Refactor current GAE abstraction library to be free of the SDK*

go/src/infra/gae/libs/gae/prod/memcache.go

Index: go/src/infra/gae/libs/gae/prod/memcache.go
diff --git a/go/src/infra/gae/libs/gae/prod/memcache.go b/go/src/infra/gae/libs/gae/prod/memcache.go
new file mode 100644
index 0000000000000000000000000000000000000000..8482d2b2d4fab24d5556c03ff315a72371039a3d
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/prod/memcache.go
@@ -0,0 +1,156 @@
+// 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 prod
+
+import (
+	"golang.org/x/net/context"
+	"time"
+
+	"infra/gae/libs/gae"
+
+	"google.golang.org/appengine/memcache"
+)
+
+// useMC adds a gae.Memcache implementation to context, accessible
+// by gae.GetMC(c)
+func useMC(c context.Context) context.Context {
+	return gae.SetMCFactory(c, func(ci context.Context) gae.Memcache {
+		return mcImpl{ci}
+	})
+}
+
+type mcImpl struct{ context.Context }
+
+type mcItem struct {
+	i *memcache.Item
+}
+
+var _ gae.MCItem = mcItem{}
+
+func (i mcItem) Key() string               { return i.i.Key }
+func (i mcItem) Value() []byte             { return i.i.Value }
+func (i mcItem) Object() interface{}       { return i.i.Object }
+func (i mcItem) Flags() uint32             { return i.i.Flags }
+func (i mcItem) Expiration() time.Duration { return i.i.Expiration }
+
+func (i mcItem) SetKey(k string) gae.MCItem {
+	i.i.Key = k
+	return i
+}
+func (i mcItem) SetValue(v []byte) gae.MCItem {
+	i.i.Value = v
+	return i
+}
+func (i mcItem) SetObject(o interface{}) gae.MCItem {
+	i.i.Object = o
+	return i
+}
+func (i mcItem) SetFlags(f uint32) gae.MCItem {
+	i.i.Flags = f
+	return i
+}
+func (i mcItem) SetExpiration(d time.Duration) gae.MCItem {
+	i.i.Expiration = d
+	return i
+}
+
+// mcR2FErr (MC real-to-fake w/ error) converts a *memcache.Item to a gae.MCItem,
+// and passes along an error.
+func mcR2FErr(i *memcache.Item, err error) (gae.MCItem, error) {
+	if err != nil {
+		return nil, err
+	}
+	return mcItem{i}, nil
+}
+
+// mcF2R (MC fake-to-real) converts a gae.MCItem. i must originate from inside
+// this package for this function to work (see the panic message for why).
+func mcF2R(i gae.MCItem) *memcache.Item {
+	if mci, ok := i.(mcItem); ok {
+		return mci.i
+	}
+	panic(
+		"you may not use other gae.MCItem implementations with this " +
+			"implementation of gae.Memcache, since it will cause all CompareAndSwap " +
+			"operations to fail. Please use the NewItem api instead.")
+}
+
+// mcMF2R (MC multi-fake-to-real) converts a slice of gae.MCItem to a slice of
+// *memcache.Item.
+func mcMF2R(items []gae.MCItem) []*memcache.Item {
+	realItems := make([]*memcache.Item, len(items))
+	for i, itm := range items {
+		realItems[i] = mcF2R(itm)
+	}
+	return realItems
+}
+
+func (m mcImpl) NewItem(key string) gae.MCItem {
+	return mcItem{&memcache.Item{Key: key}}
+}
+
+//////// MCSingleReadWriter
+func (m mcImpl) Add(item gae.MCItem) error {
+	return memcache.Add(m.Context, mcF2R(item))
+}
+func (m mcImpl) Set(item gae.MCItem) error {
+	return memcache.Set(m.Context, mcF2R(item))
+}
+func (m mcImpl) Delete(key string) error {
+	return memcache.Delete(m.Context, key)
+}
+func (m mcImpl) Get(key string) (gae.MCItem, error) {
+	return mcR2FErr(memcache.Get(m.Context, key))
+}
+func (m mcImpl) CompareAndSwap(item gae.MCItem) error {
+	return memcache.CompareAndSwap(m.Context, mcF2R(item))
+}
+
+//////// MCMultiReadWriter
+func (m mcImpl) DeleteMulti(keys []string) error {
+	return gae.FixError(memcache.DeleteMulti(m.Context, keys))
+}
+func (m mcImpl) AddMulti(items []gae.MCItem) error {
+	return gae.FixError(memcache.AddMulti(m.Context, mcMF2R(items)))
+}
+func (m mcImpl) SetMulti(items []gae.MCItem) error {
+	return gae.FixError(memcache.SetMulti(m.Context, mcMF2R(items)))
+}
+func (m mcImpl) GetMulti(keys []string) (map[string]gae.MCItem, error) {
+	realItems, err := memcache.GetMulti(m.Context, keys)
+	if err != nil {
+		return nil, gae.FixError(err)
+	}
+	items := make(map[string]gae.MCItem, len(realItems))
+	for k, itm := range realItems {
+		items[k] = mcItem{itm}
+	}
+	return items, err
+}
+func (m mcImpl) CompareAndSwapMulti(items []gae.MCItem) error {
+	return gae.FixError(memcache.CompareAndSwapMulti(m.Context, mcMF2R(items)))
+}
+
+//////// MCIncrementer
+func (m mcImpl) Increment(key string, delta int64, initialValue uint64) (uint64, error) {
+	return memcache.Increment(m.Context, key, delta, initialValue)
+}
+func (m mcImpl) IncrementExisting(key string, delta int64) (uint64, error) {
+	return memcache.IncrementExisting(m.Context, key, delta)
+}
+
+//////// MCFlusher
+func (m mcImpl) Flush() error {
+	return memcache.Flush(m.Context)
+}
+
+//////// MCStatter
+func (m mcImpl) Stats() (*gae.MCStatistics, error) {
+	stats, err := memcache.Stats(m.Context)
+	if err != nil {
+		return nil, err
+	}
+	return (*gae.MCStatistics)(stats), nil
+}