ws client: better offline reconnect behavior

Fixes webtorrent/webtorrent#318

Author: feross

lib/websocket-tracker.js

@@ -11,6 +11,9 @@ var Socket = require('simple-websocket')
 
 var common = require('./common')
 
+var RECONNECT_VARIANCE = 30 * 1000
+var RECONNECT_MINIMUM = 5 * 1000
+
 inherits(WebSocketTracker, EventEmitter)
 
 function WebSocketTracker (client, announceUrl, opts) {
@@ -27,18 +30,13 @@ function WebSocketTracker (client, announceUrl, opts) {
   self._intervalMs = self.client._intervalMs // use client interval initially
   self._interval = null
 
-  self._onSocketErrorBound = self._onSocketError.bind(self)
-  self._onSocketDataBound = self._onSocketData.bind(self)
-
-  self._socket = new Socket(announceUrl + '?' + hat(40))
-  self._socket.on('error', self._onSocketErrorBound)
-  self._socket.on('data', self._onSocketDataBound)
+  self._openSocket()
 }
 
 WebSocketTracker.prototype.announce = function (opts) {
   var self = this
   if (!self._socket.connected) {
-    return self._socket.on('connect', self.announce.bind(self, opts))
+    return self._socket.once('connect', self.announce.bind(self, opts))
   }
 
   opts.info_hash = self.client._infoHash.toString('binary')
@@ -80,15 +78,28 @@ WebSocketTracker.prototype.destroy = function () {
   var self = this
   if (self.destroyed) return
   self.destroyed = true
-  self._socket.removeListener('error', self._onSocketErrorBound)
+
   self._socket.removeListener('data', self._onSocketDataBound)
-  self._socket.close()
+  self._socket.removeListener('close', self._onSocketCloseBound)
+  self._socket.removeListener('error', self._onSocketErrorBound)
+  self._onSocketErrorBound = null
+  self._onSocketDataBound = null
+  self._onSocketCloseBound = null
+
+  try { self._socket.close() } catch (e) {}
+  self._socket = null
 }
 
-WebSocketTracker.prototype._onSocketError = function (err) {
+WebSocketTracker.prototype._openSocket = function () {
   var self = this
-  if (self.destroyed) return
-  self.client.emit('error', err)
+  self._onSocketErrorBound = self._onSocketError.bind(self)
+  self._onSocketDataBound = self._onSocketData.bind(self)
+  self._onSocketCloseBound = self._onSocketClose.bind(self)
+
+  self._socket = new Socket(self._announceUrl + '?' + hat(40))
+  self._socket.on('data', self._onSocketDataBound)
+  self._socket.on('close', self._onSocketCloseBound)
+  self._socket.on('error', self._onSocketErrorBound)
 }
 
 WebSocketTracker.prototype._onSocketData = function (data) {
@@ -167,6 +178,22 @@ WebSocketTracker.prototype._onSocketData = function (data) {
   }
 }
 
+WebSocketTracker.prototype._onSocketClose = function () {
+  var self = this
+  self.destroy()
+  var ms = Math.floor(Math.random() * RECONNECT_VARIANCE) + RECONNECT_MINIMUM
+  setTimeout(function () {
+    self._openSocket()
+  }, ms)
+  debug('reconnecting socket in %s ms', ms)
+}
+
+WebSocketTracker.prototype._onSocketError = function (err) {
+  var self = this
+  if (self.destroyed) return
+  self.client.emit('error', err)
+}
+
 WebSocketTracker.prototype._send = function (params) {
   var self = this
   if (self.destroyed) return