Game persistence

[donbonifacio]

This is part of the v0.1 milestone.

We need a way to persist and load games. For v0.1 we only need the game entity. We can have an uuid for players and the uuid will be the only player info for the moment. For the game, we need an indirection that will be able to:

• [ ] Create/Save a game
• [ ] Get a game by id
• [ ] Get the list of games at the lobby

The implementation should:

• [ ] Be an independent module at src/obb/persistence
• [ ] Be a Component
• [ ] Have a core.async interface

The talked about datastore is RethinkDB. The talked about datastore is Datomic. Datomic is not the right persistence solution for the use cases where the system needs a high write throughput, so it is likely that it becomes inappropriate to be the hot storage for games. It is OK for the time being but it is important to keep this in mind.

EDIT: Replace RethinkDB with Datomic (08-05-2016) EDIT: Mention Datomic write throughput tradeoffs (19-06-2016)

[jqmtor]

@donbonifacio Didn't have the chance to read this documents until now. 👍 I think I agree with everything just now. Will start looking into this soon and if I have any new relevant findings, will post them here.

[jqmtor]

After some conversations, we ended up deciding to try out Datomic instead of RethinkDB. The main reasons were:

• Having immutability/historic evolution of state built-in. An alternative that we considered was having a persistent message queue that allowed us to have all evolution in state stored in the form of new events. We ended up choosing Datomic because the message queue would still require us to use a secondary data source for reading.
• Learning new things. This was also one of the reasons to try out RethinkDB, but Datomic seems even more promising.

[jqmtor]

@donbonifacio check if you anything to add/change here.

[donbonifacio]

👍