Fix race in gkvlite introduced when removing `unsafe`

Fix race in gkvlite introduced when removing `unsafe`

This is very much a giant hammer approach, but it doesn't seem too bad in terms
of performance penalty. We can rip all these hacks out when we're only using
managed VMs instead of classic GAE.

R=vadimsh@chromium.org
BUG=

Committed: 107566880ec5e4c0c2ab65c0329a5ebd4f22bd19

[Vadim Sh., 2015-11-10 19:14:06]

https://chromiumcodereview.appspot.com/1415183010/diff/1/node.go
File node.go (right):

https://chromiumcodereview.appspot.com/1415183010/diff/1/node.go#newcode66
node.go:66: nodeLocGL.Unlock()
wat? did you forget "defer"?

Also you can access src.loc and src.node directly while holding the lock
(instead of taking and releasing it in LocNode).

[iannucci, 2015-11-10 20:06:54]

On 2015/11/10 at 19:14:06, vadimsh wrote:
> https://chromiumcodereview.appspot.com/1415183010/diff/1/node.go
> File node.go (right):
> 
> https://chromiumcodereview.appspot.com/1415183010/diff/1/node.go#newcode66
> node.go:66: nodeLocGL.Unlock()
> wat? did you forget "defer"?
> 
> Also you can access src.loc and src.node directly while holding the lock
(instead of taking and releasing it in LocNode).

oops... fixed >_<

[Vadim Sh., 2015-11-10 20:07:34]

lgtm

[iannucci, 2015-11-10 20:10:43]

Committed patchset #2 (id:20001) manually as
107566880ec5e4c0c2ab65c0329a5ebd4f22bd19 (presubmit successful).