Don't call sync functions inside async

Calling sync functions inside async can trigger the node max stack size.
Instead, build up our unique list of ids in advance, so we only call a
method in async for each user we actually need to look up, asynchronously.
Then use all the cached values synchronously afterwards.

services/web/app/coffee/Features/Chat/ChatController.coffee

@@ -34,32 +34,32 @@ module.exports = ChatController =
 				res.json messages
 
 	_injectUserInfoIntoThreads: (threads, callback = (error, threads) ->) ->
-		userCache = {}
+		# There will be a lot of repitition of user_ids, so first build a list
-		getUserDetails = (user_id, callback = (error, user) ->) ->
+		# of unique ones to perform db look ups on, then use these to populate the
-			return callback(null, userCache[user_id]) if userCache[user_id]?
+		# user fields
-			UserInfoManager.getPersonalInfo user_id, (err, user) ->
+		user_ids = {}
-				return callback(error) if error?
+		for thread_id, thread of threads
-				user = UserInfoController.formatPersonalInfo user
+			if thread.resolved
-				userCache[user_id] = user
+				user_ids[thread.resolved_by_user_id] = true
-				callback null, user
+			for message in thread.messages
+				user_ids[message.user_id] = true
 		
 		jobs = []
-		for thread_id, thread of threads
+		users = {}
-			do (thread) ->
+		for user_id, _ of user_ids
-				if thread.resolved
+			do (user_id) ->
-					jobs.push (cb) ->
+				jobs.push (cb) ->
-						getUserDetails thread.resolved_by_user_id, (error, user) ->
+					UserInfoManager.getPersonalInfo user_id, (err, user) ->
-							cb(error) if error?
+						return cb(error) if error?
-							thread.resolved_by_user = user
+						user = UserInfoController.formatPersonalInfo user
-							cb()
+						users[user_id] = user
-				for message in thread.messages
+						cb()
-					do (message) ->
-						jobs.push (cb) ->
-							getUserDetails message.user_id, (error, user) ->
-								cb(error) if error?
-								message.user = user
-								cb()
 
 		async.series jobs, (error) ->
 			return callback(error) if error?
+			for thread_id, thread of threads
+				if thread.resolved
+					thread.resolved_by_user = users[thread.resolved_by_user_id]
+				for message in thread.messages
+					message.user = users[message.user_id]
 			return callback null, threads