
| UNREACHABLE(); |
| } |
| v8::base::internal::CheckedNumeric<int64_t> result(ts.tv_sec); |
| result *= v8::base::Time::kMicrosecondsPerSecond; |
| #if defined(V8_OS_AIX) |
| if (clk_id == CLOCK_THREAD_CPUTIME_ID) { |
| result += (tc.stime / v8::base::Time::kNanosecondsPerMicrosecond); |
| } else { |
| result += (ts.tv_nsec / v8::base::Time::kNanosecondsPerMicrosecond); |
| } |
| #else |
| result += (ts.tv_nsec / v8::base::Time::kNanosecondsPerMicrosecond); |
| #endif |
| return result.ValueOrDie(); |
| #else // Monotonic clock not supported. |
| return 0; |
| #endif |
| } |
| #elif V8_OS_WIN |
| V8_INLINE bool IsQPCReliable() { |
| v8::base::CPU cpu; |
| // On Athlon X2 CPUs (e.g. model 15) QueryPerformanceCounter is unreliable. |
| return strcmp(cpu.vendor(), "AuthenticAMD") == 0 && cpu.family() == 15; |
| } |
| |
| // Returns the current value of the performance counter. |
| V8_INLINE uint64_t QPCNowRaw() { |
| LARGE_INTEGER perf_counter_now = {}; |
| // According to the MSDN documentation for QueryPerformanceCounter(), this |
| // will never fail on systems that run XP or later. |
| // https://msdn.microsoft.com/library/windows/desktop/ms644904.aspx |
| BOOL result = ::QueryPerformanceCounter(&perf_counter_now); |
| DCHECK(result); |
| USE(result); |
| return perf_counter_now.QuadPart; |
| } |
| #endif // V8_OS_MACOSX |
| |
| |
| } // namespace |
| |
| namespace v8 { |
| namespace base { |
| |
| TimeDelta TimeDelta::FromDays(int days) { |
| return TimeDelta(days * Time::kMicrosecondsPerDay); |
| } |
| |
| |
| TimeDelta TimeDelta::FromHours(int hours) { |
| return TimeDelta(hours * Time::kMicrosecondsPerHour); |
| } |
| |
| |
| TimeDelta TimeDelta::FromMinutes(int minutes) { |
| return TimeDelta(minutes * Time::kMicrosecondsPerMinute); |
| } |
| |
| |
| TimeDelta TimeDelta::FromSeconds(int64_t seconds) { |
| return TimeDelta(seconds * Time::kMicrosecondsPerSecond); |
| } |
| |
| |
| TimeDelta TimeDelta::FromMilliseconds(int64_t milliseconds) { |
| return TimeDelta(milliseconds * Time::kMicrosecondsPerMillisecond); |
| } |
| |
| |
| TimeDelta TimeDelta::FromNanoseconds(int64_t nanoseconds) { |
| return TimeDelta(nanoseconds / Time::kNanosecondsPerMicrosecond); |
| } |
| |
| |
| int TimeDelta::InDays() const { |
| return static_cast<int>(delta_ / Time::kMicrosecondsPerDay); |
| } |
| |
| |
| int TimeDelta::InHours() const { |
| return static_cast<int>(delta_ / Time::kMicrosecondsPerHour); |
| } |
| |
| |
| int TimeDelta::InMinutes() const { |
| return static_cast<int>(delta_ / Time::kMicrosecondsPerMinute); |
| } |
| |
| |
| double TimeDelta::InSecondsF() const { |
| return static_cast<double>(delta_) / Time::kMicrosecondsPerSecond; |
| } |
| |
| |
| int64_t TimeDelta::InSeconds() const { |
| return delta_ / Time::kMicrosecondsPerSecond; |
| } |
| |
| |
| double TimeDelta::InMillisecondsF() const { |
| return static_cast<double>(delta_) / Time::kMicrosecondsPerMillisecond; |
| } |
| |
| |
| int64_t TimeDelta::InMilliseconds() const { |
| return delta_ / Time::kMicrosecondsPerMillisecond; |
| } |
| |
| |
| int64_t TimeDelta::InNanoseconds() const { |
| return delta_ * Time::kNanosecondsPerMicrosecond; |
| } |
| |
| |
| #if V8_OS_MACOSX |
| |
| TimeDelta TimeDelta::FromMachTimespec(struct mach_timespec ts) { |
