fix: fix fair share algorithm implementation

[poolifier.git] / src / pools / selection-strategies / abstract-worker-choice-strategy.ts

diff --git a/src/pools/selection-strategies/abstract-worker-choice-strategy.ts b/src/pools/selection-strategies/abstract-worker-choice-strategy.ts
index 2f1905782f7c4a6c3d6d4c98053b3965eaa8021d..e2dd626de76106991b11d1567d70c9e6f3d21ab7 100644 (file)
--- a/src/pools/selection-strategies/abstract-worker-choice-strategy.ts
+++ b/src/pools/selection-strategies/abstract-worker-choice-strategy.ts
@@ -1,5 +1,5 @@
 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
-import { PoolType, type IPool } from '../pool'
+import type { IPool } from '../pool'
 import type { IWorker } from '../worker'
 import type {
   IWorkerChoiceStrategy,
@@ -19,8 +19,10 @@ export abstract class AbstractWorkerChoiceStrategy<
   Data = unknown,
   Response = unknown
 > implements IWorkerChoiceStrategy {
-  /** @inheritDoc */
-  protected readonly isDynamicPool: boolean
+  /**
+   * Toggles finding the last free worker node key.
+   */
+  private toggleFindLastFreeWorkerNodeKey: boolean = false
   /** @inheritDoc */
   public readonly requiredStatistics: RequiredStatistics = {
     runTime: false,
@@ -38,7 +40,6 @@ export abstract class AbstractWorkerChoiceStrategy<
     protected readonly pool: IPool<Worker, Data, Response>,
     protected opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
   ) {
-    this.isDynamicPool = this.pool.type === PoolType.DYNAMIC
     this.choose = this.choose.bind(this)
   }
 
@@ -51,11 +52,22 @@ export abstract class AbstractWorkerChoiceStrategy<
       this.requiredStatistics.avgRunTime = true
       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
     }
+    if (
+      opts.weights != null &&
+      Object.keys(opts.weights).length < this.pool.size
+    ) {
+      throw new Error(
+        'Worker choice strategy options must have a weight for each worker node.'
+      )
+    }
   }
 
   /** @inheritDoc */
   public abstract reset (): boolean
 
+  /** @inheritDoc */
+  public abstract update (workerNodeKey: number): boolean
+
   /** @inheritDoc */
   public abstract choose (): number
 
@@ -68,4 +80,55 @@ export abstract class AbstractWorkerChoiceStrategy<
     this.checkOptions(opts)
     this.opts = opts
   }
+
+  /**
+   * Finds a free worker node key.
+   *
+   * @returns The free worker node key or `-1` if there is no free worker node.
+   */
+  protected findFreeWorkerNodeKey (): number {
+    if (this.toggleFindLastFreeWorkerNodeKey) {
+      this.toggleFindLastFreeWorkerNodeKey = false
+      return this.findLastFreeWorkerNodeKey()
+    }
+    this.toggleFindLastFreeWorkerNodeKey = true
+    return this.findFirstFreeWorkerNodeKey()
+  }
+
+  /**
+   * Finds the first free worker node key based on the number of tasks the worker has applied.
+   *
+   * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
+   *
+   * If no free worker is found, `-1` is returned.
+   *
+   * @returns A worker node key if there is one, `-1` otherwise.
+   */
+  private findFirstFreeWorkerNodeKey (): number {
+    return this.pool.workerNodes.findIndex(workerNode => {
+      return workerNode.tasksUsage.running === 0
+    })
+  }
+
+  /**
+   * Finds the last free worker node key based on the number of tasks the worker has applied.
+   *
+   * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
+   *
+   * If no free worker is found, `-1` is returned.
+   *
+   * @returns A worker node key if there is one, `-1` otherwise.
+   */
+  private findLastFreeWorkerNodeKey (): number {
+    // It requires node >= 18.0.0:
+    // return this.workerNodes.findLastIndex(workerNode => {
+    //   return workerNode.tasksUsage.running === 0
+    // })
+    for (let i = this.pool.workerNodes.length - 1; i >= 0; i--) {
+      if (this.pool.workerNodes[i].tasksUsage.running === 0) {
+        return i
+      }
+    }
+    return -1
+  }
 }