fs: use pushValueToArray for readdir(Sync)

Improve performance by pushing directory entries to returned array in
batches of 8 using pushValueToArray() in JS. Add benchmarks to
demonstrate this improvement.

PR-URL: https://github.com/nodejs/node/pull/3780
Reviewed-By: Fedor Indutny <fedor@indutny.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/benchmark/fs/bench-readdir.js b/benchmark/fs/bench-readdir.js
new file mode 100644
index 0000000000..2f0eab6a82
--- /dev/null
+++ b/benchmark/fs/bench-readdir.js
@@ -0,0 +1,22 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+
+const bench = common.createBenchmark(main, {
+  n: [1e4],
+});
+
+
+function main(conf) {
+  const n = conf.n >>> 0;
+
+  bench.start();
+  (function r(cntr) {
+    if (--cntr <= 0)
+      return bench.end(n);
+    fs.readdir(__dirname + '/../../lib/', function() {
+      r(cntr);
+    });
+  }(n));
+}
diff --git a/benchmark/fs/bench-readdirSync.js b/benchmark/fs/bench-readdirSync.js
new file mode 100644
index 0000000000..9f89649138
--- /dev/null
+++ b/benchmark/fs/bench-readdirSync.js
@@ -0,0 +1,19 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+
+const bench = common.createBenchmark(main, {
+  n: [1e4],
+});
+
+
+function main(conf) {
+  const n = conf.n >>> 0;
+
+  bench.start();
+  for (var i = 0; i < n; i++) {
+    fs.readdirSync(__dirname + '/../../lib/');
+  }
+  bench.end(n);
+}