feat: add per task function strategy support

[poolifier.git] / src / pools / selection-strategies / abstract-worker-choice-strategy.ts

import type { IPool } from '../pool.js'
import { DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS } from '../utils.js'
import type { IWorker } from '../worker.js'
import type {
  IWorkerChoiceStrategy,
  MeasurementStatisticsRequirements,
  StrategyPolicy,
  TaskStatisticsRequirements,
  WorkerChoiceStrategyOptions
} from './selection-strategies-types.js'
import { buildWorkerChoiceStrategyOptions } from './selection-strategies-utils.js'

/**
 * Worker choice strategy abstract base class.
 *
 * @typeParam Worker - Type of worker which manages the strategy.
 * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
 * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
 */
export abstract class AbstractWorkerChoiceStrategy<
  Worker extends IWorker,
  Data = unknown,
  Response = unknown
> implements IWorkerChoiceStrategy {
  /**
   * The next worker node key.
   */
  protected nextWorkerNodeKey: number | undefined = 0

  /**
   * The previous worker node key.
   */
  protected previousWorkerNodeKey = 0

  /** @inheritDoc */
  public readonly strategyPolicy: StrategyPolicy = {
    dynamicWorkerUsage: false,
    dynamicWorkerReady: true
  }

  /** @inheritDoc */
  public readonly taskStatisticsRequirements: TaskStatisticsRequirements = {
    runTime: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS,
    waitTime: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS,
    elu: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS
  }

  /**
   * Constructs a worker choice strategy bound to the pool.
   *
   * @param pool - The pool instance.
   * @param opts - The worker choice strategy options.
   */
  public constructor (
    protected readonly pool: IPool<Worker, Data, Response>,
    protected opts?: WorkerChoiceStrategyOptions
  ) {
    this.choose = this.choose.bind(this)
    this.setOptions(this.opts)
  }

  protected setTaskStatisticsRequirements (
    opts: WorkerChoiceStrategyOptions | undefined
  ): void {
    this.toggleMedianMeasurementStatisticsRequirements(
      this.taskStatisticsRequirements.runTime,
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      opts!.runTime!.median
    )
    this.toggleMedianMeasurementStatisticsRequirements(
      this.taskStatisticsRequirements.waitTime,
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      opts!.waitTime!.median
    )
    this.toggleMedianMeasurementStatisticsRequirements(
      this.taskStatisticsRequirements.elu,
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      opts!.elu!.median
    )
  }

  private 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
    }
  }

  protected resetWorkerNodeKeyProperties (): void {
    this.nextWorkerNodeKey = 0
    this.previousWorkerNodeKey = 0
  }

  /** @inheritDoc */
  public abstract reset (): boolean

  /** @inheritDoc */
  public abstract update (workerNodeKey: number): boolean

  /** @inheritDoc */
  public abstract choose (): number | undefined

  /** @inheritDoc */
  public abstract remove (workerNodeKey: number): boolean

  /** @inheritDoc */
  public setOptions (opts: WorkerChoiceStrategyOptions | undefined): void {
    this.opts = buildWorkerChoiceStrategyOptions<Worker, Data, Response>(
      this.pool,
      opts
    )
    this.setTaskStatisticsRequirements(this.opts)
  }

  /**
   * Whether the worker node is ready or not.
   *
   * @param workerNodeKey - The worker node key.
   * @returns Whether the worker node is ready or not.
   */
  protected isWorkerNodeReady (workerNodeKey: number): boolean {
    return this.pool.workerNodes[workerNodeKey]?.info?.ready ?? false
  }

  /**
   * Check the next worker node key.
   */
  protected checkNextWorkerNodeKey (): void {
    if (
      this.nextWorkerNodeKey != null &&
      (this.nextWorkerNodeKey < 0 ||
        !this.isWorkerNodeReady(this.nextWorkerNodeKey))
    ) {
      delete this.nextWorkerNodeKey
    }
  }

  /**
   * Gets the worker node task runtime.
   * If the task statistics require the average runtime, the average runtime is returned.
   * If the task statistics require the median runtime , the median runtime is returned.
   *
   * @param workerNodeKey - The worker node key.
   * @returns The worker node task runtime.
   */
  protected getWorkerNodeTaskRunTime (workerNodeKey: number): number {
    return this.taskStatisticsRequirements.runTime.median
      ? this.pool.workerNodes[workerNodeKey].usage.runTime.median ?? 0
      : this.pool.workerNodes[workerNodeKey].usage.runTime.average ?? 0
  }

  /**
   * Gets the worker node task wait time.
   * If the task statistics require the average wait time, the average wait time is returned.
   * If the task statistics require the median wait time, the median wait time is returned.
   *
   * @param workerNodeKey - The worker node key.
   * @returns The worker node task wait time.
   */
  protected getWorkerNodeTaskWaitTime (workerNodeKey: number): number {
    return this.taskStatisticsRequirements.waitTime.median
      ? this.pool.workerNodes[workerNodeKey].usage.waitTime.median ?? 0
      : this.pool.workerNodes[workerNodeKey].usage.waitTime.average ?? 0
  }

  /**
   * Gets the worker node task ELU.
   * If the task statistics require the average ELU, the average ELU is returned.
   * If the task statistics require the median ELU, the median ELU is returned.
   *
   * @param workerNodeKey - The worker node key.
   * @returns The worker node task ELU.
   */
  protected getWorkerNodeTaskElu (workerNodeKey: number): number {
    return this.taskStatisticsRequirements.elu.median
      ? this.pool.workerNodes[workerNodeKey].usage.elu.active.median ?? 0
      : this.pool.workerNodes[workerNodeKey].usage.elu.active.average ?? 0
  }

  /**
   * Sets safely the previous worker node key.
   *
   * @param workerNodeKey - The worker node key.
   */
  protected setPreviousWorkerNodeKey (workerNodeKey: number | undefined): void {
    this.previousWorkerNodeKey =
      workerNodeKey != null && workerNodeKey >= 0
        ? workerNodeKey
        : this.previousWorkerNodeKey
  }
}