src/pools/pool.ts

   1 import type { ClusterSettings } from 'node:cluster'
   2 import type { EventEmitterAsyncResource } from 'node:events'
   3 import type { TransferListItem, WorkerOptions } from 'node:worker_threads'
   4
   5 import type { TaskFunctionProperties } from '../utility-types.js'
   6 import type {
   7   TaskFunction,
   8   TaskFunctionObject
   9 } from '../worker/task-functions.js'
  10 import type {
  11   WorkerChoiceStrategy,
  12   WorkerChoiceStrategyOptions
  13 } from './selection-strategies/selection-strategies-types.js'
  14 import type {
  15   ErrorHandler,
  16   ExitHandler,
  17   IWorker,
  18   IWorkerNode,
  19   MessageHandler,
  20   OnlineHandler,
  21   WorkerType
  22 } from './worker.js'
  23
  24 /**
  25  * Enumeration of pool types.
  26  */
  27 export const PoolTypes: Readonly<{
  28   fixed: 'fixed'
  29   dynamic: 'dynamic'
  30 }> = Object.freeze({
  31   /**
  32    * Fixed pool type.
  33    */
  34   fixed: 'fixed',
  35   /**
  36    * Dynamic pool type.
  37    */
  38   dynamic: 'dynamic'
  39 } as const)
  40
  41 /**
  42  * Pool type.
  43  */
  44 export type PoolType = keyof typeof PoolTypes
  45
  46 /**
  47  * Enumeration of pool events.
  48  */
  49 export const PoolEvents: Readonly<{
  50   ready: 'ready'
  51   busy: 'busy'
  52   full: 'full'
  53   empty: 'empty'
  54   destroy: 'destroy'
  55   error: 'error'
  56   taskError: 'taskError'
  57   backPressure: 'backPressure'
  58 }> = Object.freeze({
  59   ready: 'ready',
  60   busy: 'busy',
  61   full: 'full',
  62   empty: 'empty',
  63   destroy: 'destroy',
  64   error: 'error',
  65   taskError: 'taskError',
  66   backPressure: 'backPressure'
  67 } as const)
  68
  69 /**
  70  * Pool event.
  71  */
  72 export type PoolEvent = keyof typeof PoolEvents
  73
  74 /**
  75  * Pool information.
  76  */
  77 export interface PoolInfo {
  78   readonly version: string
  79   readonly type: PoolType
  80   readonly worker: WorkerType
  81   readonly started: boolean
  82   readonly ready: boolean
  83   readonly defaultStrategy: WorkerChoiceStrategy
  84   readonly strategyRetries: number
  85   readonly minSize: number
  86   readonly maxSize: number
  87   /** Pool utilization. */
  88   readonly utilization?: number
  89   /** Pool total worker nodes. */
  90   readonly workerNodes: number
  91   /** Pool stealing worker nodes. */
  92   readonly stealingWorkerNodes?: number
  93   /** Pool idle worker nodes. */
  94   readonly idleWorkerNodes: number
  95   /** Pool busy worker nodes. */
  96   readonly busyWorkerNodes: number
  97   readonly executedTasks: number
  98   readonly executingTasks: number
  99   readonly queuedTasks?: number
 100   readonly maxQueuedTasks?: number
 101   readonly backPressure?: boolean
 102   readonly stolenTasks?: number
 103   readonly failedTasks: number
 104   readonly runTime?: {
 105     readonly minimum: number
 106     readonly maximum: number
 107     readonly average?: number
 108     readonly median?: number
 109   }
 110   readonly waitTime?: {
 111     readonly minimum: number
 112     readonly maximum: number
 113     readonly average?: number
 114     readonly median?: number
 115   }
 116 }
 117
 118 /**
 119  * Worker node tasks queue options.
 120  */
 121 export interface TasksQueueOptions {
 122   /**
 123    * Maximum tasks queue size per worker node flagging it as back pressured.
 124    *
 125    * @defaultValue (pool maximum size)^2
 126    */
 127   readonly size?: number
 128   /**
 129    * Maximum number of tasks that can be executed concurrently on a worker node.
 130    *
 131    * @defaultValue 1
 132    */
 133   readonly concurrency?: number
 134   /**
 135    * Whether to enable task stealing on idle.
 136    *
 137    * @defaultValue true
 138    */
 139   readonly taskStealing?: boolean
 140   /**
 141    * Whether to enable tasks stealing under back pressure.
