* First pass at RetryWithTx
* Refactor RetryWithTx to take a writable bool (instead of reads, writes)
* Implment DirectiveMethodDiff
This commit adds support for a Directive to contain only the diffs (as
opposed to the full Directive).
* Update controller tests to allow for DirectiveMethodDiff (over Full)
* Update RetryWithTx to retry on duplicate key constraint.
If two concurrent processes call IngestShard() for the same shard, both
were trying to insert the same job into the jobs table. That resulted in
a duplicate key error from the database. We want to include that error
in the list of errors for which RetryWithTx should retry.
* Remove unused method: Directive.TranslatePartitions()
* Replace query in a loop with a single query
We had a query which was looking to see if a job already existed. That
query was inside a loop, and could potentially generate 256 queries (for
example). This commit replaces that logic so that we use a single query
wiht an `IN ()` clause.
* Convert to directive version-by-address
This commit uses a separate directive version per address. It moves the
version get/increment back inside the buildDirective method so that if
two concurrent processes are building a directive for the same address,
one of them will get rolled back trying to commit the version update.
* Migration for directive version by address
* Add a comment about DirectiveVersion lock/unlock logic
* Remove AddLastWins
* fix linter
* handle error in walkdir
* fix test failures from removing AddLastWins
Switch Serverless from using BoltDB to Postgres as metadata store.
Previously, the controller stored all metadata to BoltDB. This implements SQLDB (currently Postgres flavored) as the backing store for metadata. This will allow us to have multiple instances of the controller running for HA, and to easily inspect and repair the contents of the metadata store.
Unfortunately, it was not straightforward to keep the BoltDB implementation working alongside the SQL one, so it will be removed in a later patch. Once that's done, the SQL implementation should allow for a number of simplifications of the schemar and balancer interfaces.
Database migration is built directly into the application by embedding the migration files and logic from the `soda` command line tool. When connecting to the RDBMS, the app will always attempt to create the necessary database and apply any outstanding migrations.
Integration tests truncate all tables upon start, but *not* at the end, so the state of the database can be inspected after integration tests.
Had to refactor some of the controller's background tasks to make sure they get properly shut down on controller exit.
