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merkle tree lib
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Alexey
parent
c0e27ffafc
commit
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4 changed files with 377 additions and 8 deletions
262
lib/MerkleTree.js
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262
lib/MerkleTree.js
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// const AwaitLock = require('await-lock');
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class MerkleTree {
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constructor(prefix, storage, hasher, n_levels, zero_value) {
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this.prefix = prefix;
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this.storage = storage;
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this.hasher = hasher;
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this.n_levels = n_levels;
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this.zero_values = [];
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let current_zero_value = zero_value;
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this.zero_values.push(current_zero_value);
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for (let i = 0; i < n_levels; i++) {
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current_zero_value = this.hasher.hash(i, current_zero_value, current_zero_value);
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this.zero_values.push(
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current_zero_value.toString(),
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);
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}
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// this.lock = new AwaitLock();
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}
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static index_to_key(prefix, level, index) {
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const key = `${prefix}_tree_${level}_${index}`;
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return key;
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}
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static element_to_key(prefix, element) {
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const key = `${prefix}_element_${element}`;
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return key;
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}
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static update_log_to_key(prefix) {
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return `${prefix}_update_log_index`;
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}
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static update_log_element_to_key(prefix, update_log_index) {
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return `${prefix}_update_log_element_${update_log_index}`;
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}
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async update_log(index, old_element, new_element, update_log_index, should_put_element_update) {
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let ops = [];
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const update_log_key = MerkleTree.update_log_to_key(this.prefix);
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ops.push({
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type: 'put',
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key: update_log_key,
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value: update_log_index.toString(),
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});
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if (should_put_element_update) {
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const update_log_element_key = MerkleTree.update_log_element_to_key(this.prefix, update_log_index);
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ops.push({
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type: 'put',
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key: update_log_element_key,
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value: JSON.stringify({
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index,
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old_element,
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new_element,
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})
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});
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}
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await this.storage.put_batch(ops);
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}
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async root() {
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let root = await this.storage.get_or_element(
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MerkleTree.index_to_key(this.prefix, this.n_levels, 0),
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this.zero_values[this.n_levels],
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);
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return root;
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}
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async element_index(element) {
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const element_key = MerkleTree.element_to_key(this.prefix, element);
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const index = await this.storage.get_or_element(element_key, -1);
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return index;
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}
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async path(index) {
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class PathTraverser {
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constructor(prefix, storage, zero_values) {
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this.prefix = prefix;
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this.storage = storage;
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this.zero_values = zero_values;
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this.path_elements = [];
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this.path_index = [];
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}
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async handle_index(level, element_index, sibling_index) {
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const sibling = await this.storage.get_or_element(
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MerkleTree.index_to_key(this.prefix, level, sibling_index),
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this.zero_values[level],
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);
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this.path_elements.push(sibling);
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this.path_index.push(element_index % 2);
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}
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}
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let traverser = new PathTraverser(this.prefix, this.storage, this.zero_values);
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const root = await this.storage.get_or_element(
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MerkleTree.index_to_key(this.prefix, this.n_levels, 0),
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this.zero_values[this.n_levels],
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);
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const element = await this.storage.get_or_element(
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MerkleTree.index_to_key(this.prefix, 0, index),
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this.zero_values[0],
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);
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await this.traverse(index, traverser);
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return {
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root,
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path_elements: traverser.path_elements,
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path_index: traverser.path_index,
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element
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};
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}
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async update(index, element, update_log_index) {
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// await this.lock.acquireAsync();
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try {
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//console.log(`updating ${index}, ${element}`);
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class UpdateTraverser {
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constructor(prefix, storage, hasher, element, zero_values) {
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this.prefix = prefix;
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this.current_element = element;
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this.zero_values = zero_values;
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this.storage = storage;
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this.hasher = hasher;
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this.key_values_to_put = [];
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}
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async handle_index(level, element_index, sibling_index) {
