fix: not dial all known peers in parallel on startup

.aegir.js

@@ -45,7 +45,7 @@ const after = async () => {
 }
 
 module.exports = {
-  bundlesize: { maxSize: '200kB' },
+  bundlesize: { maxSize: '202kB' },
   hooks: {
     pre: before,
     post: after

src/connection-manager/index.js

@@ -1,9 +1,12 @@
 'use strict'
 
+const debug = require('debug')
+const log = debug('libp2p:connection-manager')
+log.error = debug('libp2p:connection-manager:error')
+
 const errcode = require('err-code')
 const mergeOptions = require('merge-options')
 const LatencyMonitor = require('./latency-monitor')
-const debug = require('debug')('libp2p:connection-manager')
 const retimer = require('retimer')
 
 const { EventEmitter } = require('events')
@@ -22,6 +25,7 @@ const defaultOptions = {
   maxReceivedData: Infinity,
   maxEventLoopDelay: Infinity,
   pollInterval: 2000,
+  autoDialInterval: 10000,
   movingAverageInterval: 60000,
   defaultPeerValue: 1
 }
@@ -45,6 +49,8 @@ class ConnectionManager extends EventEmitter {
    * @param {Number} options.pollInterval How often, in milliseconds, metrics and latency should be checked. Default=2000
    * @param {Number} options.movingAverageInterval How often, in milliseconds, to compute averages. Default=60000
    * @param {Number} options.defaultPeerValue The value of the peer. Default=1
+   * @param {boolean} options.autoDial Should preemptively guarantee connections are above the low watermark. Default=true
+   * @param {Number} options.autoDialInterval How often, in milliseconds, it should preemptively guarantee connections are above the low watermark. Default=10000
    */
   constructor (libp2p, options) {
     super()
@@ -57,7 +63,7 @@ class ConnectionManager extends EventEmitter {
       throw errcode(new Error('Connection Manager maxConnections must be greater than minConnections'), ERR_INVALID_PARAMETERS)
     }
 
-    debug('options: %j', this._options)
+    log('options: %j', this._options)
 
     this._libp2p = libp2p
 
@@ -73,8 +79,11 @@ class ConnectionManager extends EventEmitter {
      */
     this.connections = new Map()
 
+    this._started = false
     this._timer = null
+    this._autoDialTimeout = null
     this._checkMetrics = this._checkMetrics.bind(this)
+    this._autoDial = this._autoDial.bind(this)
   }
 
   /**
@@ -101,19 +110,25 @@ class ConnectionManager extends EventEmitter {
     })
     this._onLatencyMeasure = this._onLatencyMeasure.bind(this)
     this._latencyMonitor.on('data', this._onLatencyMeasure)
-    debug('started')
+
+    this._started = true
+    log('started')
+
+    this._options.autoDial && this._autoDial()
   }
 
   /**
    * Stops the Connection Manager
    * @async
    */
   async stop () {
+    this._autoDialTimeout && this._autoDialTimeout.clear()
     this._timer && this._timer.clear()
     this._latencyMonitor && this._latencyMonitor.removeListener('data', this._onLatencyMeasure)
 
+    this._started = false
     await this._close()
-    debug('stopped')
+    log('stopped')
   }
 
   /**
@@ -157,12 +172,12 @@ class ConnectionManager extends EventEmitter {
   _checkMetrics () {
     const movingAverages = this._libp2p.metrics.global.movingAverages
     const received = movingAverages.dataReceived[this._options.movingAverageInterval].movingAverage()
-    this._checkLimit('maxReceivedData', received)
+    this._checkMaxLimit('maxReceivedData', received)
     const sent = movingAverages.dataSent[this._options.movingAverageInterval].movingAverage()
-    this._checkLimit('maxSentData', sent)
+    this._checkMaxLimit('maxSentData', sent)
     const total = received + sent
-    this._checkLimit('maxData', total)
-    debug('metrics update', total)
+    this._checkMaxLimit('maxData', total)
+    log('metrics update', total)
     this._timer.reschedule(this._options.pollInterval)
   }
 
@@ -188,7 +203,7 @@ class ConnectionManager extends EventEmitter {
       this._peerValues.set(peerIdStr, this._options.defaultPeerValue)
     }
 
-    this._checkLimit('maxConnections', this.size)
+    this._checkMaxLimit('maxConnections', this.size)
   }
 
   /**
@@ -248,7 +263,7 @@ class ConnectionManager extends EventEmitter {
    * @param {*} summary The LatencyMonitor summary
    */
   _onLatencyMeasure (summary) {
-    this._checkLimit('maxEventLoopDelay', summary.avgMs)
+    this._checkMaxLimit('maxEventLoopDelay', summary.avgMs)
   }
 
