Improve string performance

HISTORY.md

@@ -1,6 +1,7 @@
 unreleased
 ==========
 
+  * Improve string performance
   * Slightly improve speed for weak ETags over 1KB
 
 1.4.0 / 2014-09-21

README.md

@@ -63,10 +63,10 @@ $ npm run-script bench
   3 tests completed.
   4 tests completed.
 
-  buffer - strong x   426,717 ops/sec ±1.34% (181 runs sampled)
-* buffer - weak   x 1,081,596 ops/sec ±0.32% (196 runs sampled)
-  string - strong x   235,880 ops/sec ±1.01% (190 runs sampled)
-  string - weak   x   373,234 ops/sec ±0.87% (192 runs sampled)
+  buffer - strong x   425,962 ops/sec ±1.21% (186 runs sampled)
+* buffer - weak   x 1,094,538 ops/sec ±0.35% (197 runs sampled)
+  string - strong x   437,636 ops/sec ±1.31% (183 runs sampled)
+  string - weak   x   316,978 ops/sec ±1.55% (188 runs sampled)
 
 > node benchmark/body1-1kb.js
 
@@ -77,10 +77,10 @@ $ npm run-script bench
   3 tests completed.
   4 tests completed.
 
-  buffer - strong x 274,188 ops/sec ±1.17% (192 runs sampled)
-* buffer - weak   x 298,451 ops/sec ±0.49% (194 runs sampled)
-  string - strong x 157,331 ops/sec ±2.12% (186 runs sampled)
-  string - weak   x 169,242 ops/sec ±1.51% (188 runs sampled)
+  buffer - strong x 278,712 ops/sec ±1.00% (193 runs sampled)
+* buffer - weak   x 300,008 ops/sec ±0.30% (196 runs sampled)
+  string - strong x 276,016 ops/sec ±1.13% (188 runs sampled)
+  string - weak   x 166,522 ops/sec ±1.47% (192 runs sampled)
 
 > node benchmark/body2-5kb.js
 
@@ -91,10 +91,10 @@ $ npm run-script bench
   3 tests completed.
   4 tests completed.
 
-  buffer - strong x 102,624 ops/sec ±0.93% (193 runs sampled)
-* buffer - weak   x 104,696 ops/sec ±1.17% (190 runs sampled)
-  string - strong x  59,097 ops/sec ±3.93% (186 runs sampled)
-  string - weak   x  59,202 ops/sec ±4.01% (185 runs sampled)
+  buffer - strong x 105,233 ops/sec ±0.65% (195 runs sampled)
+* buffer - weak   x 108,091 ops/sec ±0.81% (194 runs sampled)
+  string - strong x 102,725 ops/sec ±0.80% (192 runs sampled)
+  string - weak   x 102,649 ops/sec ±0.85% (193 runs sampled)
 
 > node benchmark/body3-10kb.js
 
@@ -105,10 +105,10 @@ $ npm run-script bench
   3 tests completed.
   4 tests completed.
 
-  buffer - strong x 54,768 ops/sec ±1.43% (188 runs sampled)
-* buffer - weak   x 57,393 ops/sec ±1.10% (192 runs sampled)
-  string - strong x 36,597 ops/sec ±3.81% (179 runs sampled)
-  string - weak   x 35,525 ops/sec ±3.82% (186 runs sampled)
+  buffer - strong x 59,673 ops/sec ±0.46% (195 runs sampled)
+* buffer - weak   x 61,525 ops/sec ±0.54% (194 runs sampled)
+  string - strong x 57,557 ops/sec ±0.62% (194 runs sampled)
+  string - weak   x 58,627 ops/sec ±0.59% (195 runs sampled)
 
 > node benchmark/body4-100kb.js
 
@@ -119,10 +119,10 @@ $ npm run-script bench
   3 tests completed.
   4 tests completed.
 
-* buffer - strong x 6,243 ops/sec ±0.84% (194 runs sampled)
-* buffer - weak   x 6,312 ops/sec ±0.95% (193 runs sampled)
-  string - strong x 4,984 ops/sec ±2.21% (191 runs sampled)
-  string - weak   x 5,068 ops/sec ±2.32% (190 runs sampled)
+  buffer - strong x 6,733 ops/sec ±0.26% (196 runs sampled)
+* buffer - weak   x 6,920 ops/sec ±0.40% (197 runs sampled)
+  string - strong x 6,344 ops/sec ±0.47% (193 runs sampled)
+  string - weak   x 6,236 ops/sec ±1.03% (189 runs sampled)
 ```
 
 ## License

index.js

@@ -41,7 +41,6 @@ function etag(entity, options) {
     throw new TypeError('argument entity is required')
   }
 
-  var isBuffer = Buffer.isBuffer(entity)
   var isStats = isstats(entity)
   var weak = options && typeof options.weak === 'boolean'
     ? options.weak
@@ -52,16 +51,13 @@ function etag(entity, options) {
     return stattag(entity, weak)
   }
 
-  if (!isBuffer && typeof entity !== 'string') {
+  if (typeof entity !== 'string' && !Buffer.isBuffer(entity)) {
     throw new TypeError('argument entity must be string, Buffer, or fs.Stats')
   }
 
-  var buf = !isBuffer
-    ? new Buffer(entity, 'utf8')
-    : entity
   var hash = weak
-    ? weakhash(buf)
-    : stronghash(buf)
+    ? weakhash(entity)
+    : stronghash(entity)
 
   return weak
     ? 'W/"' + hash + '"'
@@ -131,15 +127,15 @@ function stattag(stat, weak) {
  * @api private
  */
 
-function stronghash(buf) {
-  if (buf.length === 0) {
+function stronghash(entity) {
+  if (entity.length === 0) {
     // fast-path empty
     return '1B2M2Y8AsgTpgAmY7PhCfg=='
   }
 
   return crypto
     .createHash('md5')
-    .update(buf)
+    .update(entity, 'utf8')
     .digest('base64')
 }
 
@@ -151,20 +147,25 @@ function stronghash(buf) {
  * @api private
  */
 
-function weakhash(buf) {
-  if (buf.length === 0) {
+function weakhash(entity) {
+  if (entity.length === 0) {
     // fast-path empty
     return '0-0'
   }
 
-  if (buf.length <= crc32threshold) {
+  var len = typeof entity === 'string'
+    ? Buffer.byteLength(entity, 'utf8')
+    : entity.length
+
+  if (len <= crc32threshold) {
     // crc32 plus length when it's fast
-    return buf.length.toString(16) + '-' + crc(buf).toString(16)
+    // crc(str) only accepts utf-8 encoding
+    return len.toString(16) + '-' + crc(entity).toString(16)
   }
 
   // use md4 for long strings
   return crypto
     .createHash('md4')
-    .update(buf)
+    .update(entity, 'utf8')
     .digest('base64')
 }