perf: optimize task(s) stealing

[poolifier.git] / src / priority-queue.ts

diff --git a/src/priority-queue.ts b/src/priority-queue.ts
index 55a97169f757beb0f53c51843d6a8a87f6392612..1c0d8c929967b2fa52f728f7b395ed013f044fda 100644 (file)
--- a/src/priority-queue.ts
+++ b/src/priority-queue.ts
@@ -1,7 +1,12 @@
+// Copyright Jerome Benoit. 2024. All Rights Reserved.
+
 /**
+ * Priority queue node.
+ *
+ * @typeParam T - Type of priority queue node data.
  * @internal
  */
-interface PriorityQueueNode<T> {
+export interface PriorityQueueNode<T> {
   data: T
   priority: number
 }
@@ -14,12 +19,33 @@ interface PriorityQueueNode<T> {
  */
 export class PriorityQueue<T> {
   private nodeArray!: Array<PriorityQueueNode<T>>
+  /** Prioritized bucket size. */
+  private readonly k: number
   /** The size of the priority queue. */
   public size!: number
   /** The maximum size of the priority queue. */
   public maxSize!: number
 
-  public constructor () {
+  /**
+   * The number of filled prioritized buckets.
+   */
+  public get buckets (): number {
+    return this.k === Infinity ? 1 : Math.trunc(this.nodeArray.length / this.k)
+  }
+
+  /**
+   * Constructs a priority queue.
+   *
+   * @param k - Prioritized bucket size. @defaultValue Infinity
+   */
+  public constructor (k = Infinity) {
+    if (k !== Infinity && !Number.isSafeInteger(k)) {
+      throw new TypeError('k must be an integer')
+    }
+    if (k < 1) {
+      throw new RangeError('k must be greater than or equal to 1')
+    }
+    this.k = k
     this.clear()
   }
 
@@ -32,9 +58,10 @@ export class PriorityQueue<T> {
    */
   public enqueue (data: T, priority?: number): number {
     priority = priority ?? 0
+    const startIndex = this.k === Infinity ? 0 : this.buckets * this.k
     let inserted = false
-    for (const [index, node] of this.nodeArray.entries()) {
-      if (node.priority > priority) {
+    for (let index = startIndex; index < this.nodeArray.length; index++) {
+      if (this.nodeArray[index].priority > priority) {
         this.nodeArray.splice(index, 0, { data, priority })
         inserted = true
         break
@@ -49,9 +76,21 @@ export class PriorityQueue<T> {
   /**
    * Dequeue data from the priority queue.
    *
+   * @param bucket - The prioritized bucket to dequeue from. @defaultValue 0
    * @returns The dequeued data or `undefined` if the priority queue is empty.
    */
-  public dequeue (): T | undefined {
+  public dequeue (bucket = 0): T | undefined {
+    if (this.k !== Infinity && bucket > 0) {
+      while (bucket > 0) {
+        const index = bucket * this.k
+        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+        if (this.nodeArray[index] != null) {
+          --this.size
+          return this.nodeArray.splice(index, 1)[0].data
+        }
+        --bucket
+      }
+    }
     if (this.size > 0) {
       --this.size
     }
@@ -84,9 +123,35 @@ export class PriorityQueue<T> {
   }
 
   /**
-   * Increments the size of the deque.
+   * Returns an iterator for the priority queue.
+   *
+   * @returns An iterator for the priority queue.
+   * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
+   */
+  [Symbol.iterator] (): Iterator<T> {
+    let i = 0
+    return {
+      next: () => {
+        if (i >= this.nodeArray.length) {
+          return {
+            value: undefined,
+            done: true
+          }
+        }
+        const value = this.nodeArray[i].data
+        i++
+        return {
+          value,
+          done: false
+        }
+      }
+    }
+  }
+
+  /**
+   * Increments the size of the priority queue.
    *
-   * @returns The new size of the deque.
+   * @returns The new size of the priority queue.
    */
   private incrementSize (): number {
     ++this.size