Function inner_enqueue

readerwriterqueue.h:538–644

#else
	template<AllocationMode canAlloc, typename U>
	bool inner_enqueue(U&& element) AE_NO_TSAN
#endif
	{
#ifndef NDEBUG
		ReentrantGuard guard(this->enqueuing);
#endif

		// High-level pseudocode (assuming we're allowed to alloc a new block):
		// If room in tail block, add to tail
		// Else check next block
		//     If next block is not the head block, enqueue on next block
		//     Else create a new block and enqueue there
		//     Advance tail to the block we just enqueued to

		Block* tailBlock_ = tailBlock.load();
		size_t blockFront = tailBlock_->localFront;
		size_t blockTail = tailBlock_->tail.load();

		size_t nextBlockTail = (blockTail + 1) & tailBlock_->sizeMask;
		if (nextBlockTail != blockFront || nextBlockTail != (tailBlock_->localFront = tailBlock_->front.load())) {
			fence(memory_order_acquire);
			// This block has room for at least one more element
			char* location = tailBlock_->data + blockTail * sizeof(T);
#if MOODYCAMEL_HAS_EMPLACE
			new (location) T(std::forward<Args>(args)...);
#else
			new (location) T(std::forward<U>(element));
#endif

			fence(memory_order_release);
			tailBlock_->tail = nextBlockTail;
		}
		else {
			fence(memory_order_acquire);
			if (tailBlock_->next.load() != frontBlock) {
				// Note that the reason we can't advance to the frontBlock and start adding new entries there
				// is because if we did, then dequeue would stay in that block, eventually reading the new values,
				// instead of advancing to the next full block (whose values were enqueued first and so should be
				// consumed first).

				fence(memory_order_acquire);		// Ensure we get latest writes if we got the latest frontBlock

				// tailBlock is full, but there's a free block ahead, use it
				Block* tailBlockNext = tailBlock_->next.load();
				size_t nextBlockFront = tailBlockNext->localFront = tailBlockNext->front.load();
				nextBlockTail = tailBlockNext->tail.load();
				fence(memory_order_acquire);

				// This block must be empty since it's not the head block and we
				// go through the blocks in a circle
				assert(nextBlockFront == nextBlockTail);
				tailBlockNext->localFront = nextBlockFront;

				char* location = tailBlockNext->data + nextBlockTail * sizeof(T);
#if MOODYCAMEL_HAS_EMPLACE
				new (location) T(std::forward<Args>(args)...);
#else
				new (location) T(std::forward<U>(element));