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chore: upgrade fixed queue, lint accordingly, add jsdoc #3577

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merged 3 commits into from
Sep 10, 2024
Merged

chore: upgrade fixed queue, lint accordingly, add jsdoc #3577

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466ab08
upgrade fixed-queue
Uzlopak Sep 10, 2024
5bddab6
lint
Uzlopak Sep 10, 2024
530f061
add jsdoc
Uzlopak Sep 10, 2024
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140 changes: 91 additions & 49 deletions lib/dispatcher/fixed-queue.js
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Original file line number Diff line number Diff line change
@@ -1,12 +1,10 @@
/* eslint-disable */

'use strict'

// Extracted from node/lib/internal/fixed_queue.js

// Currently optimal queue size, tested on V8 6.0 - 6.6. Must be power of two.
const kSize = 2048;
const kMask = kSize - 1;
const kSize = 2048
const kMask = kSize - 1

// The FixedQueue is implemented as a singly-linked list of fixed-size
// circular buffers. It looks something like this:
Expand All @@ -17,18 +15,18 @@ const kMask = kSize - 1;
// +-----------+ <-----\ +-----------+ <------\ +-----------+
// | [null] | \----- | next | \------- | next |
// +-----------+ +-----------+ +-----------+
// | item | <-- bottom | item | <-- bottom | [empty] |
// | item | | item | | [empty] |
// | item | | item | | [empty] |
// | item | | item | | [empty] |
// | item | <-- bottom | item | <-- bottom | undefined |
// | item | | item | | undefined |
// | item | | item | | undefined |
// | item | | item | | undefined |
// | item | | item | bottom --> | item |
// | item | | item | | item |
// | ... | | ... | | ... |
// | item | | item | | item |
// | item | | item | | item |
// | [empty] | <-- top | item | | item |
// | [empty] | | item | | item |
// | [empty] | | [empty] | <-- top top --> | [empty] |
// | undefined | <-- top | item | | item |
// | undefined | | item | | item |
// | undefined | | undefined | <-- top top --> | undefined |
// +-----------+ +-----------+ +-----------+
//
// Or, if there is only one circular buffer, it looks something
Expand All @@ -40,12 +38,12 @@ const kMask = kSize - 1;
// +-----------+ +-----------+
// | [null] | | [null] |
// +-----------+ +-----------+
// | [empty] | | item |
// | [empty] | | item |
// | item | <-- bottom top --> | [empty] |
// | item | | [empty] |
// | [empty] | <-- top bottom --> | item |
// | [empty] | | item |
// | undefined | | item |
// | undefined | | item |
// | item | <-- bottom top --> | undefined |
// | item | | undefined |
// | undefined | <-- top bottom --> | item |
// | undefined | | item |
// +-----------+ +-----------+
//
// Adding a value means moving `top` forward by one, removing means
Expand All @@ -56,62 +54,106 @@ const kMask = kSize - 1;
// `top + 1 === bottom` it's full. This wastes a single space of storage
// but allows much quicker checks.

/**
* @type {FixedCircularBuffer}
* @template T
*/
class FixedCircularBuffer {
constructor() {
this.bottom = 0;
this.top = 0;
this.list = new Array(kSize);
this.next = null;
constructor () {
/**
* @type {number}
*/
this.bottom = 0
/**
* @type {number}
*/
this.top = 0
/**
* @type {Array<T|undefined>}
*/
this.list = new Array(kSize).fill(undefined)
/**
* @type {T|null}
*/
this.next = null
}

isEmpty() {
return this.top === this.bottom;
/**
* @returns {boolean}
*/
isEmpty () {
return this.top === this.bottom
}

isFull() {
return ((this.top + 1) & kMask) === this.bottom;
/**
* @returns {boolean}
*/
isFull () {
return ((this.top + 1) & kMask) === this.bottom
}

push(data) {
this.list[this.top] = data;
this.top = (this.top + 1) & kMask;
/**
* @param {T} data
* @returns {void}
*/
push (data) {
this.list[this.top] = data
this.top = (this.top + 1) & kMask
}

shift() {
const nextItem = this.list[this.bottom];
if (nextItem === undefined)
return null;
this.list[this.bottom] = undefined;
this.bottom = (this.bottom + 1) & kMask;
return nextItem;
/**
* @returns {T|null}
*/
shift () {
const nextItem = this.list[this.bottom]
if (nextItem === undefined) { return null }
this.list[this.bottom] = undefined
this.bottom = (this.bottom + 1) & kMask
return nextItem
}
}

/**
* @template T
*/
module.exports = class FixedQueue {
constructor() {
this.head = this.tail = new FixedCircularBuffer();
constructor () {
/**
* @type {FixedCircularBuffer<T>}
*/
this.head = this.tail = new FixedCircularBuffer()
}

isEmpty() {
return this.head.isEmpty();
/**
* @returns {boolean}
*/
isEmpty () {
return this.head.isEmpty()
}

push(data) {
/**
* @param {T} data
*/
push (data) {
if (this.head.isFull()) {
// Head is full: Creates a new queue, sets the old queue's `.next` to it,
// and sets it as the new main queue.
this.head = this.head.next = new FixedCircularBuffer();
this.head = this.head.next = new FixedCircularBuffer()
}
this.head.push(data);
this.head.push(data)
}

shift() {
const tail = this.tail;
const next = tail.shift();
/**
* @returns {T|null}
*/
shift () {
const tail = this.tail
const next = tail.shift()
if (tail.isEmpty() && tail.next !== null) {
// If there is another queue, it forms the new tail.
this.tail = tail.next;
this.tail = tail.next
tail.next = null
}
return next;
return next
}
};
}
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