osdep/timer-win2: use Waitable Timer for sleeping

Allows higher resolution sleeps than Sleep which has milliseconds
resolution. In practice Windows kernel does not really go below 0.5ms,
but we don't have to limit ourselves on API side of things and do the
best we can.

1 files changed, 31 insertions, 7 deletions

diff --git a/osdep/timer-win2.c b/osdep/timer-win2.c
index db4c39d7ef..7867b5a525 100644
--- a/osdep/timer-win2.c
+++ b/osdep/timer-win2.c
@@ -56,13 +56,37 @@ void mp_sleep_ns(int64_t ns)
 {
     if (ns < 0)
         return;
-    // Sleep(0) won't sleep for one clocktick as the unix usleep
-    // instead it will only make the thread ready
-    // it may take some time until it actually starts to run again
-    if (ns < 1e6)
-        ns = 1e6;
-    int hrt = mp_start_hires_timers(ns / 1e6);
-    Sleep(ns / 1e6);
+
+    int hrt = mp_start_hires_timers(ns < 1e6 ? 1 : ns / 1e6);
+
+#ifndef CREATE_WAITABLE_TIMER_HIGH_RESOLUTION
+#define CREATE_WAITABLE_TIMER_HIGH_RESOLUTION 0x2
+#endif
+
+    HANDLE timer = CreateWaitableTimerEx(NULL, NULL,
+                                         CREATE_WAITABLE_TIMER_HIGH_RESOLUTION,
+                                         TIMER_ALL_ACCESS);
+
+    // CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is supported in Windows 10 1803+,
+    // retry without it.
+    if (!timer)
+        timer = CreateWaitableTimerEx(NULL, NULL, 0, TIMER_ALL_ACCESS);
+
+    if (!timer)
+        goto end;
+
+    // Time is expected in 100 nanosecond intervals.
+    // Negative values indicate relative time.
+    LARGE_INTEGER time = (LARGE_INTEGER){ .QuadPart = -(ns / 100) };
+    if (!SetWaitableTimer(timer, &time, 0, NULL, NULL, 0))
+        goto end;
+
+    if (WaitForSingleObject(timer, INFINITE) != WAIT_OBJECT_0)
+        goto end;
+
+end:
+    if (timer)
+        CloseHandle(timer);
     mp_end_hires_timers(hrt);
 }