extractStructCache method - fixed unnecessary locking operation for r…

…eading existing cStruct

cache.go

@@ -100,9 +100,6 @@ type cTag struct {
 }
 
 func (v *Validate) extractStructCache(current reflect.Value, sName string) *cStruct {
-	v.structCache.lock.Lock()
-	defer v.structCache.lock.Unlock() // leave as defer! because if inner panics, it will never get unlocked otherwise!
-
 	typ := current.Type()
 
 	// could have been multiple trying to access, but once first is done this ensures struct
@@ -112,6 +109,9 @@ func (v *Validate) extractStructCache(current reflect.Value, sName string) *cStr
 		return cs
 	}
 
+	v.structCache.lock.Lock()
+	defer v.structCache.lock.Unlock() // leave as defer! because if inner panics, it will never get unlocked otherwise!
+
 	cs = &cStruct{name: sName, fields: make([]*cField, 0), fn: v.structLevelFuncs[typ]}
 
 	numFields := current.NumField()