kademlia-table/dist/index.js

XOR based routing table used for P2P networks such as a Kademlia DHT.

'use strict';

var uint8arrayTools = require('uint8array-tools');

// src/getBitwiseDistance.ts
var getBitwiseDistance = (a, b, byteLength = Math.min(a.byteLength, b.byteLength)) => {
  for (let i = 0; i < byteLength; i++) {
    const ai = a[i];
    const bi = b[i];
    if (ai !== bi)
      return 8 * byteLength - (i * 8 + Math.clz32(ai ^ bi) - 24);
  }
  return 0;
};

// src/createCompareBitwiseDistance.ts
var createCompareBitwiseDistance = (id) => {
  return (a, b) => {
    const ad = getBitwiseDistance(id, a);
    const bd = getBitwiseDistance(id, b);
    return ad > bd ? 1 : ad < bd ? -1 : 0;
  };
};
var KademliaTable = class {
  constructor(id, options) {
    this.id = id;
    this.bucketSize = options.bucketSize || 20;
    this.buckets = new Array(id.length * 8 + 1).fill(void 0).map(() => []);
    this.compare = options.compare || (() => 0);
    this.getId = options.getId;
  }
  get length() {
    return this.buckets.reduce((sum, bucket) => sum + bucket.length, 0);
  }
  *[Symbol.iterator]() {
    for (const bucket of this.buckets)
      for (const node of bucket)
        yield node;
  }
  add(node, d = this.getBitwiseDistance(this.getId(node))) {
    if (this.has(this.getId(node), d))
      return false;
    if (this.buckets[d].length < this.bucketSize) {
      this.buckets[d].push(node);
      return true;
    }
    const bucket = this.buckets[d].slice(0);
    bucket.push(node);
    const sortedBucket = bucket.sort(this.compare);
    this.buckets[d] = sortedBucket.slice(0, this.bucketSize);
    const removedNode = sortedBucket.at(-1);
    if (uint8arrayTools.compare(this.getId(node), this.getId(removedNode)) === 0)
      return false;
    return true;
  }
  clear() {
    for (let i = 0; i < this.buckets.length; i++)
      this.buckets[i] = [];
  }
  listClosestToId(id, limit = this.buckets.length * this.bucketSize) {
    const d = this.getBitwiseDistance(id);
    return this.getNodes(d, limit);
  }
  get(d) {
    const node = this.buckets[d].shift();
    if (node)
      this.buckets[d].push(node);
    return node;
  }
  getById(id, d = this.getBitwiseDistance(id)) {
    const index = this.buckets[d].findIndex((node2) => uint8arrayTools.compare(this.getId(node2), id) === 0);
    if (index === -1)
      return void 0;
    const node = this.buckets[d][index];
    this.buckets[d].splice(index, 1);
    this.buckets[d].push(node);
    return node;
  }
  getBitwiseDistance(id) {
    return getBitwiseDistance(this.id, id);
  }
  getNodes(d, limit, depth = 0) {
    const offset = (depth % 2 === 0 ? 1 : -1) * Math.ceil(depth / 2);
    if (Math.abs(offset) > Math.max(d, this.buckets.length - 1 - d))
      return [];
    const i = d + offset;
    if (0 > i || i > this.buckets.length - 1)
      return this.getNodes(d, limit, depth + 1);
    const nodes = this.buckets[i].slice(0, limit);
    if (nodes.length >= limit) {
      this.buckets[i] = this.buckets[i].slice(nodes.length).concat(this.buckets[i].slice(0, nodes.length));
      return nodes;
    }
    return nodes.concat(this.getNodes(d, limit - nodes.length, depth + 1));
  }
  has(id, d = this.getBitwiseDistance(id)) {
    return !!this.buckets[d].find((node) => uint8arrayTools.compare(this.getId(node), id) === 0);
  }
  peek(d) {
    return this.buckets[d].at(0);
  }
  peekById(id, d = this.getBitwiseDistance(id)) {
    return this.buckets[d].find((node) => uint8arrayTools.compare(this.getId(node), id) === 0);
  }
  update(node, d = this.getBitwiseDistance(this.getId(node))) {
    const index = this.buckets[d].findIndex((n) => uint8arrayTools.compare(this.getId(n), this.getId(node)) === 0);
    if (index === -1)
      return false;
    this.buckets[d][index] = node;
    return true;
  }
  remove(id, d = this.getBitwiseDistance(id)) {
    const index = this.buckets[d].findIndex((node) => uint8arrayTools.compare(this.getId(node), id) === 0);
    if (index === -1)
      return false;
    this.buckets[d].splice(index, 1);
    return true;
  }
};

exports.KademliaTable = KademliaTable;
exports.createCompareBitwiseDistance = createCompareBitwiseDistance;
exports.getBitwiseDistance = getBitwiseDistance;