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