From 4da9008300fbd7e861dea4f9ab9bea61f2bbe8db Mon Sep 17 00:00:00 2001
From: Brian Gough <bjg@network-theory.co.uk>
Date: Mon, 31 Oct 2016 15:32:01 +0000
Subject: [PATCH] rate limit on reconnection attempts (cursor/click)

---
 .../ide/connection/ConnectionManager.coffee   | 26 ++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/services/web/public/coffee/ide/connection/ConnectionManager.coffee b/services/web/public/coffee/ide/connection/ConnectionManager.coffee
index da7dbbc9b4..987186fd19 100644
--- a/services/web/public/coffee/ide/connection/ConnectionManager.coffee
+++ b/services/web/public/coffee/ide/connection/ConnectionManager.coffee
@@ -36,16 +36,19 @@ define [], () ->
 				inactive_disconnect: false
 
 			@$scope.tryReconnectNow = () =>
-				@tryReconnect()
+				# user manually requested reconnection via "Try now" button
+				@tryReconnectWithRateLimit({force:true})
 
 			@$scope.$on 'cursor:editor:update', () =>
 				@lastUserAction = new Date()  # time of last edit
 				if !@connected
-					@tryReconnect()
+					# user is editing, try to reconnect
+					@tryReconnectWithRateLimit()
 
 			document.querySelector('body').addEventListener 'click', (e) =>
 				if !@connected and e.target.id != 'try-reconnect-now-button'
-					@tryReconnect()
+					# user is editing, try to reconnect
+					@tryReconnectWithRateLimit()
 
 			@ide.socket = io.connect null,
 				reconnect: false
@@ -210,8 +213,25 @@ define [], () ->
 			# use socket.io connect() here to make a single attempt, the
 			# reconnect() method makes multiple attempts
 			@ide.socket.socket.connect()
+			# record the time of the last attempt to connect
+			@lastConnectionAttempt = new Date()
 			setTimeout (=> @startAutoReconnectCountdown() if !@connected), 2000
 
+		MIN_RETRY_INTERVAL: 1000 # ms
+		BACKGROUND_RETRY_INTERVAL : 30 * 1000 # ms
+
+		tryReconnectWithRateLimit: (options) ->
+			# bail out if the reconnect is already in progress
+			return if @$scope.connection?.reconnecting
+			# bail out if we are going to reconnect soon anyway
+			reconnectingSoon = @$scope.connection?.reconnection_countdown? and @$scope.connection.reconnection_countdown <= 5
+			clickedTryNow = options?.force  # user requested reconnection
+			return if reconnectingSoon and not clickedTryNow
+			# bail out if we tried reconnecting recently
+			allowedInterval = if clickedTryNow then @MIN_RETRY_INTERVAL else @BACKGROUND_RETRY_INTERVAL
+			return if @lastConnectionAttempt? and new Date() - @lastConnectionAttempt < allowedInterval
+			@tryReconnect()
+
 		disconnectIfInactive: ()->
 			@userIsInactive = (new Date() - @lastUserAction) > @disconnectAfterMs
 			if @userIsInactive and @connected