Reland^2 "Add Chromium-style TimeDelta, Time and TimeTicks classes, and a new ElapsedTimer class."

src/platform/time.h

Index: src/platform/time.h
diff --git a/src/platform/time.h b/src/platform/time.h
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+// 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.
+
+#ifndef V8_PLATFORM_TIME_H_
+#define V8_PLATFORM_TIME_H_
+
+#include <ctime>
+#include <limits>
+
+#include "allocation.h"
+
+// Forward declarations.
+extern "C" {
+struct _FILETIME;
+struct timeval;
+}
+
+namespace v8 {
+namespace internal {
+
+class Time;
+class TimeTicks;
+
+// -----------------------------------------------------------------------------
+// TimeDelta
+//
+// This class represents a duration of time, internally represented in
+// microseonds.
+
+class TimeDelta V8_FINAL BASE_EMBEDDED {
+ public:
+  TimeDelta() : delta_(0) {}
+
+  // Converts units of time to TimeDeltas.
+  static TimeDelta FromDays(int days);
+  static TimeDelta FromHours(int hours);
+  static TimeDelta FromMinutes(int minutes);
+  static TimeDelta FromSeconds(int64_t seconds);
+  static TimeDelta FromMilliseconds(int64_t milliseconds);
+  static TimeDelta FromMicroseconds(int64_t microseconds) {
+    return TimeDelta(microseconds);
+  }
+  static TimeDelta FromNanoseconds(int64_t nanoseconds);
+
+  // Returns the time delta in some unit. The F versions return a floating
+  // point value, the "regular" versions return a rounded-down value.
+  //
+  // InMillisecondsRoundedUp() instead returns an integer that is rounded up
+  // to the next full millisecond.
+  int InDays() const;
+  int InHours() const;
+  int InMinutes() const;
+  double InSecondsF() const;
+  int64_t InSeconds() const;
+  double InMillisecondsF() const;
+  int64_t InMilliseconds() const;
+  int64_t InMillisecondsRoundedUp() const;
+  int64_t InMicroseconds() const { return delta_; }
+  int64_t InNanoseconds() const;
+
+  TimeDelta& operator=(const TimeDelta& other) {
+    delta_ = other.delta_;
+    return *this;
+  }
+
+  // Computations with other deltas.
+  TimeDelta operator+(const TimeDelta& other) const {
+    return TimeDelta(delta_ + other.delta_);
+  }
+  TimeDelta operator-(const TimeDelta& other) const {
+    return TimeDelta(delta_ - other.delta_);
+  }
+
+  TimeDelta& operator+=(const TimeDelta& other) {
+    delta_ += other.delta_;
+    return *this;
+  }
+  TimeDelta& operator-=(const TimeDelta& other) {
+    delta_ -= other.delta_;
+    return *this;
+  }
+  TimeDelta operator-() const {
+    return TimeDelta(-delta_);
+  }
+
+  double TimesOf(const TimeDelta& other) const {
+    return static_cast<double>(delta_) / static_cast<double>(other.delta_);
+  }
+  double PercentOf(const TimeDelta& other) const {
+    return TimesOf(other) * 100.0;
+  }
+
+  // Computations with ints, note that we only allow multiplicative operations
+  // with ints, and additive operations with other deltas.
+  TimeDelta operator*(int64_t a) const {
+    return TimeDelta(delta_ * a);
+  }
+  TimeDelta operator/(int64_t a) const {
+    return TimeDelta(delta_ / a);
+  }
+  TimeDelta& operator*=(int64_t a) {
+    delta_ *= a;
+    return *this;
+  }
+  TimeDelta& operator/=(int64_t a) {
+    delta_ /= a;
+    return *this;
+  }
+  int64_t operator/(const TimeDelta& other) const {
+    return delta_ / other.delta_;
+  }
+
+  // Comparison operators.
+  bool operator==(const TimeDelta& other) const {
+    return delta_ == other.delta_;
+  }
+  bool operator!=(const TimeDelta& other) const {
+    return delta_ != other.delta_;
+  }
+  bool operator<(const TimeDelta& other) const {
+    return delta_ < other.delta_;
+  }
+  bool operator<=(const TimeDelta& other) const {
+    return delta_ <= other.delta_;
+  }
+  bool operator>(const TimeDelta& other) const {
+    return delta_ > other.delta_;
+  }
+  bool operator>=(const TimeDelta& other) const {
+    return delta_ >= other.delta_;
+  }
+
+ private:
+  // Constructs a delta given the duration in microseconds. This is private
+  // to avoid confusion by callers with an integer constructor. Use
+  // FromSeconds, FromMilliseconds, etc. instead.
