fix: discover peers faster (#86)

Previously we had to wait 10s (by default) **before** initial peer discovery, since the module uses an interval to re-emit discovered peers every 10s. This PR refactors `start` to do an initial discovery of the boostrap peers immediately after it has started (i.e. after the callback has been called).

This addresses the problem where a call to `cat`/`get`/others immediately after the IPFS `ready` event would take at minimum 10s to get content stored on the preload nodes due to the initial delay in discovery.

fixes #85
resolves ipfs/js-ipfs#1706

License: MIT
Signed-off-by: Alan Shaw <alan.shaw@protocol.ai>

src/index.js

@@ -6,10 +6,10 @@ const multiaddr = require('multiaddr')
 const mafmt = require('mafmt')
 const EventEmitter = require('events').EventEmitter
 const debug = require('debug')
-const setImmediate = require('async/setImmediate')
+const nextTick = require('async/nextTick')
 
-const log = debug('libp2p:railing')
-log.error = debug('libp2p:railing:error')
+const log = debug('libp2p:bootstrap')
+log.error = debug('libp2p:bootstrap:error')
 
 function isIPFS (addr) {
  try {
@@ -28,29 +28,36 @@ class Bootstrap extends EventEmitter {
  }
 
  start (callback) {
- setImmediate(() => callback())
+ if (this._timer) {
+ return nextTick(() => callback())
+ }
 
- if (this._timer) { return }
+ this._timer = setInterval(() => this._discoverBootstrapPeers(), this._interval)
+
+ nextTick(() => {
+ callback()
+ this._discoverBootstrapPeers()
+ })
+ }
 
-  this._timer = setInterval(() => {
-  this._list.forEach((candidate) => {
-  if (!isIPFS(candidate)) { return log.error('Invalid multiaddr') }
+ _discoverBootstrapPeers () {
+ this._list.forEach((candidate) => {
+ if (!isIPFS(candidate)) { return log.error('Invalid multiaddr') }
 
-  const ma = multiaddr(candidate)
+ const ma = multiaddr(candidate)
 
-  const peerId = PeerId.createFromB58String(ma.getPeerId())
+ const peerId = PeerId.createFromB58String(ma.getPeerId())
 
- PeerInfo.create(peerId, (err, peerInfo) => {
- if (err) { return log.error('Invalid bootstrap peer id', err) }
- peerInfo.multiaddrs.add(ma)
- this.emit('peer', peerInfo)
- })
+ PeerInfo.create(peerId, (err, peerInfo) => {
+ if (err) { return log.error('Invalid bootstrap peer id', err) }
+ peerInfo.multiaddrs.add(ma)
+ this.emit('peer', peerInfo)
  })
- }, this._interval)
+ })
  }
 
  stop (callback) {
- setImmediate(callback)
+ nextTick(callback)
 
  if (this._timer) {
  clearInterval(this._timer)

test/bootstrap.spec.js

@@ -1,7 +1,7 @@
 /* eslint-env mocha */
 'use strict'
 
-const Railing = require('../src')
+const Bootstrap = require('../src')
 const peerList = require('./default-peers')
 const partialValidPeerList = require('./some-invalid-peers')
 const { expect } = require('chai')
@@ -10,7 +10,7 @@ const mafmt = require('mafmt')
 describe('bootstrap', () => {
  it('find the other peer', function (done) {
  this.timeout(5 * 1000)
- const r = new Railing({
+ const r = new Bootstrap({
  list: peerList,
  interval: 2000
  })
@@ -22,7 +22,7 @@ describe('bootstrap', () => {
  it('not fail on malformed peers in peer list', function (done) {
  this.timeout(5 * 1000)
 
- const r = new Railing({
+ const r = new Bootstrap({
  list: partialValidPeerList,
  interval: 2000
  })