为什么铬执行时间::现在?好处是什么

why did the chromium implement Time::Now ? what is the benefit?

本文关键字：是什么 现在 执行时间 为什么      更新时间：2023-10-16

代码段如下，代码来自铬，为什么？

// Initilalize initial_ticks and initial_time
void InitializeClock() {
  initial_ticks = TimeTicks::Now();
  // Initilalize initial_time 
  initial_time = CurrentWallclockMicroseconds();
}// static
Time Time::Now() {
  if (initial_time == 0)
    InitializeClock();
  // We implement time using the high-resolution timers so that we can get
  // timeouts which are smaller than 10-15ms.  If we just used
  // CurrentWallclockMicroseconds(), we'd have the less-granular timer.
  //
  // To make this work, we initialize the clock (initial_time) and the
  // counter (initial_ctr).  To compute the initial time, we can check
  // the number of ticks that have elapsed, and compute the delta.
  //
  // To avoid any drift, we periodically resync the counters to the system
  // clock.
  while (true) {
    TimeTicks ticks = TimeTicks::Now();
    // Calculate the time elapsed since we started our timer
    TimeDelta elapsed = ticks - initial_ticks;
    // Check if enough time has elapsed that we need to resync the clock.
    if (elapsed.InMilliseconds() > kMaxMillisecondsToAvoidDrift) {
      InitializeClock();
      continue;
    }
    return Time(elapsed + Time(initial_time));
  }
}

我认为你的答案在于你粘贴的代码的注释：

// We implement time using the high-resolution timers so that we can get
// timeouts which are smaller than 10-15ms.  If we just used
// CurrentWallclockMicroseconds(), we'd have the less-granular timer.

因此，Now给出了一个高分辨率的时间值，当您需要高于10-15ms的分辨率时，这是有益的，正如他们在评论中所说的那样。例如，如果你想每100 ns重新安排一个任务，你需要更高的分辨率，或者如果你想测量某个任务的执行时间——10-15毫秒是永恒的。

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