add logging of raw updates

services/track-changes/app.coffee

@@ -1,10 +1,24 @@
 Settings = require "settings-sharelatex"
 logger = require "logger-sharelatex"
-logger.initialize("track-changes")
+TrackChangesLogger = logger.initialize("track-changes").logger
 
 if Settings.sentry?.dsn?
 	logger.initializeErrorReporting(Settings.sentry.dsn)
 
+# log updates as truncated strings
+truncateFn = (updates) ->
+		JSON.stringify updates, (key, value) ->
+			if typeof value == 'string' && (len = value.length) > 80
+				return value.substr(0,32) + "...(message of length #{len} truncated)..." + value.substr(-32)
+			else
+				return value
+
+TrackChangesLogger.addSerializers {
+	rawUpdates: truncateFn
+	newUpdates: truncateFn
+	lastUpdate: truncateFn
+}
+
 Path = require "path"
 Metrics = require "metrics-sharelatex"
 Metrics.initialize("track-changes")

services/track-changes/app/coffee/UpdatesManager.coffee

@@ -102,6 +102,7 @@ module.exports = UpdatesManager =
 					# parse the redis strings into ShareJs updates
 					RedisManager.expandDocUpdates docUpdates, (error, rawUpdates) ->
 						return callback(error) if error?
+						logger.log project_id: project_id, doc_id: doc_id, rawUpdates: rawUpdates, "retrieved raw updates from redis"
 						UpdatesManager.compressAndSaveRawUpdates project_id, doc_id, rawUpdates, temporary, (error) ->
 							return callback(error) if error?
 							logger.log project_id: project_id, doc_id: doc_id, "compressed and saved doc updates"