A transparent cache for datastore, backed by memcache.

filter/dscache/ds_txn.go

Index: filter/dscache/ds_txn.go
diff --git a/filter/dscache/ds_txn.go b/filter/dscache/ds_txn.go
new file mode 100644
index 0000000000000000000000000000000000000000..44142be0f4bf26023150632db43057047365178d
--- /dev/null
+++ b/filter/dscache/ds_txn.go
@@ -0,0 +1,32 @@
+// 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 dscache
+
+import (
+	ds "github.com/luci/gae/service/datastore"
+)
+
+type dsTxnCache struct {
+	ds.RawInterface
+
+	state *dsTxnState
+
+	sc *supportContext

[Vadim Sh., 2015/08/06 01:23:33]

so what happens with Gets in transaction? I'm lost among all context.Context
manipulations and can't figure out what's exactly called in transactions.

[iannucci, 2015/08/06 02:37:33]

documented, but all methods that aren't DeleteMulti or PutMulti just fly
straight through.

+}
+
+var _ ds.RawInterface = (*dsTxnCache)(nil)
+
+func (d *dsTxnCache) DeleteMulti(keys []ds.Key, cb ds.DeleteMultiCB) error {
+	d.state.Add(d.sc, keys)
+	return d.RawInterface.DeleteMulti(keys, cb)
+}
+
+func (d *dsTxnCache) PutMulti(keys []ds.Key, metas []ds.PropertyMap, cb ds.PutMultiCB) error {
+	d.state.Add(d.sc, keys)
+	return d.RawInterface.PutMulti(keys, metas, cb)
+}
+
+// TODO(riannucci): on GetAll, Load from memcache and invalidate entries if the
+// memcache version doesn't match the datastore version.