| 1 | import type { IPoolWorker } from '../pool-worker' |
| 2 | import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy' |
| 3 | import type { RequiredStatistics } from './selection-strategies-types' |
| 4 | |
| 5 | /** |
| 6 | * Worker virtual task timestamp. |
| 7 | */ |
| 8 | interface WorkerVirtualTaskTimestamp { |
| 9 | start: number |
| 10 | end: number |
| 11 | } |
| 12 | |
| 13 | /** |
| 14 | * Selects the next worker with a fair share scheduling algorithm. |
| 15 | * Loosely modeled after the fair queueing algorithm: https://en.wikipedia.org/wiki/Fair_queuing. |
| 16 | * |
| 17 | * @typeParam Worker - Type of worker which manages the strategy. |
| 18 | * @typeParam Data - Type of data sent to the worker. This can only be serializable data. |
| 19 | * @typeParam Response - Type of response of execution. This can only be serializable data. |
| 20 | */ |
| 21 | export class FairShareWorkerChoiceStrategy< |
| 22 | Worker extends IPoolWorker, |
| 23 | Data, |
| 24 | Response |
| 25 | > extends AbstractWorkerChoiceStrategy<Worker, Data, Response> { |
| 26 | /** {@inheritDoc} */ |
| 27 | public readonly requiredStatistics: RequiredStatistics = { |
| 28 | runTime: true |
| 29 | } |
| 30 | |
| 31 | /** |
| 32 | * Worker last virtual task execution timestamp. |
| 33 | */ |
| 34 | private readonly workerLastVirtualTaskTimestamp: Map< |
| 35 | Worker, |
| 36 | WorkerVirtualTaskTimestamp |
| 37 | > = new Map<Worker, WorkerVirtualTaskTimestamp>() |
| 38 | |
| 39 | /** {@inheritDoc} */ |
| 40 | public reset (): boolean { |
| 41 | this.workerLastVirtualTaskTimestamp.clear() |
| 42 | return true |
| 43 | } |
| 44 | |
| 45 | /** {@inheritDoc} */ |
| 46 | public choose (): Worker { |
| 47 | let minWorkerVirtualTaskEndTimestamp = Infinity |
| 48 | let chosenWorker!: Worker |
| 49 | for (const worker of this.pool.workers) { |
| 50 | this.computeWorkerLastVirtualTaskTimestamp(worker) |
| 51 | const workerLastVirtualTaskEndTimestamp = |
| 52 | this.workerLastVirtualTaskTimestamp.get(worker)?.end ?? 0 |
| 53 | if ( |
| 54 | workerLastVirtualTaskEndTimestamp < minWorkerVirtualTaskEndTimestamp |
| 55 | ) { |
| 56 | minWorkerVirtualTaskEndTimestamp = workerLastVirtualTaskEndTimestamp |
| 57 | chosenWorker = worker |
| 58 | } |
| 59 | } |
| 60 | return chosenWorker |
| 61 | } |
| 62 | |
| 63 | /** |
| 64 | * Computes worker last virtual task timestamp. |
| 65 | * |
| 66 | * @param worker - The worker. |
| 67 | */ |
| 68 | private computeWorkerLastVirtualTaskTimestamp (worker: Worker): void { |
| 69 | const workerVirtualTaskStartTimestamp = Math.max( |
| 70 | Date.now(), |
| 71 | this.workerLastVirtualTaskTimestamp.get(worker)?.end ?? -Infinity |
| 72 | ) |
| 73 | this.workerLastVirtualTaskTimestamp.set(worker, { |
| 74 | start: workerVirtualTaskStartTimestamp, |
| 75 | end: |
| 76 | workerVirtualTaskStartTimestamp + |
| 77 | (this.pool.getWorkerAverageTasksRunTime(worker) ?? 0) |
| 78 | }) |
| 79 | } |
| 80 | } |