| 1 | import type { |
| 2 | MessageValue, |
| 3 | PromiseWorkerResponseWrapper |
| 4 | } from '../utility-types' |
| 5 | import type { IPoolInternal } from './pool-internal' |
| 6 | import { PoolEmitter } from './pool-internal' |
| 7 | import type { WorkerChoiceStrategy } from './selection-strategies' |
| 8 | import { |
| 9 | WorkerChoiceStrategies, |
| 10 | WorkerChoiceStrategyContext |
| 11 | } from './selection-strategies' |
| 12 | |
| 13 | /** |
| 14 | * An intentional empty function. |
| 15 | */ |
| 16 | const EMPTY_FUNCTION: () => void = () => { |
| 17 | /* Intentionally empty */ |
| 18 | } |
| 19 | |
| 20 | /** |
| 21 | * Callback invoked if the worker raised an error. |
| 22 | */ |
| 23 | export type ErrorHandler<Worker> = (this: Worker, e: Error) => void |
| 24 | |
| 25 | /** |
| 26 | * Callback invoked when the worker has started successfully. |
| 27 | */ |
| 28 | export type OnlineHandler<Worker> = (this: Worker) => void |
| 29 | |
| 30 | /** |
| 31 | * Callback invoked when the worker exits successfully. |
| 32 | */ |
| 33 | export type ExitHandler<Worker> = (this: Worker, code: number) => void |
| 34 | |
| 35 | /** |
| 36 | * Basic interface that describes the minimum required implementation of listener events for a pool-worker. |
| 37 | */ |
| 38 | export interface IWorker { |
| 39 | /** |
| 40 | * Register a listener to the error event. |
| 41 | * |
| 42 | * @param event `'error'`. |
| 43 | * @param handler The error handler. |
| 44 | */ |
| 45 | on(event: 'error', handler: ErrorHandler<this>): void |
| 46 | /** |
| 47 | * Register a listener to the online event. |
| 48 | * |
| 49 | * @param event `'online'`. |
| 50 | * @param handler The online handler. |
| 51 | */ |
| 52 | on(event: 'online', handler: OnlineHandler<this>): void |
| 53 | /** |
| 54 | * Register a listener to the exit event. |
| 55 | * |
| 56 | * @param event `'exit'`. |
| 57 | * @param handler The exit handler. |
| 58 | */ |
| 59 | on(event: 'exit', handler: ExitHandler<this>): void |
| 60 | /** |
| 61 | * Register a listener to the exit event that will only performed once. |
| 62 | * |
| 63 | * @param event `'exit'`. |
| 64 | * @param handler The exit handler. |
| 65 | */ |
| 66 | once(event: 'exit', handler: ExitHandler<this>): void |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Options for a poolifier pool. |
| 71 | */ |
| 72 | export interface PoolOptions<Worker> { |
| 73 | /** |
| 74 | * A function that will listen for error event on each worker. |
| 75 | */ |
| 76 | errorHandler?: ErrorHandler<Worker> |
| 77 | /** |
| 78 | * A function that will listen for online event on each worker. |
| 79 | */ |
| 80 | onlineHandler?: OnlineHandler<Worker> |
| 81 | /** |
| 82 | * A function that will listen for exit event on each worker. |
| 83 | */ |
| 84 | exitHandler?: ExitHandler<Worker> |
| 85 | /** |
| 86 | * The work choice strategy to use in this pool. |
| 87 | */ |
| 88 | workerChoiceStrategy?: WorkerChoiceStrategy |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * Base class containing some shared logic for all poolifier pools. |
| 93 | * |
| 94 | * @template Worker Type of worker which manages this pool. |
| 95 | * @template Data Type of data sent to the worker. This can only be serializable data. |
| 96 | * @template Response Type of response of execution. This can only be serializable data. |
| 97 | */ |
| 98 | export abstract class AbstractPool< |
| 99 | Worker extends IWorker, |
| 100 | Data = unknown, |
| 101 | Response = unknown |
| 102 | > implements IPoolInternal<Worker, Data, Response> { |
| 103 | /** |
| 104 | * The promise map. |
| 105 | * |
| 106 | * - `key`: This is the message ID of each submitted task. |
| 107 | * - `value`: An object that contains the worker, the resolve function and the reject function. |
| 108 | * |
| 109 | * When we receive a message from the worker we get a map entry and resolve/reject the promise based on the message. |
| 110 | */ |
| 111 | protected promiseMap: Map< |
| 112 | number, |
| 113 | PromiseWorkerResponseWrapper<Worker, Response> |
| 114 | > = new Map<number, PromiseWorkerResponseWrapper<Worker, Response>>() |
| 115 | |
| 116 | /** @inheritdoc */ |
| 117 | public readonly workers: Worker[] = [] |
| 118 | |
| 119 | /** @inheritdoc */ |
| 120 | public readonly tasks: Map<Worker, number> = new Map<Worker, number>() |
| 121 | |
| 122 | /** @inheritdoc */ |
| 123 | public readonly emitter: PoolEmitter |
| 124 | |
| 125 | /** |
| 126 | * ID of the next message. |
