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

   1 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
   2 import type { IPool } from '../pool'
   3 import type { IWorker } from '../worker'
   4 import { FairShareWorkerChoiceStrategy } from './fair-share-worker-choice-strategy'
   5 import { InterleavedWeightedRoundRobinWorkerChoiceStrategy } from './interleaved-weighted-round-robin-worker-choice-strategy'
   6 import { LeastBusyWorkerChoiceStrategy } from './least-busy-worker-choice-strategy'
   7 import { LeastUsedWorkerChoiceStrategy } from './least-used-worker-choice-strategy'
   8 import { LeastEluWorkerChoiceStrategy } from './least-elu-worker-choice-strategy'
   9 import { RoundRobinWorkerChoiceStrategy } from './round-robin-worker-choice-strategy'
  10 import type {
  11   IWorkerChoiceStrategy,
  12   StrategyPolicy,
  13   TaskStatisticsRequirements,
  14   WorkerChoiceStrategy,
  15   WorkerChoiceStrategyOptions
  16 } from './selection-strategies-types'
  17 import { WorkerChoiceStrategies } from './selection-strategies-types'
  18 import { WeightedRoundRobinWorkerChoiceStrategy } from './weighted-round-robin-worker-choice-strategy'
  19
  20 /**
  21  * The worker choice strategy context.
  22  *
  23  * @typeParam Worker - Type of worker.
  24  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  25  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  26  */
  27 export class WorkerChoiceStrategyContext<
  28   Worker extends IWorker,
  29   Data = unknown,
  30   Response = unknown
  31 > {
  32   private readonly workerChoiceStrategies: Map<
  33   WorkerChoiceStrategy,
  34   IWorkerChoiceStrategy
  35   >
  36
  37   /**
  38    * Worker choice strategy context constructor.
  39    *
  40    * @param pool - The pool instance.
  41    * @param workerChoiceStrategy - The worker choice strategy.
  42    * @param opts - The worker choice strategy options.
  43    */
  44   public constructor (
  45     pool: IPool<Worker, Data, Response>,
  46     private workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN,
  47     private opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  48   ) {
  49     this.opts = { ...DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS, ...opts }
  50     this.execute = this.execute.bind(this)
  51     this.workerChoiceStrategies = new Map<
  52     WorkerChoiceStrategy,
  53     IWorkerChoiceStrategy
  54     >([
  55       [
  56         WorkerChoiceStrategies.ROUND_ROBIN,
  57         new (RoundRobinWorkerChoiceStrategy.bind(this))<Worker, Data, Response>(
  58           pool,
  59           opts
  60         )
  61       ],
  62       [
  63         WorkerChoiceStrategies.LEAST_USED,
  64         new (LeastUsedWorkerChoiceStrategy.bind(this))<Worker, Data, Response>(
  65           pool,
  66           opts
  67         )
  68       ],
  69       [
  70         WorkerChoiceStrategies.LEAST_BUSY,
  71         new (LeastBusyWorkerChoiceStrategy.bind(this))<Worker, Data, Response>(
  72           pool,
  73           opts
  74         )
  75       ],
  76       [
  77         WorkerChoiceStrategies.LEAST_ELU,
  78         new (LeastEluWorkerChoiceStrategy.bind(this))<Worker, Data, Response>(
  79           pool,
  80           opts
  81         )
  82       ],
  83       [
  84         WorkerChoiceStrategies.FAIR_SHARE,
  85         new (FairShareWorkerChoiceStrategy.bind(this))<Worker, Data, Response>(
  86           pool,
  87           opts
  88         )
  89       ],
  90       [
  91         WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN,
  92         new (WeightedRoundRobinWorkerChoiceStrategy.bind(this))<
  93         Worker,
  94         Data,
  95         Response
  96         >(pool, opts)
  97       ],
  98       [
  99         WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN,
 100         new (InterleavedWeightedRoundRobinWorkerChoiceStrategy.bind(this))<
 101         Worker,
 102         Data,
 103         Response
 104         >(pool, opts)
 105       ]
 106     ])
 107   }
 108
 109   /**
 110    * Gets the strategy policy in the context.
 111    *
 112    * @returns The strategy policy.
