Copy packages over from kubebuilder

pkg/client/cache.go

@@ -0,0 +1,308 @@
+package client
+
+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"
+
+	"github.com/kubernetes-sigs/kubebuilder/pkg/informer"
+	logf "github.com/kubernetes-sigs/kubebuilder/pkg/log"
+)
+
+var log = logf.KBLog.WithName("object-cache")
+
+// ObjectCache is a ReadInterface
+var _ ReadInterface = &ObjectCache{}
+
+type ObjectCache struct {
+	cachesByType map[reflect.Type]*SingleObjectCache
+	scheme       *runtime.Scheme
+}
+
+func ObjectCacheFromInformers(informers map[schema.GroupVersionKind]cache.SharedIndexInformer, scheme *runtime.Scheme) *ObjectCache {
+	res := NewObjectCache(scheme)
+	res.AddInformers(informers)
+	return res
+}
+
+func (o *ObjectCache) AddInformers(informers map[schema.GroupVersionKind]cache.SharedIndexInformer) {
+	for gvk, informer := range informers {
+		o.AddInformer(gvk, informer)
+	}
+}
+
+func (o *ObjectCache) Call(gvk schema.GroupVersionKind, c cache.SharedIndexInformer) {
+	o.AddInformer(gvk, c)
+}
+
+func (o *ObjectCache) AddInformer(gvk schema.GroupVersionKind, c cache.SharedIndexInformer) {
+	obj, err := o.scheme.New(gvk)
+	if err != nil {
+		log.Error(err, "could not register informer in ObjectCache for GVK", "GroupVersionKind", gvk)
+		return
+	}
+	if _, found := o.CacheFor(obj); found {
+		return
+	}
+	o.RegisterCache(obj, gvk, c.GetIndexer())
+}
+
+func NewObjectCache(scheme *runtime.Scheme) *ObjectCache {
+	return &ObjectCache{
+		cachesByType: make(map[reflect.Type]*SingleObjectCache),
+		scheme:       scheme,
+	}
+}
+
+func (c *ObjectCache) RegisterCache(obj runtime.Object, gvk schema.GroupVersionKind, store cache.Indexer) {
+	objType := reflect.TypeOf(obj)
+	c.cachesByType[objType] = &SingleObjectCache{
+		Indexer:          store,
+		GroupVersionKind: gvk,
+	}
+}
+
+func (c *ObjectCache) CacheFor(obj runtime.Object) (*SingleObjectCache, bool) {
+	objType := reflect.TypeOf(obj)
+	cache, isKnown := c.cachesByType[objType]
+	return cache, isKnown
+}
+
+func (c *ObjectCache) Get(ctx context.Context, key ObjectKey, out runtime.Object) error {
+	cache, isKnown := c.CacheFor(out)
+	if !isKnown {
+		return fmt.Errorf("no cache for objects of type %T, must have asked for an watch/informer first", out)
+	}
+	return cache.Get(ctx, key, out)
+}
+
+func (c *ObjectCache) List(ctx context.Context, opts *ListOptions, out runtime.Object) error {
+	itemsPtr, err := apimeta.GetItemsPtr(out)
+	if err != nil {
+		return nil
+	}
+	// http://knowyourmeme.com/memes/this-is-fine
+	outType := reflect.Indirect(reflect.ValueOf(itemsPtr)).Type().Elem()
+	cache, isKnown := c.cachesByType[outType]
+	if !isKnown {
+		return fmt.Errorf("no cache for objects of type %T", out)
+	}
+	return cache.List(ctx, opts, out)
+}
+
+// SingleObjectCache is a ReadInterface
+var _ ReadInterface = &SingleObjectCache{}
+
+// SingleObjectCache is a ReadInterface that retrieves objects
+// from a single local cache populated by a watch.
