Add missing Count api

filter/count/rds.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package count
 
 import (
         "golang.org/x/net/context"
 
         ds "github.com/luci/gae/service/datastore"
 )
 
 // DSCounter is the counter object for the datastore service.
 type DSCounter struct {
         AllocateIDs      Entry
         DecodeCursor     Entry
         RunInTransaction Entry
         Run              Entry
+        Count            Entry
         DeleteMulti      Entry
         GetMulti         Entry
         PutMulti         Entry
 }
 
 type dsCounter struct {
         c *DSCounter
 
         ds ds.RawInterface
 }
 
 var _ ds.RawInterface = (*dsCounter)(nil)
 
 func (r *dsCounter) AllocateIDs(incomplete *ds.Key, n int) (int64, error) {
         start, err := r.ds.AllocateIDs(incomplete, n)
         return start, r.c.AllocateIDs.up(err)
 }
 
 func (r *dsCounter) DecodeCursor(s string) (ds.Cursor, error) {
         cursor, err := r.ds.DecodeCursor(s)
         return cursor, r.c.DecodeCursor.up(err)
 }
 
 func (r *dsCounter) Run(q *ds.FinalizedQuery, cb ds.RawRunCB) error {
         return r.c.Run.up(r.ds.Run(q, cb))
 }
 
+func (r *dsCounter) Count(q *ds.FinalizedQuery) (int64, error) {
+        count, err := r.ds.Count(q)
+        return count, r.c.Count.up(err)
+}
+
 func (r *dsCounter) RunInTransaction(f func(context.Context) error, opts *ds.TransactionOptions) error {
         return r.c.RunInTransaction.up(r.ds.RunInTransaction(f, opts))
 }
 
 func (r *dsCounter) DeleteMulti(keys []*ds.Key, cb ds.DeleteMultiCB) error {
         return r.c.DeleteMulti.up(r.ds.DeleteMulti(keys, cb))
 }
 
 func (r *dsCounter) GetMulti(keys []*ds.Key, meta ds.MultiMetaGetter, cb ds.GetMultiCB) error {
         return r.c.GetMulti.up(r.ds.GetMulti(keys, meta, cb))
 }
 
 func (r *dsCounter) PutMulti(keys []*ds.Key, vals []ds.PropertyMap, cb ds.PutMultiCB) error {
         return r.c.PutMulti.up(r.ds.PutMulti(keys, vals, cb))
 }
 
 func (r *dsCounter) Testable() ds.Testable {
         return r.ds.Testable()
 }
 
 // FilterRDS installs a counter datastore filter in the context.
 func FilterRDS(c context.Context) (context.Context, *DSCounter) {
         state := &DSCounter{}
         return ds.AddRawFilters(c, func(ic context.Context, ds ds.RawInterface) ds.RawInterface {
                 return &dsCounter{state, ds}
         }), state
 }