1 import { EventEmitter
} from
'node:events'
2 import { type TransferListItem
} from
'node:worker_threads'
14 WorkerChoiceStrategyOptions
15 } from
'./selection-strategies/selection-strategies-types'
18 * Enumeration of pool types.
20 export const PoolTypes
= Object.freeze({
34 export type PoolType
= keyof
typeof PoolTypes
37 * Pool events emitter.
39 export class PoolEmitter
extends EventEmitter
{}
42 * Enumeration of pool events.
44 export const PoolEvents
= Object.freeze({
50 taskError
: 'taskError',
51 backPressure
: 'backPressure'
57 export type PoolEvent
= keyof
typeof PoolEvents
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
87 readonly minimum
: number
88 readonly maximum
: number
89 readonly average
?: number
90 readonly median
?: number
93 readonly minimum
: number
94 readonly maximum
: number
95 readonly average
?: number
96 readonly median
?: number
101 * Worker node tasks queue options.
103 export interface TasksQueueOptions
{
105 * Maximum tasks queue size per worker node flagging it as back pressured.
107 * @defaultValue (pool maximum size)^2
109 readonly size
?: number
111 * Maximum number of tasks that can be executed concurrently on a worker node.
115 readonly concurrency
?: number
117 * Whether to enable task stealing.
121 readonly taskStealing
?: boolean
123 * Whether to enable tasks stealing on back pressure.
127 readonly tasksStealingOnBackPressure
?: boolean
131 * Options for a poolifier pool.
133 * @typeParam Worker - Type of worker.
135 export interface PoolOptions
<Worker
extends IWorker
> {
137 * A function that will listen for online event on each worker.
139 * @defaultValue `() => {}`
141 onlineHandler
?: OnlineHandler
<Worker
>
143 * A function that will listen for message event on each worker.
145 * @defaultValue `() => {}`
147 messageHandler
?: MessageHandler
<Worker
>
149 * A function that will listen for error event on each worker.
151 * @defaultValue `() => {}`
153 errorHandler
?: ErrorHandler
<Worker
>
155 * A function that will listen for exit event on each worker.
157 * @defaultValue `() => {}`
159 exitHandler
?: ExitHandler
<Worker
>
161 * Whether to start the minimum number of workers at pool initialization.
165 startWorkers
?: boolean
167 * The worker choice strategy to use in this pool.
169 * @defaultValue WorkerChoiceStrategies.ROUND_ROBIN
171 workerChoiceStrategy
?: WorkerChoiceStrategy
173 * The worker choice strategy options.
175 workerChoiceStrategyOptions
?: WorkerChoiceStrategyOptions
177 * Restart worker on error.
179 restartWorkerOnError
?: boolean
181 * Pool events emission.
185 enableEvents
?: boolean
187 * Pool worker node tasks queue.
189 * @defaultValue false
191 enableTasksQueue
?: boolean
193 * Pool worker node tasks queue options.
195 tasksQueueOptions
?: TasksQueueOptions
199 * Contract definition for a poolifier pool.
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.
205 export interface IPool
<
206 Worker
extends IWorker
,
213 readonly info
: PoolInfo
219 readonly workerNodes
: Array<IWorkerNode
<Worker
, Data
>>
221 * Whether the worker node has back pressure (i.e. its tasks queue is full).
223 * @param workerNodeKey - The worker node key.
224 * @returns `true` if the worker node has back pressure, `false` otherwise.
227 readonly hasWorkerNodeBackPressure
: (workerNodeKey
: number) => boolean
229 * Emitter on which events can be listened to.
231 * Events that can currently be listened to:
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).
241 readonly emitter
?: PoolEmitter
243 * Executes the specified function in the worker constructor with the task data input parameter.
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.
253 transferList
?: TransferListItem
[]
254 ) => Promise
<Response
>
256 * Starts the minimum number of workers in this pool.
258 readonly start
: () => void
260 * Terminates all workers in this pool.
262 readonly destroy
: () => Promise
<void>
264 * Lists the names of task function available in this pool.
266 * @returns The names of task function available in this pool.
268 readonly listTaskFunctions
: () => string[]
270 * Sets the worker choice strategy in this pool.
272 * @param workerChoiceStrategy - The worker choice strategy.
273 * @param workerChoiceStrategyOptions - The worker choice strategy options.
275 readonly setWorkerChoiceStrategy
: (
276 workerChoiceStrategy
: WorkerChoiceStrategy
,
277 workerChoiceStrategyOptions
?: WorkerChoiceStrategyOptions
280 * Sets the worker choice strategy options in this pool.
282 * @param workerChoiceStrategyOptions - The worker choice strategy options.
284 readonly setWorkerChoiceStrategyOptions
: (
285 workerChoiceStrategyOptions
: WorkerChoiceStrategyOptions
288 * Enables/disables the worker node tasks queue in this pool.
290 * @param enable - Whether to enable or disable the worker node tasks queue.
291 * @param tasksQueueOptions - The worker node tasks queue options.
293 readonly enableTasksQueue
: (
295 tasksQueueOptions
?: TasksQueueOptions
298 * Sets the worker node tasks queue options in this pool.
300 * @param tasksQueueOptions - The worker node tasks queue options.
302 readonly setTasksQueueOptions
: (tasksQueueOptions
: TasksQueueOptions
) => void