Add Exists and ExistsMulti convenience methods

Add Exists and ExistsMulti convenience methods

R=dnj@chromium.org, estaab@chromium.org, maruel@chromium.org, tandrii@chromium.org, vadimsh@chromium.org
BUG=

Committed: https://github.com/luci/gae/commit/f94c8e6ebf454d7456f154b1768e4a998f6031c1

[Vadim Sh., 2015-10-13 04:05:57]

lgtm with nits

https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/da...
File service/datastore/datastore.go (right):

https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/da...
service/datastore/datastore.go:189: err := d.RawInterface.GetMulti(keys, nil,
func(_ PropertyMap, err error) {
hm, it looks less magical than in tumble CL... Is it because we are using
RawInterface here?

https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/in...
File service/datastore/interface.go (right):

https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/in...
service/datastore/interface.go:121: // Does a Get for this key and returns true
iff it exists. Will only return
Exists does a get ... Also explain why it is better than using Get(...)
directly.

https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/in...
service/datastore/interface.go:127: ExistsMulti(k []*Key) ([]bool, error)
same here

[iannucci, 2015-10-13 04:19:19]

On 2015/10/13 at 04:05:57, vadimsh wrote:
> lgtm with nits
> 
>
https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/da...
> File service/datastore/datastore.go (right):
> 
>
https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/da...
> service/datastore/datastore.go:189: err := d.RawInterface.GetMulti(keys, nil,
func(_ PropertyMap, err error) {
> hm, it looks less magical than in tumble CL... Is it because we are using
RawInterface here?

Yep. It also avoids some reflection and copying.

> 
>
https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/in...
> File service/datastore/interface.go (right):
> 
>
https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/in...
> service/datastore/interface.go:121: // Does a Get for this key and returns
true iff it exists. Will only return
> Exists does a get ... Also explain why it is better than using Get(...)
directly.
> 
>
https://chromiumcodereview.appspot.com/1398103003/diff/1/service/datastore/in...
> service/datastore/interface.go:127: ExistsMulti(k []*Key) ([]bool, error)
> same here

Done.

[iannucci, 2015-10-13 04:27:11]

The CQ bit was checked by iannucci@chromium.org

[iannucci, 2015-10-13 04:27:12]

The patchset sent to the CQ was uploaded after l-g-t-m from vadimsh@chromium.org
Link to the patchset: https://chromiumcodereview.appspot.com/1398103003/#ps20001
(title: "comments")

[commit-bot: I haz the power, 2015-10-13 04:27:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398103003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398103003/20001

[commit-bot: I haz the power, 2015-10-13 04:30:49]

Committed patchset #2 (id:20001) as
https://github.com/luci/gae/commit/f94c8e6ebf454d7456f154b1768e4a998f6031c1