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 started: boolean
  67   readonly ready: boolean
  68   readonly strategy: WorkerChoiceStrategy
  69   readonly minSize: number
  70   readonly maxSize: number
  71   /** Pool utilization. */
  72   readonly utilization?: number
  73   /** Pool total worker nodes. */
  74   readonly workerNodes: number
  75   /** Pool idle worker nodes. */
  76   readonly idleWorkerNodes: number
  77   /** Pool busy worker nodes. */
  78   readonly busyWorkerNodes: number
  79   readonly executedTasks: number
  80   readonly executingTasks: number
  81   readonly queuedTasks?: number
  82   readonly maxQueuedTasks?: number
  83   readonly backPressure?: boolean
  84   readonly stolenTasks?: number
  85   readonly failedTasks: number
  86   readonly runTime?: {
  87     readonly minimum: number
  88     readonly maximum: number
  89     readonly average?: number
  90     readonly median?: number
  91   }
  92   readonly waitTime?: {
  93     readonly minimum: number
  94     readonly maximum: number
  95     readonly average?: number
  96     readonly median?: number
  97   }
  98 }
  99
 100 /**
 101  * Worker node tasks queue options.
 102  */
 103 export interface TasksQueueOptions {
 104   /**
 105    * Maximum tasks queue size per worker node flagging it as back pressured.
 106    *
 107    * @defaultValue (pool maximum size)^2
 108    */
 109   readonly size?: number
 110   /**
 111    * Maximum number of tasks that can be executed concurrently on a worker node.
 112    *
 113    * @defaultValue 1
 114    */
 115   readonly concurrency?: number
 116   /**
 117    * Whether to enable task stealing.
 118    *
 119    * @defaultValue true
 120    */
 121   readonly taskStealing?: boolean
 122   /**
 123    * Whether to enable tasks stealing on back pressure.
 124    *
 125    * @defaultValue true
 126    */
 127   readonly tasksStealingOnBackPressure?: boolean
 128 }
 129
 130 /**
 131  * Options for a poolifier pool.
 132  *
 133  * @typeParam Worker - Type of worker.
 134  */
 135 export interface PoolOptions<Worker extends IWorker> {
 136   /**
 137    * A function that will listen for online event on each worker.
 138    *
 139    * @defaultValue `() => {}`
 140    */
 141   onlineHandler?: OnlineHandler<Worker>
 142   /**
 143    * A function that will listen for message event on each worker.
 144    *
 145    * @defaultValue `() => {}`
 146    */
 147   messageHandler?: MessageHandler<Worker>
 148   /**
 149    * A function that will listen for error event on each worker.
 150    *
 151    * @defaultValue `() => {}`
 152    */
 153   errorHandler?: ErrorHandler<Worker>
 154   /**
 155    * A function that will listen for exit event on each worker.
 156    *
 157    * @defaultValue `() => {}`
 158    */
 159   exitHandler?: ExitHandler<Worker>
 160   /**
 161    * Whether to start the minimum number of workers at pool initialization.
 162    *
 163    * @defaultValue true
 164    */
 165   startWorkers?: boolean
 166   /**
 167    * The worker choice strategy to use in this pool.
 168    *
 169    * @defaultValue WorkerChoiceStrategies.ROUND_ROBIN
 170    */
 171   workerChoiceStrategy?: WorkerChoiceStrategy
 172   /**
 173    * The worker choice strategy options.
 174    */
 175   workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 176   /**
 177    * Restart worker on error.
 178    */
 179   restartWorkerOnError?: boolean
 180   /**
 181    * Pool events emission.
 182    *
 183    * @defaultValue true
 184    */
 185   enableEvents?: boolean
 186   /**
 187    * Pool worker node tasks queue.
 188    *
 189    * @defaultValue false
 190    */
 191   enableTasksQueue?: boolean
 192   /**
 193    * Pool worker node tasks queue options.
 194    */
 195   tasksQueueOptions?: TasksQueueOptions
 196 }
 197
 198 /**
 199  * Contract definition for a poolifier pool.
