Merge pull request #960 from koldat/masterFixes2

Making use of GetSystemTimePreciseAsFileTime dynamic

db/auto_roll_logger.cc

@@ -32,8 +32,16 @@ Status AutoRollLogger::ResetLogger() {
 }
 
 void AutoRollLogger::RollLogFile() {
-  std::string old_fname = OldInfoLogFileName(
+  // This function is called when log is rotating. Two rotations
-      dbname_, env_->NowMicros(), db_absolute_path_, db_log_dir_);
+  // can happen quickly (NowMicro returns same value). To not overwrite
+  // previous log file we increment by one micro second and try again.
+  uint64_t now = env_->NowMicros();
+  std::string old_fname;
+  do {
+    old_fname = OldInfoLogFileName(
+      dbname_, now, db_absolute_path_, db_log_dir_);
+    now++;
+  } while (env_->FileExists(old_fname).ok());
   env_->RenameFile(log_fname_, old_fname);
 }
 

port/win/env_win.cc

@@ -1138,6 +1138,8 @@ void WinthreadCall(const char* label, std::error_code result) {
 }
 }
 
+typedef VOID(WINAPI * FnGetSystemTimePreciseAsFileTime)(LPFILETIME);
+
 class WinEnv : public Env {
  public:
   WinEnv();
@@ -1676,6 +1678,7 @@ class WinEnv : public Env {
   }
 
   virtual uint64_t NowMicros() override {
+    if (GetSystemTimePreciseAsFileTime_ != NULL) {
       // all std::chrono clocks on windows proved to return
       // values that may repeat that is not good enough for some uses.
       const int64_t c_UnixEpochStartTicks = 116444736000000000i64;
@@ -1685,7 +1688,7 @@ class WinEnv : public Env {
       // just any microseconds because it is often used as an argument
       // to TimedWait() on condition variable
       FILETIME ftSystemTime;
-    GetSystemTimePreciseAsFileTime(&ftSystemTime);
+      GetSystemTimePreciseAsFileTime_(&ftSystemTime);
 
       LARGE_INTEGER li;
       li.LowPart = ftSystemTime.dwLowDateTime;
@@ -1696,6 +1699,9 @@ class WinEnv : public Env {
       li.QuadPart /= c_FtToMicroSec;
       return li.QuadPart;
     }
+    using namespace std::chrono;
+    return duration_cast<microseconds>(system_clock::now().time_since_epoch()).count();
+  }
 
   virtual uint64_t NowNanos() override {
     // all std::chrono clocks on windows have the same resolution that is only
@@ -2104,6 +2110,7 @@ class WinEnv : public Env {
   std::vector<ThreadPool> thread_pools_;
   mutable std::mutex mu_;
   std::vector<std::thread> threads_to_join_;
+  FnGetSystemTimePreciseAsFileTime GetSystemTimePreciseAsFileTime_;
 };
 
 WinEnv::WinEnv()
@@ -2112,7 +2119,15 @@ WinEnv::WinEnv()
       page_size_(4 * 1012),
       allocation_granularity_(page_size_),
       perf_counter_frequency_(0),
-      thread_pools_(Priority::TOTAL) {
+      thread_pools_(Priority::TOTAL),
+      GetSystemTimePreciseAsFileTime_(NULL) {
+
+  HMODULE module = GetModuleHandle("kernel32.dll");
+  if (module != NULL) {
+    GetSystemTimePreciseAsFileTime_ = (FnGetSystemTimePreciseAsFileTime)GetProcAddress(
+      module, "GetSystemTimePreciseAsFileTime");
+  }
+
   SYSTEM_INFO sinfo;
   GetSystemInfo(&sinfo);