Add base to the repository.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@8 0039d316-1c4b-4281-b951-d872f2087c98

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+// Copyright 2008, Google Inc.
+// 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.
+
+// Time represents an absolute point in time, internally represented as
+// microseconds (s/1,000,000) since a platform-dependent epoch.  Each
+// platform's epoch, along with other system-dependent clock interface
+// routines, is defined in time_PLATFORM.cc.
+//
+// TimeDelta represents a duration of time, internally represented in
+// microseconds.
+//
+// TimeTicks represents an abstract time that is always 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).
+//
+// These classes are represented as only a 64-bit value, so they can be
+// efficiently passed by value.
+
+#ifndef BASE_TIME_H__
+#define BASE_TIME_H__
+
+#ifdef WIN32
+// For FILETIME in FromFileTime, until it moves to a new converter class.
+// See TODO(iyengar) below.
+#include <windows.h>
+#endif
+
+#include <time.h>
+#include "base/basictypes.h"
+#include "testing/gtest/include/gtest/gtest_prod.h"
+
+class Time;
+class TimeTicks;
+
+// This unit test does a lot of manual time manipulation.
+class PageLoadTrackerUnitTest;
+
+// TimeDelta ------------------------------------------------------------------
+
+class TimeDelta {
+ public:
+  TimeDelta() : delta_(0) {
+  }
+
+  // Converts units of time to TimeDeltas.
+  static TimeDelta FromDays(int64 days);
+  static TimeDelta FromHours(int64 hours);
+  static TimeDelta FromMinutes(int64 minutes);
+  static TimeDelta FromSeconds(int64 secs);
+  static TimeDelta FromMilliseconds(int64 ms);
+  static TimeDelta FromMicroseconds(int64 us);
+
+  // Returns the internal numeric value of the TimeDelta object. Please don't
+  // use this and do arithmetic on it, as it is more error prone than using the
+  // provided operators.
+  int64 ToInternalValue() const {
+    return delta_;
+  }
+
+  // Returns the time delta in some unit. The F versions return a floating
+  // point value, the "regular" versions return a rounded-down value.
+  int InDays() const;
+  int InHours() const;
+  double InSecondsF() const;
+  int64 InSeconds() const;
+  double InMillisecondsF() const;
+  int64 InMilliseconds() const;
+  int64 InMicroseconds() const;
+
+  TimeDelta& operator=(TimeDelta other) {
+    delta_ = other.delta_;
+    return *this;
+  }
+
+  // Computations with other deltas.
+  TimeDelta operator+(TimeDelta other) const {
+    return TimeDelta(delta_ + other.delta_);
+  }
+  TimeDelta operator-(TimeDelta other) const {
+    return TimeDelta(delta_ - other.delta_);
+  }
+
+  TimeDelta& operator+=(TimeDelta other) {
+    delta_ += other.delta_;
+    return *this;
+  }
+  TimeDelta& operator-=(TimeDelta other) {
+    delta_ -= other.delta_;
+    return *this;
+  }
+  TimeDelta operator-() const {
+    return TimeDelta(-delta_);
+  }
+
+  // Computations with ints, note that we only allow multiplicative operations
+  // with ints, and additive operations with other deltas.
+  TimeDelta operator*(int64 a) const {
+    return TimeDelta(delta_ * a);
+  }
+  TimeDelta operator/(int64 a) const {
+    return TimeDelta(delta_ / a);
+  }
+  TimeDelta& operator*=(int64 a) {
+    delta_ *= a;
+    return *this;
+  }
+  TimeDelta& operator/=(int64 a) {
+    delta_ /= a;
+    return *this;
+  }
+  int64 operator/(TimeDelta a) const {
+    return delta_ / a.delta_;
+  }
+
+  // Defined below because it depends on the definition of the other classes.
+  Time operator+(Time t) const;
+  TimeTicks operator+(TimeTicks t) const;
+
+  // Comparison operators.
+  bool operator==(TimeDelta other) const {
+    return delta_ == other.delta_;
+  }
+  bool operator!=(TimeDelta other) const {
+    return delta_ != other.delta_;
+  }
+  bool operator<(TimeDelta other) const {
+    return delta_ < other.delta_;
+  }
+  bool operator<=(TimeDelta other) const {
+    return delta_ <= other.delta_;
+  }
+  bool operator>(TimeDelta other) const {
+    return delta_ > other.delta_;
+  }
+  bool operator>=(TimeDelta other) const {
+    return delta_ >= other.delta_;
+  }
+
+ private:
+  friend class Time;
+  friend class TimeTicks;
+  friend TimeDelta operator*(int64 a, TimeDelta td);
+
+  // 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 delta_us) : delta_(delta_us) {
+  }
+
+  // Delta in microseconds.
