commit d6b9a238c3305b4c678deea549466d8f490b12af
author Adam Sadovsky <sadovsky@google.com> Tue Jun 16 14:04:45 2015 -0700
committer Adam Sadovsky <sadovsky@google.com> Tue Jun 16 14:08:58 2015 -0700
tree a9c3542340ff90e27d2093c3d0d605ae069e36f6
parent 612b8cbb4635404a25bea8060d05fcbbb8b30d7b

syncbase: BeginBatch() bugfix and restartability TODOs

This CL addresses a few issues uncovered by jlodhia@.

- Makes it so that Database.BeginBatch() fails gracefully if
  the database does not exist (and adds a test).
- Restores the general mechanism for tracking existence in server's
  app/db structs, to prevent this problem from recurring elsewhere.
- Adds TODOs for supporting restartability by making service.apps
  and app.dbs act like lazily-populated caches.

Change-Id: I788d6681c322cd8bc43472b4faa4663235d240c2