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lib: optimize priority queue #60039

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Oct 4, 2025
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lib: optimize priority queue #60039

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19 changes: 7 additions & 12 deletions lib/internal/priority_queue.js
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Original file line number Diff line number Diff line change
@@ -1,9 +1,5 @@
'use strict';

const {
Array,
} = primordials;

// The PriorityQueue is a basic implementation of a binary heap that accepts
// a custom sorting function via its constructor. This function is passed
// the two nodes to compare, similar to the native Array#sort. Crucially
Expand All @@ -12,7 +8,7 @@ const {

module.exports = class PriorityQueue {
#compare = (a, b) => a - b;
#heap = new Array(64);
#heap = [undefined, undefined];
#setPosition;
#size = 0;

Expand All @@ -28,9 +24,6 @@ module.exports = class PriorityQueue {
const pos = ++this.#size;
heap[pos] = value;

if (heap.length === pos)
heap.length *= 2;

this.percolateUp(pos);
}

Expand All @@ -45,6 +38,7 @@ module.exports = class PriorityQueue {
percolateDown(pos) {
const compare = this.#compare;
const setPosition = this.#setPosition;
const hasSetPosition = setPosition !== undefined;
const heap = this.#heap;
const size = this.#size;
const hsize = size >> 1;
Expand All @@ -62,22 +56,23 @@ module.exports = class PriorityQueue {

if (compare(item, childItem) <= 0) break;

if (setPosition !== undefined)
if (hasSetPosition)
setPosition(childItem, pos);

heap[pos] = childItem;
pos = child;
}

heap[pos] = item;
if (setPosition !== undefined)
if (hasSetPosition)
setPosition(item, pos);
}

percolateUp(pos) {
const heap = this.#heap;
const compare = this.#compare;
const setPosition = this.#setPosition;
const hasSetPosition = setPosition !== undefined;
const item = heap[pos];

while (pos > 1) {
Expand All @@ -86,13 +81,13 @@ module.exports = class PriorityQueue {
if (compare(parentItem, item) <= 0)
break;
heap[pos] = parentItem;
if (setPosition !== undefined)
if (hasSetPosition)
setPosition(parentItem, pos);
pos = parent;
}

heap[pos] = item;
if (setPosition !== undefined)
if (hasSetPosition)
setPosition(item, pos);
}

Expand Down
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