stillbox/internal/cache/cache.go

88 lines
1.2 KiB
Go

package cache
import (
"sync"
"time"
)
type Cache[K comparable, V any] interface {
Get(K) (V, bool)
Set(K, V)
Delete(K)
Clear()
}
type cacheItem[V any] struct {
exp int64
elem V
}
type inMem[K comparable, V any] struct {
sync.RWMutex
expiration time.Duration
m map[K]cacheItem[V]
}
type cacheOpts struct {
exp time.Duration
}
type Option func(*cacheOpts)
func WithExpiration(d time.Duration) Option {
return func(o *cacheOpts) {
o.exp = d
}
}
func New[K comparable, V any](opts ...Option) *inMem[K, V] {
co := cacheOpts{}
for _, o := range opts {
o(&co)
}
c := &inMem[K, V]{
m: make(map[K]cacheItem[V]),
expiration: co.exp,
}
return c
}
func (c *inMem[K, V]) Get(key K) (V, bool) {
c.RLock()
defer c.RUnlock()
v, found := c.m[key]
if !found || (v.exp > 0 && time.Now().UnixNano() > v.exp) {
return v.elem, false
}
return v.elem, true
}
func (c *inMem[K, V]) Set(key K, val V) {
c.Lock()
defer c.Unlock()
var ci cacheItem[V]
ci.elem = val
if c.expiration > 0 {
ci.exp = time.Now().Add(c.expiration).UnixNano()
}
c.m[key] = ci
}
func (c *inMem[K, V]) Delete(key K) {
c.Lock()
defer c.Unlock()
delete(c.m, key)
}
func (c *inMem[K, V]) Clear() {
c.Lock()
defer c.Unlock()
clear(c.m)
}