Implementation of Ruby YAML::Store and read/save of the session database

1 files changed, 47 insertions, 0 deletions

diff --git a/yamldb/yamldb.go b/yamldb/yamldb.go
new file mode 100644
index 0000000..eec23be
--- /dev/null
+++ b/yamldb/yamldb.go
@@ -0,0 +1,47 @@
+package yamldb
+
+import (
+	"github.com/pkg/errors"
+	"io/ioutil"
+	"os"
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// YamlDB represents a YAML file database instance
+type YamlDB struct {
+	Path    string
+	PathNew string
+	lock    sync.Mutex
+}
+
+// Transaction executes the given callback and safely saves
+// the data after they are modified within the callback
+func (db *YamlDB) Transaction(callback func(), marshaller func() ([]byte, error)) error {
+	var err error
+
+	log.Debug("Enter transaction")
+	db.lock.Lock()
+	defer func() {
+		db.lock.Unlock()
+		log.Debug("Exit transaction")
+	}()
+
+	callback()
+
+	yamlData, err := marshaller()
+	if err != nil {
+		return errors.Wrap(err, "Data marshalling error")
+	}
+	err = ioutil.WriteFile(db.PathNew, yamlData, 0644)
+	if err != nil {
+		return errors.Wrap(err, "YamlDB write failure")
+	}
+	err = os.Rename(db.PathNew, db.Path)
+	if err != nil {
+		return errors.Wrap(err, "Couldn't rewrite an old YamlDB file")
+	}
+
+	return nil
+}