| 1 | import EventEmitter from 'events' |
| 2 | import type { MessageValue } from '../utility-types' |
| 3 | import type { IPool } from './pool' |
| 4 | |
| 5 | /** |
| 6 | * An intentional empty function. |
| 7 | */ |
| 8 | function emptyFunction () { |
| 9 | // intentionally left blank |
| 10 | } |
| 11 | |
| 12 | /** |
| 13 | * Callback invoked if the worker raised an error. |
| 14 | */ |
| 15 | export type ErrorHandler<Worker> = (this: Worker, e: Error) => void |
| 16 | |
| 17 | /** |
| 18 | * Callback invoked when the worker has started successfully. |
| 19 | */ |
| 20 | export type OnlineHandler<Worker> = (this: Worker) => void |
| 21 | |
| 22 | /** |
| 23 | * Callback invoked when the worker exits successfully. |
| 24 | */ |
| 25 | export type ExitHandler<Worker> = (this: Worker, code: number) => void |
| 26 | |
| 27 | /** |
| 28 | * Basic interface that describes the minimum required implementation of listener events for a pool-worker. |
| 29 | */ |
| 30 | export interface IWorker { |
| 31 | /** |
| 32 | * Register a listener to the error event. |
| 33 | * |
| 34 | * @param event `'error'`. |
| 35 | * @param handler The error handler. |
| 36 | */ |
| 37 | on(event: 'error', handler: ErrorHandler<this>): void |
| 38 | /** |
| 39 | * Register a listener to the online event. |
| 40 | * |
| 41 | * @param event `'online'`. |
| 42 | * @param handler The online handler. |
| 43 | */ |
| 44 | on(event: 'online', handler: OnlineHandler<this>): void |
| 45 | /** |
| 46 | * Register a listener to the exit event. |
| 47 | * |
| 48 | * @param event `'exit'`. |
| 49 | * @param handler The exit handler. |
| 50 | */ |
| 51 | on(event: 'exit', handler: ExitHandler<this>): void |
| 52 | /** |
| 53 | * Register a listener to the exit event that will only performed once. |
| 54 | * |
| 55 | * @param event `'exit'`. |
| 56 | * @param handler The exit handler. |
| 57 | */ |
| 58 | once(event: 'exit', handler: ExitHandler<this>): void |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Options for a poolifier pool. |
| 63 | */ |
| 64 | export interface PoolOptions<Worker> { |
| 65 | /** |
| 66 | * A function that will listen for error event on each worker. |
| 67 | */ |
| 68 | errorHandler?: ErrorHandler<Worker> |
| 69 | /** |
| 70 | * A function that will listen for online event on each worker. |
| 71 | */ |
| 72 | onlineHandler?: OnlineHandler<Worker> |
| 73 | /** |
| 74 | * A function that will listen for exit event on each worker. |
| 75 | */ |
| 76 | exitHandler?: ExitHandler<Worker> |
| 77 | /** |
| 78 | * This is just to avoid non-useful warning messages. |
| 79 | * |
| 80 | * Will be used to set `maxListeners` on event emitters (workers are event emitters). |
| 81 | * |
| 82 | * @default 1000 |
| 83 | * @see [Node events emitter.setMaxListeners(n)](https://nodejs.org/api/events.html#events_emitter_setmaxlisteners_n) |
| 84 | */ |
| 85 | maxTasks?: number |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * Internal poolifier pool emitter. |
| 90 | */ |
| 91 | class PoolEmitter extends EventEmitter {} |
| 92 | |
| 93 | /** |
| 94 | * Base class containing some shared logic for all poolifier pools. |
| 95 | * |
| 96 | * @template Worker Type of worker which manages this pool. |
| 97 | * @template Data Type of data sent to the worker. This can only be serializable data. |
| 98 | * @template Response Type of response of execution. This can only be serializable data. |
| 99 | */ |
| 100 | export abstract class AbstractPool< |
| 101 | Worker extends IWorker, |
| 102 | Data = unknown, |
| 103 | Response = unknown |
| 104 | > implements IPool<Data, Response> { |
| 105 | /** |
| 106 | * List of currently available workers. |
| 107 | */ |
| 108 | public readonly workers: Worker[] = [] |
| 109 | |
| 110 | /** |
| 111 | * Index for the next worker. |
| 112 | */ |
| 113 | public nextWorkerIndex: number = 0 |
| 114 | |
| 115 | /** |
| 116 | * The tasks map. |
| 117 | * |
| 118 | * - `key`: The `Worker` |
| 119 | * - `value`: Number of tasks currently in progress on the worker. |
| 120 | */ |
