src/pools/selection-strategies/least-used-worker-choice-strategy.ts

   1 import type { IPool } from '../pool.js'
   2 import type { IWorker } from '../worker.js'
   3 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy.js'
   4 import type {
   5   IWorkerChoiceStrategy,
   6   WorkerChoiceStrategyOptions,
   7 } from './selection-strategies-types.js'
   8
   9 /**
  10  * Selects the least used worker.
  11  * @typeParam Worker - Type of worker which manages the strategy.
  12  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  13  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  14  */
  15 export class LeastUsedWorkerChoiceStrategy<
  16     Worker extends IWorker,
  17     Data = unknown,
  18     Response = unknown
  19   >
  20   extends AbstractWorkerChoiceStrategy<Worker, Data, Response>
  21   implements IWorkerChoiceStrategy {
  22   /** @inheritDoc */
  23   public constructor (
  24     pool: IPool<Worker, Data, Response>,
  25     opts?: WorkerChoiceStrategyOptions
  26   ) {
  27     super(pool, opts)
  28   }
  29
  30   /** @inheritDoc */
  31   public reset (): boolean {
  32     return true
  33   }
  34
  35   /** @inheritDoc */
  36   public update (): boolean {
  37     return true
  38   }
  39
  40   /** @inheritDoc */
  41   public choose (): number | undefined {
  42     this.setPreviousWorkerNodeKey(this.nextWorkerNodeKey)
  43     this.nextWorkerNodeKey = this.leastUsedNextWorkerNodeKey()
  44     return this.nextWorkerNodeKey
  45   }
  46
  47   /** @inheritDoc */
  48   public remove (): boolean {
  49     return true
  50   }
  51
  52   private leastUsedNextWorkerNodeKey (): number | undefined {
  53     return this.pool.workerNodes.reduce(
  54       (minWorkerNodeKey, workerNode, workerNodeKey, workerNodes) => {
  55         return this.isWorkerNodeReady(workerNodeKey) &&
  56           workerNode.usage.tasks.executing + workerNode.usage.tasks.queued <
  57             workerNodes[minWorkerNodeKey].usage.tasks.executing +
  58               workerNodes[minWorkerNodeKey].usage.tasks.queued
  59           ? workerNodeKey
  60           : minWorkerNodeKey
  61       },
  62       0
  63     )
  64   }
  65 }