Allow for selector creation without validation

pkg/labels/labels.go

@@ -61,6 +61,15 @@ func (ls Set) AsSelector() Selector {
 	return SelectorFromSet(ls)
 }
 
+// ValidatedAsSelector converts labels into a selector, but
+// assumes that labels are already validated and thus don't
+// preform any validation.
+// According to our measurements this is significantly faster
+// in codepaths that matter at high sccale.
+func (ls Set) AsSelectorPreValidated() Selector {
+	return SelectorFromValidatedSet(ls)
+}
+
 // FormatLables convert label map into plain string
 func FormatLabels(labelMap map[string]string) string {
 	l := Set(labelMap).String()

pkg/labels/selector.go

@@ -796,6 +796,22 @@ func SelectorFromSet(ls Set) Selector {
 	return internalSelector(requirements)
 }
 
+// SelectorFromValidatedSet returns a Selector which will match exactly the given Set.
+// A nil and empty Sets are considered equivalent to Everything().
+// It assumes that Set is already validated and doesn't do any validation.
+func SelectorFromValidatedSet(ls Set) Selector {
+	if ls == nil {
+		return internalSelector{}
+	}
+	var requirements internalSelector
+	for label, value := range ls {
+		requirements = append(requirements, Requirement{key: label, operator: selection.Equals, strValues: sets.NewString(value)})
+	}
+	// sort to have deterministic string representation
+	sort.Sort(ByKey(requirements))
+	return internalSelector(requirements)
+}
+
 // ParseToRequirements takes a string representing a selector and returns a list of
 // requirements. This function is suitable for those callers that perform additional
 // processing on selector requirements.