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if (level == 0) {
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this.original_element = await this.storage.get_or_element(
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MerkleTree.index_to_key(this.prefix, level, element_index),
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this.zero_values[level],
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);
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this.key_values_to_put.push({
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key: MerkleTree.element_to_key(this.prefix, element),
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value: index.toString(),
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});
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}
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const sibling = await this.storage.get_or_element(
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MerkleTree.index_to_key(this.prefix, level, sibling_index),
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this.zero_values[level],
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);
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let left, right;
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if (element_index % 2 == 0) {
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left = this.current_element;
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right = sibling;
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} else {
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left = sibling;
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right = this.current_element;
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}
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this.key_values_to_put.push({
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key: MerkleTree.index_to_key(this.prefix, level, element_index),
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value: this.current_element,
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});
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//console.log(`left: ${left}, right: ${right}`);
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this.current_element = this.hasher.hash(level, left, right);
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//console.log(`current_element: ${this.current_element}`);
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}
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}
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let traverser = new UpdateTraverser(
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this.prefix,
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this.storage,
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this.hasher,
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element,
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this.zero_values
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);
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await this.traverse(index, traverser);
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//console.log(`traverser.current_element: ${traverser.current_element}`);
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traverser.key_values_to_put.push({
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key: MerkleTree.index_to_key(this.prefix, this.n_levels, 0),
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value: traverser.current_element,
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});
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if (update_log_index == undefined) {
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const update_log_key = MerkleTree.update_log_to_key(this.prefix);
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let update_log_index_from_db = await this.storage.get_or_element(update_log_key, -1);
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update_log_index = parseInt(update_log_index_from_db) + 1;
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await this.update_log(index, traverser.original_element, element, update_log_index, true);
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} else {
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await this.update_log(index, traverser.original_element, element, update_log_index, false);
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}
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await this.storage.del(MerkleTree.element_to_key(this.prefix, traverser.original_element));
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//traverser.key_values_to_put.forEach((e) => console.log(`key_values: ${JSON.stringify(e)}`));
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await this.storage.put_batch(traverser.key_values_to_put);
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const root = await this.root();
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//console.log(`updated root ${root}`);
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} finally {
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// this.lock.release();
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}
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}
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async traverse(index, handler) {
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let current_index = index;
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for (let i = 0; i < this.n_levels; i++) {
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let sibling_index = current_index;
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if (current_index % 2 == 0) {
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sibling_index += 1;
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} else {
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sibling_index -= 1;
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}
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await handler.handle_index(i, current_index, sibling_index);
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current_index = Math.floor(current_index / 2);
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}
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}
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async rollback(updates) {
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// await this.lock.acquireAsync();
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try {
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const update_log_key = MerkleTree.update_log_to_key(this.prefix);
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const update_log_index = await this.storage.get(update_log_key);
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for (let i = 0; i < updates; i++) {
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const update_log_element_key = MerkleTree.update_log_element_to_key(this.prefix, update_log_index - i);
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const update_element_log = JSON.parse(await this.storage.get(update_log_element_key));
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await this.update(update_element_log.index, update_element_log.old_element, update_log_index - i - 1);
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}
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} finally {
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// this.lock.release();
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}
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}
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async rollback_to_root(root) {
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// await this.lock.acquireAsync();
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try {
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const update_log_key = MerkleTree.update_log_to_key(this.prefix);
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let update_log_index = await this.storage.get(update_log_key);
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while (update_log_index >= 0) {
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update_log_index -= 1;
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const update_log_element_key = MerkleTree.update_log_element_to_key(this.prefix, update_log_index - i);
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const update_element_log = JSON.parse(await this.storage.get(update_log_element_key));
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await this.update(update_element_log.index, update_element_log.old_element, update_log_index);
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const current_root = await this.root();
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if (current_root == root) {
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break;
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}
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}
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if (await this.root() != root) {
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throw new Error(`could not rollback to root ${root}`);
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}
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} finally {
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// this.lock.release();
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}
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}
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}
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module.exports = MerkleTree;
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