Enable look-up by secondary index in cache

pkg/client/cache/index.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 cache
+
+import (
+	"fmt"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/meta"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+)
+
+// Indexer is a storage interface that lets you list objects using multiple indexing functions
+type Indexer interface {
+	Store
+	// Retrieve list of objects that match on the named indexing function
+	Index(indexName string, obj interface{}) ([]interface{}, error)
+}
+
+// IndexFunc knows how to provide an indexed value for an object.
+type IndexFunc func(obj interface{}) (string, error)
+
+// MetaNamespaceIndexFunc is a default index function that indexes based on an object's namespace
+func MetaNamespaceIndexFunc(obj interface{}) (string, error) {
+	meta, err := meta.Accessor(obj)
+	if err != nil {
+		return "", fmt.Errorf("object has no meta: %v", err)
+	}
+	return meta.Namespace(), nil
+}
+
+// Index maps the indexed value to a set of keys in the store that match on that value
+type Index map[string]util.StringSet
+
+// Indexers maps a name to a IndexFunc
+type Indexers map[string]IndexFunc
+
+// Indices maps a name to an Index
+type Indices map[string]Index

pkg/client/cache/store.go

@@ -21,6 +21,7 @@ import (
 	"sync"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/meta"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 )
 
 // Store is a generic object storage interface. Reflector knows how to watch a server
@@ -65,6 +66,10 @@ type cache struct {
 	// keyFunc is used to make the key for objects stored in and retrieved from items, and
 	// should be deterministic.
 	keyFunc KeyFunc
+	// indexers maps a name to an IndexFunc
+	indexers Indexers
+	// indices maps a name to an Index
+	indices Indices
 }
 
 // Add inserts an item into the cache.
@@ -73,9 +78,66 @@ func (c *cache) Add(obj interface{}) error {
 	if err != nil {
 		return fmt.Errorf("couldn't create key for object: %v", err)
 	}
+	// keep a pointer to whatever could have been there previously
 	c.lock.Lock()
 	defer c.lock.Unlock()
+	oldObject := c.items[key]
 	c.items[key] = obj
+	c.updateIndices(oldObject, obj)
+	return nil
+}
+
+// updateIndices modifies the objects location in the managed indexes, if this is an update, you must provide an oldObj
+// updateIndices must be called from a function that already has a lock on the cache
+func (c *cache) updateIndices(oldObj interface{}, newObj interface{}) error {
+	// if we got an old object, we need to remove it before we add it again
+	if oldObj != nil {
+		c.deleteFromIndices(oldObj)
+	}
+	key, err := c.keyFunc(newObj)
+	if err != nil {
+		return err
+	}
+	for name, indexFunc := range c.indexers {
+		indexValue, err := indexFunc(newObj)
+		if err != nil {
+			return err
+		}
+		index := c.indices[name]
+		if index == nil {
+			index = Index{}
+			c.indices[name] = index
+		}
+		set := index[indexValue]
+		if set == nil {
+			set = util.StringSet{}
+			index[indexValue] = set
+		}
+		set.Insert(key)
+	}
+	return nil
+}
+
+// deleteFromIndices removes the object from each of the managed indexes
+// it is intended to be called from a function that already has a lock on the cache
+func (c *cache) deleteFromIndices(obj interface{}) error {
+	key, err := c.keyFunc(obj)
+	if err != nil {
+		return err
+	}
+	for name, indexFunc := range c.indexers {
+		indexValue, err := indexFunc(obj)
+		if err != nil {
+			return err
+		}
+		index := c.indices[name]
+		if index != nil {
+			set := index[indexValue]
+			if set != nil {
+				set.Delete(key)
+			}
+		}
+	}
 	return nil
 }
 
@@ -87,7 +149,9 @@ func (c *cache) Update(obj interface{}) error {
 	}
 	c.lock.Lock()
 	defer c.lock.Unlock()
+	oldObject := c.items[key]
 	c.items[key] = obj
+	c.updateIndices(oldObject, obj)
 	return nil
 }
 
@@ -100,6 +164,7 @@ func (c *cache) Delete(obj interface{}) error {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 	delete(c.items, key)
+	c.deleteFromIndices(obj)
 	return nil
 }
 
