src/pools/pool.ts

   1 import EventEmitter from 'node:events'
   2 import type {
   3   ErrorHandler,
   4   ExitHandler,
   5   IWorker,
   6   MessageHandler,
   7   OnlineHandler
   8 } from './worker'
   9 import type {
  10   WorkerChoiceStrategy,
  11   WorkerChoiceStrategyOptions
  12 } from './selection-strategies/selection-strategies-types'
  13
  14 /**
  15  * Pool events emitter.
  16  */
  17 export class PoolEmitter extends EventEmitter {}
  18
  19 /**
  20  * Enumeration of pool events.
  21  */
  22 export const PoolEvents = Object.freeze({
  23   full: 'full',
  24   busy: 'busy'
  25 } as const)
  26
  27 /**
  28  * Pool event.
  29  */
  30 export type PoolEvent = keyof typeof PoolEvents
  31
  32 /**
  33  * Options for a poolifier pool.
  34  */
  35 export interface PoolOptions<Worker extends IWorker> {
  36   /**
  37    * A function that will listen for message event on each worker.
  38    */
  39   messageHandler?: MessageHandler<Worker>
  40   /**
  41    * A function that will listen for error event on each worker.
  42    */
  43   errorHandler?: ErrorHandler<Worker>
  44   /**
  45    * A function that will listen for online event on each worker.
  46    */
  47   onlineHandler?: OnlineHandler<Worker>
  48   /**
  49    * A function that will listen for exit event on each worker.
  50    */
  51   exitHandler?: ExitHandler<Worker>
  52   /**
  53    * The worker choice strategy to use in this pool.
  54    */
  55   workerChoiceStrategy?: WorkerChoiceStrategy
  56   /**
  57    * The worker choice strategy options.
  58    */
  59   workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
  60   /**
  61    * Pool events emission.
  62    *
  63    * @defaultValue true
  64    */
  65   enableEvents?: boolean
  66   /**
  67    * Pool worker tasks queue.
  68    *
  69    * @experimental
  70    * @defaultValue false
  71    */
  72   enableTasksQueue?: boolean
  73 }
  74
  75 /**
  76  * Contract definition for a poolifier pool.
  77  *
  78  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  79  * @typeParam Response - Type of response of execution. This can only be serializable data.
  80  */
  81 export interface IPool<Data = unknown, Response = unknown> {
  82   /**
  83    * Emitter on which events can be listened to.
  84    *
  85    * Events that can currently be listened to:
  86    *
  87    * - `'full'`: Emitted when the pool is dynamic and full.
  88    * - `'busy'`: Emitted when the pool is busy.
  89    */
  90   readonly emitter?: PoolEmitter
  91   /**
  92    * Performs the task specified in the constructor with the data parameter.
  93    *
  94    * @param data - The input for the specified task. This can only be serializable data.
  95    * @returns Promise that will be resolved when the task is successfully completed.
  96    */
  97   execute: (data: Data) => Promise<Response>
  98   /**
  99    * Shutdowns every current worker in this pool.
 100    */
 101   destroy: () => Promise<void>
 102   /**
 103    * Sets the worker choice strategy in this pool.
 104    *
 105    * @param workerChoiceStrategy - The worker choice strategy.
 106    */
 107   setWorkerChoiceStrategy: (workerChoiceStrategy: WorkerChoiceStrategy) => void
 108 }