| DCHECK_GE(ts.tv_nsec, 0); |
| DCHECK_LT(ts.tv_nsec, |
| static_cast<long>(Time::kNanosecondsPerSecond)); // NOLINT |
| return TimeDelta(ts.tv_sec * Time::kMicrosecondsPerSecond + |
| ts.tv_nsec / Time::kNanosecondsPerMicrosecond); |
| } |
| |
| |
| struct mach_timespec TimeDelta::ToMachTimespec() const { |
| struct mach_timespec ts; |
| DCHECK_GE(delta_, 0); |
| ts.tv_sec = static_cast<unsigned>(delta_ / Time::kMicrosecondsPerSecond); |
| ts.tv_nsec = (delta_ % Time::kMicrosecondsPerSecond) * |
| Time::kNanosecondsPerMicrosecond; |
| return ts; |
| } |
| |
| #endif // V8_OS_MACOSX |
| |
| |
| #if V8_OS_POSIX |
| |
| TimeDelta TimeDelta::FromTimespec(struct timespec ts) { |
| DCHECK_GE(ts.tv_nsec, 0); |
| DCHECK_LT(ts.tv_nsec, |
| static_cast<long>(Time::kNanosecondsPerSecond)); // NOLINT |
| return TimeDelta(ts.tv_sec * Time::kMicrosecondsPerSecond + |
| ts.tv_nsec / Time::kNanosecondsPerMicrosecond); |
| } |
| |
| |
| struct timespec TimeDelta::ToTimespec() const { |
| struct timespec ts; |
| ts.tv_sec = static_cast<time_t>(delta_ / Time::kMicrosecondsPerSecond); |
| ts.tv_nsec = (delta_ % Time::kMicrosecondsPerSecond) * |
| Time::kNanosecondsPerMicrosecond; |
| return ts; |
| } |
| |
| #endif // V8_OS_POSIX |
| |
| |
| #if V8_OS_WIN |
| |
| // We implement time using the high-resolution timers so that we can get |
| // timeouts which are smaller than 10-15ms. To avoid any drift, we |
| // periodically resync the internal clock to the system clock. |
| class Clock final { |
| public: |
| Clock() : initial_ticks_(GetSystemTicks()), initial_time_(GetSystemTime()) {} |
| |
| Time Now() { |
| // Time between resampling the un-granular clock for this API (1 minute). |
| const TimeDelta kMaxElapsedTime = TimeDelta::FromMinutes(1); |
| |
| LockGuard<Mutex> lock_guard(&mutex_); |
| |
| // Determine current time and ticks. |
| TimeTicks ticks = GetSystemTicks(); |
| Time time = GetSystemTime(); |
| |
| // Check if we need to synchronize with the system clock due to a backwards |
| // time change or the amount of time elapsed. |
| TimeDelta elapsed = ticks - initial_ticks_; |
| if (time < initial_time_ || elapsed > kMaxElapsedTime) { |
| initial_ticks_ = ticks; |
| initial_time_ = time; |
| return time; |
| } |
| |
| return initial_time_ + elapsed; |
| } |
| |
| Time NowFromSystemTime() { |
| LockGuard<Mutex> lock_guard(&mutex_); |
| initial_ticks_ = GetSystemTicks(); |
| initial_time_ = GetSystemTime(); |
| return initial_time_; |
| } |
| |
| private: |
| static TimeTicks GetSystemTicks() { |
| return TimeTicks::Now(); |
| } |
| |
| static Time GetSystemTime() { |
| FILETIME ft; |
| ::GetSystemTimeAsFileTime(&ft); |
| return Time::FromFiletime(ft); |
| } |
| |
| TimeTicks initial_ticks_; |
| Time initial_time_; |
| Mutex mutex_; |
| }; |
| |
| |
| static LazyStaticInstance<Clock, DefaultConstructTrait<Clock>, |
| ThreadSafeInitOnceTrait>::type clock = |
| LAZY_STATIC_INSTANCE_INITIALIZER; |
| |
| |
| Time Time::Now() { |
| return clock.Pointer()->Now(); |
| } |
| |
| |
| Time Time::NowFromSystemTime() { |
| return clock.Pointer()->NowFromSystemTime(); |
| } |
| |
| |
| // Time between windows epoch and standard epoch. |
