mirror of
https://github.com/woodpecker-ci/woodpecker.git
synced 2024-12-24 10:07:21 +02:00
123 lines
2.9 KiB
Go
123 lines
2.9 KiB
Go
package cache
|
|
|
|
import (
|
|
"container/list"
|
|
)
|
|
|
|
// LRUNoTS Discards the least recently used items first. This algorithm
|
|
// requires keeping track of what was used when.
|
|
type LRUNoTS struct {
|
|
// list holds all items in a linked list, for finding the `tail` of the list
|
|
list *list.List
|
|
|
|
// cache holds the all cache values
|
|
cache Cache
|
|
|
|
// size holds the limit of the LRU cache
|
|
size int
|
|
}
|
|
|
|
// kv is an helper struct for keeping track of the key for the list item. Only
|
|
// place where we need the key of a value is while removing the last item from
|
|
// linked list, for other cases, all operations alread have the key
|
|
type kv struct {
|
|
k string
|
|
v interface{}
|
|
}
|
|
|
|
// NewLRUNoTS creates a new LRU cache struct for further cache operations. Size
|
|
// is used for limiting the upper bound of the cache
|
|
func NewLRUNoTS(size int) Cache {
|
|
if size < 1 {
|
|
panic("invalid cache size")
|
|
}
|
|
|
|
return &LRUNoTS{
|
|
list: list.New(),
|
|
cache: NewMemoryNoTS(),
|
|
size: size,
|
|
}
|
|
}
|
|
|
|
// Get returns the value of a given key if it exists, every get item will be
|
|
// moved to the head of the linked list for keeping track of least recent used
|
|
// item
|
|
func (l *LRUNoTS) Get(key string) (interface{}, error) {
|
|
res, err := l.cache.Get(key)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
elem := res.(*list.Element)
|
|
// move found item to the head
|
|
l.list.MoveToFront(elem)
|
|
|
|
return elem.Value.(*kv).v, nil
|
|
}
|
|
|
|
// Set sets or overrides the given key with the given value, every set item will
|
|
// be moved or prepended to the head of the linked list for keeping track of
|
|
// least recent used item. When the cache is full, last item of the linked list
|
|
// will be evicted from the cache
|
|
func (l *LRUNoTS) Set(key string, val interface{}) error {
|
|
// try to get item
|
|
res, err := l.cache.Get(key)
|
|
if err != nil && err != ErrNotFound {
|
|
return err
|
|
}
|
|
|
|
var elem *list.Element
|
|
|
|
// if elem is not in the cache, push it to front of the list
|
|
if err == ErrNotFound {
|
|
elem = l.list.PushFront(&kv{k: key, v: val})
|
|
} else {
|
|
// if elem is in the cache, update the data and move it the front
|
|
elem = res.(*list.Element)
|
|
|
|
// update the data
|
|
elem.Value.(*kv).v = val
|
|
|
|
// item already exists, so move it to the front of the list
|
|
l.list.MoveToFront(elem)
|
|
}
|
|
|
|
// in any case, set the item to the cache
|
|
err = l.cache.Set(key, elem)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// if the cache is full, evict last entry
|
|
if l.list.Len() > l.size {
|
|
// remove last element from cache
|
|
return l.removeElem(l.list.Back())
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Delete deletes the given key-value pair from cache, this function doesnt
|
|
// return an error if item is not in the cache
|
|
func (l *LRUNoTS) Delete(key string) error {
|
|
res, err := l.cache.Get(key)
|
|
if err != nil && err != ErrNotFound {
|
|
return err
|
|
}
|
|
|
|
// item already deleted
|
|
if err == ErrNotFound {
|
|
// surpress not found errors
|
|
return nil
|
|
}
|
|
|
|
elem := res.(*list.Element)
|
|
|
|
return l.removeElem(elem)
|
|
}
|
|
|
|
func (l *LRUNoTS) removeElem(e *list.Element) error {
|
|
l.list.Remove(e)
|
|
return l.cache.Delete(e.Value.(*kv).k)
|
|
}
|