Revisit time functions

Addressing https://github.com/MSOpenTech/redis/issues/188

- Made gettimeofday use GetSystemTimePreciseAsFileTime when available
- Introduced definitions for gettimeofday_fast and gettimeofday_precise,
  so that calls can be specialized based on specific usage requirements
- Introduced GetHighResRelativeTime, for high-resolution relative time
  measurements on all Windows versions.

src/Win32_Interop/Win32_QFork.cpp

@@ -57,6 +57,7 @@ using namespace std;
 
 const long long cSentinelHeapSize = 30 * 1024 * 1024;
 extern "C" int checkForSentinelMode(int argc, char **argv);
+extern "C" void InitTimeFunctions();
 
 extern "C"
 {
@@ -1274,6 +1275,7 @@ extern "C"
     // Redis will allocate.
     int main(int argc, char* argv[]) {
         try {
+            InitTimeFunctions();
             ParseCommandLineArguments(argc, argv);
             SetupLogging();
         } catch (system_error syserr) {

src/Win32_Interop/win32_wsiocp.c

@@ -443,15 +443,12 @@ int aeWinSocketAttach(int fd) {
 
 void aeShutdown(int fd) {
     char rbuf[100];
-    struct timeval timenow;
     long long waitmsecs = 50;      /* wait up to 50 millisecs */
     long long endms;
     long long nowms;
 
     /* wait for last item to complete up to tosecs seconds*/
-    gettimeofday(&timenow, NULL);
-    endms = ((long long)timenow.tv_sec * 1000) +
-                    ((long long)timenow.tv_usec / 1000) + waitmsecs;
+    endms = GetHighResRelativeTime(1000) + waitmsecs;
 
     if (shutdown(fd, SD_SEND) != SOCKET_ERROR) {
         /* read data until no more or error to ensure shutdown completed */
@@ -460,9 +457,7 @@ void aeShutdown(int fd) {
             if (rc == 0 || rc == SOCKET_ERROR)
                 break;
             else {
-                gettimeofday(&timenow, NULL);
-                nowms = ((long long)timenow.tv_sec * 1000) +
-                            ((long long)timenow.tv_usec / 1000);
+                nowms = GetHighResRelativeTime(1000);
                 if (nowms > endms)
                     break;
             }

src/Win32_Interop/win32fixes.c

@@ -401,6 +401,56 @@ struct timezone
   int  tz_dsttime;     /* type of dst correction */
 };
 
+static VOID (WINAPI *fnGetSystemTimePreciseAsFileTime)(LPFILETIME);
+
+/* Interval (in seconds) of the high-resolution clock. */
+static double highResTimeInterval = 0;
+
+void InitTimeFunctions()
+{
+  FARPROC fp;
+  HMODULE module;
+  LARGE_INTEGER perfFrequency;
+
+  /* Use GetSystemTimeAsFileTime as fallbcak where GetSystemTimePreciseAsFileTime is not available */
+  fnGetSystemTimePreciseAsFileTime = GetSystemTimeAsFileTime;
+  module = GetModuleHandleA("kernel32.dll");
+  if (module) {
+    fp = GetProcAddress(module, "GetSystemTimePreciseAsFileTime");
+    if (fp) {
+      fnGetSystemTimePreciseAsFileTime = (VOID (WINAPI*)(LPFILETIME)) fp;
+    }
+  }
+
+  /* Retrieve high-resolution timer frequency
+   * and precompute its reciprocal. 
+   */
+  if (QueryPerformanceFrequency(&perfFrequency)) {
+    highResTimeInterval = 1.0 / perfFrequency.QuadPart;
+  } else {
+      highResTimeInterval = 0;
+  }
+}
+
+unsigned long long GetHighResRelativeTime(double scale) {
+  LARGE_INTEGER counter;
+
+  /* If the performance interval is zero, there's no support. */
+  if (highResTimeInterval == 0) {
+    return 0;
+  }
+
+  if (!QueryPerformanceCounter(&counter)) {
+    return 0;
+  }
+
+  /* Because we have no guarantee about the order of magnitude of the
+   * performance counter interval, integer math could cause this computation
+   * to overflow. Therefore we resort to floating point math.
+   */
+  return (unsigned long long) ((double)counter.QuadPart * highResTimeInterval * scale);
+}
+
 time_t gettimeofdaysecs(unsigned int *usec)
 {
   FILETIME ft;
@@ -419,7 +469,7 @@ time_t gettimeofdaysecs(unsigned int *usec)
     return (tmpres / 1000000UL);
 }
 
-int gettimeofday(struct timeval *tv, struct timezone *tz)
+int gettimeofday_fast(struct timeval *tv, struct timezone *tz)
 {
   FILETIME ft;
   unsigned __int64 tmpres = 0;
@@ -454,6 +504,41 @@ int gettimeofday(struct timeval *tv, struct timezone *tz)
   return 0;
 }
 
