perf: re-use options object when generating ETags

closes expressjs#3313
closes expressjs#3314

History.md

@@ -24,6 +24,7 @@ unreleased
     - Fix parsing & compacting very deep objects
   * deps: [email protected]
   * deps: [email protected]
+  * perf: re-use options object when generating ETags
 
 4.15.5 / 2017-09-24
 ===================

lib/utils.js

@@ -31,13 +31,7 @@ var querystring = require('querystring');
  * @api private
  */
 
-exports.etag = function (body, encoding) {
-  var buf = !Buffer.isBuffer(body)
-    ? new Buffer(body, encoding)
-    : body;
-
-  return etag(buf, {weak: false});
-};
+exports.etag = createETagGenerator({ weak: false })
 
 /**
  * Return weak ETag for `body`.
@@ -48,13 +42,7 @@ exports.etag = function (body, encoding) {
  * @api private
  */
 
-exports.wetag = function wetag(body, encoding){
-  var buf = !Buffer.isBuffer(body)
-    ? new Buffer(body, encoding)
-    : body;
-
-  return etag(buf, {weak: true});
-};
+exports.wetag = createETagGenerator({ weak: true })
 
 /**
  * Check if `path` looks absolute.
@@ -273,6 +261,25 @@ exports.setCharset = function setCharset(type, charset) {
   return contentType.format(parsed);
 };
 
+/**
+ * Create an ETag generator function, generating ETags with
+ * the given options.
+ *
+ * @param {object} options
+ * @return {function}
+ * @private
+ */
+
+function createETagGenerator (options) {
+  return function generateETag (body, encoding) {
+    var buf = !Buffer.isBuffer(body)
+      ? new Buffer(body, encoding)
+      : body
+
+    return etag(buf, options)
+  }
+}
+
 /**
  * Parse an extended query string with qs.
  *