buffer: optimize from() and byteLength()

PR-URL: #12361
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: mscdex

benchmark/buffers/buffer-bytelength.js

@@ -2,7 +2,7 @@
 var common = require('../common');
 
 var bench = common.createBenchmark(main, {
-  encoding: ['utf8', 'base64'],
+  encoding: ['utf8', 'base64', 'buffer'],
   len: [1, 2, 4, 16, 64, 256], // x16
   n: [5e6]
 });
@@ -21,21 +21,27 @@ function main(conf) {
   var encoding = conf.encoding;
 
   var strings = [];
-  for (var string of chars) {
-    // Strings must be built differently, depending on encoding
-    var data = buildString(string, len);
-    if (encoding === 'utf8') {
-      strings.push(data);
-    } else if (encoding === 'base64') {
-      // Base64 strings will be much longer than their UTF8 counterparts
-      strings.push(Buffer.from(data, 'utf8').toString('base64'));
+  var results;
+  if (encoding === 'buffer') {
+    strings = [ Buffer.alloc(len * 16, 'a') ];
+    results = [ len * 16 ];
+  } else {
+    for (var string of chars) {
+      // Strings must be built differently, depending on encoding
+      var data = buildString(string, len);
+      if (encoding === 'utf8') {
+        strings.push(data);
+      } else if (encoding === 'base64') {
+        // Base64 strings will be much longer than their UTF8 counterparts
+        strings.push(Buffer.from(data, 'utf8').toString('base64'));
+      }
     }
-  }
 
-  // Check the result to ensure it is *properly* optimized
-  var results = strings.map(function(val) {
-    return Buffer.byteLength(val, encoding);
-  });
+    // Check the result to ensure it is *properly* optimized
+    results = strings.map(function(val) {
+      return Buffer.byteLength(val, encoding);
+    });
+  }
 
   bench.start();
   for (var i = 0; i < n; i++) {

benchmark/buffers/buffer-from.js

@@ -10,11 +10,12 @@ const bench = common.createBenchmark(main, {
     'buffer',
     'uint8array',
     'string',
+    'string-utf8',
     'string-base64',
     'object'
   ],
   len: [10, 2048],
-  n: [1024]
+  n: [2048]
 });
 
 function main(conf) {
@@ -75,6 +76,13 @@ function main(conf) {
       }
       bench.end(n);
       break;
+    case 'string-utf8':
+      bench.start();
+      for (i = 0; i < n * 1024; i++) {
+        Buffer.from(str, 'utf8');
+      }
+      bench.end(n);
+      break;
     case 'string-base64':
       bench.start();
       for (i = 0; i < n * 1024; i++) {

lib/buffer.js

@@ -23,8 +23,7 @@
 
 const binding = process.binding('buffer');
 const { compare: compare_, compareOffset } = binding;
-const { isArrayBuffer, isSharedArrayBuffer, isUint8Array } =
-    process.binding('util');
+const { isAnyArrayBuffer, isUint8Array } = process.binding('util');
 const bindingObj = {};
 const internalUtil = require('internal/util');
 
@@ -116,16 +115,19 @@ function Buffer(arg, encodingOrOffset, length) {
  * Buffer.from(arrayBuffer[, byteOffset[, length]])
  **/
 Buffer.from = function(value, encodingOrOffset, length) {
-  if (typeof value === 'number')
-    throw new TypeError('"value" argument must not be a number');
+  if (typeof value === 'string')
+    return fromString(value, encodingOrOffset);
 
-  if (isArrayBuffer(value) || isSharedArrayBuffer(value))
+  if (isAnyArrayBuffer(value))
     return fromArrayBuffer(value, encodingOrOffset, length);
 
-  if (typeof value === 'string')
-    return fromString(value, encodingOrOffset);