add isEmpty() method to and fix bug in Ocean::ThreadPool

Reviewed By: janherling

Differential Revision: D67174302

fbshipit-source-id: 1201715719507ffa5d803de656c82f05ec353d4a

impl/ocean/base/ThreadPool.cpp

@@ -175,7 +175,7 @@ void ThreadPool::threadRun()
 				}
 			}
 
-			while (capacity_ < busyPoolThreads_.size() + idlePoolThreads_.size() && idlePoolThreads_.empty())
+			while (capacity_ < busyPoolThreads_.size() + idlePoolThreads_.size() && !idlePoolThreads_.empty())
 			{
 				// we have an idle pool thread and we have more threads than the specified capacity (e.g., because the capacity has been reduced lately)
 

impl/ocean/base/ThreadPool.h

@@ -145,6 +145,12 @@ class OCEAN_BASE_EXPORT ThreadPool : protected Thread
 		 */
 		inline size_t pending() const;
 
+		/**
+		 * Returns whether the ThreadPool has completed all jobs that have been submitted
+		 * @return True, if the results of size() and pending() are atomically both 0
+		 */
+		inline bool isEmpty() const;
+
 	protected:
 
 		/**
@@ -220,6 +226,13 @@ inline size_t ThreadPool::pending() const
 	return pendingFunctions_.size();
 }
 
+inline bool ThreadPool::isEmpty() const
+{
+	const ScopedLock scopedLock(lock_);
+
+	return (pendingFunctions_.size() + busyPoolThreads_.size()) == 0;
+}
+
 }
 
 #endif // META_OCEAN_BASE_THREAD_POOL_H