@@ -115,6 +180,30 @@ func (c *cache) List() []interface{} {
 	return list
 }
 
+// Index returns a list of items that match on the index function
+// Index is thread-safe so long as you treat all items as immutable
+func (c *cache) Index(indexName string, obj interface{}) ([]interface{}, error) {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	indexFunc := c.indexers[indexName]
+	if indexFunc == nil {
+		return nil, fmt.Errorf("Index with name %s does not exist", indexName)
+	}
+
+	indexKey, err := indexFunc(obj)
+	if err != nil {
+		return nil, err
+	}
+	index := c.indices[indexName]
+	set := index[indexKey]
+	list := make([]interface{}, 0, set.Len())
+	for _, key := range set.List() {
+		list = append(list, c.items[key])
+	}
+	return list, nil
+}
+
 // Get returns the requested item, or sets exists=false.
 // Get is completely threadsafe as long as you treat all items as immutable.
 func (c *cache) Get(obj interface{}) (item interface{}, exists bool, err error) {
@@ -150,10 +239,22 @@ func (c *cache) Replace(list []interface{}) error {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 	c.items = items
+
+	// rebuild any index
+	c.indices = Indices{}
+	for _, item := range c.items {
+		c.updateIndices(nil, item)
+	}
+
 	return nil
 }
 
 // NewStore returns a Store implemented simply with a map and a lock.
 func NewStore(keyFunc KeyFunc) Store {
-	return &cache{items: map[string]interface{}{}, keyFunc: keyFunc}
+	return &cache{items: map[string]interface{}{}, keyFunc: keyFunc, indexers: Indexers{}, indices: Indices{}}
+}
+
+// NewIndexer returns an Indexer implemented simply with a map and a lock.
+func NewIndexer(keyFunc KeyFunc, indexers Indexers) Indexer {
+	return &cache{items: map[string]interface{}{}, keyFunc: keyFunc, indexers: indexers, indices: Indices{}}
 }

pkg/client/cache/store_test.go

@@ -86,10 +86,53 @@ func doTestStore(t *testing.T, store Store) {
 	}
 }
 
+// Test public interface
+func doTestIndex(t *testing.T, indexer Indexer) {
+	mkObj := func(id string, val string) testStoreObject {
+		return testStoreObject{id: id, val: val}
+	}
+
+	// Test Index
+	expected := map[string]util.StringSet{}
+	expected["b"] = util.NewStringSet("a", "c")
+	expected["f"] = util.NewStringSet("e")
+	expected["h"] = util.NewStringSet("g")
+	indexer.Add(mkObj("a", "b"))
+	indexer.Add(mkObj("c", "b"))
+	indexer.Add(mkObj("e", "f"))
+	indexer.Add(mkObj("g", "h"))
+	{
+		for k, v := range expected {
+			found := util.StringSet{}
+			indexResults, err := indexer.Index("by_val", mkObj("", k))
+			if err != nil {
+				t.Errorf("Unexpected error %v", err)
+			}
+			for _, item := range indexResults {
+				found.Insert(item.(testStoreObject).id)
+			}
+			items := v.List()
+			if !found.HasAll(items...) {
+				t.Errorf("missing items, index %s, expected %v but found %v", k, items, found.List())
+			}
+		}
+	}
+}
+
 func testStoreKeyFunc(obj interface{}) (string, error) {
 	return obj.(testStoreObject).id, nil
 }
 
+func testStoreIndexFunc(obj interface{}) (string, error) {
+	return obj.(testStoreObject).val, nil
+}
+
+func testStoreIndexers() Indexers {
+	indexers := Indexers{}
+	indexers["by_val"] = testStoreIndexFunc
+	return indexers
+}
+
 type testStoreObject struct {
 	id  string
 	val string
@@ -107,3 +150,7 @@ func TestUndeltaStore(t *testing.T) {
 	nop := func([]interface{}) {}
 	doTestStore(t, NewUndeltaStore(nop, testStoreKeyFunc))
 }
+
+func TestIndex(t *testing.T) {
+	doTestIndex(t, NewIndexer(testStoreKeyFunc, testStoreIndexers()))
+}