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/**
* **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/v20.2.0/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<EventEmitter | NodeJS.Timer>;
/**
* 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 low-level 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('node:domain');
* const fs = require('node: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<T>(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<T extends Function>(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<T extends Function>(callback: T): T;
}
function create(): Domain;
}
declare module "node:domain" {
export * from "domain";
}
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