src/pools/pool.ts

   1 import EventEmitter from 'node:events'
   2 import type {
   3   ErrorHandler,
   4   ExitHandler,
   5   MessageHandler,
   6   OnlineHandler
   7 } from './pool-worker'
   8 import type { WorkerChoiceStrategy } from './selection-strategies/selection-strategies-types'
   9
  10 /**
  11  * Pool events emitter.
  12  */
  13 export class PoolEmitter extends EventEmitter {}
  14
  15 /**
  16  * Enumeration of pool events.
  17  */
  18 export const PoolEvents = Object.freeze({
  19   full: 'full',
  20   busy: 'busy'
  21 } as const)
  22
  23 /**
  24  * Pool event.
  25  */
  26 export type PoolEvent = keyof typeof PoolEvents
  27
  28 /**
  29  * Options for a poolifier pool.
  30  */
  31 export interface PoolOptions<Worker> {
  32   /**
  33    * A function that will listen for message event on each worker.
  34    */
  35   messageHandler?: MessageHandler<Worker>
  36   /**
  37    * A function that will listen for error event on each worker.
  38    */
  39   errorHandler?: ErrorHandler<Worker>
  40   /**
  41    * A function that will listen for online event on each worker.
  42    */
  43   onlineHandler?: OnlineHandler<Worker>
  44   /**
  45    * A function that will listen for exit event on each worker.
  46    */
  47   exitHandler?: ExitHandler<Worker>
  48   /**
  49    * The worker choice strategy to use in this pool.
  50    */
  51   workerChoiceStrategy?: WorkerChoiceStrategy
  52   /**
  53    * Pool events emission.
  54    *
  55    * @defaultValue true
  56    */
  57   enableEvents?: boolean
  58 }
  59
  60 /**
  61  * Contract definition for a poolifier pool.
  62  *
  63  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  64  * @typeParam Response - Type of response of execution. This can only be serializable data.
  65  */
  66 export interface IPool<Data = unknown, Response = unknown> {
  67   /**
  68    * Emitter on which events can be listened to.
  69    *
  70    * Events that can currently be listened to:
  71    *
  72    * - `'full'`: Emitted when the pool is dynamic and full.
  73    * - `'busy'`: Emitted when the pool is busy.
  74    */
  75   readonly emitter?: PoolEmitter
  76   /**
  77    * Performs the task specified in the constructor with the data parameter.
  78    *
  79    * @param data - The input for the specified task. This can only be serializable data.
  80    * @returns Promise that will be resolved when the task is successfully completed.
  81    */
  82   execute: (data: Data) => Promise<Response>
  83   /**
  84    * Shutdowns every current worker in this pool.
  85    */
  86   destroy: () => Promise<void>
  87   /**
  88    * Sets the worker choice strategy in this pool.
  89    *
  90    * @param workerChoiceStrategy - The worker choice strategy.
  91    */
  92   setWorkerChoiceStrategy: (workerChoiceStrategy: WorkerChoiceStrategy) => void
  93 }