Add getTaskQueueSize() method in CPUThreadPoolExecutor

Summary: Add getTaskQueueSize() method in CPUThreadPoolExecutor

Reviewed By: yfeldblum

Differential Revision: D7294802

fbshipit-source-id: 1f37558a1f14fcc2888c654248d649365c323432

folly/executors/CPUThreadPoolExecutor.cpp

@@ -104,6 +104,10 @@ uint8_t CPUThreadPoolExecutor::getNumPriorities() const {
   return taskQueue_->getNumPriorities();
 }
 
+size_t CPUThreadPoolExecutor::getTaskQueueSize() const {
+  return taskQueue_->size();
+}
+
 BlockingQueue<CPUThreadPoolExecutor::CPUTask>*
 CPUThreadPoolExecutor::getTaskQueue() {
   return taskQueue_.get();

folly/executors/CPUThreadPoolExecutor.h

@@ -104,6 +104,8 @@ class CPUThreadPoolExecutor : public ThreadPoolExecutor {
       std::chrono::milliseconds expiration,
       Func expireCallback = nullptr);
 
+  size_t getTaskQueueSize() const;
+
   uint8_t getNumPriorities() const override;
 
   struct CPUTask : public ThreadPoolExecutor::Task {