process: implement process.hrtime.bigint()

PR-URL: #21256
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>

doc/api/process.md

@@ -1163,6 +1163,9 @@ added: v0.7.6
 * `time` {integer[]} The result of a previous call to `process.hrtime()`
 * Returns: {integer[]}
 
+This is the legacy version of [`process.hrtime.bigint()`][]
+before `bigint` was introduced in JavaScript.
+
 The `process.hrtime()` method returns the current high-resolution real time
 in a `[seconds, nanoseconds]` tuple `Array`, where `nanoseconds` is the
 remaining part of the real time that can't be represented in second precision.
@@ -1191,6 +1194,33 @@ setTimeout(() => {
 }, 1000);
 ```
 
+## process.hrtime.bigint()
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {bigint}
+
+The `bigint` version of the [`process.hrtime()`][] method returning the
+current high-resolution real time in a `bigint`.
+
+Unlike [`process.hrtime()`][], it does not support an additional `time`
+argument since the difference can just be computed directly
+by subtraction of the two `bigint`s.
+
+```js
+const start = process.hrtime.bigint();
+// 191051479007711n
+
+setTimeout(() => {
+  const end = process.hrtime.bigint();
+  // 191052633396993n
+
+  console.log(`Benchmark took ${end - start} nanoseconds`);
+  // Benchmark took 1154389282 nanoseconds
+}, 1000);
+```
+
 ## process.initgroups(user, extraGroup)
 <!-- YAML
 added: v0.9.4
@@ -2035,6 +2065,8 @@ cases:
 [`process.execPath`]: #process_process_execpath
 [`process.exit()`]: #process_process_exit_code
 [`process.exitCode`]: #process_process_exitcode
+[`process.hrtime()`]: #process_process_hrtime_time
+[`process.hrtime.bigint()`]: #process_process_hrtime_bigint
 [`process.kill()`]: #process_process_kill_pid_signal
 [`process.setUncaughtExceptionCaptureCallback()`]: process.html#process_process_setuncaughtexceptioncapturecallback_fn
 [`promise.catch()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch

lib/internal/bootstrap/node.js

@@ -18,7 +18,8 @@
                               // object.
                               { _setupProcessObject, _setupNextTick,
                                 _setupPromises, _chdir, _cpuUsage,
-                                _hrtime, _memoryUsage, _rawDebug,
+                                _hrtime, _hrtimeBigInt,
+                                _memoryUsage, _rawDebug,
                                 _umask, _initgroups, _setegid, _seteuid,
                                 _setgid, _setuid, _setgroups,
                                 _shouldAbortOnUncaughtToggle },
@@ -66,7 +67,7 @@
       NODE_PERFORMANCE_MILESTONE_BOOTSTRAP_COMPLETE,
     } = perf.constants;
 
-    _process.setup_hrtime(_hrtime);
+    _process.setup_hrtime(_hrtime, _hrtimeBigInt);
     _process.setup_cpuUsage(_cpuUsage);
     _process.setupMemoryUsage(_memoryUsage);
     _process.setupKillAndExit();

lib/internal/process.js

@@ -90,7 +90,7 @@ function setup_cpuUsage(_cpuUsage) {
 // The 3 entries filled in by the original process.hrtime contains
 // the upper/lower 32 bits of the second part of the value,
 // and the remaining nanoseconds of the value.
-function setup_hrtime(_hrtime) {
+function setup_hrtime(_hrtime, _hrtimeBigInt) {
   const hrValues = new Uint32Array(3);
 
   process.hrtime = function hrtime(time) {
@@ -115,6 +115,14 @@ function setup_hrtime(_hrtime) {
       hrValues[2]
     ];
   };
+
+  // Use a BigUint64Array in the closure because V8 does not have an API for
+  // creating a BigInt out of a uint64_t yet.
+  const hrBigintValues = new BigUint64Array(1);
+  process.hrtime.bigint = function() {
+    _hrtimeBigInt(hrBigintValues);
+    return hrBigintValues[0];
+  };
 }
 
 function setupMemoryUsage(_memoryUsage) {

src/bootstrapper.cc

@@ -109,6 +109,7 @@ void SetupBootstrapObject(Environment* env,
   BOOTSTRAP_METHOD(_chdir, Chdir);
   BOOTSTRAP_METHOD(_cpuUsage, CPUUsage);
   BOOTSTRAP_METHOD(_hrtime, Hrtime);
+  BOOTSTRAP_METHOD(_hrtimeBigInt, HrtimeBigInt);
   BOOTSTRAP_METHOD(_memoryUsage, MemoryUsage);
   BOOTSTRAP_METHOD(_rawDebug, RawDebug);
   BOOTSTRAP_METHOD(_umask, Umask);

src/node_internals.h

@@ -939,6 +939,7 @@ void Chdir(const v8::FunctionCallbackInfo<v8::Value>& args);
 void CPUUsage(const v8::FunctionCallbackInfo<v8::Value>& args);
 void Cwd(const v8::FunctionCallbackInfo<v8::Value>& args);
 void Hrtime(const v8::FunctionCallbackInfo<v8::Value>& args);
+void HrtimeBigInt(const v8::FunctionCallbackInfo<v8::Value>& args);
 void Kill(const v8::FunctionCallbackInfo<v8::Value>& args);
 void MemoryUsage(const v8::FunctionCallbackInfo<v8::Value>& args);
 void RawDebug(const v8::FunctionCallbackInfo<v8::Value>& args);

src/node_process.cc

@@ -31,6 +31,7 @@ namespace node {
 
 using v8::Array;
 using v8::ArrayBuffer;
+using v8::BigUint64Array;
 using v8::Float64Array;
 using v8::FunctionCallbackInfo;
 using v8::HeapStatistics;
@@ -114,7 +115,11 @@ void Cwd(const FunctionCallbackInfo<Value>& args) {
   args.GetReturnValue().Set(cwd);
 }
 
+
 // Hrtime exposes libuv's uv_hrtime() high-resolution timer.
+
+// This is the legacy version of hrtime before BigInt was introduced in
+// JavaScript.
 // The value returned by uv_hrtime() is a 64-bit int representing nanoseconds,
 // so this function instead fills in an Uint32Array with 3 entries,
 // to avoid any integer overflow possibility.
@@ -133,6 +138,12 @@ void Hrtime(const FunctionCallbackInfo<Value>& args) {
   fields[2] = t % NANOS_PER_SEC;
 }
 
+void HrtimeBigInt(const FunctionCallbackInfo<Value>& args) {
+  Local<ArrayBuffer> ab = args[0].As<BigUint64Array>()->Buffer();
+  uint64_t* fields = static_cast<uint64_t*>(ab->GetContents().Data());
+  fields[0] = uv_hrtime();
+}
+
 void Kill(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
 

test/parallel/test-process-hrtime-bigint.js

@@ -0,0 +1,14 @@
+'use strict';
+
+// Tests that process.hrtime.bigint() works.
+
+require('../common');
+const assert = require('assert');
+
+const start = process.hrtime.bigint();
+assert.strictEqual(typeof start, 'bigint');
+
+const end = process.hrtime.bigint();
+assert.strictEqual(typeof end, 'bigint');
+
+assert(end - start >= 0n);