@types/node/cluster.d.ts

/**
 * A single instance of Node.js runs in a single thread. To take advantage of
 * multi-core systems, the user will sometimes want to launch a cluster of Node.js
 * processes to handle the load.
 *
 * The cluster module allows easy creation of child processes that all share
 * server ports.
 *
 * ```js
 * import cluster from 'cluster';
 * import http from 'http';
 * import { cpus } from 'os';
 * import process from 'process';
 *
 * const numCPUs = cpus().length;
 *
 * if (cluster.isPrimary) {
 *   console.log(`Primary ${process.pid} is running`);
 *
 *   // Fork workers.
 *   for (let i = 0; i < numCPUs; i++) {
 *     cluster.fork();
 *   }
 *
 *   cluster.on('exit', (worker, code, signal) => {
 *     console.log(`worker ${worker.process.pid} died`);
 *   });
 * } else {
 *   // Workers can share any TCP connection
 *   // In this case it is an HTTP server
 *   http.createServer((req, res) => {
 *     res.writeHead(200);
 *     res.end('hello world\n');
 *   }).listen(8000);
 *
 *   console.log(`Worker ${process.pid} started`);
 * }
 * ```
 *
 * Running Node.js will now share port 8000 between the workers:
 *
 * ```console
 * $ node server.js
 * Primary 3596 is running
 * Worker 4324 started
 * Worker 4520 started
 * Worker 6056 started
 * Worker 5644 started
 * ```
 *
 * On Windows, it is not yet possible to set up a named pipe server in a worker.
 * @see [source](https://github.com/nodejs/node/blob/v17.0.0/lib/cluster.js)
 */
declare module 'cluster' {
    import * as child from 'node:child_process';
    import EventEmitter = require('node:events');
    import * as net from 'node:net';
    export interface ClusterSettings {
        execArgv?: string[] | undefined; // default: process.execArgv
        exec?: string | undefined;
        args?: string[] | undefined;
        silent?: boolean | undefined;
        stdio?: any[] | undefined;
        uid?: number | undefined;
        gid?: number | undefined;
        inspectPort?: number | (() => number) | undefined;
    }
    export interface Address {
        address: string;
        port: number;
        addressType: number | 'udp4' | 'udp6'; // 4, 6, -1, "udp4", "udp6"
    }
    /**
     * A `Worker` object contains all public information and method about a worker.
     * In the primary it can be obtained using `cluster.workers`. In a worker
     * it can be obtained using `cluster.worker`.
     * @since v0.7.0
     */
    export class Worker extends EventEmitter {
        /**
         * Each new worker is given its own unique id, this id is stored in the`id`.
         *
         * While a worker is alive, this is the key that indexes it in`cluster.workers`.
         * @since v0.8.0
         */
        id: number;
        /**
         * All workers are created using `child_process.fork()`, the returned object
         * from this function is stored as `.process`. In a worker, the global `process`is stored.
         *
         * See: `Child Process module`.
         *
         * Workers will call `process.exit(0)` if the `'disconnect'` event occurs
         * on `process` and `.exitedAfterDisconnect` is not `true`. This protects against
         * accidental disconnection.
         * @since v0.7.0
         */
        process: child.ChildProcess;
        /**
         * Send a message to a worker or primary, optionally with a handle.
         *
         * In the primary this sends a message to a specific worker. It is identical to `ChildProcess.send()`.
         *
         * In a worker this sends a message to the primary. It is identical to`process.send()`.
         *
         * This example will echo back all messages from the primary:
         *
         * ```js
         * if (cluster.isPrimary) {
         *   const worker = cluster.fork();
         *   worker.send('hi there');
         *
         * } else if (cluster.isWorker) {
         *   process.on('message', (msg) => {
         *     process.send(msg);
         *   });
         * }
         * ```
         * @since v0.7.0
         * @param options The `options` argument, if present, is an object used to parameterize the sending of certain types of handles. `options` supports the following properties:
         */
        send(message: child.Serializable, callback?: (error: Error | null) => void): boolean;
        send(message: child.Serializable, sendHandle: child.SendHandle, callback?: (error: Error | null) => void): boolean;
        send(message: child.Serializable, sendHandle: child.SendHandle, options?: child.MessageOptions, callback?: (error: Error | null) => void): boolean;
        /**
         * This function will kill the worker. In the primary, it does this
         * by disconnecting the `worker.process`, and once disconnected, killing
         * with `signal`. In the worker, it does it by disconnecting the channel,
         * and then exiting with code `0`.
