Add wrappers for the module module

filter/featureBreaker/mod.go

Index: filter/featureBreaker/mod.go
diff --git a/filter/featureBreaker/mod.go b/filter/featureBreaker/mod.go
new file mode 100644
index 0000000000000000000000000000000000000000..57350bf0fc12b0a967efaee157b4a638db16f552
--- /dev/null
+++ b/filter/featureBreaker/mod.go
@@ -0,0 +1,75 @@
+// Copyright 2016 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"
+
+	"github.com/luci/gae/service/module"
+)
+
+type modState struct {
+	*state
+
+	module.Interface
+}
+
+func (m *modState) List() (ret []string, err error) {
+	err = m.run(func() (err error) {
+		ret, err = m.Interface.List()
+		return
+	})
+	return
+}
+
+func (m *modState) NumInstances(mod, ver string) (ret int, err error) {
+	err = m.run(func() (err error) {
+		ret, err = m.Interface.NumInstances(mod, ver)
+		return
+	})
+	return
+}
+
+func (m *modState) SetNumInstances(mod, ver string, instances int) error {
+	return m.run(func() (err error) {
+		return m.Interface.SetNumInstances(mod, ver, instances)
+	})
+}
+
+func (m *modState) Versions(mod string) (ret []string, err error) {
+	err = m.run(func() (err error) {
+		ret, err = m.Interface.Versions(mod)
+		return
+	})
+	return
+}
+
+func (m *modState) DefaultVersion(mod string) (ret string, err error) {
+	err = m.run(func() (err error) {
+		ret, err = m.Interface.DefaultVersion(mod)
+		return
+	})
+	return
+}
+
+func (m *modState) Start(mod, ver string) error {
+	return m.run(func() (err error) {
+		return m.Interface.Start(mod, ver)
+	})
+}
+
+func (m *modState) Stop(mod, ver string) error {
+	return m.run(func() (err error) {
+		return m.Interface.Stop(mod, ver)
+	})
+}
+
+// FilterModule installs a featureBreaker module filter in the context.
+func FilterModule(c context.Context, defaultError error) (context.Context, FeatureBreaker) {
+	state := newState(defaultError)
+	return module.AddFilters(c, func(ic context.Context, i module.Interface) module.Interface {
+		return &modState{state, i}
+	}), state
+}