src/pools/selection-strategies/abstract-worker-choice-strategy.ts

   1 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
   2 import type { IPool } from '../pool'
   3 import type { IWorker } from '../worker'
   4 import type {
   5   IWorkerChoiceStrategy,
   6   RequiredStatistics,
   7   WorkerChoiceStrategyOptions
   8 } from './selection-strategies-types'
   9
  10 /**
  11  * Worker choice strategy abstract base class.
  12  *
  13  * @typeParam Worker - Type of worker which manages the strategy.
  14  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  15  * @typeParam Response - Type of execution response. This can only be serializable data.
  16  */
  17 export abstract class AbstractWorkerChoiceStrategy<
  18   Worker extends IWorker,
  19   Data = unknown,
  20   Response = unknown
  21 > implements IWorkerChoiceStrategy {
  22   /**
  23    * Toggles finding the last free worker node key.
  24    */
  25   private toggleFindLastFreeWorkerNodeKey: boolean = false
  26   /** @inheritDoc */
  27   public readonly requiredStatistics: RequiredStatistics = {
  28     runTime: false,
  29     avgRunTime: false,
  30     medRunTime: false
  31   }
  32
  33   /**
  34    * Constructs a worker choice strategy bound to the pool.
  35    *
  36    * @param pool - The pool instance.
  37    * @param opts - The worker choice strategy options.
  38    */
  39   public constructor (
  40     protected readonly pool: IPool<Worker, Data, Response>,
  41     protected opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  42   ) {
  43     this.choose = this.choose.bind(this)
  44   }
  45
  46   protected checkOptions (opts: WorkerChoiceStrategyOptions): void {
  47     if (this.requiredStatistics.avgRunTime && opts.medRunTime === true) {
  48       this.requiredStatistics.avgRunTime = false
  49       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  50     }
  51     if (this.requiredStatistics.medRunTime && opts.medRunTime === false) {
  52       this.requiredStatistics.avgRunTime = true
  53       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  54     }
  55     if (
  56       opts.weights != null &&
  57       Object.keys(opts.weights).length < this.pool.size
  58     ) {
  59       throw new Error(
  60         'Worker choice strategy options must have a weight for each worker node.'
  61       )
  62     }
  63   }
  64
  65   /** @inheritDoc */
  66   public abstract reset (): boolean
  67
  68   /** @inheritDoc */
  69   public abstract update (workerNodeKey: number): boolean
  70
  71   /** @inheritDoc */
  72   public abstract choose (): number
  73
  74   /** @inheritDoc */
  75   public abstract remove (workerNodeKey: number): boolean
  76
  77   /** @inheritDoc */
  78   public setOptions (opts: WorkerChoiceStrategyOptions): void {
  79     opts = opts ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  80     this.checkOptions(opts)
  81     this.opts = opts
  82   }
  83
  84   /**
  85    * Finds a free worker node key.
  86    *
  87    * @returns The free worker node key or `-1` if there is no free worker node.
  88    */
  89   protected findFreeWorkerNodeKey (): number {
  90     if (this.toggleFindLastFreeWorkerNodeKey) {
  91       this.toggleFindLastFreeWorkerNodeKey = false
  92       return this.findLastFreeWorkerNodeKey()
  93     }
  94     this.toggleFindLastFreeWorkerNodeKey = true
  95     return this.findFirstFreeWorkerNodeKey()
  96   }
  97
  98   /**
  99    * Finds the first free worker node key based on the number of tasks the worker has applied.
 100    *
 101    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 102    *
 103    * If no free worker is found, `-1` is returned.
 104    *
 105    * @returns A worker node key if there is one, `-1` otherwise.
 106    */
 107   private findFirstFreeWorkerNodeKey (): number {
 108     return this.pool.workerNodes.findIndex(workerNode => {
 109       return workerNode.tasksUsage.running === 0
 110     })
 111   }
 112
 113   /**
 114    * Finds the last free worker node key based on the number of tasks the worker has applied.
 115    *
 116    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 117    *
 118    * If no free worker is found, `-1` is returned.
 119    *
 120    * @returns A worker node key if there is one, `-1` otherwise.
 121    */
 122   private findLastFreeWorkerNodeKey (): number {
 123     // It requires node >= 18.0.0:
 124     // return this.workerNodes.findLastIndex(workerNode => {
 125     //   return workerNode.tasksUsage.running === 0
 126     // })
 127     for (
 128       let workerNodeKey = this.pool.workerNodes.length - 1;
 129       workerNodeKey >= 0;
 130       workerNodeKey--
 131     ) {
 132       if (this.pool.workerNodes[workerNodeKey].tasksUsage.running === 0) {
 133         return workerNodeKey
 134       }
 135     }
 136     return -1
 137   }
 138 }