+  explicit TimeDelta(int64_t delta) : delta_(delta) {}
+
+  // Delta in microseconds.
+  int64_t delta_;
+};
+
+
+// -----------------------------------------------------------------------------
+// Time
+//
+// This class represents an absolute point in time, internally represented as
+// microseconds (s/1,000,000) since 00:00:00 UTC, January 1, 1970.
+
+class Time V8_FINAL BASE_EMBEDDED {
+ public:
+  static const int64_t kMillisecondsPerSecond = 1000;
+  static const int64_t kMicrosecondsPerMillisecond = 1000;
+  static const int64_t kMicrosecondsPerSecond = kMicrosecondsPerMillisecond *
+                                                kMillisecondsPerSecond;
+  static const int64_t kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60;
+  static const int64_t kMicrosecondsPerHour = kMicrosecondsPerMinute * 60;
+  static const int64_t kMicrosecondsPerDay = kMicrosecondsPerHour * 24;
+  static const int64_t kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;
+  static const int64_t kNanosecondsPerMicrosecond = 1000;
+  static const int64_t kNanosecondsPerSecond = kNanosecondsPerMicrosecond *
+                                               kMicrosecondsPerSecond;
+
+  // Contains the NULL time. Use Time::Now() to get the current time.
+  Time() : us_(0) {}
+
+  // Returns true if the time object has not been initialized.
+  bool IsNull() const { return us_ == 0; }
+
+  // Returns true if the time object is the maximum time.
+  bool IsMax() const { return us_ == std::numeric_limits<int64_t>::max(); }
+
+  // Returns the current time. Watch out, the system might adjust its clock
+  // in which case time will actually go backwards. We don't guarantee that
+  // times are increasing, or that two calls to Now() won't be the same.
+  static Time Now();
+
+  // Returns the current time. Same as Now() except that this function always
+  // uses system time so that there are no discrepancies between the returned
+  // time and system time even on virtual environments including our test bot.
+  // For timing sensitive unittests, this function should be used.
+  static Time NowFromSystemTime();
+
+  // Returns the time for epoch in Unix-like system (Jan 1, 1970).
+  static Time UnixEpoch() { return Time(0); }
+
+  // Returns the maximum time, which should be greater than any reasonable time
+  // with which we might compare it.
+  static Time Max() { return Time(std::numeric_limits<int64_t>::max()); }
+
+  // Converts to/from POSIX time values.
+  static Time FromTimeval(struct timeval tv);
+  struct timeval ToTimeval() const;
+
+  // Converts to/from Windows file times.
+  static Time FromFiletime(struct _FILETIME ft);
+  struct _FILETIME ToFiletime() const;
+
+  // Converts to/from the Javascript convention for times, a number of
+  // milliseconds since the epoch:
+  static Time FromJsTime(double ms_since_epoch);
+  double ToJsTime() const;
+
+  Time& operator=(const Time& other) {
+    us_ = other.us_;
+    return *this;
+  }
+
+  // Compute the difference between two times.
+  TimeDelta operator-(const Time& other) const {
+    return TimeDelta::FromMicroseconds(us_ - other.us_);
+  }
+
+  // Modify by some time delta.
+  Time& operator+=(const TimeDelta& delta) {
+    us_ += delta.InMicroseconds();
+    return *this;
+  }
+  Time& operator-=(const TimeDelta& delta) {
+    us_ -= delta.InMicroseconds();
+    return *this;
+  }
+
+  // Return a new time modified by some delta.
