Add util/restmapper Cached mapper with rate limiting

Signed-off-by: Vince Prignano <vincepri@vmware.com>

util/restmapper/cached.go

@@ -0,0 +1,133 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package restmapper
+
+import (
+	"sync"
+
+	"golang.org/x/time/rate"
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/rest"
+	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
+	"sigs.k8s.io/controller-runtime/pkg/log"
+)
+
+func NewCached(config *rest.Config) meta.RESTMapper {
+	c := &Cached{
+		limiter: rate.NewLimiter(rate.Limit(1), 2),
+		factory: func() (meta.RESTMapper, error) {
+			return apiutil.NewDiscoveryRESTMapper(config)
+		},
+	}
+	c.flush()
+	return c
+}
+
+type Cached struct {
+	sync.Mutex
+
+	limiter *rate.Limiter
+	factory func() (meta.RESTMapper, error)
+	mapper  meta.RESTMapper
+}
+
+func (c *Cached) flush() error {
+	c.Lock()
+	defer c.Unlock()
+
+	var err error
+	if c.mapper == nil || c.limiter.Allow() {
+		c.mapper, err = c.factory()
+	}
+	return err
+}
+
+func (c *Cached) shouldFlushOn(err error) bool {
+	switch err.(type) {
+	case *meta.NoKindMatchError:
+		return true
+	}
+	return false
+}
+
+func (c *Cached) onError(err error) bool {
+	if !c.shouldFlushOn(err) {
+		return false
+	}
+	if err := c.flush(); err != nil {
+		log.Log.Error(err, "failed to reload RESTMapper")
+		return false
+	}
+	return true
+}
+
+func (c *Cached) KindFor(resource schema.GroupVersionResource) (schema.GroupVersionKind, error) {
+	gvk, err := c.mapper.KindFor(resource)
+	if c.onError(err) {
+		gvk, err = c.mapper.KindFor(resource)
+	}
+	return gvk, err
+}
+
+func (c *Cached) KindsFor(resource schema.GroupVersionResource) ([]schema.GroupVersionKind, error) {
+	gvks, err := c.mapper.KindsFor(resource)
+	if c.onError(err) {
+		gvks, err = c.mapper.KindsFor(resource)
+	}
+	return gvks, err
+}
+
+func (c *Cached) ResourceFor(input schema.GroupVersionResource) (schema.GroupVersionResource, error) {
+	gvr, err := c.mapper.ResourceFor(input)
+	if c.onError(err) {
+		gvr, err = c.mapper.ResourceFor(input)
+	}
+	return gvr, err
+}
+
+func (c *Cached) ResourcesFor(input schema.GroupVersionResource) ([]schema.GroupVersionResource, error) {
+	gvrs, err := c.mapper.ResourcesFor(input)
+	if c.onError(err) {
+		gvrs, err = c.mapper.ResourcesFor(input)
+	}
+	return gvrs, err
+}
+
+func (c *Cached) RESTMapping(gk schema.GroupKind, versions ...string) (*meta.RESTMapping, error) {
+	m, err := c.mapper.RESTMapping(gk, versions...)
+	if c.onError(err) {
+		m, err = c.mapper.RESTMapping(gk, versions...)
+	}
+	return m, err
+}
+
+func (c *Cached) RESTMappings(gk schema.GroupKind, versions ...string) ([]*meta.RESTMapping, error) {
+	ms, err := c.mapper.RESTMappings(gk, versions...)
+	if c.onError(err) {
+		ms, err = c.mapper.RESTMappings(gk, versions...)
+	}
+	return ms, err
+}
+
+func (c *Cached) ResourceSingularizer(resource string) (singular string, err error) {
+	s, err := c.mapper.ResourceSingularizer(resource)
+	if c.onError(err) {
+		s, err = c.mapper.ResourceSingularizer(resource)
+	}
+	return s, err
+}