| 121 | public readonly tasks: Map<Worker, number> = new Map<Worker, number>() |
| 122 | |
| 123 | /** |
| 124 | * Emitter on which events can be listened to. |
| 125 | * |
| 126 | * Events that can currently be listened to: |
| 127 | * |
| 128 | * - `'FullPool'` |
| 129 | */ |
| 130 | public readonly emitter: PoolEmitter |
| 131 | |
| 132 | /** |
| 133 | * ID of the next message. |
| 134 | */ |
| 135 | protected nextMessageId: number = 0 |
| 136 | |
| 137 | /** |
| 138 | * Constructs a new poolifier pool. |
| 139 | * |
| 140 | * @param numberOfWorkers Number of workers that this pool should manage. |
| 141 | * @param filePath Path to the worker-file. |
| 142 | * @param opts Options for the pool. Default: `{ maxTasks: 1000 }` |
| 143 | */ |
| 144 | public constructor ( |
| 145 | public readonly numberOfWorkers: number, |
| 146 | public readonly filePath: string, |
| 147 | public readonly opts: PoolOptions<Worker> = { maxTasks: 1000 } |
| 148 | ) { |
| 149 | if (!this.isMain()) { |
| 150 | throw new Error('Cannot start a pool from a worker!') |
| 151 | } |
| 152 | this.checkFilePath(this.filePath) |
| 153 | this.setupHook() |
| 154 | |
| 155 | for (let i = 1; i <= this.numberOfWorkers; i++) { |
| 156 | this.createAndSetupWorker() |
| 157 | } |
| 158 | |
| 159 | this.emitter = new PoolEmitter() |
| 160 | } |
| 161 | |
| 162 | private checkFilePath (filePath: string) { |
| 163 | if (!filePath) { |
| 164 | throw new Error('Please specify a file with a worker implementation') |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | /** |
| 169 | * Perform the task specified in the constructor with the data parameter. |
| 170 | * |
| 171 | * @param data The input for the specified task. This can only be serializable data. |
| 172 | * @returns Promise that will be resolved when the task is successfully completed. |
| 173 | */ |
| 174 | public execute (data: Data): Promise<Response> { |
| 175 | // Configure worker to handle message with the specified task |
| 176 | const worker = this.chooseWorker() |
| 177 | this.increaseWorkersTask(worker) |
| 178 | const messageId = ++this.nextMessageId |
| 179 | const res = this.internalExecute(worker, messageId) |
| 180 | this.sendToWorker(worker, { data: data || ({} as Data), id: messageId }) |
| 181 | return res |
| 182 | } |
| 183 | |
| 184 | /** |
| 185 | * Shut down every current worker in this pool. |
| 186 | */ |
| 187 | public async destroy (): Promise<void> { |
| 188 | await Promise.all(this.workers.map(worker => this.destroyWorker(worker))) |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * Shut down given worker. |
| 193 | * |
| 194 | * @param worker A worker within `workers`. |
| 195 | */ |
| 196 | protected abstract destroyWorker (worker: Worker): void | Promise<void> |
| 197 | |
| 198 | /** |
| 199 | * Setup hook that can be overridden by a Poolifier pool implementation |
| 200 | * to run code before workers are created in the abstract constructor. |
| 201 | */ |
| 202 | protected setupHook (): void { |
| 203 | // Can be overridden |
| 204 | } |
| 205 | |
| 206 | /** |
| 207 | * Should return whether the worker is the main worker or not. |
| 208 | */ |
| 209 | protected abstract isMain (): boolean |
| 210 | |
| 211 | /** |
| 212 | * Increase the number of tasks that the given workers has done. |
| 213 | * |
| 214 | * @param worker Worker whose tasks are increased. |
| 215 | */ |
| 216 | protected increaseWorkersTask (worker: Worker): void { |
| 217 | this.stepWorkerNumberOfTasks(worker, 1) |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * Decrease the number of tasks that the given workers has done. |
| 222 | * |
| 223 | * @param worker Worker whose tasks are decreased. |
| 224 | */ |
| 225 | protected decreaseWorkersTasks (worker: Worker): void { |
| 226 | this.stepWorkerNumberOfTasks(worker, -1) |
| 227 | } |
| 228 | |
| 229 | /** |
| 230 | * Step the number of tasks that the given workers has done. |
| 231 | * |
| 232 | * @param worker Worker whose tasks are set. |
| 233 | * @param step Worker number of tasks step. |
