perf_hooks: implement performance.now() with fast API calls

benchmark/perf_hooks/now.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const assert = require('assert');
+const common = require('../common.js');
+
+const bench = common.createBenchmark(main, {
+  n: [1e6],
+});
+
+function main({ n }) {
+  const arr = [];
+  for (let i = 0; i < n; ++i) {
+    arr.push(performance.now());
+  }
+
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    arr[i] = performance.now();
+  }
+  bench.end(n);
+
+  assert.strictEqual(arr.length, n);
+}

lib/internal/perf/utils.js

@@ -5,6 +5,7 @@ const {
     NODE_PERFORMANCE_MILESTONE_TIME_ORIGIN,
   },
   milestones,
+  now,
 } = internalBinding('performance');
 
 function getTimeOrigin() {
@@ -13,12 +14,6 @@ function getTimeOrigin() {
   return milestones[NODE_PERFORMANCE_MILESTONE_TIME_ORIGIN] / 1e6;
 }
 
-// Returns the time relative to the process start time in milliseconds.
-function now() {
-  const hr = process.hrtime();
-  return (hr[0] * 1000 + hr[1] / 1e6) - getTimeOrigin();
-}
-
 // Returns the milestone relative to the process start time in milliseconds.
 function getMilestoneTimestamp(milestoneIdx) {
   const ns = milestones[milestoneIdx];

src/node_external_reference.h

@@ -15,6 +15,8 @@ using CFunctionCallbackWithOneByteString =
 using CFunctionCallback = void (*)(v8::Local<v8::Value> receiver);
 using CFunctionCallbackReturnDouble =
     double (*)(v8::Local<v8::Object> receiver);
+using CFunctionCallbackValueReturnDouble =
+    double (*)(v8::Local<v8::Value> receiver);
 using CFunctionCallbackWithInt64 = void (*)(v8::Local<v8::Object> receiver,
                                             int64_t);
 using CFunctionCallbackWithBool = void (*)(v8::Local<v8::Object> receiver,
@@ -38,6 +40,7 @@ class ExternalReferenceRegistry {
   V(CFunctionCallback)                                                         \
   V(CFunctionCallbackWithOneByteString)                                        \
   V(CFunctionCallbackReturnDouble)                                             \
+  V(CFunctionCallbackValueReturnDouble)                                        \
   V(CFunctionCallbackWithInt64)                                                \
   V(CFunctionCallbackWithBool)                                                 \
   V(CFunctionCallbackWithString)                                               \

src/node_perf.cc

@@ -291,6 +291,22 @@ void MarkBootstrapComplete(const FunctionCallbackInfo<Value>& args) {
       performance::NODE_PERFORMANCE_MILESTONE_BOOTSTRAP_COMPLETE);
 }
 
+static double PerformanceNowImpl() {
+  return static_cast<double>(uv_hrtime() - performance_process_start) /
+         NANOS_PER_MILLIS;
+}
+
+static double FastPerformanceNow(v8::Local<v8::Value> receiver) {
+  return PerformanceNowImpl();
+}
+
+static void SlowPerformanceNow(const FunctionCallbackInfo<Value>& args) {
+  args.GetReturnValue().Set(PerformanceNowImpl());
+}
+
+static v8::CFunction fast_performance_now(
+    v8::CFunction::Make(FastPerformanceNow));
+
 static void CreatePerIsolateProperties(IsolateData* isolate_data,
                                        Local<ObjectTemplate> target) {
   Isolate* isolate = isolate_data->isolate();
@@ -311,6 +327,8 @@ static void CreatePerIsolateProperties(IsolateData* isolate_data,
   SetMethod(isolate, target, "getTimeOriginTimestamp", GetTimeOriginTimeStamp);
   SetMethod(isolate, target, "createELDHistogram", CreateELDHistogram);
   SetMethod(isolate, target, "markBootstrapComplete", MarkBootstrapComplete);
+  SetFastMethodNoSideEffect(
+      isolate, target, "now", SlowPerformanceNow, &fast_performance_now);
 }
 
 void CreatePerContextProperties(Local<Object> target,
@@ -376,6 +394,9 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(GetTimeOriginTimeStamp);
   registry->Register(CreateELDHistogram);
   registry->Register(MarkBootstrapComplete);
+  registry->Register(SlowPerformanceNow);
+  registry->Register(FastPerformanceNow);
+  registry->Register(fast_performance_now.GetTypeInfo());
   HistogramBase::RegisterExternalReferences(registry);
   IntervalHistogram::RegisterExternalReferences(registry);
 }