 142    *
 143    * @defaultValue false
 144    */
 145   readonly tasksStealingOnBackPressure?: boolean
 146   /**
 147    * Queued tasks finished timeout in milliseconds at worker node termination.
 148    *
 149    * @defaultValue 2000
 150    */
 151   readonly tasksFinishedTimeout?: number
 152 }
 153
 154 /**
 155  * Options for a poolifier pool.
 156  *
 157  * @typeParam Worker - Type of worker.
 158  */
 159 export interface PoolOptions<Worker extends IWorker> {
 160   /**
 161    * A function that will listen for online event on each worker.
 162    *
 163    * @defaultValue `() => {}`
 164    */
 165   onlineHandler?: OnlineHandler<Worker>
 166   /**
 167    * A function that will listen for message event on each worker.
 168    *
 169    * @defaultValue `() => {}`
 170    */
 171   messageHandler?: MessageHandler<Worker>
 172   /**
 173    * A function that will listen for error event on each worker.
 174    *
 175    * @defaultValue `() => {}`
 176    */
 177   errorHandler?: ErrorHandler<Worker>
 178   /**
 179    * A function that will listen for exit event on each worker.
 180    *
 181    * @defaultValue `() => {}`
 182    */
 183   exitHandler?: ExitHandler<Worker>
 184   /**
 185    * Whether to start the minimum number of workers at pool initialization.
 186    *
 187    * @defaultValue true
 188    */
 189   startWorkers?: boolean
 190   /**
 191    * The default worker choice strategy to use in this pool.
 192    *
 193    * @defaultValue WorkerChoiceStrategies.ROUND_ROBIN
 194    */
 195   workerChoiceStrategy?: WorkerChoiceStrategy
 196   /**
 197    * The worker choice strategy options.
 198    */
 199   workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 200   /**
 201    * Restart worker on error.
 202    */
 203   restartWorkerOnError?: boolean
 204   /**
 205    * Pool events integrated with async resource emission.
 206    *
 207    * @defaultValue true
 208    */
 209   enableEvents?: boolean
 210   /**
 211    * Pool worker node tasks queue.
 212    *
 213    * @defaultValue false
 214    */
 215   enableTasksQueue?: boolean
 216   /**
 217    * Pool worker node tasks queue options.
 218    */
 219   tasksQueueOptions?: TasksQueueOptions
 220   /**
 221    * Worker options.
 222    *
 223    * @see https://nodejs.org/api/worker_threads.html#new-workerfilename-options
 224    */
 225   workerOptions?: WorkerOptions
 226   /**
 227    * Key/value pairs to add to worker process environment.
 228    *
 229    * @see https://nodejs.org/api/cluster.html#cluster_cluster_fork_env
 230    */
 231   env?: Record<string, unknown>
 232   /**
 233    * Cluster settings.
 234    *
 235    * @see https://nodejs.org/api/cluster.html#cluster_cluster_settings
 236    */
 237   settings?: ClusterSettings
 238 }
 239
 240 /**
 241  * Contract definition for a poolifier pool.
 242  *
 243  * @typeParam Worker - Type of worker which manages this pool.
 244  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
 245  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
 246  */
 247 export interface IPool<
 248   Worker extends IWorker,
 249   Data = unknown,
 250   Response = unknown
 251 > {
 252   /**
 253    * Pool information.
 254    */
 255   readonly info: PoolInfo
 256   /**
 257    * Pool worker nodes.
 258    *
 259    * @internal
 260    */
 261   readonly workerNodes: Array<IWorkerNode<Worker, Data>>
 262   /**
 263    * Pool event emitter integrated with async resource.
 264    * The async tracking tooling identifier is `poolifier:<PoolType>-<WorkerType>-pool`.
 265    *
 266    * Events that can currently be listened to:
 267    *
 268    * - `'ready'`: Emitted when the number of workers created in the pool has reached the minimum size expected and are ready. If the pool is dynamic with a minimum number of workers is set to zero, this event is emitted when at least one dynamic worker is ready.
 269    * - `'busy'`: Emitted when the number of workers created in the pool has reached the maximum size expected and are executing concurrently their tasks quota.
 270    * - `'full'`: Emitted when the pool is dynamic and the number of workers created has reached the maximum size expected.
