From be0da3e4417176421c24a226765eb07752f8635c Mon Sep 17 00:00:00 2001
From: Patrik Nyblom <pan@erlang.org>
Date: Mon, 11 Mar 2013 15:27:26 +0100
Subject: Intermediate code with lock on gettickcount()

---
 erts/emulator/sys/win32/sys_time.c | 62 +++++++++++++++++++++++++++++++-------
 1 file changed, 51 insertions(+), 11 deletions(-)

(limited to 'erts/emulator/sys/win32')

diff --git a/erts/emulator/sys/win32/sys_time.c b/erts/emulator/sys/win32/sys_time.c
index 8775b6a24d..1a33061ef1 100644
--- a/erts/emulator/sys/win32/sys_time.c
+++ b/erts/emulator/sys/win32/sys_time.c
@@ -63,7 +63,8 @@
  
 static SysHrTime wrap = 0;
 static DWORD last_tick_count = 0;
-static erts_smp_spinlock_t wrap_lock;
+static erts_smp_mtx_t wrap_lock;
+static ULONGLONG (WINAPI *pGetTickCount64)(void) = NULL;
 
 /* Getting timezone information is a heavy operation, so we want to do this 
    only once */
@@ -78,12 +79,31 @@ static int days_in_month[2][13] = {
 int 
 sys_init_time(void)
 {
+    /*
+    char kernel_dll_name[] = "kernel32";
+    HMODULE module;
+
+    module = GetModuleHandle(kernel_dll_name);
+    pGetTickCount64 = (module != NULL) ? 
+	(ULONGLONG (WINAPI *)(void)) 
+	GetProcAddress(module,"GetTickCount64") : 
+	NULL;
+    */
     if(GetTimeZoneInformation(&static_tzi) && 
        static_tzi.StandardDate.wMonth != 0 &&
        static_tzi.DaylightDate.wMonth != 0) {
 	have_static_tzi = 1;
     }
-    erts_smp_spinlock_init(&wrap_lock, "sys_gethrtime");
+
+    erts_smp_mtx_init(&wrap_lock, "sys_gethrtime");
+    /*
+     * XXX: Debug - remove me!
+     */
+    if (pGetTickCount64 != NULL) {
+	fprintf(stderr,"got GetTickCount64!\r\n");
+	fflush(stderr);
+    } 
+
     return 1;
 }
 
@@ -365,19 +385,39 @@ sys_gettimeofday(SysTimeval *tv)
 			 EPOCH_JULIAN_DIFF);
 }
 
+extern int erts_initialized;
 SysHrTime 
 sys_gethrtime(void) 
 {
-    DWORD ticks = (SysHrTime) (GetTickCount() & 0x7FFFFFFF);
-    SysHrTime res;
-    erts_smp_spin_lock(&wrap_lock);
-    if (ticks < (SysHrTime) last_tick_count) {
-	wrap += LL_LITERAL(1) << 31;
+    if (pGetTickCount64 != NULL) {
+	return ((SysHrTime) pGetTickCount64()) * LL_LITERAL(1000000);
+    } else {
+	DWORD ticks;
+	SysHrTime res;
+	erts_smp_mtx_lock(&wrap_lock);
+	ticks = (SysHrTime) (GetTickCount() & 0x7FFFFFFF);
+	if (ticks < (SysHrTime) last_tick_count) {
+	    /* Detect a race that should no longer be here... */
+	    if ((((SysHrTime) last_tick_count) - ((SysHrTime) ticks)) > 1000) {
+		wrap += LL_LITERAL(1) << 31;
+	    } else {
+		/* 
+		 * XXX Debug: Violates locking order, remove all this,
+		 * after testing!
+		 */
+		erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
+		erts_dsprintf(dsbufp, "Did not wrap when last_tick %d "
+			      "and tick %d", 
+			      last_tick_count, ticks);
+		erts_send_error_to_logger_nogl(dsbufp);
+		ticks = last_tick_count;
+	    }
+	}
+	last_tick_count = ticks;
+	res = ((((LONGLONG) ticks) + wrap) * LL_LITERAL(1000000));
+	erts_smp_mtx_unlock(&wrap_lock);
+	return res;
     }
-    last_tick_count = ticks;
-    res = ((((LONGLONG) ticks) + wrap) * LL_LITERAL(1000000));
-    erts_smp_spin_unlock(&wrap_lock);
-    return res
 }
 
 clock_t 
-- 
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