 200  *
 201  * @typeParam Worker - Type of worker which manages this pool.
 202  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
 203  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
 204  */
 205 export interface IPool<
 206   Worker extends IWorker,
 207   Data = unknown,
 208   Response = unknown
 209 > {
 210   /**
 211    * Pool information.
 212    */
 213   readonly info: PoolInfo
 214   /**
 215    * Pool worker nodes.
 216    *
 217    * @internal
 218    */
 219   readonly workerNodes: Array<IWorkerNode<Worker, Data>>
 220   /**
 221    * Whether the worker node has back pressure (i.e. its tasks queue is full).
 222    *
 223    * @param workerNodeKey - The worker node key.
 224    * @returns `true` if the worker node has back pressure, `false` otherwise.
 225    * @internal
 226    */
 227   readonly hasWorkerNodeBackPressure: (workerNodeKey: number) => boolean
 228   /**
 229    * Emitter on which events can be listened to.
 230    *
 231    * Events that can currently be listened to:
 232    *
 233    * - `'ready'`: Emitted when the number of workers created in the pool has reached the minimum size expected and are ready.
 234    * - `'busy'`: Emitted when the number of workers created in the pool has reached the maximum size expected and are executing concurrently their tasks quota.
 235    * - `'full'`: Emitted when the pool is dynamic and the number of workers created has reached the maximum size expected.
 236    * - `'destroy'`: Emitted when the pool is destroyed.
 237    * - `'error'`: Emitted when an uncaught error occurs.
 238    * - `'taskError'`: Emitted when an error occurs while executing a task.
 239    * - `'backPressure'`: Emitted when all worker nodes have back pressure (i.e. their tasks queue is full: queue size \>= maximum queue size).
 240    */
 241   readonly emitter?: PoolEmitter
 242   /**
 243    * Executes the specified function in the worker constructor with the task data input parameter.
 244    *
 245    * @param data - The optional task input data for the specified task function. This can only be structured-cloneable data.
 246    * @param name - The optional name of the task function to execute. If not specified, the default task function will be executed.
 247    * @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.
 248    * @returns Promise that will be fulfilled when the task is completed.
 249    */
 250   readonly execute: (
 251     data?: Data,
 252     name?: string,
 253     transferList?: TransferListItem[]
 254   ) => Promise<Response>
 255   /**
 256    * Starts the minimum number of workers in this pool.
 257    */
 258   readonly start: () => void
 259   /**
 260    * Terminates all workers in this pool.
 261    */
 262   readonly destroy: () => Promise<void>
 263   /**
 264    * Lists the names of task function available in this pool.
 265    *
 266    * @returns The names of task function available in this pool.
 267    */
 268   readonly listTaskFunctions: () => string[]
 269   /**
 270    * Sets the worker choice strategy in this pool.
 271    *
 272    * @param workerChoiceStrategy - The worker choice strategy.
 273    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 274    */
 275   readonly setWorkerChoiceStrategy: (
 276     workerChoiceStrategy: WorkerChoiceStrategy,
 277     workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 278   ) => void
 279   /**
 280    * Sets the worker choice strategy options in this pool.
 281    *
 282    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 283    */
 284   readonly setWorkerChoiceStrategyOptions: (
 285     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
 286   ) => void
 287   /**
 288    * Enables/disables the worker node tasks queue in this pool.
 289    *
 290    * @param enable - Whether to enable or disable the worker node tasks queue.
 291    * @param tasksQueueOptions - The worker node tasks queue options.
 292    */
 293   readonly enableTasksQueue: (
 294     enable: boolean,
 295     tasksQueueOptions?: TasksQueueOptions
 296   ) => void
 297   /**
 298    * Sets the worker node tasks queue options in this pool.
 299    *
 300    * @param tasksQueueOptions - The worker node tasks queue options.
 301    */
 302   readonly setTasksQueueOptions: (tasksQueueOptions: TasksQueueOptions) => void
 303 }