 271    * - `'empty'`: Emitted when the pool is dynamic with a minimum number of workers set to zero and the number of workers has reached the minimum size expected.
 272    * - `'destroy'`: Emitted when the pool is destroyed.
 273    * - `'error'`: Emitted when an uncaught error occurs.
 274    * - `'taskError'`: Emitted when an error occurs while executing a task.
 275    * - `'backPressure'`: Emitted when all worker nodes have back pressure (i.e. their tasks queue is full: queue size \>= maximum queue size).
 276    */
 277   readonly emitter?: EventEmitterAsyncResource
 278   /**
 279    * Executes the specified function in the worker constructor with the task data input parameter.
 280    *
 281    * @param data - The optional task input data for the specified task function. This can only be structured-cloneable data.
 282    * @param name - The optional name of the task function to execute. If not specified, the default task function will be executed.
 283    * @param transferList - An optional array of transferable objects to transfer ownership of. Ownership of the transferred objects is given to the chosen pool's worker_threads worker and they should not be used in the main thread afterwards.
 284    * @returns Promise that will be fulfilled when the task is completed.
 285    */
 286   readonly execute: (
 287     data?: Data,
 288     name?: string,
 289     transferList?: readonly TransferListItem[]
 290   ) => Promise<Response>
 291   /**
 292    * Starts the minimum number of workers in this pool.
 293    */
 294   readonly start: () => void
 295   /**
 296    * Terminates all workers in this pool.
 297    */
 298   readonly destroy: () => Promise<void>
 299   /**
 300    * Whether the specified task function exists in this pool.
 301    *
 302    * @param name - The name of the task function.
 303    * @returns `true` if the task function exists, `false` otherwise.
 304    */
 305   readonly hasTaskFunction: (name: string) => boolean
 306   /**
 307    * Adds a task function to this pool.
 308    * If a task function with the same name already exists, it will be overwritten.
 309    *
 310    * @param name - The name of the task function.
 311    * @param fn - The task function.
 312    * @returns `true` if the task function was added, `false` otherwise.
 313    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 314    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function or task function object.
 315    */
 316   readonly addTaskFunction: (
 317     name: string,
 318     fn: TaskFunction<Data, Response> | TaskFunctionObject<Data, Response>
 319   ) => Promise<boolean>
 320   /**
 321    * Removes a task function from this pool.
 322    *
 323    * @param name - The name of the task function.
 324    * @returns `true` if the task function was removed, `false` otherwise.
 325    */
 326   readonly removeTaskFunction: (name: string) => Promise<boolean>
 327   /**
 328    * Lists the properties of task functions available in this pool.
 329    *
 330    * @returns The properties of task functions available in this pool.
 331    */
 332   readonly listTaskFunctionsProperties: () => TaskFunctionProperties[]
 333   /**
 334    * Sets the default task function in this pool.
 335    *
 336    * @param name - The name of the task function.
 337    * @returns `true` if the default task function was set, `false` otherwise.
 338    */
 339   readonly setDefaultTaskFunction: (name: string) => Promise<boolean>
 340   /**
 341    * Sets the default worker choice strategy in this pool.
 342    *
 343    * @param workerChoiceStrategy - The default worker choice strategy.
 344    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 345    */
 346   readonly setWorkerChoiceStrategy: (
 347     workerChoiceStrategy: WorkerChoiceStrategy,
 348     workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 349   ) => void
 350   /**
 351    * Sets the worker choice strategy options in this pool.
 352    *
 353    * @param workerChoiceStrategyOptions - The worker choice strategy options.
 354    * @returns `true` if the worker choice strategy options were set, `false` otherwise.
 355    */
 356   readonly setWorkerChoiceStrategyOptions: (
 357     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
 358   ) => boolean
 359   /**
 360    * Enables/disables the worker node tasks queue in this pool.
 361    *
 362    * @param enable - Whether to enable or disable the worker node tasks queue.
 363    * @param tasksQueueOptions - The worker node tasks queue options.
 364    */
 365   readonly enableTasksQueue: (
 366     enable: boolean,
 367     tasksQueueOptions?: TasksQueueOptions
 368   ) => void
 369   /**
 370    * Sets the worker node tasks queue options in this pool.
 371    *
 372    * @param tasksQueueOptions - The worker node tasks queue options.
 373    */
 374   readonly setTasksQueueOptions: (tasksQueueOptions: TasksQueueOptions) => void
 375 }