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c97c7edb S |
1 | import EventEmitter from 'events' |
2 | import type { MessageValue } from '../utility-types' | |
3 | import type { IPool } from './pool' | |
4 | ||
729c563d S |
5 | /** |
6 | * Callback invoked if the worker raised an error. | |
7 | */ | |
c97c7edb | 8 | export type ErrorHandler<Worker> = (this: Worker, e: Error) => void |
729c563d S |
9 | |
10 | /** | |
11 | * Callback invoked when the worker has started successfully. | |
12 | */ | |
c97c7edb | 13 | export type OnlineHandler<Worker> = (this: Worker) => void |
729c563d S |
14 | |
15 | /** | |
16 | * Callback invoked when the worker exits successfully. | |
17 | */ | |
c97c7edb S |
18 | export type ExitHandler<Worker> = (this: Worker, code: number) => void |
19 | ||
729c563d S |
20 | /** |
21 | * Basic interface that describes the minimum required implementation of listener events for a pool-worker. | |
22 | */ | |
c97c7edb | 23 | export interface IWorker { |
3832ad95 S |
24 | /** |
25 | * Register a listener to the error event. | |
26 | * | |
27 | * @param event `'error'`. | |
28 | * @param handler The error handler. | |
29 | */ | |
c97c7edb | 30 | on(event: 'error', handler: ErrorHandler<this>): void |
3832ad95 S |
31 | /** |
32 | * Register a listener to the online event. | |
33 | * | |
34 | * @param event `'online'`. | |
35 | * @param handler The online handler. | |
36 | */ | |
c97c7edb | 37 | on(event: 'online', handler: OnlineHandler<this>): void |
3832ad95 S |
38 | /** |
39 | * Register a listener to the exit event. | |
40 | * | |
41 | * @param event `'exit'`. | |
42 | * @param handler The exit handler. | |
43 | */ | |
c97c7edb | 44 | on(event: 'exit', handler: ExitHandler<this>): void |
3832ad95 S |
45 | /** |
46 | * Register a listener to the exit event that will only performed once. | |
47 | * | |
48 | * @param event `'exit'`. | |
49 | * @param handler The exit handler. | |
50 | */ | |
45dbbb14 | 51 | once(event: 'exit', handler: ExitHandler<this>): void |
c97c7edb S |
52 | } |
53 | ||
729c563d S |
54 | /** |
55 | * Options for a poolifier pool. | |
56 | */ | |
c97c7edb S |
57 | export interface PoolOptions<Worker> { |
58 | /** | |
59 | * A function that will listen for error event on each worker. | |
60 | */ | |
61 | errorHandler?: ErrorHandler<Worker> | |
62 | /** | |
63 | * A function that will listen for online event on each worker. | |
64 | */ | |
65 | onlineHandler?: OnlineHandler<Worker> | |
66 | /** | |
67 | * A function that will listen for exit event on each worker. | |
68 | */ | |
69 | exitHandler?: ExitHandler<Worker> | |
70 | /** | |
729c563d S |
71 | * This is just to avoid non-useful warning messages. |
72 | * | |
73 | * Will be used to set `maxListeners` on event emitters (workers are event emitters). | |
c97c7edb S |
74 | * |
75 | * @default 1000 | |
729c563d | 76 | * @see [Node events emitter.setMaxListeners(n)](https://nodejs.org/api/events.html#events_emitter_setmaxlisteners_n) |
c97c7edb S |
77 | */ |
78 | maxTasks?: number | |
79 | } | |
80 | ||
729c563d S |
81 | /** |
82 | * Internal poolifier pool emitter. | |
83 | */ | |
c97c7edb S |
84 | class PoolEmitter extends EventEmitter {} |
85 | ||
729c563d S |
86 | /** |
87 | * Base class containing some shared logic for all poolifier pools. | |
88 | * | |
89 | * @template Worker Type of worker which manages this pool. | |
90 | * @template Data Type of data sent to the worker. | |
91 | * @template Response Type of response of execution. | |
92 | */ | |
c97c7edb S |
93 | export abstract class AbstractPool< |
94 | Worker extends IWorker, | |
d3c8a1a8 S |
95 | Data = unknown, |
96 | Response = unknown | |
c97c7edb | 97 | > implements IPool<Data, Response> { |
729c563d S |
98 | /** |
99 | * List of currently available workers. | |
100 | */ | |
c97c7edb | 101 | public readonly workers: Worker[] = [] |
729c563d S |
102 | |
103 | /** | |
280c2a77 | 104 | * Index for the next worker. |
729c563d | 105 | */ |
280c2a77 | 106 | public nextWorkerIndex: number = 0 |
c97c7edb S |
107 | |
108 | /** | |
3832ad95 S |
109 | * The tasks map. |
110 | * | |
729c563d | 111 | * - `key`: The `Worker` |
c01733f1 | 112 | * - `value`: Number of tasks currently in progress on the worker. |
c97c7edb S |
113 | */ |
114 | public readonly tasks: Map<Worker, number> = new Map<Worker, number>() | |
115 | ||
