bench: add bench for fs.realpath() fix

The benchmarks included also work for the previous JS
implementation of fs.realpath(). In case the new implementation of
realpath() needs to be reverted, we want these changes to stick around.

PR-URL: https://github.com/nodejs/node/pull/7899
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

benchmark/fs/bench-realpath.js

@@ -0,0 +1,46 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+const path = require('path');
+const resolved_path = path.resolve(__dirname, '../../lib/');
+const relative_path = path.relative(__dirname, '../../lib/');
+
+const bench = common.createBenchmark(main, {
+  n: [1e4],
+  type: ['relative', 'resolved'],
+});
+
+
+function main(conf) {
+  const n = conf.n >>> 0;
+  const type = conf.type;
+
+  bench.start();
+  if (type === 'relative')
+    relativePath(n);
+  else if (type === 'resolved')
+    resolvedPath(n);
+  else
+    throw new Error('unknown "type": ' + type);
+}
+
+function relativePath(n) {
+  (function r(cntr) {
+    if (--cntr <= 0)
+      return bench.end(n);
+    fs.realpath(relative_path, function() {
+      r(cntr);
+    });
+  }(n));
+}
+
+function resolvedPath(n) {
+  (function r(cntr) {
+    if (--cntr <= 0)
+      return bench.end(n);
+    fs.realpath(resolved_path, function() {
+      r(cntr);
+    });
+  }(n));
+}

benchmark/fs/bench-realpathSync.js

@@ -0,0 +1,39 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+const path = require('path');
+const resolved_path = path.resolve(__dirname, '../../lib/');
+const relative_path = path.relative(__dirname, '../../lib/');
+
+const bench = common.createBenchmark(main, {
+  n: [1e4],
+  type: ['relative', 'resolved'],
+});
+
+
+function main(conf) {
+  const n = conf.n >>> 0;
+  const type = conf.type;
+
+  bench.start();
+  if (type === 'relative')
+    relativePath(n);
+  else if (type === 'resolved')
+    resolvedPath(n);
+  else
+    throw new Error('unknown "type": ' + type);
+  bench.end(n);
+}
+
+function relativePath(n) {
+  for (var i = 0; i < n; i++) {
+    fs.realpathSync(relative_path);
+  }
+}
+
+function resolvedPath(n) {
+  for (var i = 0; i < n; i++) {
+    fs.realpathSync(resolved_path);
+  }
+}