Add missing Count api

filter/featureBreaker/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 featureBreaker
 
 import (
         "golang.org/x/net/context"
 
         ds "github.com/luci/gae/service/datastore"
@@ skipping 22 matching lines @@
         })
         return curs, err
 }
 
 func (r *dsState) Run(q *ds.FinalizedQuery, cb ds.RawRunCB) error {
         return r.run(func() error {
                 return r.rds.Run(q, cb)
         })
 }
 
+func (r *dsState) Count(q *ds.FinalizedQuery) (int64, error) {
+        count := int64(0)
+        err := r.run(func() (err error) {
+                count, err = r.rds.Count(q)
+                return
+        })
+        return count, err
+}
+
 func (r *dsState) RunInTransaction(f func(c context.Context) error, opts *ds.TransactionOptions) error {
         return r.run(func() error {
                 return r.rds.RunInTransaction(f, opts)
         })
 }
 
 // TODO(riannucci): Allow the user to specify a multierror which will propagate
 // to the callback correctly.
 
 func (r *dsState) DeleteMulti(keys []*ds.Key, cb ds.DeleteMultiCB) error {
@@ skipping 18 matching lines @@
         return r.rds.Testable()
 }
 
 // FilterRDS installs a counter datastore filter in the context.
 func FilterRDS(c context.Context, defaultError error) (context.Context, FeatureBreaker) {
         state := newState(defaultError)
         return ds.AddRawFilters(c, func(ic context.Context, RawDatastore ds.RawInterface) ds.RawInterface {
                 return &dsState{state, RawDatastore}
         }), state
 }