[raft/memstore] Add rid memstore

[the-glu]

This PR is part of a new chain, implementing memstore.

#1525 (Generic raftstore) -> #1527 (Base memstore) -> #1529 (Aux memstore) -> #1530 (Snapshots) -> #1534 (Rid memstore) -> #1535 (Correct use of now) -> #1539 (Checkpoint) -> #1542 (Scd memstore) -> #1528 (First PR with raft using memstore)

---

It adds rid memstore, with snapshots.

Tests (minus snapshots & transaction & initialization) are identical to SQL tests and form a big part of this PR. They can be checked locally with e.g. diff pkg/rid/store/memstore/identification_service_area_test.go pkg/rid/store/sqlstore/identification_service_area_test.go

'Strange' behavior with limits has been implemented as-is.

Cell index/optimization is reserved for a future PR to keep this one as simple as possible.

[mickmis]

• None of those are concurrency-safe, that is expected, right? Maybe clarify that in the doc of the memstore.
• Is it planned that this is validated somehow by running the prober test suite against it in the CI? It not, it shoudl

[the-glu]

• None of those are concurrency-safe, that is expected, right? Maybe clarify that in the doc of the memstore.

This was stated in a previous PR and is in the code here: https://github.com/interuss/dss/blob/master/pkg/memstore/store.go#L3

Is that enough?

* Is it planned that this is validated somehow by running the prober test suite against it in the CI? It not, it shoudl

It's not expected for the memstore directly to works again the prober test suite: it mean to be internal only and not used directly via HTTPs call (especially since it's not concurrency-safe, on purpose).

Indirect validation (as underlying storage for the raft implementation) is however done in #1538 (when everything is implemented, so tests pass).

[mickmis]

This was stated in a previous PR and is in the code here: > https://github.com/interuss/dss/blob/master/pkg/memstore/store.go#L3
Is that enough?

OK was not aware of that. Sounds good to me, with just one thing: could you move on Store and/or Init so that it is caught by godoc.

It's not expected for the memstore directly to works again the prober test suite: it mean to be internal only and not used directly via HTTPs call (especially since it's not concurrency-safe, on purpose).

Indirect validation (as underlying storage for the raft implementation) is however done in #1538 (when everything is implemented, so tests pass).

👍

[mickmis]

LGTM

[mickmis]

nice