         *
         * Because `kill()` attempts to gracefully disconnect the worker process, it is
         * susceptible to waiting indefinitely for the disconnect to complete. For example,
         * if the worker enters an infinite loop, a graceful disconnect will never occur.
         * If the graceful disconnect behavior is not needed, use `worker.process.kill()`.
         *
         * Causes `.exitedAfterDisconnect` to be set.
         *
         * This method is aliased as `worker.destroy()` for backward compatibility.
         *
         * In a worker, `process.kill()` exists, but it is not this function;
         * it is `kill()`.
         * @since v0.9.12
         * @param [signal='SIGTERM'] Name of the kill signal to send to the worker process.
         */
        kill(signal?: string): void;
        destroy(signal?: string): void;
        /**
         * In a worker, this function will close all servers, wait for the `'close'` event
         * on those servers, and then disconnect the IPC channel.
         *
         * In the primary, an internal message is sent to the worker causing it to call`.disconnect()` on itself.
         *
         * Causes `.exitedAfterDisconnect` to be set.
         *
         * After a server is closed, it will no longer accept new connections,
         * but connections may be accepted by any other listening worker. Existing
         * connections will be allowed to close as usual. When no more connections exist,
         * see `server.close()`, the IPC channel to the worker will close allowing it
         * to die gracefully.
         *
         * The above applies _only_ to server connections, client connections are not
         * automatically closed by workers, and disconnect does not wait for them to close
         * before exiting.
         *
         * In a worker, `process.disconnect` exists, but it is not this function;
         * it is `disconnect()`.
         *
         * Because long living server connections may block workers from disconnecting, it
         * may be useful to send a message, so application specific actions may be taken to
         * close them. It also may be useful to implement a timeout, killing a worker if
         * the `'disconnect'` event has not been emitted after some time.
         *
         * ```js
         * if (cluster.isPrimary) {
         *   const worker = cluster.fork();
         *   let timeout;
         *
         *   worker.on('listening', (address) => {
         *     worker.send('shutdown');
         *     worker.disconnect();
         *     timeout = setTimeout(() => {
         *       worker.kill();
         *     }, 2000);
         *   });
         *
         *   worker.on('disconnect', () => {
         *     clearTimeout(timeout);
         *   });
         *
         * } else if (cluster.isWorker) {
         *   const net = require('net');
         *   const server = net.createServer((socket) => {
         *     // Connections never end
         *   });
         *
         *   server.listen(8000);
         *
         *   process.on('message', (msg) => {
         *     if (msg === 'shutdown') {
         *       // Initiate graceful close of any connections to server
         *     }
         *   });
         * }
         * ```
         * @since v0.7.7
         * @return A reference to `worker`.
         */
        disconnect(): void;
        /**
         * This function returns `true` if the worker is connected to its primary via its
         * IPC channel, `false` otherwise. A worker is connected to its primary after it
         * has been created. It is disconnected after the `'disconnect'` event is emitted.
         * @since v0.11.14
         */
        isConnected(): boolean;
        /**
         * This function returns `true` if the worker's process has terminated (either
         * because of exiting or being signaled). Otherwise, it returns `false`.
         *
         * ```js
         * import cluster from 'cluster';
         * import http from 'http';
         * import { cpus } from 'os';
         * import process from 'process';
         *
         * const numCPUs = cpus().length;
         *
         * if (cluster.isPrimary) {
         *   console.log(`Primary ${process.pid} is running`);
         *
         *   // Fork workers.
         *   for (let i = 0; i < numCPUs; i++) {
         *     cluster.fork();
         *   }
         *
         *   cluster.on('fork', (worker) => {
         *     console.log('worker is dead:', worker.isDead());
         *   });
         *
         *   cluster.on('exit', (worker, code, signal) => {
         *     console.log('worker is dead:', worker.isDead());
         *   });
         * } else {
         *   // Workers can share any TCP connection. In this case, it is an HTTP server.
         *   http.createServer((req, res) => {
         *     res.writeHead(200);
         *     res.end(`Current process\n ${process.pid}`);
         *     process.kill(process.pid);
         *   }).listen(8000);
         * }
         * ```
         * @since v0.11.14
         */
        isDead(): boolean;
        /**
         * This property is `true` if the worker exited due to `.kill()` or`.disconnect()`. If the worker exited any other way, it is `false`. If the
         * worker has not exited, it is `undefined`.
