AsyncResource - async_hooks - Node

class AsyncResource

Usage in Deno

import { AsyncResource } from "node:async_hooks";

<div class="alert alert-warning"><div><svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"> <path stroke="none" d="M0 0h24v24H0z" fill="none" /> <path d="M12 9v4" /> <path d="M10.363 3.591l-8.106 13.534a1.914 1.914 0 0 0 1.636 2.871h16.214a1.914 1.914 0 0 0 1.636 -2.87l-8.106 -13.536a1.914 1.914 0 0 0 -3.274 0z" /> <path d="M12 16h.01" /> </svg> Deno compatibility</div><div><p> The AsyncResource implementation is a non-functional stub.</p> </div></div>

The class AsyncResource is designed to be extended by the embedder's async resources. Using this, users can easily trigger the lifetime events of their own resources.

The init hook will trigger when an AsyncResource is instantiated.

The following is an overview of the AsyncResource API.

import { AsyncResource, executionAsyncId } from 'node:async_hooks';

// AsyncResource() is meant to be extended. Instantiating a
// new AsyncResource() also triggers init. If triggerAsyncId is omitted then
// async_hook.executionAsyncId() is used.
const asyncResource = new AsyncResource(
  type, { triggerAsyncId: executionAsyncId(), requireManualDestroy: false },
);

// Run a function in the execution context of the resource. This will
// * establish the context of the resource
// * trigger the AsyncHooks before callbacks
// * call the provided function `fn` with the supplied arguments
// * trigger the AsyncHooks after callbacks
// * restore the original execution context
asyncResource.runInAsyncScope(fn, thisArg, ...args);

// Call AsyncHooks destroy callbacks.
asyncResource.emitDestroy();

// Return the unique ID assigned to the AsyncResource instance.
asyncResource.asyncId();

// Return the trigger ID for the AsyncResource instance.
asyncResource.triggerAsyncId();

Constructors

new



AsyncResource(type: string,
triggerAsyncId?: number | AsyncResourceOptions,
)

AsyncResource() is meant to be extended. Instantiating a new AsyncResource() also triggers init. If triggerAsyncId is omitted then async_hook.executionAsyncId() is used.

Methods



asyncId(): number



bind<Func extends (...args: any[]) => any>(fn: Func): Func

Binds the given function to execute to this AsyncResource's scope.



emitDestroy(): this

Call all destroy hooks. This should only ever be called once. An error will be thrown if it is called more than once. This must be manually called. If the resource is left to be collected by the GC then the destroy hooks will never be called.



runInAsyncScope<This,
Result,
>(fn: (this: This,
...args: any[],
) => Result,
thisArg?: This,
...args: any[],
): Result

Call the provided function with the provided arguments in the execution context of the async resource. This will establish the context, trigger the AsyncHooks before callbacks, call the function, trigger the AsyncHooks after callbacks, and then restore the original execution context.



triggerAsyncId(): number

Static Methods



bind<Func extends (this: ThisArg,
...args: any[],
) => any,
ThisArg,
>(fn: Func,
type?: string,
thisArg?: ThisArg,
): Func

Binds the given function to the current execution context.