Function insert_block_index_entry

deps/concurrentqueue/concurrentqueue.h:2886–2916

		
		template<AllocationMode allocMode>
		inline bool insert_block_index_entry(BlockIndexEntry*& idxEntry, index_t blockStartIndex)
		{
			auto localBlockIndex = blockIndex.load(std::memory_order_relaxed);		// We're the only writer thread, relaxed is OK
			if (localBlockIndex == nullptr) {
				return false;  // this can happen if new_block_index failed in the constructor
			}
			size_t newTail = (localBlockIndex->tail.load(std::memory_order_relaxed) + 1) & (localBlockIndex->capacity - 1);
			idxEntry = localBlockIndex->index[newTail];
			if (idxEntry->key.load(std::memory_order_relaxed) == INVALID_BLOCK_BASE ||
				idxEntry->value.load(std::memory_order_relaxed) == nullptr) {
				
				idxEntry->key.store(blockStartIndex, std::memory_order_relaxed);
				localBlockIndex->tail.store(newTail, std::memory_order_release);
				return true;
			}
			
			// No room in the old block index, try to allocate another one!
			MOODYCAMEL_CONSTEXPR_IF (allocMode == CannotAlloc) {
				return false;
			}
			else if (!new_block_index()) {
				return false;
			}
			localBlockIndex = blockIndex.load(std::memory_order_relaxed);
			newTail = (localBlockIndex->tail.load(std::memory_order_relaxed) + 1) & (localBlockIndex->capacity - 1);
			idxEntry = localBlockIndex->index[newTail];
			assert(idxEntry->key.load(std::memory_order_relaxed) == INVALID_BLOCK_BASE);
			idxEntry->key.store(blockStartIndex, std::memory_order_relaxed);
			localBlockIndex->tail.store(newTail, std::memory_order_release);
			return true;
		}
		
		inline void rewind_block_index_tail()
		{