Add __namespace__ metadata query support to impl/memory.

Add __namespace__ metadata query support to impl/memory.

Ref: https://cloud.google.com/datastore/docs/concepts/metadataqueries

R=dnj@chromium.org
BUG=

Committed: https://github.com/luci/gae/commit/5c6b98bf518b449a30ea8d5488cc1cfc56087bab

[iannucci, 2016-04-15 23:47:48]

https://chromiumcodereview.appspot.com/1892343002/diff/1/service/datastore/qu...
File service/datastore/query.go (right):

https://chromiumcodereview.appspot.com/1892343002/diff/1/service/datastore/qu...
service/datastore/query.go:576: }
This fixes a bug where doing:

  q = Query("Foo").Offset(1)
  Run(q, func(val, getCursor) error {
    assert val.Key.ID == 2 
    curs = getCursor()
    return Stop
  })
  q = q.Start(curs)
  Run(q, func(val) error {
    assert val.Key.ID == 3  // fails: ID == 4 because we applied 
                            // the offset on top of the cursor
    return Stop
  })

[iannucci, 2016-04-16 00:07:38]

Description was changed from

==========
Add __namespace__ metadata query support to impl/memory.

R=dnj@chromium.org
BUG=
==========

to

==========
Add __namespace__ metadata query support to impl/memory.

Ref:
https://github.com/GoogleCloudPlatform/datastore-ndb-python/blob/master/ndb/m...

R=dnj@chromium.org
BUG=
==========

[iannucci, 2016-04-16 00:08:35]

Description was changed from

==========
Add __namespace__ metadata query support to impl/memory.

Ref:
https://github.com/GoogleCloudPlatform/datastore-ndb-python/blob/master/ndb/m...

R=dnj@chromium.org
BUG=
==========

to

==========
Add __namespace__ metadata query support to impl/memory.

Ref: https://cloud.google.com/datastore/docs/concepts/metadataqueries

R=dnj@chromium.org
BUG=
==========

[dnj, 2016-04-16 00:18:26]

lgtm

https://chromiumcodereview.appspot.com/1892343002/diff/1/impl/memory/datastor...
File impl/memory/datastore_query_execution.go (right):

https://chromiumcodereview.appspot.com/1892343002/diff/1/impl/memory/datastor...
impl/memory/datastore_query_execution.go:223: if ns == "" {
WDYT about adding a comment here about how datastore actually uses 1 as key for
empty namesapce, and that this isn't just some trick you're making up here.

[dnj, 2016-04-16 00:19:13]

Actually, want to put a helper function in service/datastore:

func GetNamespaces(c context.Context) ([]string, error)

Since ndb has it, seems useful.

[iannucci, 2016-04-16 00:49:07]

On 2016/04/16 at 00:19:13, dnj wrote:
> Actually, want to put a helper function in service/datastore:
> 
> func GetNamespaces(c context.Context) ([]string, error)
> 
> Since ndb has it, seems useful.

Helpers should be a separate subpackage (probably dsmeta). I don't have
functions for e.g. __entity_group__ right now. I'll file a bug.

[iannucci, 2016-04-16 00:51:52]

https://codereview.chromium.org/1892343002/diff/1/impl/memory/datastore_query...
File impl/memory/datastore_query_execution.go (right):

https://codereview.chromium.org/1892343002/diff/1/impl/memory/datastore_query...
impl/memory/datastore_query_execution.go:223: if ns == "" {
On 2016/04/16 at 00:18:26, dnj wrote:
> WDYT about adding a comment here about how datastore actually uses 1 as key
for empty namesapce, and that this isn't just some trick you're making up here.

Sure. Done.

[iannucci, 2016-04-16 00:51:55]

The CQ bit was checked by iannucci@chromium.org

[iannucci, 2016-04-16 00:51:55]

The patchset sent to the CQ was uploaded after l-g-t-m from dnj@chromium.org
Link to the patchset: https://chromiumcodereview.appspot.com/1892343002/#ps20001
(title: "Add comment")

[commit-bot: I haz the power, 2016-04-16 00:52:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1892343002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1892343002/20001

[commit-bot: I haz the power, 2016-04-16 00:57:21]

Description was changed from

==========
Add __namespace__ metadata query support to impl/memory.

Ref: https://cloud.google.com/datastore/docs/concepts/metadataqueries

R=dnj@chromium.org
BUG=
==========

to

==========
Add __namespace__ metadata query support to impl/memory.

Ref: https://cloud.google.com/datastore/docs/concepts/metadataqueries

R=dnj@chromium.org
BUG=

Committed:
https://github.com/luci/gae/commit/5c6b98bf518b449a30ea8d5488cc1cfc56087bab
==========

[commit-bot: I haz the power, 2016-04-16 00:57:21]

Committed patchset #2 (id:20001) as
https://github.com/luci/gae/commit/5c6b98bf518b449a30ea8d5488cc1cfc56087bab