async_hooks: remove legacy AsyncLocalStorage implementation

Remove the async_hooks-based AsyncLocalStorage fallback and the
--no-async-context-frame flag, making AsyncContextFrame the sole
implementation.

Signed-off-by: Matteo Collina <hello@matteocollina.com>

Author: mcollina

doc/api/cli.md

@@ -2277,17 +2277,6 @@ Disable the `node-addons` exports condition as well as disable loading
 native addons. When `--no-addons` is specified, calling `process.dlopen` or
 requiring a native C++ addon will fail and throw an exception.
 
-### `--no-async-context-frame`
-
-<!-- YAML
-added: v24.0.0
--->
-
-Disables the use of [`AsyncLocalStorage`][] backed by `AsyncContextFrame` and
-uses the prior implementation which relied on async\_hooks. The previous model
-is retained for compatibility with Electron and for cases where the context
-flow may differ. However, if a difference in flow is found please report it.
-
 ### `--no-deprecation`
 
 <!-- YAML
@@ -4317,7 +4306,6 @@ one is included in the list below.
 * `--max-old-space-size-percentage`
 * `--network-family-autoselection-attempt-timeout`
 * `--no-addons`
-* `--no-async-context-frame`
 * `--no-deprecation`
 * `--no-experimental-ffi`
 * `--no-experimental-global-navigator`
@@ -4937,7 +4925,6 @@ node --stack-trace-limit=12 -p -e "Error.stackTraceLimit" # prints 12
 [`--use-env-proxy`]: #--use-env-proxy
 [`--use-system-ca`]: #--use-system-ca
 [`--watch`]: #--watch
-[`AsyncLocalStorage`]: async_context.md#class-asynclocalstorage
 [`Buffer`]: buffer.md#class-buffer
 [`CRYPTO_secure_malloc_init`]: https://www.openssl.org/docs/man3.0/man3/CRYPTO_secure_malloc_init.html
 [`ERR_INVALID_TYPESCRIPT_SYNTAX`]: errors.md#err_invalid_typescript_syntax

doc/node-config-schema.json

@@ -172,10 +172,6 @@
               "type": "boolean",
               "description": "allow worker threads when any permissions are set"
             },
-            "async-context-frame": {
-              "type": "boolean",
-              "description": "Improve AsyncLocalStorage performance with AsyncContextFrame"
-            },
             "bench-isolation": {
               "type": "string",
               "description": "configures the type of benchmark isolation used in the benchmark runner"

doc/node.1

@@ -1212,12 +1212,6 @@ Disable the \fBnode-addons\fR exports condition as well as disable loading
 native addons. When \fB--no-addons\fR is specified, calling \fBprocess.dlopen\fR or
 requiring a native C++ addon will fail and throw an exception.
 .
-.It Fl -no-async-context-frame
-Disables the use of \fBAsyncLocalStorage\fR backed by \fBAsyncContextFrame\fR and
-uses the prior implementation which relied on async_hooks. The previous model
-is retained for compatibility with Electron and for cases where the context
-flow may differ. However, if a difference in flow is found please report it.
-.
 .It Fl -no-deprecation
 Silence deprecation warnings.
 .
@@ -2335,8 +2329,6 @@ one is included in the list below.
 .It
 \fB--no-addons\fR
 .It
-\fB--no-async-context-frame\fR
-.It
 \fB--no-deprecation\fR
 .It
 \fB--no-experimental-ffi\fR

lib/async_hooks.js

@@ -287,9 +287,7 @@ class AsyncResource {
 module.exports = {
   // Public API
   get AsyncLocalStorage() {
-    return AsyncContextFrame.enabled ?
-      require('internal/async_local_storage/async_context_frame') :
-      require('internal/async_local_storage/async_hooks');
+    return require('internal/async_local_storage/async_context_frame');
   },
   createHook,
   executionAsyncId,

lib/internal/async_context_frame.js

@@ -9,63 +9,34 @@ const {
   setContinuationPreservedEmbedderData,
 } = internalBinding('async_context_frame');
 
