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feat: upgrade the discovery service to random-walk
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,125 @@ | ||
| 'use strict' | ||
|
|
||
| const times = require('async/times') | ||
| const crypto = require('libp2p-crypto') | ||
| const waterfall = require('async/waterfall') | ||
| const timeout = require('async/timeout') | ||
| const multihashing = require('multihashing-async') | ||
| const PeerId = require('peer-id') | ||
| const assert = require('assert') | ||
| const errors = require('./errors') | ||
| const c = require('./constants') | ||
|
|
||
| class RandomWalk { | ||
| constructor (kadDHT) { | ||
| assert(kadDHT, 'Random Walk needs an instance of the Kademlia DHT') | ||
| this._running = false | ||
| this._kadDHT = kadDHT | ||
| } | ||
|
|
||
| /** | ||
| * Start the Random Walk process. This means running a number of queries | ||
| * every interval requesting random data. This is done to keep the dht | ||
| * healthy over time. | ||
| * | ||
| * @param {number} [queries=1] - how many queries to run per period | ||
| * @param {number} [period=300000] - how often to run the the random-walk process, in milliseconds (5min) | ||
| * @param {number} [maxTimeout=10000] - how long to wait for the the random-walk query to run, in milliseconds (10s) | ||
| * @returns {void} | ||
| */ | ||
| start (queries, period, maxTimeout) { | ||
| if (queries == null) { queries = 1 } | ||
| if (period == null) { period = 5 * c.minute } | ||
| if (maxTimeout == null) { maxTimeout = 10 * c.second } | ||
| // Don't run twice | ||
| if (this._running) { return } | ||
|
|
||
| this._running = setInterval( | ||
| () => this._walk(queries, maxTimeout), | ||
| period | ||
| ) | ||
| } | ||
|
|
||
| /** | ||
| * Stop the random-walk process. | ||
| * | ||
| * @returns {void} | ||
| */ | ||
| stop () { | ||
| if (this._running) { | ||
| clearInterval(this._running) | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Do the random walk work. | ||
| * | ||
| * @param {number} queries | ||
| * @param {number} maxTimeout | ||
| * @returns {void} | ||
| * | ||
| * @private | ||
| */ | ||
| _walk (queries, maxTimeout) { | ||
| this._kadDHT._log('random-walk:start') | ||
|
|
||
| times(queries, (i, cb) => { | ||
| waterfall([ | ||
| (cb) => this._randomPeerId(cb), | ||
| (id, cb) => timeout((cb) => { | ||
| this._query(id, cb) | ||
| }, maxTimeout)(cb) | ||
| ], (err) => { | ||
| if (err) { return this._kadDHT._log.error('random-walk:error', err) } | ||
|
|
||
| this._kadDHT._log('random-walk:done') | ||
| }) | ||
| }) | ||
| } | ||
|
|
||
| /** | ||
| * The query run during a random walk request. | ||
| * | ||
| * @param {PeerId} id | ||
| * @param {function(Error)} callback | ||
| * @returns {void} | ||
| * | ||
| * @private | ||
| */ | ||
| _query (id, callback) { | ||
| this._kadDHT._log('random-walk:query:%s', id.toB58String()) | ||
|
|
||
| this._kadDHT.findPeer(id, (err, peer) => { | ||
| if (err instanceof errors.NotFoundError) { | ||
| // expected case, we asked for random stuff after all | ||
| return callback() | ||
| } | ||
| if (err) { | ||
| return callback(err) | ||
| } | ||
| this._kadDHT._log('random-walk:query:found', err, peer) | ||
|
|
||
| // wait what, there was something found? Lucky day! | ||
| callback(new Error(`random-walk: ACTUALLY FOUND PEER: ${peer}, ${id.toB58String()}`)) | ||
| }) | ||
| } | ||
|
|
||
| /** | ||
| * Generate a random peer id for random-walk purposes. | ||
| * | ||
| * @param {function(Error, PeerId)} callback | ||
| * @returns {void} | ||
| * | ||
| * @private | ||
| */ | ||
| _randomPeerId (callback) { | ||
| multihashing(crypto.randomBytes(16), 'sha2-256', (err, digest) => { | ||
| if (err) { | ||
| return callback(err) | ||
| } | ||
| callback(null, new PeerId(digest)) | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| module.exports = RandomWalk |
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