swapped mutex for rwmutex

similiar single-goroutine performance, slightly better concurrent performance.

baked_in.go

@@ -141,18 +141,24 @@ var (
 	}
 )
 
-var oneofValCache = map[string][]string{}
-var oneofValCacheLock = sync.Mutex{}
+var oneofValsCache = map[string][]string{}
+var oneofValsCacheRWLock = sync.RWMutex{}
 
-func isOneOf(fl FieldLevel) bool {
-	param := fl.Param()
-	oneofValCacheLock.Lock()
-	vals, ok := oneofValCache[param]
+func parseOneOfParam2(s string) []string {
+	oneofValsCacheRWLock.RLock()
+	vals, ok := oneofValsCache[s]
+	oneofValsCacheRWLock.RUnlock()
 	if !ok {
-		vals = strings.Fields(param)
-		oneofValCache[param] = vals
+		oneofValsCacheRWLock.Lock()
+		vals = strings.Fields(s)
+		oneofValsCache[s] = vals
+		oneofValsCacheRWLock.Unlock()
 	}
-	oneofValCacheLock.Unlock()
+	return vals
+}
+
+func isOneOf(fl FieldLevel) bool {
+	vals := parseOneOfParam2(fl.Param())
 
 	field := fl.Field()
 

benchmarks_test.go

@@ -1184,3 +1184,27 @@ func BenchmarkStructComplexFailureParallel(b *testing.B) {
 		}
 	})
 }
+
+type TestOneof struct {
+	Color string `validate:"oneof=red green"`
+}
+
+func BenchmarkOneof(b *testing.B) {
+	w := &TestOneof{Color: "green"}
+	val := New()
+	for i := 0; i < b.N; i++ {
+		val.Struct(w)
+	}
+}
+
+func BenchmarkOneofParallel(b *testing.B) {
+	w := &TestOneof{Color: "green"}
+	val := New()
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			val.Struct(w)
+		}
+	})
+}