102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
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// Code from https://github.com/erikdubbelboer/ringqueue
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/*
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The MIT License (MIT)
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Copyright (c) 2015 Erik Dubbelboer
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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package assetserver
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type ringqueue[T any] struct {
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nodes []T
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head int
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tail int
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cnt int
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minSize int
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}
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func newRingqueue[T any](minSize uint) *ringqueue[T] {
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if minSize < 2 {
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minSize = 2
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}
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return &ringqueue[T]{
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nodes: make([]T, minSize),
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minSize: int(minSize),
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}
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}
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func (q *ringqueue[T]) resize(n int) {
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nodes := make([]T, n)
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if q.head < q.tail {
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copy(nodes, q.nodes[q.head:q.tail])
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} else {
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copy(nodes, q.nodes[q.head:])
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copy(nodes[len(q.nodes)-q.head:], q.nodes[:q.tail])
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}
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q.tail = q.cnt % n
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q.head = 0
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q.nodes = nodes
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}
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func (q *ringqueue[T]) Add(i T) {
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if q.cnt == len(q.nodes) {
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// Also tested a grow rate of 1.5, see: http://stackoverflow.com/questions/2269063/buffer-growth-strategy
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// In Go this resulted in a higher memory usage.
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q.resize(q.cnt * 2)
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}
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q.nodes[q.tail] = i
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q.tail = (q.tail + 1) % len(q.nodes)
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q.cnt++
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}
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func (q *ringqueue[T]) Peek() (T, bool) {
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if q.cnt == 0 {
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var none T
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return none, false
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}
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return q.nodes[q.head], true
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}
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func (q *ringqueue[T]) Remove() (T, bool) {
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if q.cnt == 0 {
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var none T
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return none, false
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}
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i := q.nodes[q.head]
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q.head = (q.head + 1) % len(q.nodes)
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q.cnt--
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if n := len(q.nodes) / 2; n > q.minSize && q.cnt <= n {
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q.resize(n)
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}
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return i, true
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}
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func (q *ringqueue[T]) Cap() int {
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return cap(q.nodes)
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}
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func (q *ringqueue[T]) Len() int {
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return q.cnt
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}
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