| static const int64_t kTimeToEpochInMicroseconds = int64_t{11644473600000000}; |
| |
| Time Time::FromFiletime(FILETIME ft) { |
| if (ft.dwLowDateTime == 0 && ft.dwHighDateTime == 0) { |
| return Time(); |
| } |
| if (ft.dwLowDateTime == std::numeric_limits<DWORD>::max() && |
| ft.dwHighDateTime == std::numeric_limits<DWORD>::max()) { |
| return Max(); |
| } |
| int64_t us = (static_cast<uint64_t>(ft.dwLowDateTime) + |
| (static_cast<uint64_t>(ft.dwHighDateTime) << 32)) / 10; |
| return Time(us - kTimeToEpochInMicroseconds); |
| } |
| |
| |
| FILETIME Time::ToFiletime() const { |
| DCHECK_GE(us_, 0); |
| FILETIME ft; |
| if (IsNull()) { |
| ft.dwLowDateTime = 0; |
| ft.dwHighDateTime = 0; |
| return ft; |
| } |
| if (IsMax()) { |
| ft.dwLowDateTime = std::numeric_limits<DWORD>::max(); |
| ft.dwHighDateTime = std::numeric_limits<DWORD>::max(); |
| return ft; |
| } |
| uint64_t us = static_cast<uint64_t>(us_ + kTimeToEpochInMicroseconds) * 10; |
| ft.dwLowDateTime = static_cast<DWORD>(us); |
| ft.dwHighDateTime = static_cast<DWORD>(us >> 32); |
| return ft; |
| } |
| |
| #elif V8_OS_POSIX |
| |
| Time Time::Now() { |
| struct timeval tv; |
| int result = gettimeofday(&tv, nullptr); |
| DCHECK_EQ(0, result); |
| USE(result); |
| return FromTimeval(tv); |
| } |
| |
| |
| Time Time::NowFromSystemTime() { |
| return Now(); |
| } |
| |
| |
| Time Time::FromTimespec(struct timespec ts) { |
| DCHECK_GE(ts.tv_nsec, 0); |
| DCHECK_LT(ts.tv_nsec, kNanosecondsPerSecond); |
| if (ts.tv_nsec == 0 && ts.tv_sec == 0) { |
| return Time(); |
| } |
| if (ts.tv_nsec == static_cast<long>(kNanosecondsPerSecond - 1) && // NOLINT |
| ts.tv_sec == std::numeric_limits<time_t>::max()) { |
| return Max(); |
| } |
| return Time(ts.tv_sec * kMicrosecondsPerSecond + |
| ts.tv_nsec / kNanosecondsPerMicrosecond); |
| } |
| |
| |
| struct timespec Time::ToTimespec() const { |
| struct timespec ts; |
| if (IsNull()) { |
| ts.tv_sec = 0; |
| ts.tv_nsec = 0; |
| return ts; |
| } |
| if (IsMax()) { |
| ts.tv_sec = std::numeric_limits<time_t>::max(); |
| ts.tv_nsec = static_cast<long>(kNanosecondsPerSecond - 1); // NOLINT |
| return ts; |
| } |
| ts.tv_sec = static_cast<time_t>(us_ / kMicrosecondsPerSecond); |
| ts.tv_nsec = (us_ % kMicrosecondsPerSecond) * kNanosecondsPerMicrosecond; |
| return ts; |
| } |
| |
| |
| Time Time::FromTimeval(struct timeval tv) { |
| DCHECK_GE(tv.tv_usec, 0); |
| DCHECK(tv.tv_usec < static_cast<suseconds_t>(kMicrosecondsPerSecond)); |
| if (tv.tv_usec == 0 && tv.tv_sec == 0) { |
| return Time(); |
| } |
| if (tv.tv_usec == static_cast<suseconds_t>(kMicrosecondsPerSecond - 1) && |
| tv.tv_sec == std::numeric_limits<time_t>::max()) { |
| return Max(); |
| } |
| return Time(tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec); |
| } |
| |
| |
| struct timeval Time::ToTimeval() const { |
| struct timeval tv; |
| if (IsNull()) { |
| tv.tv_sec = 0; |
| tv.tv_usec = 0; |
| return tv; |
| } |
| if (IsMax()) { |
| tv.tv_sec = std::numeric_limits<time_t>::max(); |
| tv.tv_usec = static_cast<suseconds_t>(kMicrosecondsPerSecond - 1); |
| return tv; |
| } |
| tv.tv_sec = static_cast<time_t>(us_ / kMicrosecondsPerSecond); |
| tv.tv_usec = us_ % kMicrosecondsPerSecond; |
| return tv; |
| } |
| |
| #elif V8_OS_STARBOARD |
| |
