| 1 | import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils' |
| 2 | import type { IPool } from '../pool' |
| 3 | import type { IWorker } from '../worker' |
| 4 | import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy' |
| 5 | import type { |
| 6 | IWorkerChoiceStrategy, |
| 7 | RequiredStatistics, |
| 8 | WorkerChoiceStrategyOptions |
| 9 | } from './selection-strategies-types' |
| 10 | |
| 11 | /** |
| 12 | * Selects the next worker with a fair share scheduling algorithm. |
| 13 | * Loosely modeled after the fair queueing algorithm: https://en.wikipedia.org/wiki/Fair_queuing. |
| 14 | * |
| 15 | * @typeParam Worker - Type of worker which manages the strategy. |
| 16 | * @typeParam Data - Type of data sent to the worker. This can only be serializable data. |
| 17 | * @typeParam Response - Type of execution response. This can only be serializable data. |
| 18 | */ |
| 19 | export class FairShareWorkerChoiceStrategy< |
| 20 | Worker extends IWorker, |
| 21 | Data = unknown, |
| 22 | Response = unknown |
| 23 | > |
| 24 | extends AbstractWorkerChoiceStrategy<Worker, Data, Response> |
| 25 | implements IWorkerChoiceStrategy { |
| 26 | /** @inheritDoc */ |
| 27 | public readonly requiredStatistics: RequiredStatistics = { |
| 28 | runTime: true, |
| 29 | avgRunTime: true, |
| 30 | medRunTime: false, |
| 31 | waitTime: false, |
| 32 | avgWaitTime: false, |
| 33 | medWaitTime: false |
| 34 | } |
| 35 | |
| 36 | /** |
| 37 | * Workers' virtual task end execution timestamp. |
| 38 | */ |
| 39 | private workersVirtualTaskEndTimestamp: number[] = [] |
| 40 | |
| 41 | /** @inheritDoc */ |
| 42 | public constructor ( |
| 43 | pool: IPool<Worker, Data, Response>, |
| 44 | opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS |
| 45 | ) { |
| 46 | super(pool, opts) |
| 47 | this.setRequiredStatistics(this.opts) |
| 48 | } |
| 49 | |
| 50 | /** @inheritDoc */ |
| 51 | public reset (): boolean { |
| 52 | this.workersVirtualTaskEndTimestamp = [] |
| 53 | return true |
| 54 | } |
| 55 | |
| 56 | /** @inheritDoc */ |
| 57 | public update (workerNodeKey: number): boolean { |
| 58 | this.computeWorkerVirtualTaskEndTimestamp(workerNodeKey) |
| 59 | return true |
| 60 | } |
| 61 | |
| 62 | /** @inheritDoc */ |
| 63 | public choose (): number { |
| 64 | let minWorkerVirtualTaskEndTimestamp = Infinity |
| 65 | let chosenWorkerNodeKey!: number |
| 66 | for (const [workerNodeKey] of this.pool.workerNodes.entries()) { |
| 67 | if (this.workersVirtualTaskEndTimestamp[workerNodeKey] == null) { |
| 68 | this.computeWorkerVirtualTaskEndTimestamp(workerNodeKey) |
| 69 | } |
| 70 | const workerVirtualTaskEndTimestamp = |
| 71 | this.workersVirtualTaskEndTimestamp[workerNodeKey] |
| 72 | if (workerVirtualTaskEndTimestamp < minWorkerVirtualTaskEndTimestamp) { |
| 73 | minWorkerVirtualTaskEndTimestamp = workerVirtualTaskEndTimestamp |
| 74 | chosenWorkerNodeKey = workerNodeKey |
| 75 | } |
| 76 | } |
| 77 | return chosenWorkerNodeKey |
| 78 | } |
| 79 | |
| 80 | /** @inheritDoc */ |
| 81 | public remove (workerNodeKey: number): boolean { |
| 82 | this.workersVirtualTaskEndTimestamp.splice(workerNodeKey, 1) |
| 83 | return true |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Computes the worker node key virtual task end timestamp. |
| 88 | * |
| 89 | * @param workerNodeKey - The worker node key. |
| 90 | */ |
| 91 | private computeWorkerVirtualTaskEndTimestamp (workerNodeKey: number): void { |
| 92 | this.workersVirtualTaskEndTimestamp[workerNodeKey] = |
| 93 | this.getWorkerVirtualTaskEndTimestamp( |
| 94 | workerNodeKey, |
| 95 | this.getWorkerVirtualTaskStartTimestamp(workerNodeKey) |
| 96 | ) |
| 97 | } |
| 98 | |
| 99 | private getWorkerVirtualTaskEndTimestamp ( |
| 100 | workerNodeKey: number, |
| 101 | workerVirtualTaskStartTimestamp: number |
| 102 | ): number { |
| 103 | return ( |
| 104 | workerVirtualTaskStartTimestamp + this.getWorkerTaskRunTime(workerNodeKey) |
| 105 | ) |
| 106 | } |
| 107 | |
| 108 | private getWorkerVirtualTaskStartTimestamp (workerNodeKey: number): number { |
| 109 | return Math.max( |
| 110 | performance.now(), |
| 111 | this.workersVirtualTaskEndTimestamp[workerNodeKey] ?? -Infinity |
| 112 | ) |
| 113 | } |
| 114 | } |