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    * @defaultValue false
 102    */
 103   enableTasksQueue?: boolean
 104   /**
 105    * Pool worker tasks queue options.
 106    */
 107   tasksQueueOptions?: TasksQueueOptions
 108 }
 109
 110 /**
 111  * Contract definition for a poolifier pool.
 112  *
 113  * @typeParam Worker - Type of worker which manages this pool.
 114  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
 115  * @typeParam Response - Type of execution response. This can only be serializable data.
 116  */
 117 export interface IPool<
 118   Worker extends IWorker,
 119   Data = unknown,
 120   Response = unknown
 121 > {
 122   /**
 123    * Pool type.
 124    *
 125    * If it is `'dynamic'`, it provides the `max` property.
 126    */
 127   readonly type: PoolType
 128   /**
 129    * Pool worker nodes.
 130    */
 131   readonly workerNodes: Array<WorkerNode<Worker, Data>>
 132   /**
 133    * Emitter on which events can be listened to.
 134    *
 135    * Events that can currently be listened to:
 136    *
 137    * - `'full'`: Emitted when the pool is dynamic and full.
 138    * - `'busy'`: Emitted when the pool is busy.
 139    */
 140   readonly emitter?: PoolEmitter
 141   /**
 142    * Finds a free worker node key based on the number of tasks the worker has applied.
 143    *
 144    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 145    *
 146    * If no free worker is found, `-1` is returned.
 147    *
 148    * @returns A worker node key if there is one, `-1` otherwise.
 149    */
 150   findFreeWorkerNodeKey: () => number
 151   /**
 152    * Executes the function specified in the constructor with the task data parameter.
 153    *
 154    * @param data - The input for the specified task. This can only be serializable data.
 155    * @returns Promise that will be resolved when the task is successfully completed.
 156    */
 157   execute: (data: Data) => Promise<Response>
 158   /**
 159    * Shutdowns every current worker in this pool.
 160    */
 161   destroy: () => Promise<void>
 162   /**
 163    * Sets the worker choice strategy in this pool.
 164    *
 165    * @param workerChoiceStrategy - The worker choice strategy.
 166    */
 167   setWorkerChoiceStrategy: (workerChoiceStrategy: WorkerChoiceStrategy) => void
 168   /**
 169    * Sets the worker choice strategy options in this pool.
 170    *
 171    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 172    */
 173   setWorkerChoiceStrategyOptions: (
 174     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
 175   ) => void
 176   /**
 177    * Enables/disables the worker tasks queue in this pool.
 178    *
 179    * @param enable - Whether to enable or disable the worker tasks queue.
 180    * @param tasksQueueOptions - The worker tasks queue options.
 181    */
 182   enableTasksQueue: (enable: boolean, opts?: TasksQueueOptions) => void
 183   /**
 184    * Sets the worker tasks queue options in this pool.
 185    *
 186    * @param tasksQueueOptions - The worker tasks queue options.
 187    */
 188   setTasksQueueOptions: (tasksQueueOptions: TasksQueueOptions) => void
 189 }