Initialize standalone embedder's copy of the monotonic clock on Windows.

runtime/bin/utils_win.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include <errno.h>  // NOLINT
 #include <time.h>  // NOLINT
 
@@ skipping 169 matching lines @@
   // 100-nanosecond intervals since January 1, 1601.
   union TimeStamp {
     FILETIME ft_;
     int64_t t_;
   };
   TimeStamp time;
   GetSystemTimeAsFileTime(&time.ft_);
   return (time.t_ - kTimeEpoc) / kTimeScaler;
 }
 
+static int64_t qpc_ticks_per_second = 0;
+
+void TimerUtils::InitOnce() {
+  LARGE_INTEGER ticks_per_sec;
+  if (!QueryPerformanceFrequency(&ticks_per_sec)) {
+    qpc_ticks_per_second = 0;
+  } else {
+    qpc_ticks_per_second = static_cast<int64_t>(ticks_per_sec.QuadPart);
+  }
+}
+
 int64_t TimerUtils::GetCurrentMonotonicMillis() {
   return GetCurrentMonotonicMicros() / 1000;
 }
 
-static int64_t qpc_ticks_per_second = 0;
-
 int64_t TimerUtils::GetCurrentMonotonicMicros() {
   if (qpc_ticks_per_second == 0) {
     // QueryPerformanceCounter not supported, fallback.
     return GetCurrentTimeMicros();
   }
   // Grab performance counter value.
   LARGE_INTEGER now;
   QueryPerformanceCounter(&now);
   int64_t qpc_value = static_cast<int64_t>(now.QuadPart);
   // Convert to microseconds.
   int64_t seconds = qpc_value / qpc_ticks_per_second;
   int64_t leftover_ticks = qpc_value - (seconds * qpc_ticks_per_second);
   int64_t result = seconds * kMicrosecondsPerSecond;
   result += ((leftover_ticks * kMicrosecondsPerSecond) / qpc_ticks_per_second);
   return result;
 }
 
 void TimerUtils::Sleep(int64_t millis) {
   ::Sleep(millis);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)