Using checksums to detect modified stats in the iTunes Library

persistence/checksum_repository.go

@@ -0,0 +1,61 @@
+package persistence
+
+import (
+	"errors"
+
+	"github.com/astaxie/beego"
+	"github.com/deluan/gosonic/scanner"
+	"github.com/siddontang/ledisdb/ledis"
+)
+
+var (
+	keyName = []byte("checksums")
+)
+
+type checkSumRepository struct {
+	data map[string]string
+}
+
+func NewCheckSumRepository() scanner.CheckSumRepository {
+	r := &checkSumRepository{}
+	r.loadData()
+	return r
+}
+
+func (r *checkSumRepository) loadData() {
+	r.data = make(map[string]string)
+
+	pairs, err := Db().HGetAll(keyName)
+	if err != nil {
+		beego.Error("Error loading CheckSums:", err)
+	}
+	for _, p := range pairs {
+		r.data[string(p.Field)] = string(p.Value)
+	}
+}
+
+func (r *checkSumRepository) Put(id, sum string) error {
+	if id == "" {
+		return errors.New("Id is required")
+	}
+	_, err := Db().HSet(keyName, []byte(id), []byte(sum))
+	return err
+}
+
+func (r *checkSumRepository) Get(id string) (string, error) {
+	return r.data[id], nil
+}
+
+func (r *checkSumRepository) SetData(newSums map[string]string) error {
+	Db().HClear(keyName)
+	pairs := make([]ledis.FVPair, len(newSums))
+	r.data = make(map[string]string)
+	i := 0
+	for id, sum := range newSums {
+		p := ledis.FVPair{Field: []byte(id), Value: []byte(sum)}
+		pairs[i] = p
+		r.data[id] = sum
+		i++
+	}
+	return Db().HMset(keyName, pairs...)
+}