| 1 | import { |
| 2 | DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS, |
| 3 | DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS |
| 4 | } from '../../utils' |
| 5 | import type { IPool } from '../pool' |
| 6 | import type { IWorker } from '../worker' |
| 7 | import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy' |
| 8 | import { |
| 9 | type IWorkerChoiceStrategy, |
| 10 | Measurements, |
| 11 | type TaskStatisticsRequirements, |
| 12 | type WorkerChoiceStrategyOptions |
| 13 | } from './selection-strategies-types' |
| 14 | |
| 15 | /** |
| 16 | * Selects the next worker with a fair share scheduling algorithm. |
| 17 | * Loosely modeled after the fair queueing algorithm: https://en.wikipedia.org/wiki/Fair_queuing. |
| 18 | * |
| 19 | * @typeParam Worker - Type of worker which manages the strategy. |
| 20 | * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data. |
| 21 | * @typeParam Response - Type of execution response. This can only be structured-cloneable data. |
| 22 | */ |
| 23 | export class FairShareWorkerChoiceStrategy< |
| 24 | Worker extends IWorker, |
| 25 | Data = unknown, |
| 26 | Response = unknown |
| 27 | > |
| 28 | extends AbstractWorkerChoiceStrategy<Worker, Data, Response> |
| 29 | implements IWorkerChoiceStrategy { |
| 30 | /** @inheritDoc */ |
| 31 | public readonly taskStatisticsRequirements: TaskStatisticsRequirements = { |
| 32 | runTime: { |
| 33 | aggregate: true, |
| 34 | average: true, |
| 35 | median: false |
| 36 | }, |
| 37 | waitTime: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS, |
| 38 | elu: { |
| 39 | aggregate: true, |
| 40 | average: true, |
| 41 | median: false |
| 42 | } |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Workers' virtual task end execution timestamp. |
| 47 | */ |
| 48 | private workersVirtualTaskEndTimestamp: number[] = [] |
| 49 | |
| 50 | /** @inheritDoc */ |
| 51 | public constructor ( |
| 52 | pool: IPool<Worker, Data, Response>, |
| 53 | opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS |
| 54 | ) { |
| 55 | super(pool, opts) |
| 56 | this.setTaskStatisticsRequirements(this.opts) |
| 57 | } |
| 58 | |
| 59 | /** @inheritDoc */ |
| 60 | public reset (): boolean { |
| 61 | this.workersVirtualTaskEndTimestamp = [] |
| 62 | return true |
| 63 | } |
| 64 | |
| 65 | /** @inheritDoc */ |
| 66 | public update (workerNodeKey: number): boolean { |
| 67 | this.computeWorkerVirtualTaskEndTimestamp(workerNodeKey) |
| 68 | return true |
| 69 | } |
| 70 | |
| 71 | /** @inheritDoc */ |
| 72 | public choose (): number | undefined { |
| 73 | this.nextWorkerNodeKey = this.fairShareNextWorkerNodeKey() |
| 74 | return this.nextWorkerNodeKey |
| 75 | } |
| 76 | |
| 77 | /** @inheritDoc */ |
| 78 | public remove (workerNodeKey: number): boolean { |
| 79 | this.workersVirtualTaskEndTimestamp.splice(workerNodeKey, 1) |
| 80 | return true |
| 81 | } |
| 82 | |
| 83 | private fairShareNextWorkerNodeKey (): number | undefined { |
| 84 | let minWorkerVirtualTaskEndTimestamp = Infinity |
| 85 | let chosenWorkerNodeKey: number | undefined |
| 86 | for (const [workerNodeKey] of this.pool.workerNodes.entries()) { |
| 87 | if (this.workersVirtualTaskEndTimestamp[workerNodeKey] == null) { |
| 88 | this.computeWorkerVirtualTaskEndTimestamp(workerNodeKey) |
| 89 | } |
| 90 | const workerVirtualTaskEndTimestamp = |
| 91 | this.workersVirtualTaskEndTimestamp[workerNodeKey] |
| 92 | if ( |
| 93 | this.isWorkerNodeEligible(workerNodeKey) && |
| 94 | workerVirtualTaskEndTimestamp < minWorkerVirtualTaskEndTimestamp |
| 95 | ) { |
| 96 | minWorkerVirtualTaskEndTimestamp = workerVirtualTaskEndTimestamp |
| 97 | chosenWorkerNodeKey = workerNodeKey |
| 98 | } |
| 99 | } |
| 100 | return chosenWorkerNodeKey |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * Computes the worker node key virtual task end timestamp. |
| 105 | * |
| 106 | * @param workerNodeKey - The worker node key. |
| 107 | */ |
| 108 | private computeWorkerVirtualTaskEndTimestamp (workerNodeKey: number): void { |
| 109 | this.workersVirtualTaskEndTimestamp[workerNodeKey] = |
| 110 | this.getWorkerVirtualTaskEndTimestamp( |
| 111 | workerNodeKey, |
| 112 | this.getWorkerVirtualTaskStartTimestamp(workerNodeKey) |
| 113 | ) |
| 114 | } |
| 115 | |
| 116 | private getWorkerVirtualTaskEndTimestamp ( |
| 117 | workerNodeKey: number, |
| 118 | workerVirtualTaskStartTimestamp: number |
| 119 | ): number { |
| 120 | const workerTaskRunTime = |
| 121 | this.opts.measurement === Measurements.elu |
| 122 | ? this.getWorkerTaskElu(workerNodeKey) |
| 123 | : this.getWorkerTaskRunTime(workerNodeKey) |
| 124 | return workerVirtualTaskStartTimestamp + workerTaskRunTime |
| 125 | } |
| 126 | |
| 127 | private getWorkerVirtualTaskStartTimestamp (workerNodeKey: number): number { |
| 128 | return Math.max( |
| 129 | performance.now(), |
| 130 | this.workersVirtualTaskEndTimestamp[workerNodeKey] ?? -Infinity |
| 131 | ) |
| 132 | } |
| 133 | } |