Method sizeKeyTree

Experimental/KeyTree.cc:70–89

Same logic as writeKeyTree, but just returns the size it would write, without writing.

        // Same logic as writeKeyTree, but just returns the size it would write, without writing.
        size_t sizeKeyTree(size_t begin, size_t end)
        {
            size_t mid = (begin + end) / 2;
            slice str = _strings[mid];
            size_t size = SizeOfVarInt(str.size) + str.size;   // middle string, with length prefix

            if (end - begin > 1) {
                size_t leftSize = sizeKeyTree(begin, mid);
                if (mid+1 < end) {
                    size += SizeOfVarInt(leftSize);             // right subtree offset
                    size += leftSize;                           // left subtree
                    size += sizeKeyTree(mid+1, end);            // right subtree
                } else {
                    size += 1;                                  // no right subtree (offset 0)
                    size += leftSize;                           // left subtree
                }
            }
            _sizes[mid] = size;
            return size;
        }

        void writeKeyTree(size_t begin, size_t end)
        {