+import { cpus } from 'node:os'
+
+import type { IPool } from '../pool.js'
+import type { IWorker } from '../worker.js'
+import { FairShareWorkerChoiceStrategy } from './fair-share-worker-choice-strategy.js'
+import { InterleavedWeightedRoundRobinWorkerChoiceStrategy } from './interleaved-weighted-round-robin-worker-choice-strategy.js'
+import { LeastBusyWorkerChoiceStrategy } from './least-busy-worker-choice-strategy.js'
+import { LeastEluWorkerChoiceStrategy } from './least-elu-worker-choice-strategy.js'
+import { LeastUsedWorkerChoiceStrategy } from './least-used-worker-choice-strategy.js'
+import { RoundRobinWorkerChoiceStrategy } from './round-robin-worker-choice-strategy.js'
+import {
+ type IWorkerChoiceStrategy,
+ type MeasurementStatisticsRequirements,
+ type StrategyPolicy,
+ type TaskStatisticsRequirements,
+ WorkerChoiceStrategies,
+ type WorkerChoiceStrategy,
+ type WorkerChoiceStrategyOptions
+} from './selection-strategies-types.js'
+import { WeightedRoundRobinWorkerChoiceStrategy } from './weighted-round-robin-worker-choice-strategy.js'
+import type { WorkerChoiceStrategiesContext } from './worker-choice-strategies-context.js'
+
+const estimatedCpuSpeed = (): number => {
+ const runs = 150000000
+ const begin = performance.now()
+ // eslint-disable-next-line no-empty
+ for (let i = runs; i > 0; i--) {}
+ const end = performance.now()
+ const duration = end - begin
+ return Math.trunc(runs / duration / 1000) // in MHz
+}
+
+const getDefaultWorkerWeight = (): number => {
+ const currentCpus = cpus()
+ let estCpuSpeed: number | undefined
+ // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+ if (currentCpus.every(cpu => cpu.speed == null || cpu.speed === 0)) {
+ estCpuSpeed = estimatedCpuSpeed()
+ }
+ let cpusCycleTimeWeight = 0
+ for (const cpu of currentCpus) {
+ // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+ if (cpu.speed == null || cpu.speed === 0) {
+ cpu.speed =
+ // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+ currentCpus.find(cpu => cpu.speed != null && cpu.speed !== 0)?.speed ??
+ estCpuSpeed ??
+ 2000
+ }
+ // CPU estimated cycle time
+ const numberOfDigits = cpu.speed.toString().length - 1
+ const cpuCycleTime = 1 / (cpu.speed / Math.pow(10, numberOfDigits))
+ cpusCycleTimeWeight += cpuCycleTime * Math.pow(10, numberOfDigits)
+ }
+ return Math.round(cpusCycleTimeWeight / currentCpus.length)
+}
+
+const getDefaultWeights = (
+ poolMaxSize: number,
+ defaultWorkerWeight?: number
+): Record<number, number> => {
+ defaultWorkerWeight = defaultWorkerWeight ?? getDefaultWorkerWeight()
+ const weights: Record<number, number> = {}
+ for (let workerNodeKey = 0; workerNodeKey < poolMaxSize; workerNodeKey++) {
+ weights[workerNodeKey] = defaultWorkerWeight
+ }
+ return weights
+}
+
+export const getWorkerChoiceStrategiesRetries = <
+ Worker extends IWorker,
+ Data,
+ Response
+>(
+ pool: IPool<Worker, Data, Response>,
+ opts?: WorkerChoiceStrategyOptions
+ ): number => {
+ return (
+ pool.info.maxSize +
+ Object.keys(opts?.weights ?? getDefaultWeights(pool.info.maxSize)).length
+ )
+}
+
+export const buildWorkerChoiceStrategyOptions = <
+ Worker extends IWorker,
+ Data,
+ Response
+>(
+ pool: IPool<Worker, Data, Response>,
+ opts?: WorkerChoiceStrategyOptions
+ ): WorkerChoiceStrategyOptions => {
+ opts = structuredClone(opts ?? {})
+ opts.weights = opts.weights ?? getDefaultWeights(pool.info.maxSize)
+ return {
+ ...{
+ runTime: { median: false },
+ waitTime: { median: false },
+ elu: { median: false }
+ },
+ ...opts
+ }
+}
+
+export const toggleMedianMeasurementStatisticsRequirements = (
+ measurementStatisticsRequirements: MeasurementStatisticsRequirements,
+ toggleMedian: boolean
+): void => {
+ if (measurementStatisticsRequirements.average && toggleMedian) {
+ measurementStatisticsRequirements.average = false
+ measurementStatisticsRequirements.median = toggleMedian
+ }
+ if (measurementStatisticsRequirements.median && !toggleMedian) {
+ measurementStatisticsRequirements.average = true
+ measurementStatisticsRequirements.median = toggleMedian
+ }
+}
+
+export const buildWorkerChoiceStrategiesPolicy = (
+ workerChoiceStrategies: Map<WorkerChoiceStrategy, IWorkerChoiceStrategy>
+): StrategyPolicy => {
+ const policies: StrategyPolicy[] = Array.from(
+ workerChoiceStrategies,
+ ([_, workerChoiceStrategy]) => workerChoiceStrategy.strategyPolicy
+ )
+ return {
+ dynamicWorkerUsage: policies.some(p => p.dynamicWorkerUsage),
+ dynamicWorkerReady: policies.some(p => p.dynamicWorkerReady)
+ }
+}
+
+export const buildWorkerChoiceStrategiesTaskStatisticsRequirements = (
+ workerChoiceStrategies: Map<WorkerChoiceStrategy, IWorkerChoiceStrategy>
+): TaskStatisticsRequirements => {
+ const taskStatisticsRequirements: TaskStatisticsRequirements[] = Array.from(
+ workerChoiceStrategies,
+ ([_, workerChoiceStrategy]) =>
+ workerChoiceStrategy.taskStatisticsRequirements
+ )
+ return {
+ runTime: {
+ aggregate: taskStatisticsRequirements.some(r => r.runTime.aggregate),
+ average: taskStatisticsRequirements.some(r => r.runTime.average),
+ median: taskStatisticsRequirements.some(r => r.runTime.median)
+ },
+ waitTime: {
+ aggregate: taskStatisticsRequirements.some(r => r.waitTime.aggregate),
+ average: taskStatisticsRequirements.some(r => r.waitTime.average),
+ median: taskStatisticsRequirements.some(r => r.waitTime.median)
+ },
+ elu: {
+ aggregate: taskStatisticsRequirements.some(r => r.elu.aggregate),
+ average: taskStatisticsRequirements.some(r => r.elu.average),
+ median: taskStatisticsRequirements.some(r => r.elu.median)
+ }
+ }
+}
+
+export const getWorkerChoiceStrategy = <Worker extends IWorker, Data, Response>(
+ workerChoiceStrategy: WorkerChoiceStrategy,
+ pool: IPool<Worker, Data, Response>,
+ context: ThisType<WorkerChoiceStrategiesContext<Worker, Data, Response>>,
+ opts?: WorkerChoiceStrategyOptions
+): IWorkerChoiceStrategy => {