Akka.Util.ListPriorityQueue.Dequeue C# (CSharp) Method

        public Envelope Dequeue()
        {
            // assumes pq is not empty; up to calling code
            var li = _data.Count - 1; // last index (before removal)
            var frontItem = _data[0];   // fetch the front
            _data[0] = _data[li];
            _data.RemoveAt(li);

            --li; // last index (after removal)
            var pi = 0; // parent index. start at front of pq
            while (true)
            {
                var ci = pi * 2 + 1; // left child index of parent
                if (ci > li) break;  // no children so done
                var rc = ci + 1;     // right child
                if (rc <= li && _priorityCalculator(_data[rc].Message).CompareTo(_priorityCalculator(_data[ci].Message)) < 0) // if there is a rc (ci + 1), and it is smaller than left child, use the rc instead
                    ci = rc;
                if (_priorityCalculator(_data[pi].Message).CompareTo(_priorityCalculator(_data[ci].Message)) <= 0) break; // parent is smaller than (or equal to) smallest child so done
                var tmp = _data[pi]; _data[pi] = _data[ci]; _data[ci] = tmp; // swap parent and child
                pi = ci;
            }
            return frontItem;
        }