reduce memory capture in http logger

only capture the properties of 'req' that we need, to avoid leaking
the whole req object for responses that never call res.end()

libraries/metrics/http.coffee

@@ -4,23 +4,35 @@ module.exports.monitor = (logger) ->
 	return (req, res, next) ->
 		Metrics = require("./metrics")
 		startTime = new Date()
+
+		# only capture the properties of 'req' that we need, to avoid
+		# leaking the whole req object for responses that never call
+		# res.end()
+		url = req.originalUrl || req.url
+		method = req.method
+		referrer = req.headers['referer'] || req.headers['referrer']
+		remoteAddr = req.ip || req.socket?.socket?.remoteAddress || req.socket?.remoteAddress
+		userAgent = req.headers["user-agent"]
+		contentLength = req.headers["content-length"]
+		path = req.route?.path
+
 		end = res.end
 		res.end = () ->
 			end.apply(this, arguments)
 			responseTime = new Date() - startTime
-			if req.route?.path?
-				routePath = req.route.path.toString().replace(/\//g, '_').replace(/\:/g, '').slice(1)
-				key = "http-requests.#{routePath}.#{req.method}.#{res.statusCode}"
+			if path?
+				routePath = path.toString().replace(/\//g, '_').replace(/\:/g, '').slice(1)
+				key = "http-requests.#{routePath}.#{method}.#{res.statusCode}"
 
 				Metrics.timing(key, responseTime)
 				logger.log
 					req:
-						url: req.originalUrl || req.url
-						method: req.method
-						referrer: req.headers['referer'] || req.headers['referrer']
-						"remote-addr": req.ip || req.socket?.socket?.remoteAddress || req.socket?.remoteAddress
-						"user-agent": req.headers["user-agent"]
-						"content-length": req.headers["content-length"]
+						url: url
+						method: method
+						referrer: referrer
+						"remote-addr": remoteAddr
+						"user-agent": userAgent
+						"content-length": contentLength
 					res:
 						"content-length": res._headers?["content-length"]
 						statusCode: res.statusCode