| Time Time::Now() { |
| return Time(SbTimeToPosix(SbTimeGetNow())); |
| } |
| |
| Time Time::NowFromSystemTime() { |
| return Now(); |
| } |
| |
| #endif // V8_OS_WIN |
| |
| |
| Time Time::FromJsTime(double ms_since_epoch) { |
| // The epoch is a valid time, so this constructor doesn't interpret |
| // 0 as the null time. |
| if (ms_since_epoch == std::numeric_limits<double>::max()) { |
| return Max(); |
| } |
| return Time( |
| static_cast<int64_t>(ms_since_epoch * kMicrosecondsPerMillisecond)); |
| } |
| |
| |
| double Time::ToJsTime() const { |
| if (IsNull()) { |
| // Preserve 0 so the invalid result doesn't depend on the platform. |
| return 0; |
| } |
| if (IsMax()) { |
| // Preserve max without offset to prevent overflow. |
| return std::numeric_limits<double>::max(); |
| } |
| return static_cast<double>(us_) / kMicrosecondsPerMillisecond; |
| } |
| |
| |
| std::ostream& operator<<(std::ostream& os, const Time& time) { |
| return os << time.ToJsTime(); |
| } |
| |
| |
| #if V8_OS_WIN |
| |
| class TickClock { |
| public: |
| virtual ~TickClock() {} |
| virtual int64_t Now() = 0; |
| virtual bool IsHighResolution() = 0; |
| }; |
| |
| |
| // Overview of time counters: |
| // (1) CPU cycle counter. (Retrieved via RDTSC) |
| // The CPU counter provides the highest resolution time stamp and is the least |
| // expensive to retrieve. However, the CPU counter is unreliable and should not |
| // be used in production. Its biggest issue is that it is per processor and it |
| // is not synchronized between processors. Also, on some computers, the counters |
| // will change frequency due to thermal and power changes, and stop in some |
| // states. |
| // |
| // (2) QueryPerformanceCounter (QPC). The QPC counter provides a high- |
| // resolution (100 nanoseconds) time stamp but is comparatively more expensive |
| // to retrieve. What QueryPerformanceCounter actually does is up to the HAL. |
| // (with some help from ACPI). |
| // According to http://blogs.msdn.com/oldnewthing/archive/2005/09/02/459952.aspx |
| // in the worst case, it gets the counter from the rollover interrupt on the |
| // programmable interrupt timer. In best cases, the HAL may conclude that the |
| // RDTSC counter runs at a constant frequency, then it uses that instead. On |
| // multiprocessor machines, it will try to verify the values returned from |
| // RDTSC on each processor are consistent with each other, and apply a handful |
| // of workarounds for known buggy hardware. In other words, QPC is supposed to |
| // give consistent result on a multiprocessor computer, but it is unreliable in |
| // reality due to bugs in BIOS or HAL on some, especially old computers. |
| // With recent updates on HAL and newer BIOS, QPC is getting more reliable but |
| // it should be used with caution. |
| // |
| // (3) System time. The system time provides a low-resolution (typically 10ms |
| // to 55 milliseconds) time stamp but is comparatively less expensive to |
| // retrieve and more reliable. |
| class HighResolutionTickClock final : public TickClock { |
| public: |
| explicit HighResolutionTickClock(int64_t ticks_per_second) |
| : ticks_per_second_(ticks_per_second) { |
| DCHECK_LT(0, ticks_per_second); |
| } |
