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  *
  12  * @typeParam Worker - Type of worker which manages the strategy.
  13  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  14  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  15  */
  16 export class LeastUsedWorkerChoiceStrategy<
  17     Worker extends IWorker,
  18     Data = unknown,
  19     Response = unknown
  20   >
  21   extends AbstractWorkerChoiceStrategy<Worker, Data, Response>
  22   implements IWorkerChoiceStrategy {
  23   /** @inheritDoc */
  24   public constructor (
  25     pool: IPool<Worker, Data, Response>,
  26     opts?: WorkerChoiceStrategyOptions
  27   ) {
  28     super(pool, opts)
  29   }
  30
  31   /** @inheritDoc */
  32   public reset (): boolean {
  33     return true
  34   }
  35
  36   /** @inheritDoc */
  37   public update (): boolean {
  38     return true
  39   }
  40
  41   /** @inheritDoc */
  42   public choose (): number | undefined {
  43     this.setPreviousWorkerNodeKey(this.nextWorkerNodeKey)
  44     this.nextWorkerNodeKey = this.leastUsedNextWorkerNodeKey()
  45     return this.nextWorkerNodeKey
  46   }
  47
  48   /** @inheritDoc */
  49   public remove (): boolean {
  50     return true
  51   }
  52
  53   private leastUsedNextWorkerNodeKey (): number | undefined {
  54     if (this.pool.workerNodes.length === 0) {
  55       return undefined
  56     }
  57     return this.pool.workerNodes.reduce(
  58       (minWorkerNodeKey, workerNode, workerNodeKey, workerNodes) => {
  59         return this.isWorkerNodeReady(workerNodeKey) &&
  60           workerNode.usage.tasks.executing + workerNode.usage.tasks.queued <
  61             workerNodes[minWorkerNodeKey].usage.tasks.executing +
  62               workerNodes[minWorkerNodeKey].usage.tasks.queued
  63           ? workerNodeKey
  64           : minWorkerNodeKey
  65       },
  66       0
  67     )
  68   }
  69 }