From 336d12f97aba485809005f27d4952705e312251c Mon Sep 17 00:00:00 2001
From: Javan Makhmali <javan@javan.us>
Date: Sat, 27 Jun 2015 16:17:00 -0400
Subject: Rework connection monitor

---
 lib/assets/javascripts/cable/connection.js.coffee  |  3 --
 .../javascripts/cable/connection_monitor.js.coffee | 62 +++++++++++++++-------
 lib/assets/javascripts/cable/consumer.js.coffee    |  2 +
 .../javascripts/cable/subscriber_manager.js.coffee |  6 ++-
 4 files changed, 49 insertions(+), 24 deletions(-)

diff --git a/lib/assets/javascripts/cable/connection.js.coffee b/lib/assets/javascripts/cable/connection.js.coffee
index 98af9ad8ab..4f7d2abada 100644
--- a/lib/assets/javascripts/cable/connection.js.coffee
+++ b/lib/assets/javascripts/cable/connection.js.coffee
@@ -1,8 +1,5 @@
-#= require cable/connection_monitor
-
 class Cable.Connection
   constructor: (@consumer) ->
-    new Cable.ConnectionMonitor @consumer
     @open()
 
   send: (data) ->
diff --git a/lib/assets/javascripts/cable/connection_monitor.js.coffee b/lib/assets/javascripts/cable/connection_monitor.js.coffee
index bb4ee8f7f6..fc5093c5eb 100644
--- a/lib/assets/javascripts/cable/connection_monitor.js.coffee
+++ b/lib/assets/javascripts/cable/connection_monitor.js.coffee
@@ -1,13 +1,17 @@
 class Cable.ConnectionMonitor
-  MAX_CONNECTION_INTERVAL: 5 * 1000
-  PING_STALE_INTERVAL: 8 * 1000
-
   identifier: Cable.PING_IDENTIFIER
 
+  pollInterval:
+    min: 2
+    max: 30
+
+  staleThreshold:
+    startedAt: 4
+    pingedAt: 8
+
   constructor: (@consumer) ->
-    @reset()
     @consumer.subscribers.add(this)
-    @pollConnection()
+    @start()
 
   connected: ->
     @reset()
@@ -17,25 +21,45 @@ class Cable.ConnectionMonitor
     @pingedAt = now()
 
   reset: ->
-    @connectionAttempts = 1
+    @reconnectAttempts = 0
+
+  start: ->
+    @reset()
+    delete @stoppedAt
+    @startedAt = now()
+    @poll()
 
-  pollConnection: ->
+  stop: ->
+    @stoppedAt = now()
+
+  poll: ->
     setTimeout =>
-      @reconnect() if @connectionIsStale()
-      @pollConnection()
-    , @getPollTimeout()
+      unless @stoppedAt
+        @reconnectIfStale()
+        @poll()
+    , @getInterval()
 
-  getPollTimeout: ->
-    interval = (Math.pow(2, @connectionAttempts) - 1) * 1000
-    if interval > @MAX_CONNECTION_INTERVAL then @MAX_CONNECTION_INTERVAL else interval
+  getInterval: ->
+    {min, max} = @pollInterval
+    interval = 4 * Math.log(@reconnectAttempts + 1)
+    clamp(interval, min, max) * 1000
 
-  connectionIsStale: ->
-    @pingedAt? and (now() - @pingedAt) > @PING_STALE_INTERVAL
+  reconnectIfStale: ->
+    if @connectionIsStale()
+      @reconnectAttempts += 1
+      @consumer.connection.reopen()
 
-  reconnect: ->
-    console.log "Ping took too long to arrive. Reconnecting.."
-    @connectionAttempts += 1
-    @consumer.connection.reopen()
+  connectionIsStale: ->
+    if @pingedAt
+      secondsSince(@pingedAt) > @staleThreshold.pingedAt
+    else
+      secondsSince(@startedAt) > @staleThreshold.startedAt
 
   now = ->
     new Date().getTime()
+
+  secondsSince = (time) ->
+    (now() - time) / 1000
+
+  clamp = (number, min, max) ->
+    Math.max(min, Math.min(max, number))
diff --git a/lib/assets/javascripts/cable/consumer.js.coffee b/lib/assets/javascripts/cable/consumer.js.coffee
index a9abd6256a..b9c08807f2 100644
--- a/lib/assets/javascripts/cable/consumer.js.coffee
+++ b/lib/assets/javascripts/cable/consumer.js.coffee
@@ -1,4 +1,5 @@
 #= require cable/connection
+#= require cable/connection_monitor
 #= require cable/subscription
 #= require cable/subscriber_manager
 
@@ -6,6 +7,7 @@ class Cable.Consumer
   constructor: (@url) ->
     @subscribers = new Cable.SubscriberManager this
     @connection = new Cable.Connection this
+    @connectionMonitor = new Cable.ConnectionMonitor this
 
   createSubscription: (channelName, mixin) ->
     channel = channelName
diff --git a/lib/assets/javascripts/cable/subscriber_manager.js.coffee b/lib/assets/javascripts/cable/subscriber_manager.js.coffee
index 922c74808c..0b6a16590c 100644
--- a/lib/assets/javascripts/cable/subscriber_manager.js.coffee
+++ b/lib/assets/javascripts/cable/subscriber_manager.js.coffee
@@ -32,5 +32,7 @@ class Cable.SubscriberManager
 
   sendCommand: (subscriber, command) ->
     {identifier} = subscriber
-    return true if identifier is Cable.PING_IDENTIFIER
-    @consumer.send({command, identifier})
+    if identifier is Cable.PING_IDENTIFIER
+      @consumer.connection.isOpen()
+    else
+      @consumer.send({command, identifier})
-- 
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