+  int64 delta_;
+};
+
+inline TimeDelta operator*(int64 a, TimeDelta td) {
+  return TimeDelta(a * td.delta_);
+}
+
+// Time -----------------------------------------------------------------------
+
+// Represents a wall clock time.
+class Time {
+ public:
+  static const int64 kMillisecondsPerSecond = 1000;
+  static const int64 kMicrosecondsPerMillisecond = 1000;
+  static const int64 kMicrosecondsPerSecond = kMicrosecondsPerMillisecond *
+                                              kMillisecondsPerSecond;
+  static const int64 kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60;
+  static const int64 kMicrosecondsPerHour = kMicrosecondsPerMinute * 60;
+  static const int64 kMicrosecondsPerDay = kMicrosecondsPerHour * 24;
+  static const int64 kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;
+
+  // Represents an exploded time that can be formatted nicely. This is kind of
+  // like the Win32 SYSTEMTIME structure or the Unix "struct tm" with a few
+  // additions and changes to prevent errors.
+  struct Exploded {
+    int year;          // Four digit year "2007"
+    int month;         // 1-based month (values 1 = January, etc.)
+    int day_of_week;   // 0-based day of week (0 = Sunday, etc.)
+    int day_of_month;  // 1-based day of month (1-31)
+    int hour;          // Hour within the current day (0-23)
+    int minute;        // Minute within the current hour (0-59)
+    int second;        // Second within the current minute (0-59 plus leap
+                       //   seconds which may take it up to 60).
+    int millisecond;   // Milliseconds within the current second (0-999)
+  };
+
+  // Contains the NULL time. Use Time::Now() to get the current time.
+  explicit Time() : us_(0) {
+  }
+
+  // Returns true if the time object has not been initialized.
+  bool is_null() const {
+    return us_ == 0;
+  }
+
+  // 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();
+
+  // Converts to/from time_t in UTC and a Time class.
+  // TODO(brettw) this should be removed once everybody starts using the |Time|
+  // class.
+  static Time FromTimeT(time_t tt);
+  time_t ToTimeT() const;
+
+  // Converts time to a double which is the number of seconds since epoch
+  // (Jan 1, 1970).  Webkit uses this format to represent time.
+  double ToDoubleT() const;
+
+#ifdef WIN32
+  static Time FromFileTime(FILETIME ft);
+  FILETIME ToFileTime() const;
+#endif
+
+  // Converts an exploded structure representing either the local time or UTC
+  // into a Time class.
+  static Time FromUTCExploded(const Exploded& exploded) {
+    return FromExploded(false, exploded);
+  }
+  static Time FromLocalExploded(const Exploded& exploded) {
+    return FromExploded(true, exploded);
+  }
+
+  // Converts an integer value representing Time to a class. This is used
+  // when deserializing a |Time| structure, using a value known to be
+  // compatible. It is not provided as a constructor because the integer type
+  // may be unclear from the perspective of a caller.
+  static Time FromInternalValue(int64 us) {
+    return Time(us);
+  }
+
+  // Converts a string representation of time to a Time object.
+  // An example of a time string which is converted is as below:-
+  // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified
+  // in the input string, we assume local time.
+  // TODO(iyengar) Move the FromString/FromTimeT/ToTimeT/FromFileTime to
+  // a new time converter class.
+  static bool FromString(const wchar_t* time_string, Time* parsed_time);
+
+  // For serializing, use FromInternalValue to reconstitute. Please don't use
+  // this and do arithmetic on it, as it is more error prone than using the
+  // provided operators.
+  int64 ToInternalValue() const {
+    return us_;
+  }
+
+  // Fills the given exploded structure with either the local time or UTC from
+  // this time structure (containing UTC).
+  void UTCExplode(Exploded* exploded) const {
+    return Explode(false, exploded);
+  }
+  void LocalExplode(Exploded* exploded) const {
+    return Explode(true, exploded);
+  }
+
+  // Rounds this time down to the nearest day in local time. It will represent
+  // midnight on that day.
+  Time LocalMidnight() const;
+
+  Time& operator=(Time other) {
+    us_ = other.us_;
+    return *this;
+  }
+
+  // Compute the difference between two times.
+  TimeDelta operator-(Time other) const {
+    return TimeDelta(us_ - other.us_);
+  }
+
+  // Modify by some time delta.
+  Time& operator+=(TimeDelta delta) {
+    us_ += delta.delta_;
+    return *this;
+  }
+  Time& operator-=(TimeDelta delta) {
+    us_ -= delta.delta_;
+    return *this;
+  }
+
+  // Return a new time modified by some delta.
