src/pools/pool.ts

   1 import EventEmitter from 'node:events'
   2 import type {
   3   ErrorHandler,
   4   ExitHandler,
   5   IWorker,
   6   MessageHandler,
   7   OnlineHandler,
   8   WorkerNode
   9 } from './worker'
  10 import type {
  11   WorkerChoiceStrategy,
  12   WorkerChoiceStrategyOptions
  13 } from './selection-strategies/selection-strategies-types'
  14
  15 /**
  16  * Pool types.
  17  *
  18  * @enum
  19  * @internal
  20  */
  21 export enum PoolType {
  22   /**
  23    * Fixed pool type.
  24    */
  25   FIXED = 'fixed',
  26   /**
  27    * Dynamic pool type.
  28    */
  29   DYNAMIC = 'dynamic'
  30 }
  31
  32 /**
  33  * Pool events emitter.
  34  */
  35 export class PoolEmitter extends EventEmitter {}
  36
  37 /**
  38  * Enumeration of pool events.
  39  */
  40 export const PoolEvents = Object.freeze({
  41   full: 'full',
  42   busy: 'busy'
  43 } as const)
  44
  45 /**
  46  * Pool event.
  47  */
  48 export type PoolEvent = keyof typeof PoolEvents
  49
  50 /**
  51  * Worker tasks queue options.
  52  */
  53 export interface TasksQueueOptions {
  54   /**
  55    * Maximum number of tasks that can be executed concurrently on a worker.
  56    *
  57    * @defaultValue 1
  58    */
  59   concurrency?: number
  60 }
  61
  62 /**
  63  * Options for a poolifier pool.
  64  *
  65  * @typeParam Worker - Type of worker.
  66  */
  67 export interface PoolOptions<Worker extends IWorker> {
  68   /**
  69    * A function that will listen for message event on each worker.
  70    */
  71   messageHandler?: MessageHandler<Worker>
  72   /**
  73    * A function that will listen for error event on each worker.
  74    */
  75   errorHandler?: ErrorHandler<Worker>
  76   /**
  77    * A function that will listen for online event on each worker.
  78    */
  79   onlineHandler?: OnlineHandler<Worker>
  80   /**
  81    * A function that will listen for exit event on each worker.
  82    */
  83   exitHandler?: ExitHandler<Worker>
  84   /**
  85    * The worker choice strategy to use in this pool.
  86    */
  87   workerChoiceStrategy?: WorkerChoiceStrategy
  88   /**
  89    * The worker choice strategy options.
  90    */
  91   workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
  92   /**
  93    * Pool events emission.
  94    *
  95    * @defaultValue true
  96    */
  97   enableEvents?: boolean
  98   /**
  99    * Pool worker tasks queue.
 100    *
 101    * @experimental
 102    * @defaultValue false
 103    */
 104   enableTasksQueue?: boolean
 105   /**
 106    * Pool worker tasks queue options.
 107    *
 108    * @experimental
 109    */
 110   tasksQueueOptions?: TasksQueueOptions
 111 }
 112
 113 /**
 114  * Contract definition for a poolifier pool.
 115  *
 116  * @typeParam Worker - Type of worker which manages this pool.
 117  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
 118  * @typeParam Response - Type of execution response. This can only be serializable data.
 119  */
 120 export interface IPool<
 121   Worker extends IWorker,
 122   Data = unknown,
 123   Response = unknown
 124 > {
 125   /**
 126    * Pool type.
 127    *
 128    * If it is `'dynamic'`, it provides the `max` property.
 129    */
 130   readonly type: PoolType
 131   /**
 132    * Pool worker nodes.
 133    */
 134   readonly workerNodes: Array<WorkerNode<Worker, Data>>
 135   /**
 136    * Emitter on which events can be listened to.
 137    *
 138    * Events that can currently be listened to:
 139    *
 140    * - `'full'`: Emitted when the pool is dynamic and full.
 141    * - `'busy'`: Emitted when the pool is busy.
 142    */
 143   readonly emitter?: PoolEmitter
 144   /**
 145    * Finds a free worker node key based on the number of tasks the worker has applied.
 146    *
 147    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 148    *
 149    * If no free worker is found, `-1` is returned.
 150    *
 151    * @returns A worker node key if there is one, `-1` otherwise.
 152    */
 153   findFreeWorkerNodeKey: () => number
 154   /**
 155    * Executes the function specified in the constructor with the task data parameter.
 156    *
 157    * @param data - The input for the specified task. This can only be serializable data.
 158    * @returns Promise that will be resolved when the task is successfully completed.
 159    */
 160   execute: (data: Data) => Promise<Response>
 161   /**
 162    * Shutdowns every current worker in this pool.
 163    */
 164   destroy: () => Promise<void>
 165   /**
 166    * Sets the worker choice strategy in this pool.
 167    *
 168    * @param workerChoiceStrategy - The worker choice strategy.
 169    */
 170   setWorkerChoiceStrategy: (workerChoiceStrategy: WorkerChoiceStrategy) => void
 171 }