src/pools/pool.ts

   1 import { EventEmitter } from 'node:events'
   2 import { type TransferListItem } from 'node:worker_threads'
   3 import type {
   4   ErrorHandler,
   5   ExitHandler,
   6   IWorker,
   7   IWorkerNode,
   8   MessageHandler,
   9   OnlineHandler,
  10   WorkerType
  11 } from './worker'
  12 import type {
  13   WorkerChoiceStrategy,
  14   WorkerChoiceStrategyOptions
  15 } from './selection-strategies/selection-strategies-types'
  16
  17 /**
  18  * Enumeration of pool types.
  19  */
  20 export const PoolTypes = Object.freeze({
  21   /**
  22    * Fixed pool type.
  23    */
  24   fixed: 'fixed',
  25   /**
  26    * Dynamic pool type.
  27    */
  28   dynamic: 'dynamic'
  29 } as const)
  30
  31 /**
  32  * Pool type.
  33  */
  34 export type PoolType = keyof typeof PoolTypes
  35
  36 /**
  37  * Pool events emitter.
  38  */
  39 export class PoolEmitter extends EventEmitter {}
  40
  41 /**
  42  * Enumeration of pool events.
  43  */
  44 export const PoolEvents = Object.freeze({
  45   ready: 'ready',
  46   busy: 'busy',
  47   full: 'full',
  48   destroy: 'destroy',
  49   error: 'error',
  50   taskError: 'taskError',
  51   backPressure: 'backPressure'
  52 } as const)
  53
  54 /**
  55  * Pool event.
  56  */
  57 export type PoolEvent = keyof typeof PoolEvents
  58
  59 /**
  60  * Pool information.
  61  */
  62 export interface PoolInfo {
  63   readonly version: string
  64   readonly type: PoolType
  65   readonly worker: WorkerType
  66   readonly ready: boolean
  67   readonly strategy: WorkerChoiceStrategy
  68   readonly minSize: number
  69   readonly maxSize: number
  70   /** Pool utilization. */
  71   readonly utilization?: number
  72   /** Pool total worker nodes. */
  73   readonly workerNodes: number
  74   /** Pool idle worker nodes. */
  75   readonly idleWorkerNodes: number
  76   /** Pool busy worker nodes. */
  77   readonly busyWorkerNodes: number
  78   readonly executedTasks: number
  79   readonly executingTasks: number
  80   readonly queuedTasks?: number
  81   readonly maxQueuedTasks?: number
  82   readonly failedTasks: number
  83   readonly runTime?: {
  84     readonly minimum: number
  85     readonly maximum: number
  86     readonly average: number
  87     readonly median?: number
  88   }
  89   readonly waitTime?: {
  90     readonly minimum: number
  91     readonly maximum: number
  92     readonly average: number
  93     readonly median?: number
  94   }
  95 }
  96
  97 /**
  98  * Worker tasks queue options.
  99  */
 100 export interface TasksQueueOptions {
 101   /**
 102    * Maximum number of tasks that can be executed concurrently on a worker.
 103    *
 104    * @defaultValue 1
 105    */
 106   readonly concurrency?: number
 107 }
 108
 109 /**
 110  * Options for a poolifier pool.
 111  *
 112  * @typeParam Worker - Type of worker.
 113  */
 114 export interface PoolOptions<Worker extends IWorker> {
 115   /**
 116    * A function that will listen for online event on each worker.
 117    */
 118   onlineHandler?: OnlineHandler<Worker>
 119   /**
 120    * A function that will listen for message event on each worker.
 121    */
 122   messageHandler?: MessageHandler<Worker>
 123   /**
 124    * A function that will listen for error event on each worker.
 125    */
 126   errorHandler?: ErrorHandler<Worker>
 127   /**
 128    * A function that will listen for exit event on each worker.
 129    */
 130   exitHandler?: ExitHandler<Worker>
 131   /**
 132    * The worker choice strategy to use in this pool.
 133    *
 134    * @defaultValue WorkerChoiceStrategies.ROUND_ROBIN
 135    */
 136   workerChoiceStrategy?: WorkerChoiceStrategy
 137   /**
 138    * The worker choice strategy options.
 139    */
 140   workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 141   /**
 142    * Restart worker on error.
 143    */
 144   restartWorkerOnError?: boolean
 145   /**
 146    * Pool events emission.