+type SingleObjectCache 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
+}
+
+func (c *SingleObjectCache) Get(_ context.Context, key ObjectKey, out runtime.Object) error {
+	storeKey := objectKeyToStoreKey(key)
+	obj, exists, err := c.Indexer.GetByKey(storeKey)
+	if err != nil {
+		return err
+	}
+	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)
+	}
+	if _, isObj := obj.(runtime.Object); !isObj {
+		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()
+
+	// 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))
+	return nil
+}
+
+func (c *SingleObjectCache) List(ctx context.Context, opts *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 := make([]runtime.Object, 0, len(objs))
+	for _, item := range objs {
+		obj, isObj := item.(runtime.Object)
+		if !isObj {
+			return fmt.Errorf("cache contained %T, which is not an Object", obj)
+		}
+		meta, err := apimeta.Accessor(obj)
+		if err != nil {
+			return err
+		}
+		if labelSel != nil {
+			lbls := labels.Set(meta.GetLabels())
+			if !labelSel.Matches(lbls) {
+				continue
+			}
+		}
+		outItems = append(outItems, obj.DeepCopyObject())
+	}
+	if err := apimeta.SetList(out, outItems); err != nil {
+		return err
+	}
+	return nil
+}
+
+// TODO: Make an interface with this function that has an Informers as an object on the struct
+// that automatically calls InformerFor and passes in the Indexer into IndexByField
+
+// noNamespaceNamespace is used as the "namespace" when we want to list across all namespaces
+const allNamespacesNamespace = "__all_namespaces"
+
+type InformerFieldIndexer struct {
+	Informers informer.Informers
+}
+
+func (i *InformerFieldIndexer) IndexField(obj runtime.Object, field string, extractValue IndexerFunc) error {
+	informer, err := i.Informers.InformerFor(obj)
+	if err != nil {
+		return err
+	}
+	return IndexByField(informer.GetIndexer(), field, extractValue)
+}
+
+// IndexByField adds an indexer to the underlying cache, using extraction function to get
+// value(s) from the given field.  This index can then be used by passing a field selector
+// to List. For one-to-one compatibility with "normal" field selectors, only return one value.
+// The values may be anything.  They will automatically be prefixed with the namespace of the
+// given object, if present.  The objects passed are guaranteed to be objects of the correct type.
+func IndexByField(indexer cache.Indexer, field string, extractor IndexerFunc) error {
+	indexFunc := func(objRaw interface{}) ([]string, error) {
+		// TODO(directxman12): check if this is the correct type?
+		obj, isObj := objRaw.(runtime.Object)
+		if !isObj {
+			return nil, fmt.Errorf("object of type %T is not an Object", objRaw)
+		}
+		meta, err := apimeta.Accessor(obj)
+		if err != nil {
+			return nil, err
+		}
+		ns := meta.GetNamespace()
+
+		rawVals := extractor(obj)
+		var vals []string
+		if ns == "" {
+			// if we're not doubling the keys for the namespaced case, just re-use what was returned to us
+			vals = rawVals
+		} else {
+			// if we need to add non-namespaced versions too, double the length
+			vals = make([]string, len(rawVals)*2)
+		}
+		for i, rawVal := range rawVals {
+			// save a namespaced variant, so that we can ask
+			// "what are all the object matching a given index *in a given namespace*"
+			vals[i] = keyToNamespacedKey(ns, rawVal)
+			if ns != "" {
+				// if we have a namespace, also inject a special index key for listing
+				// regardless of the object namespace
+				vals[i+len(rawVals)] = keyToNamespacedKey("", rawVal)
+			}
+		}
+
+		return vals, nil
+	}
+
+	if err := indexer.AddIndexers(cache.Indexers{fieldIndexName(field): indexFunc}); err != nil {
+		return err
+	}
+	return nil
+}
+
+// fieldIndexName constructs the name of the index over the given field,
+// for use with an Indexer.
+func fieldIndexName(field string) string {
+	return "field:" + field
+}
+
+// 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
+}
+
+// objectKeyToStorageKey converts an object key to store key.
+// It's akin to MetaNamespaceKeyFunc.  It's seperate from
+// String to allow keeping the key format easily in sync with
+// MetaNamespaceKeyFunc.
+func objectKeyToStoreKey(k 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
+}
+
+// SplitReaderWriter forms an interface Interface by composing separate
+// read and write interfaces.  This way, you can have an Interface that
+// reads from a cache and writes to the API server.
+type SplitReaderWriter struct {
+	ReadInterface
+	WriteInterface
+}