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author | Egor Tensin <egor@tensin.name> | 2024-01-28 11:18:12 +0100 |
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committer | Egor Tensin <egor@tensin.name> | 2024-01-28 11:18:12 +0100 |
commit | 2d40e8046a08373b1740922690b695a16d5e5fa6 (patch) | |
tree | eb086741d1bb01ef9ed3d0ac8e1301447e835971 /node_modules/undici/lib/node | |
parent | workflows/test: upgrade actions (diff) | |
download | cleanup-path-2d40e8046a08373b1740922690b695a16d5e5fa6.tar.gz cleanup-path-2d40e8046a08373b1740922690b695a16d5e5fa6.zip |
bump version in package.json, upgrade dependencies
Diffstat (limited to 'node_modules/undici/lib/node')
-rw-r--r-- | node_modules/undici/lib/node/fixed-queue.js | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/node_modules/undici/lib/node/fixed-queue.js b/node_modules/undici/lib/node/fixed-queue.js new file mode 100644 index 0000000..3572681 --- /dev/null +++ b/node_modules/undici/lib/node/fixed-queue.js @@ -0,0 +1,117 @@ +/* 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; + +// The FixedQueue is implemented as a singly-linked list of fixed-size +// circular buffers. It looks something like this: +// +// head tail +// | | +// v v +// +-----------+ <-----\ +-----------+ <------\ +-----------+ +// | [null] | \----- | next | \------- | next | +// +-----------+ +-----------+ +-----------+ +// | item | <-- bottom | item | <-- bottom | [empty] | +// | item | | item | | [empty] | +// | item | | item | | [empty] | +// | item | | item | | [empty] | +// | 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] | +// +-----------+ +-----------+ +-----------+ +// +// Or, if there is only one circular buffer, it looks something +// like either of these: +// +// head tail head tail +// | | | | +// v v v v +// +-----------+ +-----------+ +// | [null] | | [null] | +// +-----------+ +-----------+ +// | [empty] | | item | +// | [empty] | | item | +// | item | <-- bottom top --> | [empty] | +// | item | | [empty] | +// | [empty] | <-- top bottom --> | item | +// | [empty] | | item | +// +-----------+ +-----------+ +// +// Adding a value means moving `top` forward by one, removing means +// moving `bottom` forward by one. After reaching the end, the queue +// wraps around. +// +// When `top === bottom` the current queue is empty and when +// `top + 1 === bottom` it's full. This wastes a single space of storage +// but allows much quicker checks. + +class FixedCircularBuffer { + constructor() { + this.bottom = 0; + this.top = 0; + this.list = new Array(kSize); + this.next = null; + } + + isEmpty() { + return this.top === this.bottom; + } + + isFull() { + return ((this.top + 1) & kMask) === this.bottom; + } + + 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; + } +} + +module.exports = class FixedQueue { + constructor() { + this.head = this.tail = new FixedCircularBuffer(); + } + + isEmpty() { + return this.head.isEmpty(); + } + + 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.push(data); + } + + 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; + } + return next; + } +}; |