benchmark,lib: add process.hrtime.bigint benchmark

Add a benchmark, and amend the relevant source code comment to state that currently, switching to directly returning a BigInt is not stopped by technical obstacles but rather the fact that using a typed array is actually a bit faster (about 2.5 %, measured locally). PR-URL: #26381 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: addaleax

benchmark/process/bench-hrtime.js

@@ -5,27 +5,38 @@ const assert = require('assert');
 
 const bench = common.createBenchmark(main, {
  n: [1e6],
- type: ['raw', 'diff']
+ type: ['raw', 'diff', 'bigint']
 });
 
 function main({ n, type }) {
  const hrtime = process.hrtime;
- var noDead = hrtime();
+ var noDead = type === 'bigint' ? hrtime.bigint() : hrtime();
  var i;
 
- if (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);
+ switch (type) {
+ case 'raw':
+ bench.start();
+ for (i = 0; i < n; i++) {
+ noDead = hrtime();
+ }
+ bench.end(n);
+ break;
+ case 'diff':
+ bench.start();
+ for (i = 0; i < n; i++) {
+ noDead = hrtime(noDead);
+ }
+ bench.end(n);
+ break;
+ case 'bigint':
+ bench.start();
+ for (i = 0; i < n; i++) {
+ noDead = hrtime.bigint();
+ }
+ bench.end(n);
+ break;
  }
 
- assert.ok(Array.isArray(noDead));
+ // eslint-disable-next-line valid-typeof
+ assert.ok(Array.isArray(noDead) || typeof noDead === 'bigint');
 }

lib/internal/process/per_thread.js

@@ -120,8 +120,8 @@ function setupHrtime(_hrtime, _hrtimeBigInt) {
  ];
  };
 
- // Use a BigUint64Array in the closure because V8 does not have an API for
- // creating a BigInt out of a uint64_t yet.
+ // Use a BigUint64Array in the closure because this is actually a bit
+ // faster than simply returning a BigInt from C++ in V8 7.1.
  const hrBigintValues = new BigUint64Array(1);
  process.hrtime.bigint = function() {
  _hrtimeBigInt(hrBigintValues);