-function activeCurrent() {
-  return getContinuationPreservedEmbedderData();
-}
-
-function activeSet(frame) {
-  setContinuationPreservedEmbedderData(frame);
-}
-
-function activeExchange(frame) {
-  const prior = getContinuationPreservedEmbedderData();
-  setContinuationPreservedEmbedderData(frame);
-  return prior;
-}
-
-function activeDisable(store) {
-  getContinuationPreservedEmbedderData()?.disable(store);
-}
-
-class InactiveAsyncContextFrame extends SafeMap {
-  static get enabled() {
-    enabled_ ??= checkEnabled();
-    return enabled_;
-  }
-
-  static current() {}
-  static set(frame) {}
-  static exchange(frame) {}
-  static disable(store) {}
-}
-
-class AsyncContextFrame extends InactiveAsyncContextFrame {
+class AsyncContextFrame extends SafeMap {
   constructor(store, data) {
     super(AsyncContextFrame.current());
     this.set(store, data);
   }
 
-  disable(store) {
-    this.delete(store);
+  static current() {
+    return getContinuationPreservedEmbedderData();
   }
-}
 
-let enabled_;
+  static set(frame) {
+    setContinuationPreservedEmbedderData(frame);
+  }
 
-function checkEnabled() {
-  const enabled = require('internal/options')
-    .getOptionValue('--async-context-frame');
+  static exchange(frame) {
+    const prior = this.current();
+    this.set(frame);
+    return prior;
+  }
 
-  // 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;
+  static disable(store) {
+    const frame = this.current();
+    frame?.disable(store);
   }
 
-  return enabled;
+  disable(store) {
+    this.delete(store);
+  }
 }
 
 module.exports = AsyncContextFrame;

lib/internal/async_hooks.js

@@ -105,7 +105,6 @@ const before_symbol = Symbol('before');
 const after_symbol = Symbol('after');
 const destroy_symbol = Symbol('destroy');
 const promise_resolve_symbol = Symbol('promiseResolve');
-const async_local_storage_context_symbol = Symbol('kAsyncLocalStorageContext');
 const emitBeforeNative = emitHookFactory(before_symbol, 'emitBeforeNative');
 const emitAfterNative = emitHookFactory(after_symbol, 'emitAfterNative');
 const emitDestroyNative = emitHookFactory(destroy_symbol, 'emitDestroyNative');
@@ -585,7 +584,7 @@ module.exports = {
   symbols: {
     async_id_symbol, trigger_async_id_symbol,
     init_symbol, before_symbol, after_symbol, destroy_symbol,
-    promise_resolve_symbol, async_local_storage_context_symbol,
+    promise_resolve_symbol,
     owner_symbol,
   },
   constants: {

lib/internal/async_local_storage/async_hooks.js

@@ -100,9 +100,6 @@ const {
   emitBefore,
   emitAfter,
   emitDestroy,
-  symbols: {
-    async_local_storage_context_symbol,
-  },
 } = require('internal/async_hooks');
 
 // Symbols for storing async id state.
@@ -132,12 +129,8 @@ const AsyncContextFrame = require('internal/async_context_frame');
 const async_context_frame = Symbol('kAsyncContextFrame');
 
 function removeStoresFromResource(resource) {
-  if (AsyncContextFrame.enabled) {
-    if (resource[async_context_frame] !== undefined) {
-      resource[async_context_frame] = undefined;
-    }
-  } else if (resource[async_local_storage_context_symbol] !== undefined) {
-    resource[async_local_storage_context_symbol] = undefined;
+  if (resource[async_context_frame] !== undefined) {
+    resource[async_context_frame] = undefined;
   }
 }
 

lib/internal/timers.js

@@ -38,10 +38,6 @@ Local<Value> current(Isolate* isolate) {
 }
 
 void set(Environment* env, Local<Value> value) {
-  if (!env->async_context_frame_enabled()) {
-    return;
-  }
-
   env->isolate()->SetContinuationPreservedEmbedderDataV2(value);
 }
 

src/async_context_frame.cc

@@ -460,10 +460,6 @@ inline std::shared_ptr<EnvironmentOptions> Environment::options() {
   return options_;
 }
 
-inline bool Environment::async_context_frame_enabled() const {
-  return options_->async_context_frame;
-}
-
 inline const std::vector<std::string>& Environment::argv() {
   return argv_;
 }