Initial commit

vendor/sigs.k8s.io/controller-runtime/pkg/cache/internal/cache_reader.go

@@ -0,0 +1,187 @@
+/*
+Copyright 2018 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 internal
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+
+	"k8s.io/apimachinery/pkg/api/errors"
+	apimeta "k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/selection"
+	"k8s.io/client-go/tools/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+// CacheReader is a CacheReader
+var _ client.Reader = &CacheReader{}
+
+// CacheReader wraps a cache.Index to implement the client.CacheReader interface for a single type
+type CacheReader struct {
+	// indexer is the underlying indexer wrapped by this cache.
+	indexer cache.Indexer
+
+	// groupVersionKind is the group-version-kind of the resource.
+	groupVersionKind schema.GroupVersionKind
+}
+
+// Get checks the indexer for the object and writes a copy of it if found
+func (c *CacheReader) Get(_ context.Context, key client.ObjectKey, out runtime.Object) error {
+	storeKey := objectKeyToStoreKey(key)
+
+	// Lookup the object from the indexer cache
+	obj, exists, err := c.indexer.GetByKey(storeKey)
+	if err != nil {
+		return err
+	}
+
+	// Not found, return an error
+	if !exists {
+		// Resource gets transformed into Kind in the error anyway, so this is fine
+		return errors.NewNotFound(schema.GroupResource{
+			Group:    c.groupVersionKind.Group,
+			Resource: c.groupVersionKind.Kind,
+		}, key.Name)
+	}
+
+	// Verify the result is a runtime.Object
+	if _, isObj := obj.(runtime.Object); !isObj {
+		// This should never happen
+		return fmt.Errorf("cache contained %T, which is not an Object", obj)
+	}
+
+	// deep copy to avoid mutating cache
+	// TODO(directxman12): revisit the decision to always deepcopy
+	obj = obj.(runtime.Object).DeepCopyObject()
+
+	// Copy the value of the item in the cache to the returned value
+	// TODO(directxman12): this is a terrible hack, pls fix (we should have deepcopyinto)
+	outVal := reflect.ValueOf(out)
+	objVal := reflect.ValueOf(obj)
+	if !objVal.Type().AssignableTo(outVal.Type()) {
+		return fmt.Errorf("cache had type %s, but %s was asked for", objVal.Type(), outVal.Type())
+	}
+	reflect.Indirect(outVal).Set(reflect.Indirect(objVal))
+	out.GetObjectKind().SetGroupVersionKind(c.groupVersionKind)
+
+	return nil
+}
+
+// List lists items out of the indexer and writes them to out
+func (c *CacheReader) List(_ context.Context, opts *client.ListOptions, out runtime.Object) error {
+	var objs []interface{}
+	var err error
+
+	if opts != nil && opts.FieldSelector != nil {
+		// TODO(directxman12): support more complicated field selectors by
+		// combining multiple indicies, GetIndexers, etc
+		field, val, requiresExact := requiresExactMatch(opts.FieldSelector)
+		if !requiresExact {
+			return fmt.Errorf("non-exact field matches are not supported by the cache")
+		}
+		// list all objects by the field selector.  If this is namespaced and we have one, ask for the
+		// namespaced index key.  Otherwise, ask for the non-namespaced variant by using the fake "all namespaces"
+		// namespace.
+		objs, err = c.indexer.ByIndex(FieldIndexName(field), KeyToNamespacedKey(opts.Namespace, val))
+	} else if opts != nil && opts.Namespace != "" {
+		objs, err = c.indexer.ByIndex(cache.NamespaceIndex, opts.Namespace)
+	} else {
+		objs = c.indexer.List()
+	}
+	if err != nil {
+		return err
+	}
+	var labelSel labels.Selector
+	if opts != nil && opts.LabelSelector != nil {
+		labelSel = opts.LabelSelector
+	}
+
+	outItems, err := c.getListItems(objs, labelSel)
+	if err != nil {
+		return err
+	}
+	return apimeta.SetList(out, outItems)
+}
+
+func (c *CacheReader) getListItems(objs []interface{}, labelSel labels.Selector) ([]runtime.Object, error) {
+	outItems := make([]runtime.Object, 0, len(objs))
+	for _, item := range objs {
+		obj, isObj := item.(runtime.Object)
+		if !isObj {
+			return nil, fmt.Errorf("cache contained %T, which is not an Object", obj)
+		}
+		meta, err := apimeta.Accessor(obj)
+		if err != nil {
+			return nil, err
+		}
+		if labelSel != nil {
+			lbls := labels.Set(meta.GetLabels())
+			if !labelSel.Matches(lbls) {
+				continue
+			}
+		}
+		outItems = append(outItems, obj.DeepCopyObject())
+	}
+	return outItems, nil
+}
+
+// objectKeyToStorageKey converts an object key to store key.
+// It's akin to MetaNamespaceKeyFunc.  It's separate from
+// String to allow keeping the key format easily in sync with
+// MetaNamespaceKeyFunc.
+func objectKeyToStoreKey(k client.ObjectKey) string {
+	if k.Namespace == "" {
+		return k.Name
+	}
+	return k.Namespace + "/" + k.Name
+}
+
+// requiresExactMatch checks if the given field selector is of the form `k=v` or `k==v`.
+func requiresExactMatch(sel fields.Selector) (field, val string, required bool) {
+	reqs := sel.Requirements()
+	if len(reqs) != 1 {
+		return "", "", false
+	}
+	req := reqs[0]
+	if req.Operator != selection.Equals && req.Operator != selection.DoubleEquals {
+		return "", "", false
+	}
+	return req.Field, req.Value, true
+}
+
+// FieldIndexName constructs the name of the index over the given field,
+// for use with an indexer.
+func FieldIndexName(field string) string {
+	return "field:" + field
+}
+
+// noNamespaceNamespace is used as the "namespace" when we want to list across all namespaces
+const allNamespacesNamespace = "__all_namespaces"
+
+// KeyToNamespacedKey prefixes the given index key with a namespace
+// for use in field selector indexes.
+func KeyToNamespacedKey(ns string, baseKey string) string {
+	if ns != "" {
+		return ns + "/" + baseKey
+	}
+	return allNamespacesNamespace + "/" + baseKey
+}