[Flight] Wire up async_hooks in Node.js DEV for inspecting Promises (#27840)

This wires up the use of `async_hooks` in the Node build (as well as the
Edge build when a global is available) in DEV mode only. This will be
used to track debug info about what suspended during an RSC pass.

Enabled behind a flag for now.

Author: sebmarkbage

.eslintrc.js

@@ -532,6 +532,7 @@ module.exports = {
     trustedTypes: 'readonly',
     IS_REACT_ACT_ENVIRONMENT: 'readonly',
     AsyncLocalStorage: 'readonly',
+    async_hooks: 'readonly',
     globalThis: 'readonly',
   },
 };

packages/react-server/src/ReactFlightServer.js

@@ -70,6 +70,7 @@ import {
   requestStorage,
   prepareHostDispatcher,
   createHints,
+  initAsyncDebugInfo,
 } from './ReactFlightServerConfig';
 
 import {
@@ -117,6 +118,8 @@ import binaryToComparableString from 'shared/binaryToComparableString';
 
 import {SuspenseException, getSuspendedThenable} from './ReactFlightThenable';
 
+initAsyncDebugInfo();
+
 const ObjectPrototype = Object.prototype;
 
 type JSONValue =

packages/react-server/src/ReactFlightServerConfigDebugNode.js

@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import {createAsyncHook, executionAsyncId} from './ReactFlightServerConfig';
+import {enableAsyncDebugInfo} from 'shared/ReactFeatureFlags';
+
+// Initialize the tracing of async operations.
+// We do this globally since the async work can potentially eagerly
+// start before the first request and once requests start they can interleave.
+// In theory we could enable and disable using a ref count of active requests
+// but given that typically this is just a live server, it doesn't really matter.
+export function initAsyncDebugInfo(): void {
+  if (__DEV__ && enableAsyncDebugInfo) {
+    createAsyncHook({
+      init(asyncId: number, type: string, triggerAsyncId: number): void {
+        // TODO
+      },
+      promiseResolve(asyncId: number): void {
+        // TODO
+        executionAsyncId();
+      },
+      destroy(asyncId: number): void {
+        // TODO
+      },
+    }).enable();
+  }
+}

packages/react-server/src/ReactFlightServerConfigDebugNoop.js

@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+// Exported for runtimes that don't support Promise instrumentation for async debugging.
+export function initAsyncDebugInfo(): void {}

packages/react-server/src/forks/ReactFlightServerConfig.custom.js

@@ -11,6 +11,8 @@ import type {Request} from 'react-server/src/ReactFlightServer';
 
 export * from '../ReactFlightServerConfigBundlerCustom';
 
+export * from '../ReactFlightServerConfigDebugNoop';
+
 export type Hints = any;
 export type HintCode = any;
 // eslint-disable-next-line no-unused-vars

packages/react-server/src/forks/ReactFlightServerConfig.dom-browser-esm.js

@@ -16,3 +16,5 @@ export * from 'react-dom-bindings/src/server/ReactFlightServerConfigDOM';
 export const supportsRequestStorage = true;
 export const requestStorage: AsyncLocalStorage<Request> =
   new AsyncLocalStorage();
+
+export * from '../ReactFlightServerConfigDebugNoop';

packages/react-server/src/forks/ReactFlightServerConfig.dom-browser-turbopack.js

@@ -14,3 +14,5 @@ export * from 'react-dom-bindings/src/server/ReactFlightServerConfigDOM';
 
 export const supportsRequestStorage = false;
 export const requestStorage: AsyncLocalStorage<Request> = (null: any);
+
+export * from '../ReactFlightServerConfigDebugNoop';

packages/react-server/src/forks/ReactFlightServerConfig.dom-browser.js

@@ -14,3 +14,5 @@ export * from 'react-dom-bindings/src/server/ReactFlightServerConfigDOM';
 
 export const supportsRequestStorage = false;
 export const requestStorage: AsyncLocalStorage<Request> = (null: any);
+
+export * from '../ReactFlightServerConfigDebugNoop';

packages/react-server/src/forks/ReactFlightServerConfig.dom-bun.js

@@ -14,3 +14,5 @@ export * from 'react-dom-bindings/src/server/ReactFlightServerConfigDOM';
 
 export const supportsRequestStorage = false;
 export const requestStorage: AsyncLocalStorage<Request> = (null: any);
+
+export * from '../ReactFlightServerConfigDebugNoop';

packages/react-server/src/forks/ReactFlightServerConfig.dom-edge-turbopack.js

@@ -16,3 +16,18 @@ export const supportsRequestStorage = typeof AsyncLocalStorage === 'function';
 export const requestStorage: AsyncLocalStorage<Request> = supportsRequestStorage
   ? new AsyncLocalStorage()
   : (null: any);
+
+// We use the Node version but get access to async_hooks from a global.
+import type {HookCallbacks, AsyncHook} from 'async_hooks';
+export const createAsyncHook: HookCallbacks => AsyncHook =
+  typeof async_hooks === 'object'
+    ? async_hooks.createHook
+    : function () {
+        return ({
+          enable() {},
+          disable() {},
+        }: any);
+      };
+export const executionAsyncId: () => number =
+  typeof async_hooks === 'object' ? async_hooks.executionAsyncId : (null: any);
+export * from '../ReactFlightServerConfigDebugNode';