Manual Context Tracking with AsyncResource

Snippet

Manual Context Tracking with AsyncResource

While AsyncLocalStorage is the standard for context, AsyncResource provides low-level control for manual context propagation. It is essential when integrating with legacy libraries or event-driven systems where the execution flow doesn't automatically preserve the asynchronous context.

snippet.js
javascript
import { AsyncResource } from 'node:async_hooks';
 
class DatabaseQuery extends AsyncResource {
  constructor(queryId) {
    super('DB_QUERY');
    this.queryId = queryId;
  }
 
  run(callback) {
    this.runInAsyncScope(callback);
  }
}
 
const query = new DatabaseQuery('req-123');
query.run(() => {
  // Async context is now preserved even through legacy callbacks
});

nodejs

Breakdown

super('DB_QUERY')

Initializes the async resource with a custom type for monitoring and debugging.

this.runInAsyncScope(callback)

Executes the callback within the asynchronous context associated with this specific resource instance.

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Manual Context Tracking with AsyncResource

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