add singleton for logging

internal/utils/singleton.go

@@ -5,6 +5,8 @@ package utils
 import (
 	"sync"
 	"sync/atomic"
+
+	"github.com/harmony-one/harmony/log"
 )
 
 // UniqueValidatorID defines the structure of unique validator ID
@@ -13,7 +15,9 @@ type UniqueValidatorID struct {
 }
 
 var instance *UniqueValidatorID
+var logInstance log.Logger
 var once sync.Once
+var onceForLog sync.Once
 
 // GetUniqueValidatorIDInstance returns a singleton instance
 func GetUniqueValidatorIDInstance() *UniqueValidatorID {
@@ -29,3 +33,10 @@ func GetUniqueValidatorIDInstance() *UniqueValidatorID {
 func (s *UniqueValidatorID) GetUniqueID() uint32 {
 	return atomic.AddUint32(&s.uniqueID, 1)
 }
+
+func GetLogInstance() log.Logger {
+	onceForLog.Do(func() {
+		logInstance = log.New()
+	})
+	return logInstance
+}