util: add PrefixLogger

util/logging.go

@@ -0,0 +1,20 @@
+package util
+
+import "fmt"
+
+type Logger interface {
+	Printf(format string, args ...interface{})
+}
+
+type PrefixLogger struct {
+	Log    Logger
+	Prefix string
+}
+
+func NewPrefixLogger(logger Logger, prefix string) (l PrefixLogger) {
+	return PrefixLogger{logger, prefix}
+}
+
+func (l PrefixLogger) Printf(format string, v ...interface{}) {
+	l.Log.Printf(fmt.Sprintf("[%s]: %s", l.Prefix, format), v...)
+}