Outline most of TimedDrivableExecutor implementation

Summary: This header is widely included (via `Future.h`) and instantiations of `UnboundedQueue`'s methods are expensive, so outline them (note that the template methods will only be instantiated if used, so that's fine).

Reviewed By: philippv

Differential Revision: D22014083

fbshipit-source-id: b6a71c38c142917e9e0d86fbb64a88462382952a

folly/executors/TimedDrivableExecutor.cpp

@@ -23,6 +23,14 @@
 
 namespace folly {
 
+TimedDrivableExecutor::TimedDrivableExecutor() = default;
+
+TimedDrivableExecutor::~TimedDrivableExecutor() noexcept {
+  // Drain on destruction so that if work is added here during the collapse
+  // of a future train, it will propagate.
+  drain();
+}
+
 void TimedDrivableExecutor::add(Func callback) {
   queue_.enqueue(std::move(callback));
 }
@@ -32,6 +40,10 @@ void TimedDrivableExecutor::drive() noexcept {
   run();
 }
 
+bool TimedDrivableExecutor::try_drive() noexcept {
+  return try_wait() && run() > 0;
+}
+
 size_t TimedDrivableExecutor::run() noexcept {
   size_t count = 0;
   size_t n = queue_.size();
@@ -67,4 +79,8 @@ void TimedDrivableExecutor::wait() noexcept {
   }
 }
 
+bool TimedDrivableExecutor::try_wait() noexcept {
+  return func_ || queue_.try_dequeue(func_);
+}
+
 } // namespace folly

folly/executors/TimedDrivableExecutor.h

@@ -29,20 +29,15 @@ namespace folly {
  */
 class TimedDrivableExecutor : public DrivableExecutor {
  public:
-  ~TimedDrivableExecutor() noexcept {
-    // Drain on destruction so that if work is added here during the collapse
-    // of a future train, it will propagate.
-    drain();
-  }
+  TimedDrivableExecutor();
+  ~TimedDrivableExecutor() noexcept override;
 
   /// Implements DrivableExecutor
   void drive() noexcept override;
 
   // Make progress if there is work to do and return true. Otherwise return
   // false.
-  bool try_drive() noexcept {
-    return try_wait() && run() > 0;
-  }
+  bool try_drive() noexcept;
 
   // Make progress on this Executor's work. Acts as drive, except it will only
   // wait for a period of timeout for work to be enqueued. If no work is
@@ -84,9 +79,7 @@ class TimedDrivableExecutor : public DrivableExecutor {
   void wait() noexcept;
 
   // Return true if there is work to do, false otherwise
-  bool try_wait() noexcept {
-    return func_ || queue_.try_dequeue(func_);
-  }
+  bool try_wait() noexcept;
 
   /// Wait for work to do or for a period of timeout, whichever is sooner.
   template <typename Rep, typename Period>