729c563d S |
116 | /** |
117 | * Emitter on which events can be listened to. | |
118 | * | |
119 | * Events that can currently be listened to: | |
120 | * | |
121 | * - `'FullPool'` | |
122 | */ | |
c97c7edb S |
123 | public readonly emitter: PoolEmitter |
124 | ||
729c563d S |
125 | /** |
126 | * ID of the next message. | |
127 | */ | |
280c2a77 | 128 | protected nextMessageId: number = 0 |
c97c7edb | 129 | |
729c563d S |
130 | /** |
131 | * Constructs a new poolifier pool. | |
132 | * | |
5c5a1fb7 | 133 | * @param numberOfWorkers Number of workers that this pool should manage. |
729c563d S |
134 | * @param filePath Path to the worker-file. |
135 | * @param opts Options for the pool. Default: `{ maxTasks: 1000 }` | |
136 | */ | |
c97c7edb | 137 | public constructor ( |
5c5a1fb7 | 138 | public readonly numberOfWorkers: number, |
c97c7edb S |
139 | public readonly filePath: string, |
140 | public readonly opts: PoolOptions<Worker> = { maxTasks: 1000 } | |
141 | ) { | |
142 | if (!this.isMain()) { | |
143 | throw new Error('Cannot start a pool from a worker!') | |
144 | } | |
145 | // TODO christopher 2021-02-07: Improve this check e.g. with a pattern or blank check | |
146 | if (!this.filePath) { | |
147 | throw new Error('Please specify a file with a worker implementation') | |
148 | } | |
c97c7edb S |
149 | this.setupHook() |
150 | ||
5c5a1fb7 | 151 | for (let i = 1; i <= this.numberOfWorkers; i++) { |
280c2a77 | 152 | this.createAndSetupWorker() |
c97c7edb S |
153 | } |
154 | ||
155 | this.emitter = new PoolEmitter() | |
156 | } | |
157 | ||
3832ad95 S |
158 | /** |
159 | * Perform the task specified in the constructor with the data parameter. | |
160 | * | |
161 | * @param data The input for the specified task. | |
162 | * @returns Promise that will be resolved when the task is successfully completed. | |
163 | */ | |
280c2a77 S |
164 | public execute (data: Data): Promise<Response> { |
165 | // Configure worker to handle message with the specified task | |
166 | const worker = this.chooseWorker() | |
167 | this.increaseWorkersTask(worker) | |
168 | const messageId = ++this.nextMessageId | |
169 | const res = this.internalExecute(worker, messageId) | |
170 | this.sendToWorker(worker, { data: data || ({} as Data), id: messageId }) | |
171 | return res | |
172 | } | |
c97c7edb | 173 | |
3832ad95 S |
174 | /** |
175 | * Shut down every current worker in this pool. | |
176 | */ | |
c97c7edb | 177 | public async destroy (): Promise<void> { |
45dbbb14 | 178 | await Promise.all(this.workers.map(worker => this.destroyWorker(worker))) |
c97c7edb S |
179 | } |
180 | ||
729c563d S |
181 | /** |
182 | * Shut down given worker. | |
183 | * | |
184 | * @param worker A worker within `workers`. | |
185 | */ | |
c97c7edb S |
186 | protected abstract destroyWorker (worker: Worker): void | Promise<void> |
187 | ||
729c563d | 188 | /** |
280c2a77 S |
189 | * Setup hook that can be overridden by a Poolifier pool implementation |
190 | * to run code before workers are created in the abstract constructor. | |
729c563d | 191 | */ |
280c2a77 S |
192 | protected setupHook (): void { |
193 | // Can be overridden | |
194 | } | |
c97c7edb | 195 | |
729c563d | 196 | /** |
280c2a77 S |
197 | * Should return whether the worker is the main worker or not. |
198 | */ | |
199 | protected abstract isMain (): boolean | |
200 | ||
201 | /** | |
202 | * Increase the number of tasks that the given workers has done. | |
729c563d | 203 | * |
f416c098 | 204 | * @param worker Worker whose tasks are increased. |
729c563d | 205 | */ |
280c2a77 | 206 | protected increaseWorkersTask (worker: Worker): void { |
f416c098 | 207 | this.stepWorkerNumberOfTasks(worker, 1) |
c97c7edb S |
208 | } |
209 | ||
c01733f1 | 210 | /** |
d63d3be3 | 211 | * Decrease the number of tasks that the given workers has done. |
c01733f1 | 212 | * |
f416c098 | 213 | * @param worker Worker whose tasks are decreased. |
c01733f1 | 214 | */ |
215 | protected decreaseWorkersTasks (worker: Worker): void { | |
f416c098 JB |
216 | this.stepWorkerNumberOfTasks(worker, -1) |
217 | } | |
218 | ||
219 | /** | |
220 | * Step the number of tasks that the given workers has done. | |
221 | * | |
222 | * @param worker Worker whose tasks are set. | |
223 | * @param step Worker number of tasks step. | |
224 | */ | |
225 | private stepWorkerNumberOfTasks (worker: Worker, step: number) { | |
