HHWheelTimerBase: use different DEFAULT_TICK_INTERVAL values for milliseconds and microseconds

Summary: HHWheelTimerBase: use different DEFAULT_TICK_INTERVAL values for milliseconds and microseconds

Reviewed By: djwatson

Differential Revision: D14608368

fbshipit-source-id: 81ca30dead56e0ec954fce05c9f920e15dc20405

folly/io/async/HHWheelTimer.cpp

@@ -40,8 +40,15 @@ namespace folly {
  * start showing up in cpu perf.  Also, it might not be possible to set
  * tick interval less than 10ms on older kernels.
  */
-template <class Duration>
-int HHWheelTimerBase<Duration>::DEFAULT_TICK_INTERVAL = 10;
+template <>
+int HHWheelTimerBase<std::chrono::milliseconds>::DEFAULT_TICK_INTERVAL = 10;
+
+/*
+ * An interval of 200usec will give us 200usec * WHEEL_SIZE^WHEEL_BUCKETS
+ * for the largest timeout possible, or about 9 days.
+ */
+template <>
+int HHWheelTimerBase<std::chrono::microseconds>::DEFAULT_TICK_INTERVAL = 200;
 
 template <class Duration>
 HHWheelTimerBase<Duration>::Callback::Callback() {}

folly/io/async/HHWheelTimer.h

@@ -343,11 +343,16 @@ class HHWheelTimerBase : private folly::AsyncTimeout,
   }
 };
 
+// std::chrono::milliseconds
+template <>
+int HHWheelTimerBase<std::chrono::milliseconds>::DEFAULT_TICK_INTERVAL;
 using HHWheelTimer = HHWheelTimerBase<std::chrono::milliseconds>;
 extern template class HHWheelTimerBase<std::chrono::milliseconds>;
 
 // std::chrono::microseconds
 template <>
+int HHWheelTimerBase<std::chrono::microseconds>::DEFAULT_TICK_INTERVAL;
+template <>
 void HHWheelTimerBase<std::chrono::microseconds>::scheduleTimeoutInternal(
     std::chrono::microseconds timeout);