Common: ensures thread safety of ffTimeInitQpcMultiplier

Author: CarterLi

src/common/impl/time.c

@@ -84,4 +84,12 @@ FFTimeGetAgeResult ffTimeGetAge(uint64_t birthMs, uint64_t nowMs)
 
 #ifdef _WIN32
     double ffQpcMultiplier;
+
+    __attribute__((constructor))
+    static void ffTimeInitQpcMultiplier(void)
+    {
+        LARGE_INTEGER frequency;
+        QueryPerformanceFrequency(&frequency);
+        ffQpcMultiplier = 1000. / (double) frequency.QuadPart;
+    }
 #endif

src/common/time.h

@@ -25,12 +25,6 @@ static inline double ffTimeGetTick(void) //In msec
 {
     #ifdef _WIN32
         extern double ffQpcMultiplier;
-        if (ffQpcMultiplier == 0)
-        {
-            LARGE_INTEGER frequency;
-            QueryPerformanceFrequency(&frequency);
-            ffQpcMultiplier = 1000. / (double) frequency.QuadPart;
-        }
         LARGE_INTEGER start;
         QueryPerformanceCounter(&start);
         return (double) start.QuadPart * ffQpcMultiplier;