From bb15c0e268906c01dd120449eb46f4821cf3e30b Mon Sep 17 00:00:00 2001
From: Bert Belder <bertbelder@gmail.com>
Date: Sun, 11 Sep 2011 22:54:16 +0200
Subject: [PATCH] win: make uv_hrtime() thread-safe

---
 src/win/timer.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/src/win/timer.c b/src/win/timer.c
index c21ea6ec..ac209252 100644
--- a/src/win/timer.c
+++ b/src/win/timer.c
@@ -33,7 +33,7 @@
 /* The resolution of the high-resolution clock. */
 static int64_t uv_ticks_per_msec_ = 0;
 static uint64_t uv_hrtime_frequency_ = 0;
-static char uv_hrtime_initialized_ = 0;
+static uv_once_t uv_hrtime_init_guard_ = UV_ONCE_INIT;
 
 
 void uv_update_time(uv_loop_t* loop) {
@@ -57,23 +57,23 @@ int64_t uv_now(uv_loop_t* loop) {
   return loop->time;
 }
 
-/* TODO: thread safety */
+
+static void uv_hrtime_init(void) {
+  LARGE_INTEGER frequency;
+
+  if (!QueryPerformanceFrequency(&frequency)) {
+    uv_hrtime_frequency_ = 0;
+    return;
+  }
+
+  uv_hrtime_frequency_ = frequency.QuadPart;
+}
+
+
 uint64_t uv_hrtime(void) {
   LARGE_INTEGER counter;
 
-  /* When called for the first time, obtain the high-resolution clock */
-  /* frequency. */
-  if (!uv_hrtime_initialized_) {
-    uv_hrtime_initialized_ = 1;
-
-    if (!QueryPerformanceFrequency(&counter)) {
-      uv_hrtime_frequency_ = 0;
-      /* uv_set_sys_error(loop, GetLastError()); */
-      return 0;
-    }
-
-    uv_hrtime_frequency_ = counter.QuadPart;
-  }
+  uv_once(&uv_hrtime_init_guard_, uv_hrtime_init);
 
   /* If the performance frequency is zero, there's no support. */
   if (!uv_hrtime_frequency_) {