Extract connection monitoring and rewrite as a subscriber

lib/assets/javascripts/cable.js.coffee

@@ -4,6 +4,8 @@
 #= require cable/channel
 
 class @Cable
+  @PING_IDENTIFIER: "_ping"
+
   constructor: (@url) ->
     @subscribers = new Cable.SubscriberManager this
     @connection = new Cable.Connection this

lib/assets/javascripts/cable/connection.js.coffee

@@ -1,10 +1,8 @@
-class Cable.Connection
-  MAX_CONNECTION_INTERVAL: 5 * 1000
-  PING_STALE_INTERVAL: 8
+#= require cable/connection_monitor
 
+class Cable.Connection
   constructor: (@cable) ->
-    @resetPingTime()
-    @resetConnectionAttemptsCount()
+    new Cable.ConnectionMonitor @cable
     @connect()
 
   send: (data) ->
@@ -15,88 +13,40 @@ class Cable.Connection
       false
 
   connect: ->
-    @websocket = @createWebSocket()
+    @removeWebsocket()
+    @createWebSocket()
 
   createWebSocket: ->
-    ws = new WebSocket(@cable.url)
-    ws.onmessage = @onMessage
-    ws.onopen    = @onConnect
-    ws.onclose   = @onClose
-    ws.onerror   = @onError
-    ws
+    @websocket = new WebSocket(@cable.url)
+    @websocket.onmessage = @onMessage
+    @websocket.onopen    = @onConnect
+    @websocket.onclose   = @onClose
+    @websocket.onerror   = @onError
+    @websocket
 
-  onMessage: (message) =>
-    data = JSON.parse message.data
-
-    if data.identifier is '_ping'
-      @pingReceived(data.message)
-    else
-      @cable.subscribers.notify(data.identifier, "received", data.message)
-
-  onConnect: =>
-    @startWaitingForPing()
-    @resetConnectionAttemptsCount()
-    @cable.subscribers.reload()
-
-  onClose: =>
-    @reconnect()
-
-  onError: =>
-    @reconnect()
-
-  isConnected: ->
-    @websocket?.readyState is 1
-
-  disconnect: ->
-    @removeExistingConnection()
-    @resetPingTime()
-    @cable.subscribers.notifyAll("disconnected")
-
-  reconnect: ->
-    @disconnect()
-
-    setTimeout =>
-      @incrementConnectionAttemptsCount()
-      @connect()
-    , @generateReconnectInterval()
-
-  removeExistingConnection: ->
+  removeWebsocket: ->
     if @websocket?
-      @clearPingWaitTimeout()
-
       @websocket.onclose = -> # no-op
       @websocket.onerror = -> # no-op
       @websocket.close()
       @websocket = null
 
-  resetConnectionAttemptsCount: ->
-    @connectionAttempts = 1
+  onMessage: (message) =>
+    data = JSON.parse message.data
+    @cable.subscribers.notify(data.identifier, "received", data.message)
 
-  incrementConnectionAttemptsCount: ->
-    @connectionAttempts += 1
+  onConnect: =>
+    @cable.subscribers.reload()
 
-  generateReconnectInterval: () ->
-    interval = (Math.pow(2, @connectionAttempts) - 1) * 1000
-    if interval > @MAX_CONNECTION_INTERVAL then @MAX_CONNECTION_INTERVAL else interval
+  onClose: =>
+    @disconnect()
 
-  startWaitingForPing: ->
-    @clearPingWaitTimeout()
+  onError: =>
+    @disconnect()
 
-    @waitForPingTimeout = setTimeout =>
-      console.log "Ping took too long to arrive. Reconnecting.."
-      @reconnect()
-    , @PING_STALE_INTERVAL * 1000
+  isConnected: ->
+    @websocket?.readyState is 1
 
-  clearPingWaitTimeout: ->
-    clearTimeout(@waitForPingTimeout)
-
-  resetPingTime: ->
-    @lastPingTime = null
-
-  pingReceived: (timestamp) ->
-    if @lastPingTime? and (timestamp - @lastPingTime) > @PING_STALE_INTERVAL
-      console.log "Websocket connection is stale. Reconnecting.."
-      @reconnect()
-    else
-      @startWaitingForPing()
-      @lastPingTime = timestamp
+  disconnect: ->
+    @cable.subscribers.notifyAll("disconnected")
+    @removeWebsocket()

lib/assets/javascripts/cable/connection_monitor.js.coffee

@@ -0,0 +1,41 @@
+class Cable.ConnectionMonitor
+  MAX_CONNECTION_INTERVAL: 5 * 1000
+  PING_STALE_INTERVAL: 8 * 1000
+
+  identifier: Cable.PING_IDENTIFIER
+
+  constructor: (@cable) ->
+    @reset()
+    @cable.subscribers.add(this)
+    @pollConnection()
+
+  connected: ->
+    @reset()
+    @pingedAt = now()
+
+  received: ->
+    @pingedAt = now()
+
+  reset: ->
+    @connectionAttempts = 1
+
+  pollConnection: ->
+    setTimeout =>
+      @reconnect() if @connectionIsStale()
+      @pollConnection()
+    , @getPollTimeout()
+
+  getPollTimeout: ->
+    interval = (Math.pow(2, @connectionAttempts) - 1) * 1000
+    if interval > @MAX_CONNECTION_INTERVAL then @MAX_CONNECTION_INTERVAL else interval
+
+  connectionIsStale: ->
+    @pingedAt? and (now() - @pingedAt) > @PING_STALE_INTERVAL
+
+  reconnect: ->
+    console.log "Ping took too long to arrive. Reconnecting.."
+    @connectionAttempts += 1
+    @cable.connection.connect()
+
+  now = ->
+    new Date().getTime()

lib/assets/javascripts/cable/subscriber_manager.js.coffee

@@ -30,4 +30,5 @@ class Cable.SubscriberManager
       subscriber[event]?(args...)
 
   sendCommand: (command, identifier) ->
+    return true if identifier is Cable.PING_IDENTIFIER
     @cable.send({command, identifier})