process: improve process.hrtime

* Add benchmarks for diffing a previous result
* Improvements to the documentation, including type annotation
* Update the outdated comments in src/node.cc, improve comments
  in lib/internal/process.js
* Check the argument is an Array Tuple with length 2

PR-URL: https://github.com/nodejs/node/pull/10764
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Brian White <mscdex@mscdex.net>

1 files changed, 21 insertions, 7 deletions

diff --git a/benchmark/process/bench-hrtime.js b/benchmark/process/bench-hrtime.js
index 661dff43b0..8a2920a238 100644
--- a/benchmark/process/bench-hrtime.js
+++ b/benchmark/process/bench-hrtime.js
@@ -1,18 +1,32 @@
 'use strict';
 
 const common = require('../common');
+const assert = require('assert');
 
 const bench = common.createBenchmark(main, {
-  n: [1e6]
+  n: [1e6],
+  type: ['raw', 'diff']
 });
 
-
 function main(conf) {
-  const n = conf.n >>> 0;
+  const n = conf.n | 0;
+  const hrtime = process.hrtime;
+  var noDead = hrtime();
+  var i;
 
-  bench.start();
-  for (var i = 0; i < n; i++) {
-    process.hrtime();
+  if (conf.type === 'raw') {
+    bench.start();
+    for (i = 0; i < n; i++) {
+      noDead = hrtime();
+    }
+    bench.end(n);
+  } else {
+    bench.start();
+    for (i = 0; i < n; i++) {
+      noDead = hrtime(noDead);
+    }
+    bench.end(n);
   }
-  bench.end(n);
+
+  assert.ok(Array.isArray(noDead));
 }