Using reply struct instead of folly::Function

Summary: Using folly::Function as node type for EventBaseAtomicNotificationQueue involves two mallocs (for creating the function and also to create the queue node). In this diff, I have created a class to hold the data required to send replies and using emplaceMessage to add to the queue.

Differential Revision: D26778920

fbshipit-source-id: 2dcf8395dc77db1d7c73d1d68c9a69e767191b95

folly/io/async/EventBase.cpp

@@ -151,6 +151,11 @@ class ExecutionObserverScopeGuard {
 
 namespace folly {
 
+class EventBase::FuncRunner {
+ public:
+  void operator()(Func func) noexcept { func(); }
+};
+
 /*
  * EventBase methods
  */

folly/io/async/EventBase.h

@@ -143,16 +143,6 @@ class EventBase : public TimeoutManager,
 
   using Func = folly::Function<void()>;
 
-  class FuncRunner {
-   public:
-    void operator()(Func&& func) noexcept {
-      func();
-      func = nullptr;
-    }
-  };
-
-  using EventBaseQueue = EventBaseAtomicNotificationQueue<Func, FuncRunner>;
-
   /**
    * A callback interface to use with runInLoop()
    *
@@ -865,6 +855,8 @@ class EventBase : public TimeoutManager,
   }
 
  private:
+  class FuncRunner;
+
   folly::VirtualEventBase* tryGetVirtualEventBase();
 
   void applyLoopKeepAlive();
@@ -914,7 +906,7 @@ class EventBase : public TimeoutManager,
 
   // A notification queue for runInEventBaseThread() to use
   // to send function requests to the EventBase thread.
-  std::unique_ptr<EventBaseQueue> queue_;
+  std::unique_ptr<EventBaseAtomicNotificationQueue<Func, FuncRunner>> queue_;
   ssize_t loopKeepAliveCount_{0};
   std::atomic<ssize_t> loopKeepAliveCountAtomic_{0};
   bool loopKeepAliveActive_{false};