| virtual ~HighResolutionTickClock() {} |
| |
| int64_t Now() override { |
| uint64_t now = QPCNowRaw(); |
| |
| // Intentionally calculate microseconds in a round about manner to avoid |
| // overflow and precision issues. Think twice before simplifying! |
| int64_t whole_seconds = now / ticks_per_second_; |
| int64_t leftover_ticks = now % ticks_per_second_; |
| int64_t ticks = (whole_seconds * Time::kMicrosecondsPerSecond) + |
| ((leftover_ticks * Time::kMicrosecondsPerSecond) / ticks_per_second_); |
| |
| // Make sure we never return 0 here, so that TimeTicks::HighResolutionNow() |
| // will never return 0. |
| return ticks + 1; |
| } |
| |
| bool IsHighResolution() override { return true; } |
| |
| private: |
| int64_t ticks_per_second_; |
| }; |
| |
| |
| class RolloverProtectedTickClock final : public TickClock { |
| public: |
| RolloverProtectedTickClock() : rollover_(0) {} |
| virtual ~RolloverProtectedTickClock() {} |
| |
| int64_t Now() override { |
| // We use timeGetTime() to implement TimeTicks::Now(), which rolls over |
| // every ~49.7 days. We try to track rollover ourselves, which works if |
| // TimeTicks::Now() is called at least every 24 days. |
| // Note that we do not use GetTickCount() here, since timeGetTime() gives |
| // more predictable delta values, as described here: |
| // http://blogs.msdn.com/b/larryosterman/archive/2009/09/02/what-s-the-difference-between-gettickcount-and-timegettime.aspx |
| // timeGetTime() provides 1ms granularity when combined with |
| // timeBeginPeriod(). If the host application for V8 wants fast timers, it |
| // can use timeBeginPeriod() to increase the resolution. |
| // We use a lock-free version because the sampler thread calls it |
| // while having the rest of the world stopped, that could cause a deadlock. |
| base::Atomic32 rollover = base::Acquire_Load(&rollover_); |
| uint32_t now = static_cast<uint32_t>(timeGetTime()); |
| if ((now >> 31) != static_cast<uint32_t>(rollover & 1)) { |
| base::Release_CompareAndSwap(&rollover_, rollover, rollover + 1); |
| ++rollover; |
| } |
| uint64_t ms = (static_cast<uint64_t>(rollover) << 31) | now; |
| return static_cast<int64_t>(ms * Time::kMicrosecondsPerMillisecond); |
| } |
| |
| bool IsHighResolution() override { return false; } |
| |
| private: |
| base::Atomic32 rollover_; |
| }; |
| |
| |
| static LazyStaticInstance<RolloverProtectedTickClock, |
| DefaultConstructTrait<RolloverProtectedTickClock>, |
| ThreadSafeInitOnceTrait>::type tick_clock = |
| LAZY_STATIC_INSTANCE_INITIALIZER; |
| |
| |
| struct CreateHighResTickClockTrait { |
| static TickClock* Create() { |
| // Check if the installed hardware supports a high-resolution performance |
| // counter, and if not fallback to the low-resolution tick clock. |
| LARGE_INTEGER ticks_per_second; |
| if (!QueryPerformanceFrequency(&ticks_per_second)) { |
| return tick_clock.Pointer(); |
| } |
| |
| // If QPC not reliable, fallback to low-resolution tick clock. |
| if (IsQPCReliable()) { |
| return tick_clock.Pointer(); |
| } |
| |
| return new HighResolutionTickClock(ticks_per_second.QuadPart); |
| } |
| }; |
| |
| |
| static LazyDynamicInstance<TickClock, CreateHighResTickClockTrait, |
| ThreadSafeInitOnceTrait>::type high_res_tick_clock = |
