Merge pull request #10756 from Icinga/improve-parallel-for

Improve `WorkQueue::ParallelFor()`

Author: jschmidt-icinga

lib/base/workqueue.hpp

@@ -67,18 +67,17 @@ class WorkQueue
 	void Join(bool stop = false);
 
 	template<typename VectorType, typename FuncType>
-	void ParallelFor(const VectorType& items, const FuncType& func)
+	void ParallelFor(VectorType&& items, const FuncType& func)
 	{
-		ParallelFor(items, true, func);
+		ParallelFor(std::forward<VectorType>(items), true, func);
 	}
 
-	template<typename VectorType, typename FuncType>
-	void ParallelFor(const VectorType& items, bool preChunk, const FuncType& func)
+	template<typename VectorType, typename FuncType, typename = std::enable_if_t<!std::is_rvalue_reference_v<VectorType&&>>>
+	void ParallelFor(VectorType&& items, bool preChunk, const FuncType& func)
 	{
-		using SizeType = decltype(items.size());
-
-		SizeType totalCount = items.size();
-		SizeType chunks = preChunk ? m_ThreadCount : totalCount;
+		const auto totalCount = std::size(items);
+		using SizeType = std::remove_const_t<decltype(totalCount)>;
+		const auto chunks = preChunk ? m_ThreadCount : totalCount;
 
 		auto lock = AcquireLock();
 
@@ -103,7 +102,7 @@ class WorkQueue
 			offset += count;
 		}
 
-		ASSERT(offset == items.size());
+		ASSERT(offset == totalCount);
 	}
 
 	bool IsWorkerThread() const;