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/**
* Standalone signaling server for the Nextcloud Spreed app.
* Copyright (C) 2017 struktur AG
*
* @author Joachim Bauch <bauch@struktur.de>
*
* @license GNU AGPL version 3 or any later version
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package signaling
import (
"container/list"
"sync"
)
type cacheEntry struct {
key string
value interface{}
}
type LruCache struct {
size int
mu sync.Mutex
entries *list.List
data map[string]*list.Element
}
func NewLruCache(size int) *LruCache {
return &LruCache{
size: size,
entries: list.New(),
data: make(map[string]*list.Element),
}
}
func (c *LruCache) Set(key string, value interface{}) {
c.mu.Lock()
if v, found := c.data[key]; found {
c.entries.MoveToFront(v)
v.Value.(*cacheEntry).value = value
c.mu.Unlock()
return
}
v := c.entries.PushFront(&cacheEntry{
key: key,
value: value,
})
c.data[key] = v
if c.size > 0 && c.entries.Len() > c.size {
c.removeOldestLocked()
}
c.mu.Unlock()
}
func (c *LruCache) Get(key string) interface{} {
c.mu.Lock()
if v, found := c.data[key]; found {
c.entries.MoveToFront(v)
value := v.Value.(*cacheEntry).value
c.mu.Unlock()
return value
}
c.mu.Unlock()
return nil
}
func (c *LruCache) Remove(key string) {
c.mu.Lock()
if v, found := c.data[key]; found {
c.removeElement(v)
}
c.mu.Unlock()
}
func (c *LruCache) removeOldestLocked() {
v := c.entries.Back()
if v != nil {
c.removeElement(v)
}
}
func (c *LruCache) RemoveOldest() {
c.mu.Lock()
c.removeOldestLocked()
c.mu.Unlock()
}
func (c *LruCache) removeElement(e *list.Element) {
c.entries.Remove(e)
entry := e.Value.(*cacheEntry)
delete(c.data, entry.key)
}
func (c *LruCache) Len() int {
c.mu.Lock()
defer c.mu.Unlock()
return c.entries.Len()
}