| LAZY_DYNAMIC_INSTANCE_INITIALIZER; |
| |
| // static |
| TimeTicks TimeTicks::Now() { |
| // Make sure we never return 0 here. |
| TimeTicks ticks(tick_clock.Pointer()->Now()); |
| DCHECK(!ticks.IsNull()); |
| return ticks; |
| } |
| |
| // static |
| TimeTicks TimeTicks::HighResolutionNow() { |
| // Make sure we never return 0 here. |
| TimeTicks ticks(high_res_tick_clock.Pointer()->Now()); |
| DCHECK(!ticks.IsNull()); |
| return ticks; |
| } |
| |
| |
| // static |
| bool TimeTicks::IsHighResolutionClockWorking() { |
| return high_res_tick_clock.Pointer()->IsHighResolution(); |
| } |
| |
| #else // V8_OS_WIN |
| |
| TimeTicks TimeTicks::Now() { |
| return HighResolutionNow(); |
| } |
| |
| |
| TimeTicks TimeTicks::HighResolutionNow() { |
| int64_t ticks; |
| #if V8_OS_MACOSX |
| static struct mach_timebase_info info; |
| if (info.denom == 0) { |
| kern_return_t result = mach_timebase_info(&info); |
| DCHECK_EQ(KERN_SUCCESS, result); |
| USE(result); |
| } |
| ticks = (mach_absolute_time() / Time::kNanosecondsPerMicrosecond * |
| info.numer / info.denom); |
| #elif V8_OS_SOLARIS |
| ticks = (gethrtime() / Time::kNanosecondsPerMicrosecond); |
| #elif V8_OS_POSIX |
| ticks = ClockNow(CLOCK_MONOTONIC); |
| #elif V8_OS_STARBOARD |
| ticks = SbTimeGetMonotonicNow(); |
| #else |
| #error platform does not implement TimeTicks::HighResolutionNow. |
| #endif // V8_OS_MACOSX |
| // Make sure we never return 0 here. |
| return TimeTicks(ticks + 1); |
| } |
| |
| |
| // static |
| bool TimeTicks::IsHighResolutionClockWorking() { |
| return true; |
| } |
| |
| #endif // V8_OS_WIN |
| |
| |
| bool ThreadTicks::IsSupported() { |
| #if V8_OS_STARBOARD |
| #if SB_HAS(TIME_THREAD_NOW) |
| return true; |
| #else |
| return false; |
| #endif |
| #elif (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \ |
| defined(V8_OS_MACOSX) || defined(V8_OS_ANDROID) || defined(V8_OS_SOLARIS) |
| return true; |
| #elif defined(V8_OS_WIN) |
| return IsSupportedWin(); |
| #else |
| return false; |
| #endif |
| } |
| |
| |
| ThreadTicks ThreadTicks::Now() { |
| #if V8_OS_STARBOARD |
| #if SB_HAS(TIME_THREAD_NOW) |
| return ThreadTicks(SbTimeGetMonotonicThreadNow()); |
| #else |
| UNREACHABLE(); |
| #endif |
| #elif V8_OS_MACOSX |
| return ThreadTicks(ComputeThreadTicks()); |
| #elif(defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \ |
| defined(V8_OS_ANDROID) |
| return ThreadTicks(ClockNow(CLOCK_THREAD_CPUTIME_ID)); |
| #elif V8_OS_SOLARIS |
| return ThreadTicks(gethrvtime() / Time::kNanosecondsPerMicrosecond); |
| #elif V8_OS_WIN |
| return ThreadTicks::GetForThread(::GetCurrentThread()); |
| #else |
| UNREACHABLE(); |
| #endif |
| } |
| |
| |
| #if V8_OS_WIN |
| ThreadTicks ThreadTicks::GetForThread(const HANDLE& thread_handle) { |
| DCHECK(IsSupported()); |
| |
| // Get the number of TSC ticks used by the current thread. |
| ULONG64 thread_cycle_time = 0; |
| ::QueryThreadCycleTime(thread_handle, &thread_cycle_time); |
| |
| // Get the frequency of the TSC. |
| double tsc_ticks_per_second = TSCTicksPerSecond(); |
| if (tsc_ticks_per_second == 0) |
| return ThreadTicks(); |
| |
| // Return the CPU time of the current thread. |
| double thread_time_seconds = thread_cycle_time / tsc_ticks_per_second; |
