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|
package cache
import (
"errors"
"os"
"sync"
"time"
"github.com/vmihailenco/msgpack"
)
type DB[K any, V any] struct {
file *os.File
Store Store
stop chan struct{}
wg sync.WaitGroup
}
func OpenFile[K any, V any](filename string) (*DB[K, V], error) {
ret := &DB[K, V]{}
file, err := os.OpenFile(filename, os.O_RDWR, 0)
if errors.Is(err, os.ErrNotExist) {
file, err := os.Create(filename)
if err != nil {
return nil, err
}
ret.file = file
ret.SetStratergy(StrategyNone)
ret.Clear()
ret.Flush()
} else if err == nil {
ret.Clear()
ret.file = file
ret.Store.LoadSnapshot(ret.file)
} else {
return nil, err
}
ret.wg.Add(1)
go ret.backgroundWorker()
return ret, nil
}
func OpenMem[K any, V any]() *DB[K, V] {
ret := &DB[K, V]{}
ret.SetStratergy(StrategyNone)
ret.Clear()
return ret
}
func (d *DB[K, V]) SetStratergy(e EvictionPolicy) error {
strategy, err := e.ToStratergy(&d.Store.evict)
if err != nil {
return err
}
d.Store.strategy = strategy
return nil
}
func (d *DB[K, V]) SetMaxCost(e EvictionPolicy) {
d.Store.max_cost = d.Store.max_cost
}
func (d *DB[K, V]) backgroundWorker() {
defer d.wg.Done()
for {
select {
case <-d.stop:
return
// TODO: Do house keeping
}
}
}
func (d *DB[K, V]) Close() {
close(d.stop)
d.wg.Wait()
d.Flush()
d.Clear()
if d.file != nil {
d.file.Close()
}
}
func (d *DB[K, V]) Flush() error {
if d.file != nil {
return d.Store.Snapshot(d.file)
}
return nil
}
func (d *DB[K, V]) Clear() {
d.Store.Clear()
}
var ErrKeyNotFound = errors.New("key not found")
func (h *DB[K, V]) Get(key K) (V, time.Duration, error) {
keyData, err := msgpack.Marshal(key)
if err != nil {
return zero[V](), 0, err
}
v, ttl, ok := h.Store.Get(keyData)
if !ok {
return zero[V](), 0, ErrKeyNotFound
}
var ret V
if err = msgpack.Unmarshal(v, &ret); err != nil {
return zero[V](), 0, err
}
return ret, ttl, err
}
func (h *DB[K, V]) Set(key K, value V, ttl time.Duration) error {
keyData, err := msgpack.Marshal(key)
if err != nil {
return err
}
valueData, err := msgpack.Marshal(value)
if err != nil {
return err
}
h.Store.Set(keyData, valueData, ttl)
return nil
}
func (h *DB[K, V]) Delete(key K) error {
keyData, err := msgpack.Marshal(key)
if err != nil {
return err
}
ok := h.Store.Delete(keyData)
if !ok {
return ErrKeyNotFound
}
return nil
}
|
