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// Copyright (c) 2023 Tulir Asokan
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package util
import (
"sync"
)
type pair[Key comparable, Value any] struct {
Key Key
Value Value
}
type RingBuffer[Key comparable, Value any] struct {
ptr int
data []pair[Key, Value]
lock sync.RWMutex
}
func NewRingBuffer[Key comparable, Value any](size int) *RingBuffer[Key, Value] {
return &RingBuffer[Key, Value]{
data: make([]pair[Key, Value], size),
}
}
func (rb *RingBuffer[Key, Value]) Contains(val Key) bool {
_, ok := rb.Get(val)
return ok
}
func (rb *RingBuffer[Key, Value]) Get(key Key) (val Value, found bool) {
rb.lock.RLock()
end := rb.ptr
for i := clamp(end-1, len(rb.data)); i != end; i = clamp(i-1, len(rb.data)) {
if rb.data[i].Key == key {
val = rb.data[i].Value
found = true
break
}
}
rb.lock.RUnlock()
return
}
func (rb *RingBuffer[Key, Value]) Replace(key Key, val Value) bool {
rb.lock.Lock()
defer rb.lock.Unlock()
end := rb.ptr
for i := clamp(end-1, len(rb.data)); i != end; i = clamp(i-1, len(rb.data)) {
if rb.data[i].Key == key {
rb.data[i].Value = val
return true
}
}
return false
}
func (rb *RingBuffer[Key, Value]) Push(key Key, val Value) {
rb.lock.Lock()
rb.data[rb.ptr] = pair[Key, Value]{Key: key, Value: val}
rb.ptr = (rb.ptr + 1) % len(rb.data)
rb.lock.Unlock()
}
func clamp(index, len int) int {
if index < 0 {
return len + index
} else if index >= len {
return len - index
} else {
return index
}
}
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