Fuchsia port of base/time, with some refactoring of POSIX time modules.

base/time/time.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Time represents an absolute point in coordinated universal time (UTC),
 // internally represented as microseconds (s/1,000,000) since the Windows epoch
 // (1601-01-01 00:00:00 UTC). System-dependent clock interface routines are
 // defined in time_PLATFORM.cc. Note that values for Time may skew and jump
 // around as the operating system makes adjustments to synchronize (e.g., with
 // NTP servers). Thus, client code that uses the Time class must account for
@@ skipping 45 matching lines @@
 
 #include <iosfwd>
 #include <limits>
 
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/numerics/safe_math.h"
 #include "build/build_config.h"
 
+#if defined(OS_FUCHSIA)
+#include <magenta/types.h>
+#endif
+
 #if defined(OS_MACOSX)
 #include <CoreFoundation/CoreFoundation.h>
 // Avoid Mac system header macro leak.
 #undef TYPE_BOOL
 #endif
 
 #if defined(OS_POSIX)
 #include <unistd.h>
 #include <sys/time.h>
 #endif
@@ skipping 330 matching lines @@
 inline TimeClass operator+(TimeDelta delta, TimeClass t) {
   return t + delta;
 }
 
 // Time -----------------------------------------------------------------------
 
 // Represents a wall clock time in UTC. Values are not guaranteed to be
 // monotonically non-decreasing and are subject to large amounts of skew.
 class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
  public:
-  // The representation of Jan 1, 1970 UTC in microseconds since the
-  // platform-dependent epoch.
-  static const int64_t kTimeTToMicrosecondsOffset;
+  // Offset of UNIX epoch (1970-01-01 00:00:00 UTC) from Windows FILETIME epoch
+  // (1601-01-01 00:00:00 UTC), in microseconds. This value is derived from the
+  // following: ((1970-1601)*365+89)*24*60*60*1000*1000, where 89 is the number
+  // of leap year days between 1601 and 1970: (1970-1601)/4 excluding 1700,
+  // 1800, and 1900.
+  static constexpr int64_t kTimeTToMicrosecondsOffset =
+      INT64_C(11644473600000000);
 
-#if !defined(OS_WIN)
-  // On Mac & Linux, this value is the delta from the Windows epoch of 1601 to
-  // the Posix delta of 1970. This is used for migrating between the old
-  // 1970-based epochs to the new 1601-based ones. It should be removed from
-  // this global header and put in the platform-specific ones when we remove the
-  // migration code.
-  static const int64_t kWindowsEpochDeltaMicroseconds;
-#else
+#if defined(OS_WIN)
   // To avoid overflow in QPC to Microseconds calculations, since we multiply
   // by kMicrosecondsPerSecond, then the QPC value should not exceed
   // (2^63 - 1) / 1E6. If it exceeds that threshold, we divide then multiply.
-  enum : int64_t{kQPCOverflowThreshold = 0x8637BD05AF7};
+  static constexpr int64_t kQPCOverflowThreshold = INT64_C(0x8637BD05AF7);
 #endif
 
   // 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 BASE_EXPORT 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)
@@ skipping 252 matching lines @@
 // For logging use only.
 BASE_EXPORT std::ostream& operator<<(std::ostream& os, Time time);
 
 // TimeTicks ------------------------------------------------------------------
 
 // Represents monotonically non-decreasing clock time.
 class BASE_EXPORT TimeTicks : public time_internal::TimeBase<TimeTicks> {
  public:
   // The underlying clock used to generate new TimeTicks.
   enum class Clock {
+    FUCHSIA_MX_CLOCK_MONOTONIC,
     LINUX_CLOCK_MONOTONIC,
     IOS_CF_ABSOLUTE_TIME_MINUS_KERN_BOOTTIME,
     MAC_MACH_ABSOLUTE_TIME,
     WIN_QPC,
     WIN_ROLLOVER_PROTECTED_TIME_GET_TIME
   };
 
   TimeTicks() : TimeBase(0) {
   }
 
   // Platform-dependent tick count representing "right now." When
   // IsHighResolution() returns false, the resolution of the clock could be
   // as coarse as ~15.6ms. Otherwise, the resolution should be no worse than one
   // microsecond.
   static TimeTicks Now();
 
   // Returns true if the high resolution clock is working on this system and
   // Now() will return high resolution values. Note that, on systems where the
   // high resolution clock works but is deemed inefficient, the low resolution
   // clock will be used instead.
   static bool IsHighResolution() WARN_UNUSED_RESULT;
 
   // Returns true if TimeTicks is consistent across processes, meaning that
   // timestamps taken on different processes can be safely compared with one
   // another. (Note that, even on platforms where this returns true, time values
   // from different threads that are within one tick of each other must be
   // considered to have an ambiguous ordering.)
   static bool IsConsistentAcrossProcesses() WARN_UNUSED_RESULT;
 
+#if defined(OS_FUCHSIA)
+  // Creates a TimeTicks from a mx_time_t value. Note that the mx_time_t value
+  // is interpreted in terms of the MX_CLOCK_MONOTONIC clock.
+  static TimeTicks FromMXTime(mx_time_t nanos_since_boot);
+#endif
+
 #if defined(OS_WIN)
   // Translates an absolute QPC timestamp into a TimeTicks value. The returned
   // value has the same origin as Now(). Do NOT attempt to use this if
   // IsHighResolution() returns false.
   static TimeTicks FromQPCValue(LONGLONG qpc_value);
 #endif
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   static TimeTicks FromMachAbsoluteTime(uint64_t mach_absolute_time);
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
@@ skipping 41 matching lines @@
 // Represents a clock, specific to a particular thread, than runs only while the
 // thread is running.
 class BASE_EXPORT ThreadTicks : public time_internal::TimeBase<ThreadTicks> {
  public:
   ThreadTicks() : TimeBase(0) {
   }
 
   // Returns true if ThreadTicks::Now() is supported on this system.
   static bool IsSupported() WARN_UNUSED_RESULT {
 #if (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \
-    (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_ANDROID)
+    (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_ANDROID) ||  \
+    defined(OS_FUCHSIA)
     return true;
 #elif defined(OS_WIN)
     return IsSupportedWin();
 #else
     return false;
 #endif
   }
 
   // Waits until the initialization is completed. Needs to be guarded with a
   // call to IsSupported().
@@ skipping 39 matching lines @@
   static void WaitUntilInitializedWin();
 #endif
 };
 
 // For logging use only.
 BASE_EXPORT std::ostream& operator<<(std::ostream& os, ThreadTicks time_ticks);
 
 }  // namespace base
 
 #endif  // BASE_TIME_TIME_H_