   /**
@@ -257,15 +272,69 @@ class ConnectionManager extends EventEmitter {
    * @param {string} name The name of the field to check limits for
    * @param {number} value The current value of the field
    */
-  _checkLimit (name, value) {
+  _checkMaxLimit (name, value) {
     const limit = this._options[name]
-    debug('checking limit of %s. current value: %d of %d', name, value, limit)
+    log('checking limit of %s. current value: %d of %d', name, value, limit)
     if (value > limit) {
-      debug('%s: limit exceeded: %s, %d', this._peerId, name, value)
+      log('%s: limit exceeded: %s, %d', this._peerId, name, value)
       this._maybeDisconnectOne()
     }
   }
 
+  /**
+   * Proactively tries to connect to known peers stored in the PeerStore.
+   * It will keep the number of connections below the upper limit and sort
+   * the peers to connect based on wether we know their keys and protocols.
+   * @async
+   * @private
+   */
+  async _autoDial () {
+    const minConnections = this._options.minConnections
+
+    const recursiveTimeoutTrigger = () => {
+      if (this._autoDialTimeout) {
+        this._autoDialTimeout.reschedule(this._options.autoDialInterval)
+      } else {
+        this._autoDialTimeout = retimer(this._autoDial, this._options.autoDialInterval)
+      }
+    }
+
+    // Already has enough connections
+    if (this.size >= minConnections) {
+      recursiveTimeoutTrigger()
+      return
+    }
+
+    // Sort peers on wether we know protocols of public keys for them
+    const peers = Array.from(this._libp2p.peerStore.peers.values())
+      .sort((a, b) => {
+        if (b.protocols && b.protocols.length && (!a.protocols || !a.protocols.length)) {
+          return 1
+        } else if (b.id.pubKey && !a.id.pubKey) {
+          return 1
+        }
+        return -1
+      })
+
+    for (let i = 0; i < peers.length && this.size < minConnections; i++) {
+      if (!this.get(peers[i].id)) {
+        log('connecting to a peerStore stored peer %s', peers[i].id.toB58String())
+        try {
+          await this._libp2p.dialer.connectToPeer(peers[i].id)
+
+          // Connection Manager was stopped
+          if (!this._started) {
+            return
+          }
+        } catch (err) {
+          log.error('could not connect to peerStore stored peer', err)
+        }
+      }
+    }
+
+    recursiveTimeoutTrigger()
+  }
+
   /**
    * If we have more connections than our maximum, close a connection
    * to the lowest valued peer.
@@ -274,12 +343,12 @@ class ConnectionManager extends EventEmitter {
   _maybeDisconnectOne () {
     if (this._options.minConnections < this.connections.size) {
       const peerValues = Array.from(this._peerValues).sort(byPeerValue)
-      debug('%s: sorted peer values: %j', this._peerId, peerValues)
+      log('%s: sorted peer values: %j', this._peerId, peerValues)
       const disconnectPeer = peerValues[0]
       if (disconnectPeer) {
         const peerId = disconnectPeer[0]
-        debug('%s: lowest value peer is %s', this._peerId, peerId)
-        debug('%s: closing a connection to %j', this._peerId, peerId)
+        log('%s: lowest value peer is %s', this._peerId, peerId)
+        log('%s: closing a connection to %j', this._peerId, peerId)
         for (const connections of this.connections.values()) {
           if (connections[0].remotePeer.toB58String() === peerId) {
             connections[0].close()

src/index.js

@@ -65,7 +65,10 @@ class Libp2p extends EventEmitter {
     this._discovery = new Map() // Discovery service instances/references
 
     // Create the Connection Manager
-    this.connectionManager = new ConnectionManager(this, this._options.connectionManager)
+    this.connectionManager = new ConnectionManager(this, {
+      autoDial: this._config.peerDiscovery.autoDial,
+      ...this._options.connectionManager
+    })
 
     // Create Metrics
     if (this._options.metrics.enabled) {
@@ -459,19 +462,19 @@ class Libp2p extends EventEmitter {
   async _onDidStart () {
     this._isStarted = true
 
-    this.connectionManager.start()
-
     this.peerStore.on('peer', peerId => {
       this.emit('peer:discovery', peerId)
       this._maybeConnect(peerId)
     })
 
-    // Once we start, emit and dial any peers we may have already discovered
+    // Once we start, emit any peers we may have already discovered
+    // TODO: this should be removed, as we already discovered these peers in the past
     for (const peer of this.peerStore.peers.values()) {
       this.emit('peer:discovery', peer.id)
-      this._maybeConnect(peer.id)
     }
 
+    this.connectionManager.start()
+
     // Peer discovery
     await this._setupPeerDiscovery()
   }