         *
         * The boolean `worker.exitedAfterDisconnect` allows distinguishing between
         * voluntary and accidental exit, the primary may choose not to respawn a worker
         * based on this value.
         *
         * ```js
         * cluster.on('exit', (worker, code, signal) => {
         *   if (worker.exitedAfterDisconnect === true) {
         *     console.log('Oh, it was just voluntary – no need to worry');
         *   }
         * });
         *
         * // kill worker
         * worker.kill();
         * ```
         * @since v6.0.0
         */
        exitedAfterDisconnect: boolean;
        /**
         * events.EventEmitter
         *   1. disconnect
         *   2. error
         *   3. exit
         *   4. listening
         *   5. message
         *   6. online
         */
        addListener(event: string, listener: (...args: any[]) => void): this;
        addListener(event: 'disconnect', listener: () => void): this;
        addListener(event: 'error', listener: (error: Error) => void): this;
        addListener(event: 'exit', listener: (code: number, signal: string) => void): this;
        addListener(event: 'listening', listener: (address: Address) => void): this;
        addListener(event: 'message', listener: (message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        addListener(event: 'online', listener: () => void): this;
        emit(event: string | symbol, ...args: any[]): boolean;
        emit(event: 'disconnect'): boolean;
        emit(event: 'error', error: Error): boolean;
        emit(event: 'exit', code: number, signal: string): boolean;
        emit(event: 'listening', address: Address): boolean;
        emit(event: 'message', message: any, handle: net.Socket | net.Server): boolean;
        emit(event: 'online'): boolean;
        on(event: string, listener: (...args: any[]) => void): this;
        on(event: 'disconnect', listener: () => void): this;
        on(event: 'error', listener: (error: Error) => void): this;
        on(event: 'exit', listener: (code: number, signal: string) => void): this;
        on(event: 'listening', listener: (address: Address) => void): this;
        on(event: 'message', listener: (message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        on(event: 'online', listener: () => void): this;
        once(event: string, listener: (...args: any[]) => void): this;
        once(event: 'disconnect', listener: () => void): this;
        once(event: 'error', listener: (error: Error) => void): this;
        once(event: 'exit', listener: (code: number, signal: string) => void): this;
        once(event: 'listening', listener: (address: Address) => void): this;
        once(event: 'message', listener: (message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        once(event: 'online', listener: () => void): this;
        prependListener(event: string, listener: (...args: any[]) => void): this;
        prependListener(event: 'disconnect', listener: () => void): this;
        prependListener(event: 'error', listener: (error: Error) => void): this;
        prependListener(event: 'exit', listener: (code: number, signal: string) => void): this;
        prependListener(event: 'listening', listener: (address: Address) => void): this;
        prependListener(event: 'message', listener: (message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        prependListener(event: 'online', listener: () => void): this;
        prependOnceListener(event: string, listener: (...args: any[]) => void): this;
        prependOnceListener(event: 'disconnect', listener: () => void): this;
        prependOnceListener(event: 'error', listener: (error: Error) => void): this;
        prependOnceListener(event: 'exit', listener: (code: number, signal: string) => void): this;
        prependOnceListener(event: 'listening', listener: (address: Address) => void): this;
        prependOnceListener(event: 'message', listener: (message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        prependOnceListener(event: 'online', listener: () => void): this;
    }
    export interface Cluster extends EventEmitter {
        disconnect(callback?: () => void): void;
        fork(env?: any): Worker;
        /** @deprecated since v16.0.0 - use isPrimary. */
        readonly isMaster: boolean;
        readonly isPrimary: boolean;
        readonly isWorker: boolean;
        schedulingPolicy: number;
        readonly settings: ClusterSettings;
        /** @deprecated since v16.0.0 - use setupPrimary. */
        setupMaster(settings?: ClusterSettings): void;
        /**
         * `setupPrimary` is used to change the default 'fork' behavior. Once called, the settings will be present in cluster.settings.