d63d3be3 | 226 | const numberOfTasksInProgress = this.tasks.get(worker) |
227 | if (numberOfTasksInProgress !== undefined) { | |
f416c098 | 228 | this.tasks.set(worker, numberOfTasksInProgress + step) |
c01733f1 | 229 | } else { |
230 | throw Error('Worker could not be found in tasks map') | |
231 | } | |
232 | } | |
233 | ||
729c563d S |
234 | /** |
235 | * Removes the given worker from the pool. | |
236 | * | |
237 | * @param worker Worker that will be removed. | |
238 | */ | |
f2fdaa86 JB |
239 | protected removeWorker (worker: Worker): void { |
240 | // Clean worker from data structure | |
241 | const workerIndex = this.workers.indexOf(worker) | |
242 | this.workers.splice(workerIndex, 1) | |
243 | this.tasks.delete(worker) | |
244 | } | |
245 | ||
280c2a77 S |
246 | /** |
247 | * Choose a worker for the next task. | |
248 | * | |
249 | * The default implementation uses a round robin algorithm to distribute the load. | |
250 | * | |
251 | * @returns Worker. | |
252 | */ | |
253 | protected chooseWorker (): Worker { | |
254 | const chosenWorker = this.workers[this.nextWorkerIndex] | |
aacd8188 S |
255 | this.nextWorkerIndex = |
256 | this.workers.length - 1 === this.nextWorkerIndex | |
257 | ? 0 | |
258 | : this.nextWorkerIndex + 1 | |
280c2a77 | 259 | return chosenWorker |
c97c7edb S |
260 | } |
261 | ||
280c2a77 S |
262 | /** |
263 | * Send a message to the given worker. | |
264 | * | |
265 | * @param worker The worker which should receive the message. | |
266 | * @param message The message. | |
267 | */ | |
268 | protected abstract sendToWorker ( | |
269 | worker: Worker, | |
270 | message: MessageValue<Data> | |
271 | ): void | |
272 | ||
4f7fa42a S |
273 | protected abstract registerWorkerMessageListener< |
274 | Message extends Data | Response | |
275 | > (worker: Worker, listener: (message: MessageValue<Message>) => void): void | |
c97c7edb | 276 | |
4f7fa42a S |
277 | protected abstract unregisterWorkerMessageListener< |
278 | Message extends Data | Response | |
279 | > (worker: Worker, listener: (message: MessageValue<Message>) => void): void | |
c97c7edb | 280 | |
280c2a77 S |
281 | protected internalExecute ( |
282 | worker: Worker, | |
283 | messageId: number | |
284 | ): Promise<Response> { | |
c97c7edb S |
285 | return new Promise((resolve, reject) => { |
286 | const listener: (message: MessageValue<Response>) => void = message => { | |
280c2a77 | 287 | if (message.id === messageId) { |
c97c7edb | 288 | this.unregisterWorkerMessageListener(worker, listener) |
c01733f1 | 289 | this.decreaseWorkersTasks(worker) |
c97c7edb S |
290 | if (message.error) reject(message.error) |
291 | else resolve(message.data as Response) | |
292 | } | |
293 | } | |
294 | this.registerWorkerMessageListener(worker, listener) | |
295 | }) | |
296 | } | |
297 | ||
729c563d S |
298 | /** |
299 | * Returns a newly created worker. | |
300 | */ | |
280c2a77 | 301 | protected abstract createWorker (): Worker |
c97c7edb | 302 | |
729c563d S |
303 | /** |
304 | * Function that can be hooked up when a worker has been newly created and moved to the workers registry. | |
305 | * | |
306 | * Can be used to update the `maxListeners` or binding the `main-worker`<->`worker` connection if not bind by default. | |
307 | * | |
308 | * @param worker The newly created worker. | |
309 | */ | |
280c2a77 | 310 | protected abstract afterWorkerSetup (worker: Worker): void |
c97c7edb | 311 | |
729c563d S |
312 | /** |
313 | * Creates a new worker for this pool and sets it up completely. | |
50eceb07 S |
314 | * |
315 | * @returns New, completely set up worker. | |
729c563d | 316 | */ |
280c2a77 S |
317 | protected createAndSetupWorker (): Worker { |
318 | const worker: Worker = this.createWorker() | |
319 | ||
c97c7edb S |
320 | worker.on('error', this.opts.errorHandler ?? (() => {})) |
321 | worker.on('online', this.opts.onlineHandler ?? (() => {})) | |
c97c7edb | 322 | worker.on('exit', this.opts.exitHandler ?? (() => {})) |
45dbbb14 | 323 | worker.once('exit', () => this.removeWorker(worker)) |
280c2a77 | 324 | |
c97c7edb | 325 | this.workers.push(worker) |
280c2a77 S |
326 | |
327 | // Init tasks map | |
c97c7edb | 328 | this.tasks.set(worker, 0) |
280c2a77 S |
329 | |
330 | this.afterWorkerSetup(worker) | |
331 | ||
c97c7edb S |
332 | return worker |
333 | } | |
334 | } |