| return ThreadTicks( |
| static_cast<int64_t>(thread_time_seconds * Time::kMicrosecondsPerSecond)); |
| } |
| |
| // static |
| bool ThreadTicks::IsSupportedWin() { |
| static bool is_supported = base::CPU().has_non_stop_time_stamp_counter() && |
| !IsQPCReliable(); |
| return is_supported; |
| } |
| |
| // static |
| void ThreadTicks::WaitUntilInitializedWin() { |
| while (TSCTicksPerSecond() == 0) |
| ::Sleep(10); |
| } |
| |
| double ThreadTicks::TSCTicksPerSecond() { |
| DCHECK(IsSupported()); |
| |
| // The value returned by QueryPerformanceFrequency() cannot be used as the TSC |
| // frequency, because there is no guarantee that the TSC frequency is equal to |
| // the performance counter frequency. |
| |
| // The TSC frequency is cached in a static variable because it takes some time |
| // to compute it. |
| static double tsc_ticks_per_second = 0; |
| if (tsc_ticks_per_second != 0) |
| return tsc_ticks_per_second; |
| |
| // Increase the thread priority to reduces the chances of having a context |
| // switch during a reading of the TSC and the performance counter. |
| int previous_priority = ::GetThreadPriority(::GetCurrentThread()); |
| ::SetThreadPriority(::GetCurrentThread(), THREAD_PRIORITY_HIGHEST); |
| |
| // The first time that this function is called, make an initial reading of the |
| // TSC and the performance counter. |
| static const uint64_t tsc_initial = __rdtsc(); |
| static const uint64_t perf_counter_initial = QPCNowRaw(); |
| |
| // Make a another reading of the TSC and the performance counter every time |
| // that this function is called. |
| uint64_t tsc_now = __rdtsc(); |
| uint64_t perf_counter_now = QPCNowRaw(); |
| |
| // Reset the thread priority. |
| ::SetThreadPriority(::GetCurrentThread(), previous_priority); |
| |
| // Make sure that at least 50 ms elapsed between the 2 readings. The first |
| // time that this function is called, we don't expect this to be the case. |
| // Note: The longer the elapsed time between the 2 readings is, the more |
| // accurate the computed TSC frequency will be. The 50 ms value was |
| // chosen because local benchmarks show that it allows us to get a |
| // stddev of less than 1 tick/us between multiple runs. |
| // Note: According to the MSDN documentation for QueryPerformanceFrequency(), |
| // this will never fail on systems that run XP or later. |
| // https://msdn.microsoft.com/library/windows/desktop/ms644905.aspx |
| LARGE_INTEGER perf_counter_frequency = {}; |
| ::QueryPerformanceFrequency(&perf_counter_frequency); |
| DCHECK_GE(perf_counter_now, perf_counter_initial); |
| uint64_t perf_counter_ticks = perf_counter_now - perf_counter_initial; |
| double elapsed_time_seconds = |
| perf_counter_ticks / static_cast<double>(perf_counter_frequency.QuadPart); |
| |
| const double kMinimumEvaluationPeriodSeconds = 0.05; |
| if (elapsed_time_seconds < kMinimumEvaluationPeriodSeconds) |
| return 0; |
| |
| // Compute the frequency of the TSC. |
| DCHECK_GE(tsc_now, tsc_initial); |
| uint64_t tsc_ticks = tsc_now - tsc_initial; |
| tsc_ticks_per_second = tsc_ticks / elapsed_time_seconds; |
| |
| return tsc_ticks_per_second; |
| } |
| #endif // V8_OS_WIN |
| |
| } // namespace base |
| } // namespace v8 |