域和 promise

\Domains and promises

从 Node.js 8.0.0 开始,promise 的句柄在调用 .then() 或 .catch() 本身的域内运行:

\As of Node.js 8.0.0, the handlers of promises are run inside the domain in which the call to .then() or .catch() itself was made:

const d1 = domain.create();
const d2 = domain.create();
let p;
d1.run(() => {
 p = Promise.resolve(42);
});
d2.run(() => {
 p.then((v) => {
 // running in d2
 });
}); 拷贝

可以使用 domain.bind(callback) 将回调绑定到特定域:

\A callback may be bound to a specific domain using domain.bind(callback):

const d1 = domain.create();
const d2 = domain.create();
let p;
d1.run(() => {
 p = Promise.resolve(42);
});
d2.run(() => {
 p.then(p.domain.bind((v) => {
 // running in d1
 }));
}); 拷贝

域不会干扰 promise 的错误处理机制。换句话说,对于未处理的 Promise 拒绝,不会触发 'error' 事件。

\Domains will not interfere with the error handling mechanisms for promises. In other words, no 'error' event will be emitted for unhandled Promise rejections.