Interface update, per-method Contexts.

service/datastore/meta/eg.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package meta
 
 import (
-        "github.com/luci/gae/service/datastore"
+        ds "github.com/luci/gae/service/datastore"
+
         "golang.org/x/net/context"
 )
 
 // EntityGroupMeta is the model corresponding to the __entity_group__ model in
 // appengine. You shouldn't need to use this struct directly, but instead should
 // use GetEntityGroupVersion.
 type EntityGroupMeta struct {
-        kind   string         `gae:"$kind,__entity_group__"`
-        id     int64          `gae:"$id,1"`
-        Parent *datastore.Key `gae:"$parent"`
+        kind   string  `gae:"$kind,__entity_group__"`
+        id     int64   `gae:"$id,1"`
+        Parent *ds.Key `gae:"$parent"`
 
         Version int64 `gae:"__version__"`
 }
 
 // GetEntityGroupVersion returns the entity group version for the entity group
 // containing root. If the entity group doesn't exist, this function will return
 // zero and a nil error.
-func GetEntityGroupVersion(c context.Context, key *datastore.Key) (int64, error) {
-        ds := datastore.Get(c)
+func GetEntityGroupVersion(c context.Context, key *ds.Key) (int64, error) {
         egm := &EntityGroupMeta{Parent: key.Root()}
-        err := ds.Get(egm)
+        err := ds.Get(c, egm)
         ret := egm.Version
-        if err == datastore.ErrNoSuchEntity {
+        if err == ds.ErrNoSuchEntity {
                 // this is OK for callers. The version of the entity group is effectively 0
                 // in this case.
                 err = nil
         }
         return ret, err
 }