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package kv
import (
"errors"
"io/ioutil"
"os"
"path/filepath"
"strings"
"sync"
)
var (
ErrInvalidKey = errors.New("kv: invalid key")
ErrNoSuchKey = errors.New("kv: no such key")
)
type DB struct {
cache map[string][]byte
basedir string
m sync.RWMutex
}
func NewDB(basedir string) (db *DB, err error) {
err = os.Mkdir(basedir, 0755)
if err != nil && !os.IsExist(err) {
return
}
return &DB{
cache: make(map[string][]byte),
basedir: basedir,
}, nil
}
func (db *DB) Set(key string, val []byte) (err error) {
if len(key) < 1 || strings.ContainsRune(key, os.PathSeparator) {
return ErrInvalidKey
}
db.m.Lock()
defer db.m.Unlock()
err = ioutil.WriteFile(filepath.Join(db.basedir, key), val, 0644)
if err != nil {
return
}
db.cache[key] = val
return
}
func (db *DB) Get(key string) (val []byte, err error) {
if len(key) < 1 || strings.ContainsRune(key, os.PathSeparator) {
return nil, ErrInvalidKey
}
db.m.Lock()
defer db.m.Unlock()
data, ok := db.cache[key]
if !ok {
data, err = ioutil.ReadFile(filepath.Join(db.basedir, key))
if err != nil {
if os.IsNotExist(err) {
err = ErrNoSuchKey
}
return nil, err
}
db.cache[key] = data
}
val = make([]byte, len(data))
copy(val, data)
return
}
func (db *DB) Remove(key string) (err error) {
if len(key) < 1 || strings.ContainsRune(key, os.PathSeparator) {
return ErrInvalidKey
}
db.m.Lock()
defer db.m.Unlock()
err = os.Remove(filepath.Join(db.basedir, key))
if err != nil {
if os.IsNotExist(err) {
err = ErrNoSuchKey
}
return
}
delete(db.cache, key)
return
}
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