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

go/src/infra/gae/epservice/example/service_cas.go

Index: go/src/infra/gae/epservice/example/service_cas.go
diff --git a/go/src/infra/gae/epservice/example/service_cas.go b/go/src/infra/gae/epservice/example/service_cas.go
index f01804ec488218dcbfcd47732a3885d8319f929f..4c2d8214f9cf0d303b2e3ac198d835edffc1ab3b 100644
--- a/go/src/infra/gae/epservice/example/service_cas.go
+++ b/go/src/infra/gae/epservice/example/service_cas.go
@@ -6,8 +6,8 @@ package example
 
 import (
 	"golang.org/x/net/context"
-	"infra/gae/libs/wrapper"
-	"infra/gae/libs/wrapper/gae"
+	"infra/gae/libs/gae"
+	"infra/gae/libs/gae/prod"
 
 	"github.com/GoogleCloudPlatform/go-endpoints/endpoints"
 )
@@ -21,18 +21,20 @@ type CASReq struct {
 }
 
 // CAS does an atomic compare-and-swap on a counter.
-func (Example) CAS(c endpoints.Context, r *CASReq) (err error) {
+func (Example) CAS(c context.Context, r *CASReq) (err error) {
 	success := false
-	ds := wrapper.GetDS(gae.Use(context.Background(), c))
-	err = ds.RunInTransaction(func(context.Context) error {
-		ctr := &Counter{ID: r.Name}
-		if err := ds.Get(ctr); err != nil {
+	c = prod.Use(c)
+	err = gae.GetRDS(c).RunInTransaction(func(c context.Context) error {
+		rds := gae.GetRDS(c)
+		key := rds.NewKey("Counter", r.Name, 0, nil)
+		ctr := &Counter{}
+		if err := rds.Get(key, ctr); err != nil {
 			return err
 		}
 		if ctr.Val == r.OldVal {
 			success = true
 			ctr.Val = r.NewVal
-			_, err := ds.Put(ctr)
+			_, err := rds.Put(key, ctr)
 			return err
 		}
 		success = false