Refactor serialization helpers from impl/memory -> service/datastore/serialize

Refactor serialization helpers from impl/memory -> service/datastore/serialize

These will be used to aid in joining query results for nested transactions.

R=dnj@chromium.org, estaab@chromium.org, maruel@chromium.org, tandrii@chromium.org, vadimsh@chromium.org
BUG=533021
Committed: https://github.com/luci/gae/commit/26095c34b14a58c20d8415abd8c358e7d89dc3dd

[iannucci, 2015-09-23 20:28:46]

Patchset #2 (id:20001) has been deleted

[iannucci, 2015-09-24 00:01:23]

PTALP

[iannucci, 2015-09-24 18:31:54]

On 2015/09/24 at 00:01:23, iannucci wrote:
> PTALP

ping

[Vadim Sh., 2015-09-24 19:06:14]

lgtm with nits

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_i...
File impl/memory/datastore_index_selection.go (right):

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_i...
impl/memory/datastore_index_selection.go:18: var bjoin = serialize.Join
why?

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_q...
File impl/memory/datastore_query.go (right):

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_q...
impl/memory/datastore_query.go:249: var invert = serialize.Invert
same here. why?

https://codereview.chromium.org/1365743002/diff/40001/service/datastore/seria...
File service/datastore/serialize/binary_tools.go (right):

https://codereview.chromium.org/1365743002/diff/40001/service/datastore/seria...
service/datastore/serialize/binary_tools.go:11: func Join(itms ...[]byte) []byte
{
consider using https://golang.org/pkg/bytes/#Join

https://codereview.chromium.org/1365743002/diff/40001/service/datastore/seria...
service/datastore/serialize/binary_tools.go:43: ret := Join(bstr)
append(nil, bstr...) is a common pattern for copying afaik

[iannucci, 2015-09-24 19:43:41]

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_i...
File impl/memory/datastore_index_selection.go (right):

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_i...
impl/memory/datastore_index_selection.go:18: var bjoin = serialize.Join
On 2015/09/24 at 19:06:14, Vadim Sh. wrote:
> why?

lazy >_< 

fixed.

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_q...
File impl/memory/datastore_query.go (right):

https://codereview.chromium.org/1365743002/diff/40001/impl/memory/datastore_q...
impl/memory/datastore_query.go:249: var invert = serialize.Invert
On 2015/09/24 at 19:06:14, Vadim Sh. wrote:
> same here. why?

same :)

https://codereview.chromium.org/1365743002/diff/40001/service/datastore/seria...
File service/datastore/serialize/binary_tools.go (right):

https://codereview.chromium.org/1365743002/diff/40001/service/datastore/seria...
service/datastore/serialize/binary_tools.go:11: func Join(itms ...[]byte) []byte
{
On 2015/09/24 at 19:06:14, Vadim Sh. wrote:
> consider using https://golang.org/pkg/bytes/#Join

LOL! TIL....

https://codereview.chromium.org/1365743002/diff/40001/service/datastore/seria...
service/datastore/serialize/binary_tools.go:43: ret := Join(bstr)
On 2015/09/24 at 19:06:14, Vadim Sh. wrote:
> append(nil, bstr...) is a common pattern for copying afaik

Hm... Is that efficient? Probably...

It's more verbose though `append([]byte(nil), bstr...)`

[iannucci, 2015-09-24 19:43:48]

The CQ bit was checked by iannucci@chromium.org

[iannucci, 2015-09-24 19:43:49]

The patchset sent to the CQ was uploaded after l-g-t-m from vadimsh@chromium.org
Link to the patchset: https://codereview.chromium.org/1365743002/#ps60001
(title: "fix comments")

[commit-bot: I haz the power, 2015-09-24 19:44:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1365743002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1365743002/60001

[commit-bot: I haz the power, 2015-09-24 19:45:28]

Committed patchset #3 (id:60001) as
https://github.com/luci/gae/commit/26095c34b14a58c20d8415abd8c358e7d89dc3dd