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 choose (): number
  70
  71   /** @inheritDoc */
  72   public abstract remove (workerNodeKey: number): boolean
  73
  74   /** @inheritDoc */
  75   public setOptions (opts: WorkerChoiceStrategyOptions): void {
  76     opts = opts ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  77     this.checkOptions(opts)
  78     this.opts = opts
  79   }
  80
  81   /**
  82    * Finds a free worker node key.
  83    *
  84    * @returns The free worker node key or `-1` if there is no free worker node.
  85    */
  86   protected findFreeWorkerNodeKey (): number {
  87     if (this.toggleFindLastFreeWorkerNodeKey) {
  88       this.toggleFindLastFreeWorkerNodeKey = false
  89       return this.findLastFreeWorkerNodeKey()
  90     }
  91     this.toggleFindLastFreeWorkerNodeKey = true
  92     return this.findFirstFreeWorkerNodeKey()
  93   }
  94
  95   /**
  96    * Finds the first free worker node key based on the number of tasks the worker has applied.
  97    *
  98    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
  99    *
 100    * If no free worker is found, `-1` is returned.
 101    *
 102    * @returns A worker node key if there is one, `-1` otherwise.
 103    */
 104   private findFirstFreeWorkerNodeKey (): number {
 105     return this.pool.workerNodes.findIndex(workerNode => {
 106       return workerNode.tasksUsage?.running === 0
 107     })
 108   }
 109
 110   /**
 111    * Finds the last free worker node key based on the number of tasks the worker has applied.
 112    *
 113    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 114    *
 115    * If no free worker is found, `-1` is returned.
 116    *
 117    * @returns A worker node key if there is one, `-1` otherwise.
 118    */
 119   private findLastFreeWorkerNodeKey (): number {
 120     // It requires node >= 18.0.0:
 121     // return this.workerNodes.findLastIndex(workerNode => {
 122     //   return workerNode.tasksUsage?.running === 0
 123     // })
 124     for (let i = this.pool.workerNodes.length - 1; i >= 0; i--) {
 125       if (this.pool.workerNodes[i].tasksUsage?.running === 0) {
 126         return i
 127       }
 128     }
 129     return -1
 130   }
 131 }