libnetwork/datastore: unconditionally use ds.cache

ds.cache is never nil so the uncached code paths are unreachable in
practice. And given how many KVObject deep-copy implementations shallow
copy pointers and other reference-typed values, there is the distinct
possibility that disabling the datastore cache could break things.

Signed-off-by: Cory Snider <csnider@mirantis.com>

libnetwork/datastore/cache.go

@@ -1,7 +1,6 @@
 package datastore
 
 import (
-	"errors"
 	"fmt"
 	"sync"
 
@@ -34,12 +33,6 @@ func (c *cache) kmap(kvObject KVObject) (kvMap, error) {
 
 	kmap = kvMap{}
 
-	// Bail out right away if the kvObject does not implement KVConstructor
-	ctor, ok := kvObject.(KVConstructor)
-	if !ok {
-		return nil, errors.New("error while populating kmap, object does not implement KVConstructor interface")
-	}
-
 	kvList, err := c.ds.List(keyPrefix)
 	if err != nil {
 		if err == store.ErrKeyNotFound {
@@ -57,7 +50,7 @@ func (c *cache) kmap(kvObject KVObject) (kvMap, error) {
 			continue
 		}
 
-		dstO := ctor.New()
+		dstO := kvObject.New()
 		err = dstO.SetValue(kvPair.Value)
 		if err != nil {
 			return nil, err
@@ -152,12 +145,7 @@ func (c *cache) get(kvObject KVObject) error {
 		return ErrKeyNotFound
 	}
 
-	ctor, ok := o.(KVConstructor)
-	if !ok {
-		return errors.New("kvobject does not implement KVConstructor interface. could not get object")
-	}
-
-	return ctor.CopyTo(kvObject)
+	return o.CopyTo(kvObject)
 }
 
 func (c *cache) list(kvObject KVObject) ([]KVObject, error) {

libnetwork/datastore/datastore.go

@@ -47,10 +47,6 @@ type KVObject interface {
 	DataScope() string
 	// Skip provides a way for a KV Object to avoid persisting it in the KV Store
 	Skip() bool
-}
-
-// KVConstructor interface defines methods which can construct a KVObject from another.
-type KVConstructor interface {
 	// New returns a new object which is created based on the
 	// source object
 	New() KVObject
@@ -232,13 +228,9 @@ func (ds *Store) PutObjectAtomic(kvObject KVObject) error {
 	kvObject.SetIndex(pair.LastIndex)
 
 add_cache:
-	if ds.cache != nil {
-		// If persistent store is skipped, sequencing needs to
-		// happen in cache.
-		return ds.cache.add(kvObject, kvObject.Skip())
-	}
-
-	return nil
+	// If persistent store is skipped, sequencing needs to
+	// happen in cache.
+	return ds.cache.add(kvObject, kvObject.Skip())
 }
 
 // GetObject gets data from the store and unmarshals to the specified object.
@@ -246,23 +238,7 @@ func (ds *Store) GetObject(key string, o KVObject) error {
 	ds.mu.Lock()
 	defer ds.mu.Unlock()
 
-	if ds.cache != nil {
-		return ds.cache.get(o)
-	}
-
-	kvPair, err := ds.store.Get(key)
-	if err != nil {
-		return err
-	}
-
-	if err := o.SetValue(kvPair.Value); err != nil {
-		return err
-	}
-
-	// Make sure the object has a correct view of the DB index in
-	// case we need to modify it and update the DB.
-	o.SetIndex(kvPair.LastIndex)
-	return nil
+	return ds.cache.get(o)
 }
 
 func (ds *Store) ensureParent(parent string) error {
@@ -282,27 +258,10 @@ func (ds *Store) List(key string, kvObject KVObject) ([]KVObject, error) {
 	ds.mu.Lock()
 	defer ds.mu.Unlock()
 
-	if ds.cache != nil {
-		return ds.cache.list(kvObject)
-	}
-
-	var kvol []KVObject
-	err := ds.iterateKVPairsFromStore(key, kvObject, func(key string, val KVObject) {
-		kvol = append(kvol, val)
-	})
-	if err != nil {
-		return nil, err
-	}
-	return kvol, nil
+	return ds.cache.list(kvObject)
 }
 
-func (ds *Store) iterateKVPairsFromStore(key string, kvObject KVObject, callback func(string, KVObject)) error {
-	// Bail out right away if the kvObject does not implement KVConstructor
-	ctor, ok := kvObject.(KVConstructor)
-	if !ok {
-		return fmt.Errorf("error listing objects, object does not implement KVConstructor interface")
-	}
-
+func (ds *Store) iterateKVPairsFromStore(key string, ctor KVObject, callback func(string, KVObject)) error {
 	// Make sure the parent key exists
 	if err := ds.ensureParent(key); err != nil {
 		return err
@@ -372,11 +331,7 @@ func (ds *Store) DeleteObjectAtomic(kvObject KVObject) error {
 
 deleteCache:
 	// cleanup the cache only if AtomicDelete went through successfully
-	if ds.cache != nil {
-		// If persistent store is skipped, sequencing needs to
-		// happen in cache.
-		return ds.cache.del(kvObject, kvObject.Skip())
-	}
-
-	return nil
+	// If persistent store is skipped, sequencing needs to
+	// happen in cache.
+	return ds.cache.del(kvObject, kvObject.Skip())
 }

libnetwork/datastore/datastore_test.go

@@ -14,7 +14,8 @@ const dummyKey = "dummy"
 
 // NewTestDataStore can be used by other Tests in order to use custom datastore
 func NewTestDataStore() *Store {
-	return &Store{scope: scope.Local, store: NewMockStore()}
+	s := NewMockStore()
+	return &Store{scope: scope.Local, store: s, cache: newCache(s)}
 }
 
 func TestKey(t *testing.T) {
@@ -157,6 +158,18 @@ func (n *dummyObject) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+func (n *dummyObject) New() KVObject {
+	return &dummyObject{}
+}
+
+func (n *dummyObject) CopyTo(o KVObject) error {
+	if err := o.SetValue(n.Value()); err != nil {
+		return err
+	}
+	o.SetIndex(n.Index())
+	return nil
+}
+
 // dummy structure to test "recursive" cases
 type recStruct struct {
 	Name     string            `kv:"leaf"`

libnetwork/datastore/mockstore_test.go

@@ -1,7 +1,7 @@
 package datastore
 
 import (
-	"errors"
+	"strings"
 
 	store "github.com/docker/docker/libnetwork/internal/kvstore"
 	"github.com/docker/docker/libnetwork/types"
@@ -52,7 +52,16 @@ func (s *MockStore) Exists(key string) (bool, error) {
 
 // List gets a range of values at "directory"
 func (s *MockStore) List(prefix string) ([]*store.KVPair, error) {
-	return nil, errors.New("not implemented")
+	var res []*store.KVPair
+	for k, v := range s.db {
+		if strings.HasPrefix(k, prefix) {
+			res = append(res, &store.KVPair{Key: k, Value: v.Data, LastIndex: v.Index})
+		}
+	}
+	if len(res) == 0 {
+		return nil, store.ErrKeyNotFound
+	}
+	return res, nil
 }
 
 // AtomicPut put a value at "key" if the key has not been