+  Time operator+(TimeDelta delta) const {
+    return us_ + delta.delta_;
+  }
+  Time operator-(TimeDelta delta) const {
+    return us_ - delta.delta_;
+  }
+
+  // Comparison operators
+  bool operator==(Time other) const {
+    return us_ == other.us_;
+  }
+  bool operator!=(Time other) const {
+    return us_ != other.us_;
+  }
+  bool operator<(Time other) const {
+    return us_ < other.us_;
+  }
+  bool operator<=(Time other) const {
+    return us_ <= other.us_;
+  }
+  bool operator>(Time other) const {
+    return us_ > other.us_;
+  }
+  bool operator>=(Time other) const {
+    return us_ >= other.us_;
+  }
+
+ private:
+  friend class TimeDelta;
+
+  // Platform-dependent wall clock interface
+  static int64 CurrentWallclockMicroseconds();
+
+  // Initialize or resynchronize the clock.
+  static void InitializeClock();
+
+  // Explodes the given time to either local time |is_local = true| or UTC
+  // |is_local = false|.
+  void Explode(bool is_local, Exploded* exploded) const;
+
+  // Unexplodes a given time assuming the source is either local time
+  // |is_local = true| or UTC |is_local = false|.
+  static Time FromExploded(bool is_local, const Exploded& exploded);
+
+  Time(int64 us) : us_(us) {
+  }
+
+  // The representation of Jan 1, 1970 UTC in microseconds since the
+  // platform-dependent epoch.
+  static const int64 kTimeTToMicrosecondsOffset;
+
+  // Time in microseconds in UTC.
+  int64 us_;
+
+  // The initial time sampled via this API.
+  static int64 initial_time_;
+
+  // The initial clock counter sampled via this API.
+  static TimeTicks initial_ticks_;
+};
+
+inline Time TimeDelta::operator+(Time t) const {
+  return Time(t.us_ + delta_);
+}
+
+// TimeTicks ------------------------------------------------------------------
+
+class TimeTicks {
+ public:
+  TimeTicks() : ticks_(0) {
+  }
+
+  // Platform-dependent tick count representing "right now."
+  // The resolution of this clock is ~1-5ms.  Resolution varies depending
+  // on hardware/operating system configuration.
+  static TimeTicks Now();
+
+  // Returns a platform-dependent high-resolution tick count. IT IS BROKEN ON
+  // SOME HARDWARE and is designed to be used for profiling and perf testing
+  // only (see the impl for more information).
+  static TimeTicks UnreliableHighResNow();
+
+
+  // Returns true if this object has not been initialized.
+  bool is_null() const {
+    return ticks_ == 0;
+  }
+
+  TimeTicks& operator=(TimeTicks other) {
+    ticks_ = other.ticks_;
+    return *this;
+  }
+
+  // Compute the difference between two times.
+  TimeDelta operator-(TimeTicks other) const {
+    return TimeDelta(ticks_ - other.ticks_);
+  }
+
+  // Modify by some time delta.
+  TimeTicks& operator+=(TimeDelta delta) {
+    ticks_ += delta.delta_;
+    return *this;
+  }
+  TimeTicks& operator-=(TimeDelta delta) {
+    ticks_ -= delta.delta_;
+    return *this;
+  }
+
+  // Return a new TimeTicks modified by some delta.
+  TimeTicks operator+(TimeDelta delta) const {
+    return TimeTicks(ticks_ + delta.delta_);
+  }
+  TimeTicks operator-(TimeDelta delta) const {
+    return TimeTicks(ticks_ - delta.delta_);
+  }
+
+  // Comparison operators
+  bool operator==(TimeTicks other) const {
+    return ticks_ == other.ticks_;
+  }
+  bool operator!=(TimeTicks other) const {
+    return ticks_ != other.ticks_;
+  }
+  bool operator<(TimeTicks other) const {
+    return ticks_ < other.ticks_;
+  }
+  bool operator<=(TimeTicks other) const {
+    return ticks_ <= other.ticks_;
+  }
+  bool operator>(TimeTicks other) const {
+    return ticks_ > other.ticks_;
+  }
+  bool operator>=(TimeTicks other) const {
+    return ticks_ >= other.ticks_;
+  }
+
+ protected:
+  friend class TimeDelta;
+  friend class PageLoadTrackerUnitTest;
+
+  // Please use Now() to create a new object. This is for internal use
+  // and testing. Ticks is in microseconds.
+  explicit TimeTicks(int64 ticks) : ticks_(ticks) {
+  }
+
+  // Tick count in microseconds.
+  int64 ticks_;
+
+#ifdef WIN32
+  // The function to use for counting ticks.
+  typedef int (__stdcall *TickFunction)(void);
+  static TickFunction tick_function_;
+#endif
+};
+
+inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
+  return TimeTicks(t.ticks_ + delta_);
+}
+
+#endif  // BASE_TIME_H__