| 127 | */ |
| 128 | protected nextMessageId: number = 0 |
| 129 | |
| 130 | /** |
| 131 | * Worker choice strategy instance implementing the worker choice algorithm. |
| 132 | * |
| 133 | * Default to a strategy implementing a round robin algorithm. |
| 134 | */ |
| 135 | protected workerChoiceStrategyContext: WorkerChoiceStrategyContext< |
| 136 | Worker, |
| 137 | Data, |
| 138 | Response |
| 139 | > |
| 140 | |
| 141 | /** |
| 142 | * Constructs a new poolifier pool. |
| 143 | * |
| 144 | * @param numberOfWorkers Number of workers that this pool should manage. |
| 145 | * @param filePath Path to the worker-file. |
| 146 | * @param opts Options for the pool. |
| 147 | */ |
| 148 | public constructor ( |
| 149 | public readonly numberOfWorkers: number, |
| 150 | public readonly filePath: string, |
| 151 | public readonly opts: PoolOptions<Worker> |
| 152 | ) { |
| 153 | if (!this.isMain()) { |
| 154 | throw new Error('Cannot start a pool from a worker!') |
| 155 | } |
| 156 | this.checkNumberOfWorkers(this.numberOfWorkers) |
| 157 | this.checkFilePath(this.filePath) |
| 158 | this.setupHook() |
| 159 | |
| 160 | for (let i = 1; i <= this.numberOfWorkers; i++) { |
| 161 | this.createAndSetupWorker() |
| 162 | } |
| 163 | |
| 164 | this.emitter = new PoolEmitter() |
| 165 | this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext( |
| 166 | this, |
| 167 | opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN |
| 168 | ) |
| 169 | } |
| 170 | |
| 171 | private checkFilePath (filePath: string): void { |
| 172 | if (!filePath) { |
| 173 | throw new Error('Please specify a file with a worker implementation') |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | private checkNumberOfWorkers (numberOfWorkers: number): void { |
| 178 | if (numberOfWorkers == null) { |
| 179 | throw new Error( |
| 180 | 'Cannot instantiate a pool without specifying the number of workers' |
| 181 | ) |
| 182 | } else if (!Number.isSafeInteger(numberOfWorkers)) { |
| 183 | throw new Error( |
| 184 | 'Cannot instantiate a pool with a non integer number of workers' |
| 185 | ) |
| 186 | } else if (numberOfWorkers < 0) { |
| 187 | throw new Error( |
| 188 | 'Cannot instantiate a pool with a negative number of workers' |
| 189 | ) |
| 190 | } else if (!this.isDynamic() && numberOfWorkers === 0) { |
| 191 | throw new Error('Cannot instantiate a fixed pool with no worker') |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | /** @inheritdoc */ |
| 196 | public isDynamic (): boolean { |
| 197 | return false |
| 198 | } |
| 199 | |
| 200 | /** @inheritdoc */ |
| 201 | public setWorkerChoiceStrategy ( |
| 202 | workerChoiceStrategy: WorkerChoiceStrategy |
| 203 | ): void { |
| 204 | this.opts.workerChoiceStrategy = workerChoiceStrategy |
| 205 | this.workerChoiceStrategyContext.setWorkerChoiceStrategy( |
| 206 | workerChoiceStrategy |
| 207 | ) |
| 208 | } |
| 209 | |
| 210 | /** @inheritdoc */ |
| 211 | public execute (data: Data): Promise<Response> { |
| 212 | // Configure worker to handle message with the specified task |
| 213 | const worker = this.chooseWorker() |
| 214 | this.increaseWorkersTask(worker) |
| 215 | const messageId = ++this.nextMessageId |
| 216 | const res = this.internalExecute(worker, messageId) |
| 217 | this.sendToWorker(worker, { data: data || ({} as Data), id: messageId }) |
| 218 | return res |
| 219 | } |
| 220 | |
| 221 | /** @inheritdoc */ |
| 222 | public async destroy (): Promise<void> { |
| 223 | await Promise.all(this.workers.map(worker => this.destroyWorker(worker))) |
| 224 | } |
| 225 | |
| 226 | /** @inheritdoc */ |
| 227 | public abstract destroyWorker (worker: Worker): void | Promise<void> |
| 228 | |
| 229 | /** |
| 230 | * Setup hook that can be overridden by a Poolifier pool implementation |
| 231 | * to run code before workers are created in the abstract constructor. |
| 232 | */ |
| 233 | protected setupHook (): void { |
| 234 | // Can be overridden |
| 235 | } |
| 236 | |
| 237 | /** |
| 238 | * Should return whether the worker is the main worker or not. |
| 239 | */ |
| 240 | protected abstract isMain (): boolean |
| 241 | |
| 242 | /** |
| 243 | * Increase the number of tasks that the given workers has done. |
| 244 | * |
| 245 | * @param worker Worker whose tasks are increased. |
| 246 | */ |
| 247 | protected increaseWorkersTask (worker: Worker): void { |
| 248 | this.stepWorkerNumberOfTasks(worker, 1) |
| 249 | } |
| 250 | |
| 251 | /** |
