lib: optimize async context frame activation

lib/internal/async_context_frame.js

@@ -1,7 +1,6 @@
 'use strict';
 
 const {
-  ObjectSetPrototypeOf,
   SafeMap,
 } = primordials;
 
@@ -10,45 +9,22 @@ const {
   setContinuationPreservedEmbedderData,
 } = internalBinding('async_context_frame');
 
-let enabled_;
-
-class ActiveAsyncContextFrame extends SafeMap {
-  static get enabled() {
-    return true;
-  }
-
-  static current() {
-    return getContinuationPreservedEmbedderData();
-  }
-
-  static set(frame) {
-    setContinuationPreservedEmbedderData(frame);
-  }
-
-  static exchange(frame) {
-    const prior = this.current();
-    this.set(frame);
-    return prior;
-  }
-
-  static disable(store) {
-    const frame = this.current();
-    frame?.disable(store);
-  }
+function activeCurrent() {
+  return getContinuationPreservedEmbedderData();
 }
 
-function checkEnabled() {
-  const enabled = require('internal/options')
-    .getOptionValue('--async-context-frame');
+function activeSet(frame) {
+  setContinuationPreservedEmbedderData(frame);
+}
 
-  // If enabled, swap to active prototype so we don't need to check status
-  // on every interaction with the async context frame.
-  if (enabled) {
-    // eslint-disable-next-line no-use-before-define
-    ObjectSetPrototypeOf(AsyncContextFrame, ActiveAsyncContextFrame);
-  }
+function activeExchange(frame) {
+  const prior = getContinuationPreservedEmbedderData();
+  setContinuationPreservedEmbedderData(frame);
+  return prior;
+}
 
-  return enabled;
+function activeDisable(store) {
+  getContinuationPreservedEmbedderData()?.disable(store);
 }
 
 class InactiveAsyncContextFrame extends SafeMap {
@@ -74,4 +50,22 @@ class AsyncContextFrame extends InactiveAsyncContextFrame {
   }
 }
 
+let enabled_;
+
+function checkEnabled() {
+  const enabled = require('internal/options')
+    .getOptionValue('--async-context-frame');
+
+  // If enabled, install the active implementations directly. We use props
+  // rather than a prototype replacement to preserve V8 optimizations.
+  if (enabled) {
+    AsyncContextFrame.current = activeCurrent;
+    AsyncContextFrame.set = activeSet;
+    AsyncContextFrame.exchange = activeExchange;
+    AsyncContextFrame.disable = activeDisable;
+  }
+
+  return enabled;
+}
+
 module.exports = AsyncContextFrame;