+  Time operator+(const TimeDelta& delta) const {
+    return Time(us_ + delta.InMicroseconds());
+  }
+  Time operator-(const TimeDelta& delta) const {
+    return Time(us_ - delta.InMicroseconds());
+  }
+
+  // Comparison operators
+  bool operator==(const Time& other) const {
+    return us_ == other.us_;
+  }
+  bool operator!=(const Time& other) const {
+    return us_ != other.us_;
+  }
+  bool operator<(const Time& other) const {
+    return us_ < other.us_;
+  }
+  bool operator<=(const Time& other) const {
+    return us_ <= other.us_;
+  }
+  bool operator>(const Time& other) const {
+    return us_ > other.us_;
+  }
+  bool operator>=(const Time& other) const {
+    return us_ >= other.us_;
+  }
+
+ private:
+  explicit Time(int64_t us) : us_(us) {}
+
+  // Time in microseconds in UTC.
+  int64_t us_;
+};
+
+inline Time operator+(const TimeDelta& delta, const Time& time) {
+  return time + delta;
+}
+
+
+// -----------------------------------------------------------------------------
+// TimeTicks
+//
+// This class represents an abstract time that is most of the time incrementing
+// for use in measuring time durations. It is internally represented in
+// microseconds.  It can not be converted to a human-readable time, but is
+// guaranteed not to decrease (if the user changes the computer clock,
+// Time::Now() may actually decrease or jump).  But note that TimeTicks may
+// "stand still", for example if the computer suspended.
+
+class TimeTicks V8_FINAL BASE_EMBEDDED {
+ public:
+  TimeTicks() : ticks_(0) {}
+
+  // Platform-dependent tick count representing "right now."
+  // The resolution of this clock is ~1-15ms.  Resolution varies depending
+  // on hardware/operating system configuration.
+  // This method never returns a null TimeTicks.
+  static TimeTicks Now();
+
+  // Returns a platform-dependent high-resolution tick count. Implementation
+  // is hardware dependent and may or may not return sub-millisecond
+  // resolution.  THIS CALL IS GENERALLY MUCH MORE EXPENSIVE THAN Now() AND
+  // SHOULD ONLY BE USED WHEN IT IS REALLY NEEDED.
+  // This method never returns a null TimeTicks.
+  static TimeTicks HighResNow();
+
+  // Returns true if this object has not been initialized.
+  bool IsNull() const { return ticks_ == 0; }
+
+  TimeTicks& operator=(const TimeTicks other) {
+    ticks_ = other.ticks_;
+    return *this;
+  }
+
+  // Compute the difference between two times.
+  TimeDelta operator-(const TimeTicks other) const {
+    return TimeDelta::FromMicroseconds(ticks_ - other.ticks_);
+  }
+
+  // Modify by some time delta.
+  TimeTicks& operator+=(const TimeDelta& delta) {
+    ticks_ += delta.InMicroseconds();
+    return *this;
+  }
+  TimeTicks& operator-=(const TimeDelta& delta) {
+    ticks_ -= delta.InMicroseconds();
+    return *this;
+  }
+
+  // Return a new TimeTicks modified by some delta.
+  TimeTicks operator+(const TimeDelta& delta) const {
+    return TimeTicks(ticks_ + delta.InMicroseconds());
+  }
+  TimeTicks operator-(const TimeDelta& delta) const {
+    return TimeTicks(ticks_ - delta.InMicroseconds());
+  }
+
+  // Comparison operators
+  bool operator==(const TimeTicks& other) const {
+    return ticks_ == other.ticks_;
+  }
+  bool operator!=(const TimeTicks& other) const {
+    return ticks_ != other.ticks_;
+  }
+  bool operator<(const TimeTicks& other) const {
+    return ticks_ < other.ticks_;
+  }
+  bool operator<=(const TimeTicks& other) const {
+    return ticks_ <= other.ticks_;
+  }
+  bool operator>(const TimeTicks& other) const {
+    return ticks_ > other.ticks_;
+  }
+  bool operator>=(const TimeTicks& other) const {
+    return ticks_ >= other.ticks_;
+  }
+
+ private:
+  // Please use Now() to create a new object. This is for internal use
+  // and testing. Ticks is in microseconds.
+  explicit TimeTicks(int64_t ticks) : ticks_(ticks) {}
+
+  // Tick count in microseconds.
+  int64_t ticks_;
+};
+
+inline TimeTicks operator+(const TimeDelta& delta, const TimeTicks& ticks) {
+  return ticks + delta;
+}
+
+} }  // namespace v8::internal
+
+#endif  // V8_PLATFORM_TIME_H_