add client-side spelling cache to reduce load on server

services/web/app/views/project/editor/editor.jade

@@ -20,6 +20,7 @@ div.full-size(
 			keybindings="settings.mode",
 			font-size="settings.fontSize",
 			auto-complete="settings.autoComplete",
+			spell-check="true",
 			spell-check-language="project.spellCheckLanguage",
 			highlights="onlineUserCursorHighlights[editor.open_doc_id]"
 			show-print-margin="false",

services/web/public/coffee/ide/editor/directives/aceEditor.coffee

@@ -18,7 +18,7 @@ define [
 			url = ace.config._moduleUrl(args...) + "?fingerprint=#{window.aceFingerprint}"
 			return url
 
-	App.directive "aceEditor", ($timeout, $compile, $rootScope, event_tracking, localStorage) ->
+	App.directive "aceEditor", ($timeout, $compile, $rootScope, event_tracking, localStorage, $cacheFactory) ->
 		monkeyPatchSearch($rootScope, $compile)
 
 		return  {
@@ -29,6 +29,7 @@ define [
 				fontSize: "="
 				autoComplete: "="
 				sharejsDoc: "="
+				spellCheck: "="
 				spellCheckLanguage: "="
 				highlights: "="
 				text: "="
@@ -55,7 +56,9 @@ define [
 				scope.name = attrs.aceEditor
 
 				autoCompleteManager   = new AutoCompleteManager(scope, editor, element)
-				spellCheckManager     = new SpellCheckManager(scope, editor, element)
+				if scope.spellCheck # only enable spellcheck when explicitly required
+					spellCheckCache =  $cacheFactory("spellCheck-#{scope.name}", {capacity: 1000})
+					spellCheckManager = new SpellCheckManager(scope, editor, element, spellCheckCache)
 				undoManager           = new UndoManager(scope, editor, element)
 				highlightsManager     = new HighlightsManager(scope, editor, element)
 				cursorPositionManager = new CursorPositionManager(scope, editor, element, localStorage)

services/web/public/coffee/ide/editor/directives/aceEditor/spell-check/SpellCheckManager.coffee

@@ -5,7 +5,7 @@ define [
 	Range = ace.require("ace/range").Range
 
 	class SpellCheckManager
-		constructor: (@$scope, @editor, @element) ->
+		constructor: (@$scope, @editor, @element, @cache) ->
 			$(document.body).append @element.find(".spell-check-menu")
 			
 			@updatedLines = []
@@ -102,6 +102,8 @@ define [
 		learnWord: (highlight) ->
 			@apiRequest "/learn", word: highlight.word
 			@highlightedWordManager.removeWord highlight.word
+			language = @$scope.spellCheckLanguage
+			@cache?.put("#{language}:#{highlight.word}", true)
 
 		getHighlightedWordAtCursor: () ->
 			cursor = @editor.getCursorPosition()
@@ -143,24 +145,67 @@ define [
 		runSpellCheck: (linesToProcess) ->
 			{words, positions} = @getWords(linesToProcess)
 			language = @$scope.spellCheckLanguage
-			@apiRequest "/check", {language: language, words: words}, (error, result) =>
-				if error? or !result? or !result.misspellings?
-					return null
 
+			highlights = []
+			seen = {}
+			newWords = []
+			newPositions = []
+
+			# iterate through all words, building up a list of
+			# newWords/newPositions not in the cache
+			for word, i in words
+				key = "#{language}:#{word}"
+				seen[key] ?= @cache.get(key) # avoid hitting the cache unnecessarily
+				cached = seen[key]
+				if not cached?
+					newWords.push words[i]
+					newPositions.push positions[i]
+				else if cached is true
+					# word is correct
+				else
+					highlights.push
+						column: positions[i].column
+						row: positions[i].row
+						word: word
+						suggestions: cached
+			words = newWords
+			positions = newPositions
+
+			displayResult = (highlights) =>
 				if linesToProcess?
 					for shouldProcess, row in linesToProcess
 						@highlightedWordManager.clearRows(row, row) if shouldProcess
 				else
 					@highlightedWordManager.clearRows()
+				for highlight in highlights
+					@highlightedWordManager.addHighlight highlight
 
-				for misspelling in result.misspellings
-					word = words[misspelling.index]
-					position = positions[misspelling.index]
-					@highlightedWordManager.addHighlight
-						column: position.column
-						row: position.row
-						word: word
-						suggestions: misspelling.suggestions
+			if not words.length
+				displayResult highlights
+			else
+				@apiRequest "/check", {language: language, words: words}, (error, result) =>
+					if error? or !result? or !result.misspellings?
+						return null
+					mispelled = []
+					for misspelling in result.misspellings
+						word = words[misspelling.index]
+						position = positions[misspelling.index]
+						mispelled[misspelling.index] = true
+						highlights.push
+							column: position.column
+							row: position.row
+							word: word
+							suggestions: misspelling.suggestions
+						key = "#{language}:#{word}"
+						if not seen[key]
+							@cache.put key, misspelling.suggestions
+							seen[key] = true
+					for word, i in words when not mispelled[i]
+						key = "#{language}:#{word}"
+						if not seen[key]
+							@cache.put(key, true)
+							seen[key] = true
+					displayResult highlights
 
 		getWords: (linesToProcess) ->
 			lines = @editor.getValue().split("\n")