/
l2cache.go
90 lines (84 loc) · 1.66 KB
/
l2cache.go
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package stored
import (
"github.com/jenchik/stored/api"
"sync/atomic"
)
type L2Cache struct {
sm api.StoredMap
maxItems int
order []string
cntGcHit uint64
cntHit uint64
cntInsert uint64
cntMissed uint64
}
func NewL2Cache(opt Options, sm api.StoredMap) Cacher {
c := &L2Cache{
sm: sm,
maxItems: saneMaxItems(opt.MaxItems),
}
c.order = make([]string, 0, c.maxItems)
return c
}
func (c *L2Cache) GetItem(key string, fback api.GetterFunc) (interface{}, error) {
var value interface{}
if value, found := c.sm.Find(key); found {
atomic.AddUint64(&c.cntHit, 1)
return value, nil
}
var err error
c.sm.AtomicWait(func(m api.Mapper) {
atomic.AddUint64(&c.cntHit, 1)
m.SetKey(key)
value = m.Value()
if value != nil {
return
}
c.cntMissed++
value, err = fback(key)
if err != nil {
return
}
if len(c.order) == c.maxItems {
c.cntGcHit++
m.SetKey(c.order[0])
m.Delete()
c.order = c.order[1:]
m.SetKey(key)
}
c.order = append(c.order, key)
m.Update(value)
c.cntInsert++
})
if err != nil {
return nil, err
}
return value, nil
}
func (c *L2Cache) ResetItem(key string) {
c.sm.Atomic(func(m api.Mapper) {
if _, found := m.Find(key); found {
m.SetKey(key)
m.Delete()
for i := 0; i < len(c.order); i++ {
if key == c.order[i] {
c.order = append(c.order[:i], c.order[i+1:]...)
break
}
}
}
})
}
func (c *L2Cache) Stats() map[string]uint64 {
var s map[string]uint64
c.sm.AtomicWait(func(m api.Mapper) {
s = map[string]uint64{
"gcHit": c.cntGcHit,
"hit": c.cntHit,
"insert": c.cntInsert,
"missed": c.cntMissed,
"len": uint64(m.Len()),
}
})
return s
}