events.EventEmitterAsyncResource 类继承 EventEmitter 类
为需要手动异步跟踪的 EventEmitter
集成 EventEmitter
和 <AsyncResource>。
具体来说,events.EventEmitterAsyncResource
实例触发的所有事件都将在其异步上下文中运行。
import { EventEmitterAsyncResource, EventEmitter } from 'node:events';
import { notStrictEqual, strictEqual } from 'node:assert';
import { executionAsyncId, triggerAsyncId } from 'node:async_hooks';
// 异步跟踪工具会将其识别为 'Q'。
const ee1 = new EventEmitterAsyncResource({ name: 'Q' });
// 'foo' 监听器将在 EventEmitter 异步上下文中运行。
ee1.on('foo', () => {
strictEqual(executionAsyncId(), ee1.asyncId);
strictEqual(triggerAsyncId(), ee1.triggerAsyncId);
});
const ee2 = new EventEmitter();
// 普通 EventEmitter 上的 'foo' 监听器不跟踪异步上下文,
// 但是,在与 emit() 相同的异步上下文中运行。
ee2.on('foo', () => {
notStrictEqual(executionAsyncId(), ee2.asyncId);
notStrictEqual(triggerAsyncId(), ee2.triggerAsyncId);
});
Promise.resolve().then(() => {
ee1.emit('foo');
ee2.emit('foo');
});
const { EventEmitterAsyncResource, EventEmitter } = require('node:events');
const { notStrictEqual, strictEqual } = require('node:assert');
const { executionAsyncId, triggerAsyncId } = require('node:async_hooks');
// 异步跟踪工具会将其识别为 'Q'。
const ee1 = new EventEmitterAsyncResource({ name: 'Q' });
// 'foo' 监听器将在 EventEmitter 异步上下文中运行。
ee1.on('foo', () => {
strictEqual(executionAsyncId(), ee1.asyncId);
strictEqual(triggerAsyncId(), ee1.triggerAsyncId);
});
const ee2 = new EventEmitter();
// 普通 EventEmitter 上的 'foo' 监听器不跟踪异步上下文,
// 但是,在与 emit() 相同的异步上下文中运行。
ee2.on('foo', () => {
notStrictEqual(executionAsyncId(), ee2.asyncId);
notStrictEqual(triggerAsyncId(), ee2.triggerAsyncId);
});
Promise.resolve().then(() => {
ee1.emit('foo');
ee2.emit('foo');
});
EventEmitterAsyncResource
类具有与 EventEmitter
和 AsyncResource
本身相同的方法和选项。
Integrates EventEmitter
with <AsyncResource> for EventEmitter
s that
require manual async tracking. Specifically, all events emitted by instances
of events.EventEmitterAsyncResource
will run within its async context.
import { EventEmitterAsyncResource, EventEmitter } from 'node:events';
import { notStrictEqual, strictEqual } from 'node:assert';
import { executionAsyncId, triggerAsyncId } from 'node:async_hooks';
// Async tracking tooling will identify this as 'Q'.
const ee1 = new EventEmitterAsyncResource({ name: 'Q' });
// 'foo' listeners will run in the EventEmitters async context.
ee1.on('foo', () => {
strictEqual(executionAsyncId(), ee1.asyncId);
strictEqual(triggerAsyncId(), ee1.triggerAsyncId);
});
const ee2 = new EventEmitter();
// 'foo' listeners on ordinary EventEmitters that do not track async
// context, however, run in the same async context as the emit().
ee2.on('foo', () => {
notStrictEqual(executionAsyncId(), ee2.asyncId);
notStrictEqual(triggerAsyncId(), ee2.triggerAsyncId);
});
Promise.resolve().then(() => {
ee1.emit('foo');
ee2.emit('foo');
});
const { EventEmitterAsyncResource, EventEmitter } = require('node:events');
const { notStrictEqual, strictEqual } = require('node:assert');
const { executionAsyncId, triggerAsyncId } = require('node:async_hooks');
// Async tracking tooling will identify this as 'Q'.
const ee1 = new EventEmitterAsyncResource({ name: 'Q' });
// 'foo' listeners will run in the EventEmitters async context.
ee1.on('foo', () => {
strictEqual(executionAsyncId(), ee1.asyncId);
strictEqual(triggerAsyncId(), ee1.triggerAsyncId);
});
const ee2 = new EventEmitter();
// 'foo' listeners on ordinary EventEmitters that do not track async
// context, however, run in the same async context as the emit().
ee2.on('foo', () => {
notStrictEqual(executionAsyncId(), ee2.asyncId);
notStrictEqual(triggerAsyncId(), ee2.triggerAsyncId);
});
Promise.resolve().then(() => {
ee1.emit('foo');
ee2.emit('foo');
});
The EventEmitterAsyncResource
class has the same methods and takes the
same options as EventEmitter
and AsyncResource
themselves.