         */
        setupPrimary(settings?: ClusterSettings): void;
        readonly worker?: Worker | undefined;
        readonly workers?: NodeJS.Dict<Worker> | undefined;
        readonly SCHED_NONE: number;
        readonly SCHED_RR: number;
        /**
         * events.EventEmitter
         *   1. disconnect
         *   2. exit
         *   3. fork
         *   4. listening
         *   5. message
         *   6. online
         *   7. setup
         */
        addListener(event: string, listener: (...args: any[]) => void): this;
        addListener(event: 'disconnect', listener: (worker: Worker) => void): this;
        addListener(event: 'exit', listener: (worker: Worker, code: number, signal: string) => void): this;
        addListener(event: 'fork', listener: (worker: Worker) => void): this;
        addListener(event: 'listening', listener: (worker: Worker, address: Address) => void): this;
        addListener(event: 'message', listener: (worker: Worker, message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        addListener(event: 'online', listener: (worker: Worker) => void): this;
        addListener(event: 'setup', listener: (settings: ClusterSettings) => void): this;
        emit(event: string | symbol, ...args: any[]): boolean;
        emit(event: 'disconnect', worker: Worker): boolean;
        emit(event: 'exit', worker: Worker, code: number, signal: string): boolean;
        emit(event: 'fork', worker: Worker): boolean;
        emit(event: 'listening', worker: Worker, address: Address): boolean;
        emit(event: 'message', worker: Worker, message: any, handle: net.Socket | net.Server): boolean;
        emit(event: 'online', worker: Worker): boolean;
        emit(event: 'setup', settings: ClusterSettings): boolean;
        on(event: string, listener: (...args: any[]) => void): this;
        on(event: 'disconnect', listener: (worker: Worker) => void): this;
        on(event: 'exit', listener: (worker: Worker, code: number, signal: string) => void): this;
        on(event: 'fork', listener: (worker: Worker) => void): this;
        on(event: 'listening', listener: (worker: Worker, address: Address) => void): this;
        on(event: 'message', listener: (worker: Worker, message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        on(event: 'online', listener: (worker: Worker) => void): this;
        on(event: 'setup', listener: (settings: ClusterSettings) => void): this;
        once(event: string, listener: (...args: any[]) => void): this;
        once(event: 'disconnect', listener: (worker: Worker) => void): this;
        once(event: 'exit', listener: (worker: Worker, code: number, signal: string) => void): this;
        once(event: 'fork', listener: (worker: Worker) => void): this;
        once(event: 'listening', listener: (worker: Worker, address: Address) => void): this;
        once(event: 'message', listener: (worker: Worker, message: any, handle: net.Socket | net.Server) => void): this; // the handle is a net.Socket or net.Server object, or undefined.
        once(event: 'online', listener: (worker: Worker) => void): this;
        once(event: 'setup', listener: (settings: ClusterSettings) => void): this;
        prependListener(event: string, listener: (...args: any[]) => void): this;
        prependListener(event: 'disconnect', listener: (worker: Worker) => void): this;
        prependListener(event: 'exit', listener: (worker: Worker, code: number, signal: string) => void): this;
        prependListener(event: 'fork', listener: (worker: Worker) => void): this;
        prependListener(event: 'listening', listener: (worker: Worker, address: Address) => void): this;
        // the handle is a net.Socket or net.Server object, or undefined.
        prependListener(event: 'message', listener: (worker: Worker, message: any, handle?: net.Socket | net.Server) => void): this;
        prependListener(event: 'online', listener: (worker: Worker) => void): this;
        prependListener(event: 'setup', listener: (settings: ClusterSettings) => void): this;
        prependOnceListener(event: string, listener: (...args: any[]) => void): this;
        prependOnceListener(event: 'disconnect', listener: (worker: Worker) => void): this;
        prependOnceListener(event: 'exit', listener: (worker: Worker, code: number, signal: string) => void): this;
        prependOnceListener(event: 'fork', listener: (worker: Worker) => void): this;
        prependOnceListener(event: 'listening', listener: (worker: Worker, address: Address) => void): this;
        // the handle is a net.Socket or net.Server object, or undefined.
        prependOnceListener(event: 'message', listener: (worker: Worker, message: any, handle: net.Socket | net.Server) => void): this;
        prependOnceListener(event: 'online', listener: (worker: Worker) => void): this;
        prependOnceListener(event: 'setup', listener: (settings: ClusterSettings) => void): this;
    }
    const cluster: Cluster;
    export default cluster;
}
declare module 'node:cluster' {
    export * from 'cluster';
    export { default as default } from 'cluster';
}