CSE2410 Fall 2014 Bounce

// Copyright 2013 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "platform/time.h"

#if V8_OS_POSIX

#include <sys/time.h>

#endif

#if V8_OS_MACOSX

#include <mach/mach_time.h>

#endif

#include <cstring>

#include "checks.h"

#include "cpu.h"

#include "platform.h"

#if V8_OS_WIN

#include "win32-headers.h"

#endif

namespace v8 {

namespace internal {

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) {

  ASSERT_GE(ts.tv_nsec, 0);

  ASSERT_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;

  ASSERT(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) {

  ASSERT_GE(ts.tv_nsec, 0);

  ASSERT_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 {

  ASSERT(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);

  ASSERT_EQ(0, result);

  USE(result);

  return FromTimeval(tv);

}

Time Time::NowFromSystemTime() {

  return Now();

}

Time Time::FromTimespec(struct timespec ts) {

  ASSERT(ts.tv_nsec >= 0);

  ASSERT(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) {

  ASSERT(tv.tv_usec >= 0);

  ASSERT(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) {

    ASSERT_LT(0, ticks_per_second);

  }

  virtual ~HighResolutionTickClock() {}

  virtual int64_t Now() V8_OVERRIDE {

    LARGE_INTEGER now;

    BOOL result = QueryPerformanceCounter(&now);

    ASSERT(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());

  ASSERT(!ticks.IsNull());

  return ticks;

}

TimeTicks TimeTicks::HighResolutionNow() {

  // Make sure we never return 0 here.

  TimeTicks ticks(high_res_tick_clock.Pointer()->Now());

  ASSERT(!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);

    ASSERT_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);

  ASSERT_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);

  ASSERT_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;

}

#endif  // V8_OS_WIN

} }  // namespace v8::internal