Add "filters/count" filter.

go/src/infra/gae/libs/gae/filters/count/rds.go

Index: go/src/infra/gae/libs/gae/filters/count/rds.go
diff --git a/go/src/infra/gae/libs/gae/filters/count/rds.go b/go/src/infra/gae/libs/gae/filters/count/rds.go
new file mode 100644
index 0000000000000000000000000000000000000000..20e1caf29fb232a2a3e2b12a22eda603e63b7310
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/filters/count/rds.go
@@ -0,0 +1,104 @@
+// 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"
+
+	"infra/gae/libs/gae"
+)
+
+// RDSCounter is the counter object for the RawDatastore service.
+type RDSCounter struct {
+	NewKey           Entry
+	DecodeKey        Entry
+	NewQuery         Entry
+	Count            Entry
+	RunInTransaction Entry
+	Run              Entry
+	GetAll           Entry
+	Put              Entry
+	Get              Entry
+	Delete           Entry
+	DeleteMulti      Entry
+	GetMulti         Entry
+	PutMulti         Entry
+}
+
+type rdsCounter struct {
+	c *RDSCounter
+
+	rds gae.RawDatastore
+}
+
+var _ gae.RawDatastore = (*rdsCounter)(nil)
+
+func (r *rdsCounter) NewKey(kind, stringID string, intID int64, parent gae.DSKey) gae.DSKey {
+	r.c.NewKey.up()
+	return r.rds.NewKey(kind, stringID, intID, parent)
+}
+
+func (r *rdsCounter) DecodeKey(encoded string) (gae.DSKey, error) {
+	ret, err := r.rds.DecodeKey(encoded)
+	return ret, r.c.DecodeKey.up(err)
+}
+
+func (r *rdsCounter) NewQuery(kind string) gae.DSQuery {
+	r.c.NewQuery.up()
+	return r.rds.NewQuery(kind)
+}
+
+func (r *rdsCounter) Run(q gae.DSQuery) gae.RDSIterator {
+	r.c.Run.up()
+	return r.rds.Run(q)
+}
+
+func (r *rdsCounter) GetAll(q gae.DSQuery, dst *[]gae.DSPropertyMap) ([]gae.DSKey, error) {
+	ret, err := r.rds.GetAll(q, dst)
+	return ret, r.c.GetAll.up(err)
+}
+
+func (r *rdsCounter) Count(q gae.DSQuery) (int, error) {
+	ret, err := r.rds.Count(q)
+	return ret, r.c.Count.up(err)
+}
+
+func (r *rdsCounter) RunInTransaction(f func(context.Context) error, opts *gae.DSTransactionOptions) error {
+	return r.c.RunInTransaction.up(r.rds.RunInTransaction(f, opts))
+}
+
+func (r *rdsCounter) Put(key gae.DSKey, src gae.DSPropertyLoadSaver) (gae.DSKey, error) {
+	ret, err := r.rds.Put(key, src)
+	return ret, r.c.Put.up(err)
+}
+
+func (r *rdsCounter) Get(key gae.DSKey, dst gae.DSPropertyLoadSaver) error {
+	return r.c.Get.up(r.rds.Get(key, dst))
+}
+
+func (r *rdsCounter) Delete(key gae.DSKey) error {
+	return r.c.Delete.up(r.rds.Delete(key))
+}
+
+func (r *rdsCounter) DeleteMulti(keys []gae.DSKey) error {
+	return r.c.DeleteMulti.up(r.rds.DeleteMulti(keys))
+}
+
+func (r *rdsCounter) GetMulti(keys []gae.DSKey, dst []gae.DSPropertyLoadSaver) error {
+	return r.c.GetMulti.up(r.rds.GetMulti(keys, dst))
+}
+
+func (r *rdsCounter) PutMulti(keys []gae.DSKey, src []gae.DSPropertyLoadSaver) ([]gae.DSKey, error) {
+	ret, err := r.rds.PutMulti(keys, src)
+	return ret, r.c.PutMulti.up(err)
+}
+
+// FilterRDS installs a counter RawDatastore filter in the context.
+func FilterRDS(c context.Context) (context.Context, *RDSCounter) {
+	state := &RDSCounter{}
+	return gae.AddRDSFilters(c, func(ic context.Context, rds gae.RawDatastore) gae.RawDatastore {
+		return &rdsCounter{state, rds}
+	}), state
+}