Microsoft.AspNet.Server.Kestrel.Infrastructure.MemoryPoolIterator2.GetLength C# (CSharp) Method

        public int GetLength(MemoryPoolIterator2 end)
        {
            if (IsDefault || end.IsDefault)
            {
                return -1;
            }

            var block = _block;
            var index = _index;
            var length = 0;
            while (true)
            {
                if (block == end._block)
                {
                    return length + end._index - index;
                }
                else if (block.Next == null)
                {
                    throw new InvalidOperationException("end did not follow iterator");
                }
                else
                {
                    length += block.End - index;
                    block = block.Next;
                    index = block.Start;
                }
            }
        }

        public static ArraySegment <byte> GetArraySegment(this MemoryPoolIterator2 start, MemoryPoolIterator2 end)
        {
            if (start.IsDefault || end.IsDefault)
            {
                return(default(ArraySegment <byte>));
            }
            if (end.Block == start.Block)
            {
                return(new ArraySegment <byte>(start.Block.Array, start.Index, end.Index - start.Index));
            }

            var length = start.GetLength(end);
            var array  = new byte[length];

            start.CopyTo(array, 0, length, out length);
            return(new ArraySegment <byte>(array, 0, length));
        }