| 252 | * Decrease the number of tasks that the given workers has done. |
| 253 | * |
| 254 | * @param worker Worker whose tasks are decreased. |
| 255 | */ |
| 256 | protected decreaseWorkersTasks (worker: Worker): void { |
| 257 | this.stepWorkerNumberOfTasks(worker, -1) |
| 258 | } |
| 259 | |
| 260 | /** |
| 261 | * Step the number of tasks that the given workers has done. |
| 262 | * |
| 263 | * @param worker Worker whose tasks are set. |
| 264 | * @param step Worker number of tasks step. |
| 265 | */ |
| 266 | private stepWorkerNumberOfTasks (worker: Worker, step: number): void { |
| 267 | const numberOfTasksInProgress = this.tasks.get(worker) |
| 268 | if (numberOfTasksInProgress !== undefined) { |
| 269 | this.tasks.set(worker, numberOfTasksInProgress + step) |
| 270 | } else { |
| 271 | throw Error('Worker could not be found in tasks map') |
| 272 | } |
| 273 | } |
| 274 | |
| 275 | /** |
| 276 | * Removes the given worker from the pool. |
| 277 | * |
| 278 | * @param worker Worker that will be removed. |
| 279 | */ |
| 280 | protected removeWorker (worker: Worker): void { |
| 281 | // Clean worker from data structure |
| 282 | const workerIndex = this.workers.indexOf(worker) |
| 283 | this.workers.splice(workerIndex, 1) |
| 284 | this.tasks.delete(worker) |
| 285 | } |
| 286 | |
| 287 | /** |
| 288 | * Choose a worker for the next task. |
| 289 | * |
| 290 | * The default implementation uses a round robin algorithm to distribute the load. |
| 291 | * |
| 292 | * @returns Worker. |
| 293 | */ |
| 294 | protected chooseWorker (): Worker { |
| 295 | return this.workerChoiceStrategyContext.execute() |
| 296 | } |
| 297 | |
| 298 | /** |
| 299 | * Send a message to the given worker. |
| 300 | * |
| 301 | * @param worker The worker which should receive the message. |
| 302 | * @param message The message. |
| 303 | */ |
| 304 | protected abstract sendToWorker ( |
| 305 | worker: Worker, |
| 306 | message: MessageValue<Data> |
| 307 | ): void |
| 308 | |
| 309 | /** @inheritdoc */ |
| 310 | public abstract registerWorkerMessageListener< |
| 311 | Message extends Data | Response |
| 312 | > (worker: Worker, listener: (message: MessageValue<Message>) => void): void |
| 313 | |
| 314 | protected internalExecute ( |
| 315 | worker: Worker, |
| 316 | messageId: number |
| 317 | ): Promise<Response> { |
| 318 | return new Promise<Response>((resolve, reject) => { |
| 319 | this.promiseMap.set(messageId, { resolve, reject, worker }) |
| 320 | }) |
| 321 | } |
| 322 | |
| 323 | /** |
| 324 | * Returns a newly created worker. |
| 325 | */ |
| 326 | protected abstract createWorker (): Worker |
| 327 | |
| 328 | /** |
| 329 | * Function that can be hooked up when a worker has been newly created and moved to the workers registry. |
| 330 | * |
| 331 | * Can be used to update the `maxListeners` or binding the `main-worker`<->`worker` connection if not bind by default. |
| 332 | * |
| 333 | * @param worker The newly created worker. |
| 334 | */ |
| 335 | protected abstract afterWorkerSetup (worker: Worker): void |
| 336 | |
| 337 | /** @inheritdoc */ |
| 338 | public createAndSetupWorker (): Worker { |
| 339 | const worker: Worker = this.createWorker() |
| 340 | |
| 341 | worker.on('error', this.opts.errorHandler ?? EMPTY_FUNCTION) |
| 342 | worker.on('online', this.opts.onlineHandler ?? EMPTY_FUNCTION) |
| 343 | worker.on('exit', this.opts.exitHandler ?? EMPTY_FUNCTION) |
| 344 | worker.once('exit', () => this.removeWorker(worker)) |
| 345 | |
| 346 | this.workers.push(worker) |
| 347 | |
| 348 | // Init tasks map |
| 349 | this.tasks.set(worker, 0) |
| 350 | |
| 351 | this.afterWorkerSetup(worker) |
| 352 | |
| 353 | return worker |
| 354 | } |
| 355 | |
| 356 | /** |
| 357 | * This function is the listener registered for each worker. |
| 358 | * |
| 359 | * @returns The listener function to execute when a message is sent from a worker. |
| 360 | */ |
| 361 | protected workerListener (): (message: MessageValue<Response>) => void { |
| 362 | const listener: (message: MessageValue<Response>) => void = message => { |
| 363 | if (message.id) { |
| 364 | const value = this.promiseMap.get(message.id) |
| 365 | if (value) { |
| 366 | this.decreaseWorkersTasks(value.worker) |
| 367 | if (message.error) value.reject(message.error) |
| 368 | else value.resolve(message.data as Response) |
| 369 | this.promiseMap.delete(message.id) |
| 370 | } |
| 371 | } |
| 372 | } |
| 373 | return listener |
| 374 | } |
| 375 | } |