+int gettimeofday_highres(struct timeval *tv, struct timezone *tz)
+{
+  FILETIME ft;
+  unsigned __int64 tmpres = 0;
+  static int tzflag;
+
+  if (NULL != tv)
+  {
+    fnGetSystemTimePreciseAsFileTime(&ft);
+
+    tmpres |= ft.dwHighDateTime;
+    tmpres <<= 32;
+    tmpres |= ft.dwLowDateTime;
+
+    /*converting file time to unix epoch*/
+    tmpres /= 10;  /*convert into microseconds*/
+    tmpres -= DELTA_EPOCH_IN_MICROSECS; 
+    tv->tv_sec = (long)(tmpres / 1000000UL);
+    tv->tv_usec = (long)(tmpres % 1000000UL);
+  }
+
+  if (NULL != tz)
+  {
+    if (!tzflag)
+    {
+      _tzset();
+      tzflag++;
+    }
+    tz->tz_minuteswest = _timezone / 60;
+    tz->tz_dsttime = _daylight;
+  }
+
+  return 0;
+}
+
 static _locale_t clocale = NULL;
 double wstrtod(const char *nptr, char **eptr) {
     double d;

src/Win32_Interop/win32fixes.h

@@ -268,8 +268,12 @@ int w32initWinSock(void);
 void *mmap(void *start, size_t length, int prot, int flags, int fd, off offset);
 int munmap(void *start, size_t length);
 
-int gettimeofday(struct timeval *tv, struct timezone *tz);
+void InitTimeFunctions();
+unsigned long long GetHighResRelativeTime(double scale);
+int gettimeofday_fast(struct timeval *tv, struct timezone *tz);
+int gettimeofday_highres(struct timeval *tv, struct timezone *tz);
 time_t gettimeofdaysecs(unsigned int *usec);
+#define gettimeofday gettimeofday_highres
 
 char *ctime_r(const time_t *clock, char *buf);
 

src/dict.c

@@ -326,7 +326,7 @@ int dictRehash(dict *d, int n) {
 
 long long timeInMilliseconds(void) {
 #ifdef _WIN32
-    return GetTickCount();
+    return GetHighResRelativeTime(1000);
 #else
     struct timeval tv;
 

src/redis-benchmark.c

@@ -107,30 +107,12 @@ typedef struct _client {
 static void writeHandler(aeEventLoop *el, int fd, void *privdata, int mask);
 static void createMissingClients(client c);
 
-#ifdef _WIN32
-/*acquires high resolution time stamps on windows, more details can be found here http://msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx */
-static long long getQPCTimeStamp()
-{
-	LARGE_INTEGER time;
-	QueryPerformanceCounter(&time);
-	return time.QuadPart;
-}
-static long long getQPCElapsedMicroSeconds(long long startime, long long endtime)
-{
-	long long elapsedMicroseconds = endtime - startime;
-	LARGE_INTEGER Frequency;
-	QueryPerformanceFrequency(&Frequency);
-
-	// To guard against loss-of-precision, we convert
-	// to microseconds *before* dividing by ticks-per-second.
-	elapsedMicroseconds *= 1000000;
-	elapsedMicroseconds /= Frequency.QuadPart;
-	return elapsedMicroseconds;
-}
-#endif
 
 /* Implementation */
 static long long ustime(void) {
+#ifdef _WIN32
+    return GetHighResRelativeTime(1000000);
+#else
     struct timeval tv;
     long long ust;
 
@@ -138,9 +120,13 @@ static long long ustime(void) {
     ust = ((long)tv.tv_sec)*1000000;
     ust += tv.tv_usec;
     return ust;
+#endif
 }
 
 static long long mstime(void) {
+#ifdef _WIN32
+    return GetHighResRelativeTime(1000);
+#else
     struct timeval tv;
     long long mst;
 
@@ -148,6 +134,7 @@ static long long mstime(void) {
     mst = ((long long)tv.tv_sec)*1000;
     mst += tv.tv_usec/1000;
     return mst;
+#endif
 }
 
 static void freeClient(client c) {
@@ -234,11 +221,7 @@ static void readHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
      * is not part of the latency, so calculate it only once, here. */
 	if (c->latency < 0)
 	{
-#ifdef _WIN32
-		c->latency = getQPCElapsedMicroSeconds(c->start, getQPCTimeStamp());
-#else
 		c->latency = ustime() - (c->start);
-#endif
 	}
 
 #ifdef WIN32_IOCP
@@ -334,11 +317,7 @@ static void writeHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
 
         /* Really initialize: randomize keys and set start time. */
         if (config.randomkeys) randomizeClientKey(c);
-#ifdef _WIN32
-		c->start = getQPCTimeStamp();
-#else
-		c->start = ustime();
-#endif
+        c->start = ustime();
         c->latency = -1;
     }
 

src/redis-cli.c

@@ -134,6 +134,9 @@ char *redisGitDirty(void);
  *--------------------------------------------------------------------------- */
 
 static long long ustime(void) {
+#ifdef _WIN32
+    return GetHighResRelativeTime(1000000);
+#else
     struct timeval tv;
     long long ust;
 
@@ -141,6 +144,7 @@ static long long ustime(void) {
     ust = ((long long)tv.tv_sec)*1000000;
     ust += tv.tv_usec;
     return ust;
+#endif
 }
 
 static long long mstime(void) {

src/ziplist.c

@@ -991,9 +991,13 @@ unsigned char *createIntList() {
 }
 
 long long usec(void) {
+#ifdef _WIN32
+    return GetHighResRelativeTime(1000000);
+#else
     struct timeval tv;
     gettimeofday(&tv,NULL);
     return (((long long)tv.tv_sec)*1000000)+tv.tv_usec;
+#endif
 }
 
 void stress(int pos, int num, int maxsize, int dnum) {