deps/v8/src/base/platform/time.cc
// 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_time.h>
#endif
#include <string.h>
#if V8_OS_WIN
#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"
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(delta_ >= 0);
ts.tv_sec = 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 = 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 V8_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 = V8_INT64_C(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(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, NULL);
DCHECK_EQ(0, result);
USE(result);
return FromTimeval(tv);
}
Time Time::NowFromSystemTime() {
return Now();
}
Time Time::FromTimespec(struct timespec ts) {
DCHECK(ts.tv_nsec >= 0);
DCHECK(ts.tv_nsec < static_cast<long>(kNanosecondsPerSecond)); // NOLINT
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 = us_ / kMicrosecondsPerSecond;
ts.tv_nsec = (us_ % kMicrosecondsPerSecond) * kNanosecondsPerMicrosecond;
return ts;
}
Time Time::FromTimeval(struct timeval tv) {
DCHECK(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 = us_ / kMicrosecondsPerSecond;
tv.tv_usec = us_ % kMicrosecondsPerSecond;
return tv;
}
#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;
}
#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 V8_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() {}
virtual int64_t Now() V8_OVERRIDE {
LARGE_INTEGER now;
BOOL result = QueryPerformanceCounter(&now);
DCHECK(result);
USE(result);
// Intentionally calculate microseconds in a round about manner to avoid
// overflow and precision issues. Think twice before simplifying!
int64_t whole_seconds = now.QuadPart / ticks_per_second_;
int64_t leftover_ticks = now.QuadPart % 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;
}
virtual bool IsHighResolution() V8_OVERRIDE {
return true;
}
private:
int64_t ticks_per_second_;
};
class RolloverProtectedTickClock V8_FINAL : public TickClock {
public:
// We initialize rollover_ms_ to 1 to ensure that we will never
// return 0 from TimeTicks::HighResolutionNow() and TimeTicks::Now() below.
RolloverProtectedTickClock() : last_seen_now_(0), rollover_ms_(1) {}
virtual ~RolloverProtectedTickClock() {}
virtual int64_t Now() V8_OVERRIDE {
LockGuard<Mutex> lock_guard(&mutex_);
// 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 49 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.
DWORD now = timeGetTime();
if (now < last_seen_now_) {
rollover_ms_ += V8_INT64_C(0x100000000); // ~49.7 days.
}
last_seen_now_ = now;
return (now + rollover_ms_) * Time::kMicrosecondsPerMillisecond;
}
virtual bool IsHighResolution() V8_OVERRIDE {
return false;
}
private:
Mutex mutex_;
DWORD last_seen_now_;
int64_t rollover_ms_;
};
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();
}
// On Athlon X2 CPUs (e.g. model 15) the QueryPerformanceCounter
// is unreliable, fallback to the low-resolution tick clock.
CPU cpu;
if (strcmp(cpu.vendor(), "AuthenticAMD") == 0 && cpu.family() == 15) {
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;
TimeTicks TimeTicks::Now() {
// Make sure we never return 0 here.
TimeTicks ticks(tick_clock.Pointer()->Now());
DCHECK(!ticks.IsNull());
return ticks;
}
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();
}
// static
TimeTicks TimeTicks::KernelTimestampNow() { return TimeTicks(0); }
// static
bool TimeTicks::KernelTimestampAvailable() { return false; }
#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_LIBRT_NOT_AVAILABLE
// TODO(bmeurer): This is a temporary hack to support cross-compiling
// Chrome for Android in AOSP. Remove this once AOSP is fixed, also
// cleanup the tools/gyp/v8.gyp file.
struct timeval tv;
int result = gettimeofday(&tv, NULL);
DCHECK_EQ(0, result);
USE(result);
ticks = (tv.tv_sec * Time::kMicrosecondsPerSecond + tv.tv_usec);
#elif V8_OS_POSIX
struct timespec ts;
int result = clock_gettime(CLOCK_MONOTONIC, &ts);
DCHECK_EQ(0, result);
USE(result);
ticks = (ts.tv_sec * Time::kMicrosecondsPerSecond +
ts.tv_nsec / Time::kNanosecondsPerMicrosecond);
#endif // V8_OS_MACOSX
// Make sure we never return 0 here.
return TimeTicks(ticks + 1);
}
// static
bool TimeTicks::IsHighResolutionClockWorking() {
return true;
}
#if V8_OS_LINUX && !V8_LIBRT_NOT_AVAILABLE
class KernelTimestampClock {
public:
KernelTimestampClock() : clock_fd_(-1), clock_id_(kClockInvalid) {
clock_fd_ = open(kTraceClockDevice, O_RDONLY);
if (clock_fd_ == -1) {
return;
}
clock_id_ = get_clockid(clock_fd_);
}
virtual ~KernelTimestampClock() {
if (clock_fd_ != -1) {
close(clock_fd_);
}
}
int64_t Now() {
if (clock_id_ == kClockInvalid) {
return 0;
}
struct timespec ts;
clock_gettime(clock_id_, &ts);
return ((int64_t)ts.tv_sec * kNsecPerSec) + ts.tv_nsec;
}
bool Available() { return clock_id_ != kClockInvalid; }
private:
static const clockid_t kClockInvalid = -1;
static const char kTraceClockDevice[];
static const uint64_t kNsecPerSec = 1000000000;
int clock_fd_;
clockid_t clock_id_;
static int get_clockid(int fd) { return ((~(clockid_t)(fd) << 3) | 3); }
};
// Timestamp module name
const char KernelTimestampClock::kTraceClockDevice[] = "/dev/trace_clock";
#else
class KernelTimestampClock {
public:
KernelTimestampClock() {}
int64_t Now() { return 0; }
bool Available() { return false; }
};
#endif // V8_OS_LINUX && !V8_LIBRT_NOT_AVAILABLE
static LazyStaticInstance<KernelTimestampClock,
DefaultConstructTrait<KernelTimestampClock>,
ThreadSafeInitOnceTrait>::type kernel_tick_clock =
LAZY_STATIC_INSTANCE_INITIALIZER;
// static
TimeTicks TimeTicks::KernelTimestampNow() {
return TimeTicks(kernel_tick_clock.Pointer()->Now());
}
// static
bool TimeTicks::KernelTimestampAvailable() {
return kernel_tick_clock.Pointer()->Available();
}
#endif // V8_OS_WIN
} } // namespace v8::base