| 234 | */ |
| 235 | private stepWorkerNumberOfTasks (worker: Worker, step: number) { |
| 236 | const numberOfTasksInProgress = this.tasks.get(worker) |
| 237 | if (numberOfTasksInProgress !== undefined) { |
| 238 | this.tasks.set(worker, numberOfTasksInProgress + step) |
| 239 | } else { |
| 240 | throw Error('Worker could not be found in tasks map') |
| 241 | } |
| 242 | } |
| 243 | |
| 244 | /** |
| 245 | * Removes the given worker from the pool. |
| 246 | * |
| 247 | * @param worker Worker that will be removed. |
| 248 | */ |
| 249 | protected removeWorker (worker: Worker): void { |
| 250 | // Clean worker from data structure |
| 251 | const workerIndex = this.workers.indexOf(worker) |
| 252 | this.workers.splice(workerIndex, 1) |
| 253 | this.tasks.delete(worker) |
| 254 | } |
| 255 | |
| 256 | /** |
| 257 | * Choose a worker for the next task. |
| 258 | * |
| 259 | * The default implementation uses a round robin algorithm to distribute the load. |
| 260 | * |
| 261 | * @returns Worker. |
| 262 | */ |
| 263 | protected chooseWorker (): Worker { |
| 264 | const chosenWorker = this.workers[this.nextWorkerIndex] |
| 265 | this.nextWorkerIndex = |
| 266 | this.workers.length - 1 === this.nextWorkerIndex |
| 267 | ? 0 |
| 268 | : this.nextWorkerIndex + 1 |
| 269 | return chosenWorker |
| 270 | } |
| 271 | |
| 272 | /** |
| 273 | * Send a message to the given worker. |
| 274 | * |
| 275 | * @param worker The worker which should receive the message. |
| 276 | * @param message The message. |
| 277 | */ |
| 278 | protected abstract sendToWorker ( |
| 279 | worker: Worker, |
| 280 | message: MessageValue<Data> |
| 281 | ): void |
| 282 | |
| 283 | protected abstract registerWorkerMessageListener< |
| 284 | Message extends Data | Response |
| 285 | > (worker: Worker, listener: (message: MessageValue<Message>) => void): void |
| 286 | |
| 287 | protected abstract unregisterWorkerMessageListener< |
| 288 | Message extends Data | Response |
| 289 | > (worker: Worker, listener: (message: MessageValue<Message>) => void): void |
| 290 | |
| 291 | protected internalExecute ( |
| 292 | worker: Worker, |
| 293 | messageId: number |
| 294 | ): Promise<Response> { |
| 295 | return new Promise((resolve, reject) => { |
| 296 | const listener: (message: MessageValue<Response>) => void = message => { |
| 297 | if (message.id === messageId) { |
| 298 | this.unregisterWorkerMessageListener(worker, listener) |
| 299 | this.decreaseWorkersTasks(worker) |
| 300 | if (message.error) reject(message.error) |
| 301 | else resolve(message.data as Response) |
| 302 | } |
| 303 | } |
| 304 | this.registerWorkerMessageListener(worker, listener) |
| 305 | }) |
| 306 | } |
| 307 | |
| 308 | /** |
| 309 | * Returns a newly created worker. |
| 310 | */ |
| 311 | protected abstract createWorker (): Worker |
| 312 | |
| 313 | /** |
| 314 | * Function that can be hooked up when a worker has been newly created and moved to the workers registry. |
| 315 | * |
| 316 | * Can be used to update the `maxListeners` or binding the `main-worker`<->`worker` connection if not bind by default. |
| 317 | * |
| 318 | * @param worker The newly created worker. |
| 319 | */ |
| 320 | protected abstract afterWorkerSetup (worker: Worker): void |
| 321 | |
| 322 | /** |
| 323 | * Creates a new worker for this pool and sets it up completely. |
| 324 | * |
| 325 | * @returns New, completely set up worker. |
| 326 | */ |
| 327 | protected createAndSetupWorker (): Worker { |
| 328 | const worker: Worker = this.createWorker() |
| 329 | |
| 330 | worker.on('error', this.opts.errorHandler ?? emptyFunction) |
| 331 | worker.on('online', this.opts.onlineHandler ?? emptyFunction) |
| 332 | worker.on('exit', this.opts.exitHandler ?? emptyFunction) |
| 333 | worker.once('exit', () => this.removeWorker(worker)) |
| 334 | |
| 335 | this.workers.push(worker) |
| 336 | |
| 337 | // Init tasks map |
| 338 | this.tasks.set(worker, 0) |
| 339 | |
| 340 | this.afterWorkerSetup(worker) |
| 341 | |
| 342 | return worker |
| 343 | } |
| 344 | } |