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    */
 168   public execute (): number {
 169     const workerChoiceStrategy = this.workerChoiceStrategies.get(
 170       this.workerChoiceStrategy
 171     ) as IWorkerChoiceStrategy
 172     if (!workerChoiceStrategy.hasPoolWorkerNodesReady()) {
 173       // wait for a worker node to be ready without blocking the event loop
 174     }
 175     return this.executeStrategy(workerChoiceStrategy)
 176   }
 177
 178   /**
 179    * Executes the given worker choice strategy.
 180    *
 181    * @param workerChoiceStrategy - The worker choice strategy.
 182    * @returns The key of the worker node.
 183    * @throws {@link https://nodejs.org/api/errors.html#class-error} If after configured retries the worker node key is null or undefined.
 184    */
 185   private executeStrategy (workerChoiceStrategy: IWorkerChoiceStrategy): number {
 186     let workerNodeKey: number | undefined
 187     let chooseCount = 0
 188     let retriesCount = 0
 189     do {
 190       workerNodeKey = workerChoiceStrategy.choose()
 191       if (workerNodeKey == null && chooseCount > 0) {
 192         retriesCount++
 193       }
 194       chooseCount++
 195     } while (
 196       workerNodeKey == null &&
 197       retriesCount < (this.opts.retries as number)
 198     )
 199     if (workerNodeKey == null) {
 200       throw new Error(
 201         `Worker node key chosen is null or undefined after ${retriesCount} retries`
 202       )
 203     }
 204     return workerNodeKey
 205   }
 206
 207   /**
 208    * Removes the worker node key from the worker choice strategy in the context.
 209    *
 210    * @param workerNodeKey - The worker node key.
 211    * @returns `true` if the removal is successful, `false` otherwise.
 212    */
 213   public remove (workerNodeKey: number): boolean {
 214     return (
 215       this.workerChoiceStrategies.get(
 216         this.workerChoiceStrategy
 217       ) as IWorkerChoiceStrategy
 218     ).remove(workerNodeKey)
 219   }
 220
 221   /**
 222    * Sets the worker choice strategies in the context options.
 223    *
 224    * @param opts - The worker choice strategy options.
 225    */
 226   public setOptions (opts: WorkerChoiceStrategyOptions): void {
 227     this.opts = { ...DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS, ...opts }
 228     for (const workerChoiceStrategy of this.workerChoiceStrategies.values()) {
 229       workerChoiceStrategy.setOptions(opts)
 230     }
 231   }
 232 }