Adding the ability to use a simulated clock for unit tests.

webrtc/base/timeutils.cc

 /*
  *  Copyright 2004 The WebRTC 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 in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 12 matching lines @@
 #endif
 #include <windows.h>
 #include <mmsystem.h>
 #endif
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/timeutils.h"
 
 namespace rtc {
 
+ClockInterface* g_clock = nullptr;
+
+void SetClock(ClockInterface* clock) {
+  g_clock = clock;
+}
+
 uint64_t TimeNanos() {
-  int64_t ticks = 0;
+  if (g_clock) {
+    return g_clock->TimeNanos();
+  }
+  int64_t ticks;
 #if defined(WEBRTC_MAC)
   static mach_timebase_info_data_t timebase;
   if (timebase.denom == 0) {
     // Get the timebase if this is the first time we run.
     // Recommended by Apple's QA1398.
     if (mach_timebase_info(&timebase) != KERN_SUCCESS) {
       RTC_DCHECK(false);
     }
   }
   // Use timebase to convert absolute time tick units into nanoseconds.
   ticks = mach_absolute_time() * timebase.numer / timebase.denom;
 #elif defined(WEBRTC_POSIX)
   struct timespec ts;
-  // TODO: Do we need to handle the case when CLOCK_MONOTONIC
-  // is not supported?
+  // TODO(deadbeef): Do we need to handle the case when CLOCK_MONOTONIC is not
+  // supported?
   clock_gettime(CLOCK_MONOTONIC, &ts);
   ticks = kNumNanosecsPerSec * static_cast<int64_t>(ts.tv_sec) +
           static_cast<int64_t>(ts.tv_nsec);
 #elif defined(WEBRTC_WIN)
   static volatile LONG last_timegettime = 0;
   static volatile int64_t num_wrap_timegettime = 0;
   volatile LONG* last_timegettime_ptr = &last_timegettime;
   DWORD now = timeGetTime();
   // Atomically update the last gotten time
   DWORD old = InterlockedExchange(last_timegettime_ptr, now);
   if (now < old) {
-    // If now is earlier than old, there may have been a race between
-    // threads.
+    // If now is earlier than old, there may have been a race between threads.
     // 0x0fffffff ~3.1 days, the code will not take that long to execute
     // so it must have been a wrap around.
     if (old > 0xf0000000 && now < 0x0fffffff) {
       num_wrap_timegettime++;
     }
   }
   ticks = now + (num_wrap_timegettime << 32);
-  // TODO: Calculate with nanosecond precision.  Otherwise, we're just
-  // wasting a multiply and divide when doing Time() on Windows.
+  // TODO(deadbeef): Calculate with nanosecond precision. Otherwise, we're
+  // just wasting a multiply and divide when doing Time() on Windows.
   ticks = ticks * kNumNanosecsPerMillisec;
 #else
 #error Unsupported platform.
 #endif
   return ticks;
 }
 
 uint32_t Time32() {
   return static_cast<uint32_t>(TimeNanos() / kNumNanosecsPerMillisec);
 }
@@ skipping 79 matching lines @@
   if (expiry_in_leap_year && month <= 2 - 1) // |month| is zero based.
     day -= 1;
 
   // Combine all variables into seconds from 1970-01-01 00:00 (except |month|
   // which was accumulated into |day| above).
   return (((static_cast<int64_t>
             (year - 1970) * 365 + day) * 24 + hour) * 60 + min) * 60 + sec;
 }
 
 } // namespace rtc