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 backPressure?: boolean
  83   readonly failedTasks: number
  84   readonly runTime?: {
  85     readonly minimum: number
  86     readonly maximum: number
  87     readonly average: number
  88     readonly median?: number
  89   }
  90   readonly waitTime?: {
  91     readonly minimum: number
  92     readonly maximum: number
  93     readonly average: number
  94     readonly median?: number
  95   }
  96 }
  97
  98 /**
  99  * Worker node tasks queue options.
 100  */
 101 export interface TasksQueueOptions {
 102   /**
 103    * Maximum tasks queue size per worker node flagging it as back pressured.
 104    *
 105    * @defaultValue (pool maximum size)^2
 106    */
 107   readonly queueMaxSize?: number
 108   /**
 109    * Maximum number of tasks that can be executed concurrently on a worker node.
 110    *
 111    * @defaultValue 1
 112    */
 113   readonly concurrency?: number
 114 }
 115
 116 /**
 117  * Options for a poolifier pool.
 118  *
 119  * @typeParam Worker - Type of worker.
 120  */
 121 export interface PoolOptions<Worker extends IWorker> {
 122   /**
 123    * A function that will listen for online event on each worker.
 124    */
 125   onlineHandler?: OnlineHandler<Worker>
 126   /**
 127    * A function that will listen for message event on each worker.
 128    */
 129   messageHandler?: MessageHandler<Worker>
 130   /**
 131    * A function that will listen for error event on each worker.
 132    */
 133   errorHandler?: ErrorHandler<Worker>
 134   /**
 135    * A function that will listen for exit event on each worker.
 136    */
 137   exitHandler?: ExitHandler<Worker>
 138   /**
 139    * The worker choice strategy to use in this pool.
 140    *
 141    * @defaultValue WorkerChoiceStrategies.ROUND_ROBIN
 142    */
 143   workerChoiceStrategy?: WorkerChoiceStrategy
 144   /**
 145    * The worker choice strategy options.
 146    */
 147   workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 148   /**
 149    * Restart worker on error.
 150    */
 151   restartWorkerOnError?: boolean
 152   /**
 153    * Pool events emission.
 154    *
 155    * @defaultValue true
 156    */
 157   enableEvents?: boolean
 158   /**
 159    * Pool worker node tasks queue.
 160    *
 161    * @defaultValue false
 162    */
 163   enableTasksQueue?: boolean
 164   /**
 165    * Pool worker node tasks queue options.
 166    */
 167   tasksQueueOptions?: TasksQueueOptions
 168 }
 169
 170 /**
 171  * Contract definition for a poolifier pool.
 172  *
 173  * @typeParam Worker - Type of worker which manages this pool.
 174  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
 175  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
 176  */
 177 export interface IPool<
 178   Worker extends IWorker,
 179   Data = unknown,
 180   Response = unknown
 181 > {
 182   /**
 183    * Pool information.
 184    */
 185   readonly info: PoolInfo
 186   /**
 187    * Pool worker nodes.
 188    *
 189    * @internal
 190    */
 191   readonly workerNodes: Array<IWorkerNode<Worker, Data>>
 192   /**
 193    * Whether the worker node has back pressure (i.e. its tasks queue is full).
 194    *
 195    * @param workerNodeKey - The worker node key.
 196    * @returns `true` if the worker node has back pressure, `false` otherwise.
 197    * @internal
 198    */
 199   readonly hasWorkerNodeBackPressure: (workerNodeKey: number) => boolean
 200   /**
 201    * Emitter on which events can be listened to.
 202    *
 203    * Events that can currently be listened to:
 204    *
 205    * - `'ready'`: Emitted when the number of workers created in the pool has reached the minimum size expected and are ready.
 206    * - `'busy'`: Emitted when the number of workers created in the pool has reached the maximum size expected and are executing at least one task.
 207    * - `'full'`: Emitted when the pool is dynamic and the number of workers created has reached the maximum size expected.
 208    * - '`destroy`': Emitted when the pool is destroyed.
 209    * - `'error'`: Emitted when an uncaught error occurs.
 210    * - `'taskError'`: Emitted when an error occurs while executing a task.
 211    * - `'backPressure'`: Emitted when all worker nodes have back pressure (i.e. their tasks queue is full: queue size \>= maximum queue size).
 212    */
 213   readonly emitter?: PoolEmitter
 214   /**
 215    * Executes the specified function in the worker constructor with the task data input parameter.
 216    *
 217    * @param data - The optional task input data for the specified task function. This can only be structured-cloneable data.
 218    * @param name - The optional name of the task function to execute. If not specified, the default task function will be executed.
 219    * @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.
 220    * @returns Promise that will be fulfilled when the task is completed.
 221    */
 222   readonly execute: (
 223     data?: Data,
 224     name?: string,
 225     transferList?: TransferListItem[]
 226   ) => Promise<Response>
 227   /**
 228    * Terminates all workers in this pool.
 229    */
 230   readonly destroy: () => Promise<void>
 231   /**
 232    * Lists the names of task function available in this pool.
 233    *
 234    * @returns The names of task function available in this pool.
 235    */
 236   readonly listTaskFunctions: () => string[]
 237   /**
 238    * Sets the worker choice strategy in this pool.
 239    *
 240    * @param workerChoiceStrategy - The worker choice strategy.
 241    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 242    */
 243   readonly setWorkerChoiceStrategy: (
 244     workerChoiceStrategy: WorkerChoiceStrategy,
 245     workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 246   ) => void
 247   /**
 248    * Sets the worker choice strategy options in this pool.
 249    *
 250    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 251    */
 252   readonly setWorkerChoiceStrategyOptions: (
 253     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
 254   ) => void
 255   /**
 256    * Enables/disables the worker node tasks queue in this pool.
 257    *
 258    * @param enable - Whether to enable or disable the worker node tasks queue.
 259    * @param tasksQueueOptions - The worker node tasks queue options.
 260    */
 261   readonly enableTasksQueue: (
 262     enable: boolean,
 263     tasksQueueOptions?: TasksQueueOptions
 264   ) => void
 265   /**
 266    * Sets the worker node tasks queue options in this pool.
 267    *
 268    * @param tasksQueueOptions - The worker node tasks queue options.
 269    */
 270   readonly setTasksQueueOptions: (tasksQueueOptions: TasksQueueOptions) => void
 271 }