 113    */
 114   public getStrategyPolicy (): StrategyPolicy {
 115     return (
 116       this.workerChoiceStrategies.get(
 117         this.workerChoiceStrategy
 118       ) as IWorkerChoiceStrategy
 119     ).strategyPolicy
 120   }
 121
 122   /**
 123    * Gets the worker choice strategy in the context task statistics requirements.
 124    *
 125    * @returns The task statistics requirements.
 126    */
 127   public getTaskStatisticsRequirements (): TaskStatisticsRequirements {
 128     return (
 129       this.workerChoiceStrategies.get(
 130         this.workerChoiceStrategy
 131       ) as IWorkerChoiceStrategy
 132     ).taskStatisticsRequirements
 133   }
 134
 135   /**
 136    * Sets the worker choice strategy to use in the context.
 137    *
 138    * @param workerChoiceStrategy - The worker choice strategy to set.
 139    */
 140   public setWorkerChoiceStrategy (
 141     workerChoiceStrategy: WorkerChoiceStrategy
 142   ): void {
 143     if (this.workerChoiceStrategy !== workerChoiceStrategy) {
 144       this.workerChoiceStrategy = workerChoiceStrategy
 145     }
 146     this.workerChoiceStrategies.get(this.workerChoiceStrategy)?.reset()
 147   }
 148
 149   /**
 150    * Updates the worker node key in the worker choice strategy in the context internals.
 151    *
 152    * @returns `true` if the update is successful, `false` otherwise.
 153    */
 154   public update (workerNodeKey: number): boolean {
 155     return (
 156       this.workerChoiceStrategies.get(
 157         this.workerChoiceStrategy
 158       ) as IWorkerChoiceStrategy
 159     ).update(workerNodeKey)
 160   }
 161
 162   /**
 163    * Executes the worker choice strategy in the context algorithm.
 164    *
 165    * @returns The key of the worker node.
 166    * @throws {@link https://nodejs.org/api/errors.html#class-error} If after configured retries the worker node key is null or undefined.
 167    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the maximum consecutive worker choice strategy executions has been reached.
 168    */
 169   public execute (): number {
 170     const workerChoiceStrategy = this.workerChoiceStrategies.get(
 171       this.workerChoiceStrategy
 172     ) as IWorkerChoiceStrategy
 173     let workerNodeKey: number | undefined
 174     const maxExecutionCount = 10000
 175     let executionCount = 0
 176     let chooseCount = 0
 177     let retriesCount = 0
 178     do {
 179       if (workerChoiceStrategy.hasPoolWorkerNodesReady()) {
 180         workerNodeKey = workerChoiceStrategy.choose()
 181         if (chooseCount > 0) {
 182           retriesCount++
 183         }
 184         chooseCount++
 185       }
 186       executionCount++
 187     } while (
 188       executionCount < maxExecutionCount &&
 189       (!workerChoiceStrategy.hasPoolWorkerNodesReady() ||
 190         (workerNodeKey == null && retriesCount < (this.opts.retries as number)))
 191     )
 192     if (executionCount >= maxExecutionCount) {
 193       throw new RangeError(
 194         `Worker choice strategy consecutive executions has exceeded the maximum of ${maxExecutionCount}`
 195       )
 196     }
 197     if (workerNodeKey == null) {
 198       throw new Error(
 199         `Worker node key chosen is null or undefined after ${retriesCount} retries`
 200       )
 201     }
 202     return workerNodeKey
 203   }
 204
 205   /**
 206    * Removes the worker node key from the worker choice strategy in the context.
 207    *
 208    * @param workerNodeKey - The worker node key.
 209    * @returns `true` if the removal is successful, `false` otherwise.
 210    */
 211   public remove (workerNodeKey: number): boolean {
 212     return (
 213       this.workerChoiceStrategies.get(
 214         this.workerChoiceStrategy
 215       ) as IWorkerChoiceStrategy
 216     ).remove(workerNodeKey)
 217   }
 218
 219   /**
 220    * Sets the worker choice strategies in the context options.
 221    *
 222    * @param opts - The worker choice strategy options.
 223    */
 224   public setOptions (opts: WorkerChoiceStrategyOptions): void {
 225     this.opts = { ...DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS, ...opts }
 226     for (const workerChoiceStrategy of this.workerChoiceStrategies.values()) {
 227       workerChoiceStrategy.setOptions(opts)
 228     }
 229   }
 230 }