buffer: optimize writing short strings

PR-URL: #54310

benchmark/buffers/buffer-write-string-short.js

@@ -0,0 +1,20 @@
+'use strict';
+
+const common = require('../common.js');
+const bench = common.createBenchmark(main, {
+  len: [0, 1, 8, 16, 32],
+  fallback: [1, 0],
+  n: [1e6],
+});
+
+function main({ len, n, fallback }) {
+  const buf = Buffer.allocUnsafe(len);
+  const string = fallback && len > 0
+    ? Buffer.from('a'.repeat(len - 1) + '€').toString()
+    : Buffer.from('a'.repeat(len)).toString()
+  bench.start();
+  for (let i = 0; i < n; ++i) {
+    buf.write(string);
+  }
+  bench.end(n);
+}

benchmark/buffers/buffer-write-string.js

@@ -2,67 +2,25 @@
 
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  encoding: [
-    '', 'utf8', 'ascii', 'hex', 'utf16le', 'latin1',
-  ],
-  args: [ '', 'offset', 'offset+length' ],
-  len: [2048],
+  encoding: [ '', 'utf8', 'ascii' ],
+  len: [0, 1, 8, 16, 32],
   n: [1e6],
 });
 
-function main({ len, n, encoding, args }) {
-  let string;
-  let start = 0;
+function main({ len, n, encoding }) {
   const buf = Buffer.allocUnsafe(len);
-
-  switch (args) {
-    case 'offset':
-      string = 'a'.repeat(Math.floor(len / 2));
-      start = len - string.length;
-      if (encoding) {
-        bench.start();
-        for (let i = 0; i < n; ++i) {
-          buf.write(string, start, encoding);
-        }
-        bench.end(n);
-      } else {
-        bench.start();
-        for (let i = 0; i < n; ++i) {
-          buf.write(string, start);
-        }
-        bench.end(n);
-      }
-      break;
-    case 'offset+length':
-      string = 'a'.repeat(len);
-      if (encoding) {
-        bench.start();
-        for (let i = 0; i < n; ++i) {
-          buf.write(string, 0, buf.length, encoding);
-        }
-        bench.end(n);
-      } else {
-        bench.start();
-        for (let i = 0; i < n; ++i) {
-          buf.write(string, 0, buf.length);
-        }
-        bench.end(n);
-      }
-      break;
-    default:
-      string = 'a'.repeat(len);
-      if (encoding) {
-        bench.start();
-        for (let i = 0; i < n; ++i) {
-          buf.write(string, encoding);
-        }
-        bench.end(n);
-      } else {
-        bench.start();
-        for (let i = 0; i < n; ++i) {
-          buf.write(string);
-        }
-        bench.end(n);
-      }
+  const string = 'a'.repeat(len);
+  if (encoding) {
+    bench.start();
+    for (let i = 0; i < n; ++i) {
+      buf.write(string, encoding);
+    }
+    bench.end(n);
+  } else {
+    bench.start();
+    for (let i = 0; i < n; ++i) {
+      buf.write(string);
+    }
+    bench.end(n);
   }
 }

lib/buffer.js

@@ -1082,10 +1082,10 @@ function _fill(buf, value, offset, end, encoding) {
 Buffer.prototype.write = function write(string, offset, length, encoding) {
   // Buffer#write(string);
   if (offset === undefined) {
-    return this.utf8Write(string, 0, this.length);
-  }
+    offset = 0;
+    length = this.length;
   // Buffer#write(string, encoding)
-  if (length === undefined && typeof offset === 'string') {
+  } else if (length === undefined && typeof offset === 'string') {
     encoding = offset;
     length = this.length;
     offset = 0;
@@ -1108,6 +1108,27 @@ Buffer.prototype.write = function write(string, offset, length, encoding) {
     }
   }
 
+  const len = string?.length;
+  if (
+    len <= 16 &&
+    len <= length &&
+    (!encoding || encoding === 'ascii' || encoding === 'utf8') &&
+    typeof string === 'string'
+  ) {
+    for (let n = 0; true; n++) {
+      if (n === len) {
+        return len;
+      }
+
+      const code = StringPrototypeCharCodeAt(string, n);
+      if (code >= 128) {
+        break;
+      }
+
+      this[offset + n] = code;
+    }
+  }
+
   if (!encoding)
     return this.utf8Write(string, offset, length);