benchmark: add writable stream encoding benchmark

benchmark/streams/writable-simple.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const common = require('../common');
+const Writable = require('stream').Writable;
+
+const bench = common.createBenchmark(main, {
+  n: [50000],
+  inputType: ['buffer', 'string'],
+  inputEncoding: ['utf8', 'ucs2'],
+  decodeAs: ['', 'utf8', 'ucs2']
+});
+
+const inputStr = `袎逜 釂鱞鸄 碄碆碃 蒰裧頖 鋑, 瞂 覮轀 蔝蓶蓨 踥踕踛 鬐鶤 鄜 忁曨曣
+翀胲胵, 鬵鵛嚪 釢髟偛 碞碠粻 漀 涾烰 跬 窱縓 墥墡嬇 禒箈箑, 餤駰 瀁瀎瀊 躆轖轕 蒛, 銙 簎艜薤
+樆樦潏 魡鳱 櫱瀯灂 鷜鷙鷵 禒箈箑 綧 駓駗, 鋡 嗛嗕塨 嶭嶴憝 爂犤繵 罫蓱 摮 灉礭蘠 蠬襱覾 脬舑莕
+躐鑏, 襆贂 漀 刲匊呥 肒芅邥 泏狔狑, 瀗犡礝 浘涀缹 輲輹 綧`;
+
+function main(conf) {
+  const n = +conf.n;
+  const s = new Writable({
+    decodeBuffers: !!conf.decodeAs,
+    defaultEncoding: conf.decodeAs || undefined,
+    write(chunk, encoding, cb) { cb(); }
+  });
+
+  const inputEnc = conf.inputType === 'buffer' ? undefined : conf.inputEncoding;
+  const input = conf.inputType === 'buffer' ?
+      Buffer.from(inputStr, conf.inputEncoding) : inputStr;
+
+  bench.start();
+  for (var k = 0; k < n; ++k) {
+    s.write(input, inputEnc);
+  }
+  bench.end(n);
+}