tree a9c3542340ff90e27d2093c3d0d605ae069e36f6
parent 612b8cbb4635404a25bea8060d05fcbbb8b30d7b
author Adam Sadovsky <sadovsky@google.com> 1434488685 -0700
committer Adam Sadovsky <sadovsky@google.com> 1434488938 -0700

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