/** * **This module is pending deprecation.** Once a replacement API has been * finalized, this module will be fully deprecated. Most developers should * **not** have cause to use this module. Users who absolutely must have * the functionality that domains provide may rely on it for the time being * but should expect to have to migrate to a different solution * in the future. * * Domains provide a way to handle multiple different IO operations as a * single group. If any of the event emitters or callbacks registered to a * domain emit an `'error'` event, or throw an error, then the domain object * will be notified, rather than losing the context of the error in the`process.on('uncaughtException')` handler, or causing the program to * exit immediately with an error code. * @deprecated Since v1.4.2 - Deprecated * @see [source](https://github.com/nodejs/node/blob/v18.0.0/lib/domain.js) */ declare module 'domain' { import EventEmitter = require('node:events'); /** * The `Domain` class encapsulates the functionality of routing errors and * uncaught exceptions to the active `Domain` object. * * To handle the errors that it catches, listen to its `'error'` event. */ class Domain extends EventEmitter { /** * An array of timers and event emitters that have been explicitly added * to the domain. */ members: Array; /** * The `enter()` method is plumbing used by the `run()`, `bind()`, and`intercept()` methods to set the active domain. It sets `domain.active` and`process.domain` to the domain, and implicitly * pushes the domain onto the domain * stack managed by the domain module (see {@link exit} for details on the * domain stack). The call to `enter()` delimits the beginning of a chain of * asynchronous calls and I/O operations bound to a domain. * * Calling `enter()` changes only the active domain, and does not alter the domain * itself. `enter()` and `exit()` can be called an arbitrary number of times on a * single domain. */ enter(): void; /** * The `exit()` method exits the current domain, popping it off the domain stack. * Any time execution is going to switch to the context of a different chain of * asynchronous calls, it's important to ensure that the current domain is exited. * The call to `exit()` delimits either the end of or an interruption to the chain * of asynchronous calls and I/O operations bound to a domain. * * If there are multiple, nested domains bound to the current execution context,`exit()` will exit any domains nested within this domain. * * Calling `exit()` changes only the active domain, and does not alter the domain * itself. `enter()` and `exit()` can be called an arbitrary number of times on a * single domain. */ exit(): void; /** * Run the supplied function in the context of the domain, implicitly * binding all event emitters, timers, and lowlevel requests that are * created in that context. Optionally, arguments can be passed to * the function. * * This is the most basic way to use a domain. * * ```js * const domain = require('domain'); * const fs = require('fs'); * const d = domain.create(); * d.on('error', (er) => { * console.error('Caught error!', er); * }); * d.run(() => { * process.nextTick(() => { * setTimeout(() => { // Simulating some various async stuff * fs.open('non-existent file', 'r', (er, fd) => { * if (er) throw er; * // proceed... * }); * }, 100); * }); * }); * ``` * * In this example, the `d.on('error')` handler will be triggered, rather * than crashing the program. */ run(fn: (...args: any[]) => T, ...args: any[]): T; /** * Explicitly adds an emitter to the domain. If any event handlers called by * the emitter throw an error, or if the emitter emits an `'error'` event, it * will be routed to the domain's `'error'` event, just like with implicit * binding. * * This also works with timers that are returned from `setInterval()` and `setTimeout()`. If their callback function throws, it will be caught by * the domain `'error'` handler. * * If the Timer or `EventEmitter` was already bound to a domain, it is removed * from that one, and bound to this one instead. * @param emitter emitter or timer to be added to the domain */ add(emitter: EventEmitter | NodeJS.Timer): void; /** * The opposite of {@link add}. Removes domain handling from the * specified emitter. * @param emitter emitter or timer to be removed from the domain */ remove(emitter: EventEmitter | NodeJS.Timer): void; /** * The returned function will be a wrapper around the supplied callback * function. When the returned function is called, any errors that are * thrown will be routed to the domain's `'error'` event. * * ```js * const d = domain.create(); * * function readSomeFile(filename, cb) { * fs.readFile(filename, 'utf8', d.bind((er, data) => { * // If this throws, it will also be passed to the domain. * return cb(er, data ? JSON.parse(data) : null); * })); * } * * d.on('error', (er) => { * // An error occurred somewhere. If we throw it now, it will crash the program * // with the normal line number and stack message. * }); * ``` * @param callback The callback function * @return The bound function */ bind(callback: T): T; /** * This method is almost identical to {@link bind}. However, in * addition to catching thrown errors, it will also intercept `Error` objects sent as the first argument to the function. * * In this way, the common `if (err) return callback(err);` pattern can be replaced * with a single error handler in a single place. * * ```js * const d = domain.create(); * * function readSomeFile(filename, cb) { * fs.readFile(filename, 'utf8', d.intercept((data) => { * // Note, the first argument is never passed to the * // callback since it is assumed to be the 'Error' argument * // and thus intercepted by the domain. * * // If this throws, it will also be passed to the domain * // so the error-handling logic can be moved to the 'error' * // event on the domain instead of being repeated throughout * // the program. * return cb(null, JSON.parse(data)); * })); * } * * d.on('error', (er) => { * // An error occurred somewhere. If we throw it now, it will crash the program * // with the normal line number and stack message. * }); * ``` * @param callback The callback function * @return The intercepted function */ intercept(callback: T): T; } function create(): Domain; } declare module 'node:domain' { export * from 'domain'; }