Use filesystem based kv store instead of sqlite

kv/kv.go

@@ -0,0 +1,92 @@
+package kv
+
+import (
+	"errors"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+)
+
+var (
+	errInvalidKey = errors.New("invalid key")
+	errNoSuchKey  = errors.New("no such key")
+)
+
+type Database struct {
+	data    map[string][]byte
+	basedir string
+	m       sync.RWMutex
+}
+
+func NewDatabse(basedir string) (db *Database, err error) {
+	err = os.Mkdir(basedir, 0755)
+	if err != nil && !os.IsExist(err) {
+		return
+	}
+
+	return &Database{
+		data:    make(map[string][]byte),
+		basedir: basedir,
+	}, nil
+}
+
+func (db *Database) Set(key string, val []byte) (err error) {
+	if len(key) < 1 {
+		return errInvalidKey
+	}
+
+	db.m.Lock()
+	defer func() {
+		if err != nil {
+			delete(db.data, key)
+		}
+		db.m.Unlock()
+	}()
+
+	db.data[key] = val
+
+	err = ioutil.WriteFile(filepath.Join(db.basedir, key), val, 0644)
+
+	return
+}
+
+func (db *Database) Get(key string) (val []byte, err error) {
+	if len(key) < 1 {
+		return nil, errInvalidKey
+	}
+
+	db.m.RLock()
+	defer db.m.RUnlock()
+
+	data, ok := db.data[key]
+	if !ok {
+		data, err = ioutil.ReadFile(filepath.Join(db.basedir, key))
+		if err != nil {
+			err = errNoSuchKey
+			return nil, err
+		}
+
+		db.data[key] = data
+	}
+
+	val = make([]byte, len(data))
+	copy(val, data)
+
+	return
+}
+
+func (db *Database) Remove(key string) {
+	if len(key) < 1 || strings.ContainsRune(key, os.PathSeparator) {
+		return
+	}
+
+	db.m.Lock()
+	defer db.m.Unlock()
+
+	delete(db.data, key)
+	os.Remove(filepath.Join(db.basedir, key))
+
+	return
+}