 147    *
 148    * @defaultValue true
 149    */
 150   enableEvents?: boolean
 151   /**
 152    * Pool worker tasks queue.
 153    *
 154    * @defaultValue false
 155    */
 156   enableTasksQueue?: boolean
 157   /**
 158    * Pool worker tasks queue options.
 159    */
 160   tasksQueueOptions?: TasksQueueOptions
 161 }
 162
 163 /**
 164  * Contract definition for a poolifier pool.
 165  *
 166  * @typeParam Worker - Type of worker which manages this pool.
 167  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
 168  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
 169  */
 170 export interface IPool<
 171   Worker extends IWorker,
 172   Data = unknown,
 173   Response = unknown
 174 > {
 175   /**
 176    * Pool information.
 177    */
 178   readonly info: PoolInfo
 179   /**
 180    * Pool worker nodes.
 181    */
 182   readonly workerNodes: Array<IWorkerNode<Worker, Data>>
 183   /**
 184    * Whether the worker node has back pressure (i.e. its tasks queue is full).
 185    *
 186    * @param workerNodeKey - The worker node key.
 187    * @returns `true` if the worker node has back pressure, `false` otherwise.
 188    */
 189   readonly hasWorkerNodeBackPressure: (workerNodeKey: number) => boolean
 190   /**
 191    * Emitter on which events can be listened to.
 192    *
 193    * Events that can currently be listened to:
 194    *
 195    * - `'ready'`: Emitted when the number of workers created in the pool has reached the minimum size expected and are ready.
 196    * - `'busy'`: Emitted when the number of workers created in the pool has reached the maximum size expected and are executing at least one task.
 197    * - `'full'`: Emitted when the pool is dynamic and the number of workers created has reached the maximum size expected.
 198    * - '`destroy`': Emitted when the pool is destroyed.
 199    * - `'error'`: Emitted when an uncaught error occurs.
 200    * - `'taskError'`: Emitted when an error occurs while executing a task.
 201    * - `'backPressure'`: Emitted when a worker node has back pressure (i.e. its tasks queue is full).
 202    */
 203   readonly emitter?: PoolEmitter
 204   /**
 205    * Executes the specified function in the worker constructor with the task data input parameter.
 206    *
 207    * @param data - The optional task input data for the specified task function. This can only be structured-cloneable data.
 208    * @param name - The optional name of the task function to execute. If not specified, the default task function will be executed.
 209    * @param transferList - An optional array of transferable objects to transfer ownership of. Ownership of the transferred objects is given to the pool's worker_threads worker and they should not be used in the main thread afterwards.
 210    * @returns Promise that will be fulfilled when the task is completed.
 211    */
 212   readonly execute: (
 213     data?: Data,
 214     name?: string,
 215     transferList?: TransferListItem[]
 216   ) => Promise<Response>
 217   /**
 218    * Terminates all workers in this pool.
 219    */
 220   readonly destroy: () => Promise<void>
 221   /**
 222    * Lists the names of task function available in this pool.
 223    *
 224    * @returns The names of task function available in this pool.
 225    */
 226   readonly listTaskFunctions: () => string[]
 227   /**
 228    * Sets the worker choice strategy in this pool.
 229    *
 230    * @param workerChoiceStrategy - The worker choice strategy.
 231    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 232    */
 233   readonly setWorkerChoiceStrategy: (
 234     workerChoiceStrategy: WorkerChoiceStrategy,
 235     workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 236   ) => void
 237   /**
 238    * Sets the worker choice strategy options in this pool.
 239    *
 240    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 241    */
 242   readonly setWorkerChoiceStrategyOptions: (
 243     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
 244   ) => void
 245   /**
 246    * Enables/disables the worker tasks queue in this pool.
 247    *
 248    * @param enable - Whether to enable or disable the worker tasks queue.
 249    * @param tasksQueueOptions - The worker tasks queue options.
 250    */
 251   readonly enableTasksQueue: (
 252     enable: boolean,
 253     tasksQueueOptions?: TasksQueueOptions
 254   ) => void
 255   /**
 256    * Sets the worker tasks queue options in this pool.
 257    *
 258    * @param tasksQueueOptions - The worker tasks queue options.
 259    */
 260   readonly setTasksQueueOptions: (tasksQueueOptions: TasksQueueOptions) => void
 261 }