src/pools/cluster/dynamic.ts

   1 import { PoolEvents, type PoolType, PoolTypes } from '../pool.js'
   2 import { checkDynamicPoolSize } from '../utils.js'
   3 import { type ClusterPoolOptions, FixedClusterPool } from './fixed.js'
   4
   5 /**
   6  * A cluster pool with a dynamic number of workers, but a guaranteed minimum number of workers.
   7  *
   8  * This cluster pool creates new workers when the others are busy, up to the maximum number of workers.
   9  * When the maximum number of workers is reached and workers are busy, an event is emitted. If you want to listen to this event, use the pool's `emitter`.
  10  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  11  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  12  * @author [Christopher Quadflieg](https://github.com/Shinigami92)
  13  * @since 2.0.0
  14  */
  15 export class DynamicClusterPool<
  16   Data = unknown,
  17   Response = unknown
  18 > extends FixedClusterPool<Data, Response> {
  19   /**
  20    * Whether the pool empty event has been emitted or not
  21    */
  22   private emptyEventEmitted: boolean
  23
  24   /**
  25    * Whether the pool full event has been emitted or not.
  26    */
  27   private fullEventEmitted: boolean
  28
  29   /**
  30    * Constructs a new poolifier dynamic cluster pool.
  31    * @param min - Minimum number of workers which are always active.
  32    * @param max - Maximum number of workers that can be created by this pool.
  33    * @param filePath - Path to an implementation of a `ClusterWorker` file, which can be relative or absolute.
  34    * @param opts - Options for this dynamic cluster pool.
  35    */
  36   public constructor (
  37     min: number,
  38     max: number,
  39     filePath: string,
  40     opts: ClusterPoolOptions = {}
  41   ) {
  42     super(min, filePath, opts, max)
  43     checkDynamicPoolSize(
  44       this.minimumNumberOfWorkers,
  45       this.maximumNumberOfWorkers
  46     )
  47     this.emptyEventEmitted = false
  48     this.fullEventEmitted = false
  49   }
  50
  51   /** @inheritDoc */
  52   protected override checkAndEmitDynamicWorkerCreationEvents (): void {
  53     if (this.emitter != null) {
  54       if (!this.fullEventEmitted && this.full) {
  55         this.emitter.emit(PoolEvents.full, this.info)
  56         this.fullEventEmitted = true
  57       }
  58       if (this.emptyEventEmitted && !this.empty) {
  59         this.emptyEventEmitted = false
  60       }
  61     }
  62   }
  63
  64   /** @inheritDoc */
  65   protected override checkAndEmitDynamicWorkerDestructionEvents (): void {
  66     if (this.emitter != null) {
  67       if (this.fullEventEmitted && !this.full) {
  68         this.emitter.emit(PoolEvents.fullEnd, this.info)
  69         this.fullEventEmitted = false
  70       }
  71       if (!this.emptyEventEmitted && this.empty) {
  72         this.emitter.emit(PoolEvents.empty, this.info)
  73         this.emptyEventEmitted = true
  74       }
  75     }
  76   }
  77
  78   /** @inheritDoc */
  79   protected override shallCreateDynamicWorker (): boolean {
  80     return (!this.full && this.internalBusy()) || this.empty
  81   }
  82
  83   /** @inheritDoc */
  84   protected override get backPressure (): boolean {
  85     return this.full && this.internalBackPressure()
  86   }
  87
  88   /** @inheritDoc */
  89   protected override get busy (): boolean {
  90     return this.full && this.internalBusy()
  91   }
  92
  93   /**
  94    * Whether the pool is empty or not.
  95    * @returns The pool emptiness boolean status.
  96    */
  97   private get empty (): boolean {
  98     return (
  99       this.minimumNumberOfWorkers === 0 &&
 100       this.workerNodes.length === this.minimumNumberOfWorkers
 101     )
 102   }
 103
 104   /**
 105    * Whether the pool is full or not.
 106    * @returns The pool fullness boolean status.
 107    */
 108   private get full (): boolean {
 109     return (
 110       this.workerNodes.length >=
 111       (this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers)
 112     )
 113   }
 114
 115   /** @inheritDoc */
 116   protected override get type (): PoolType {
 117     return PoolTypes.dynamic
 118   }
 119 }