* Pre: remove remnants of 'open_empty'
* Pre: Cleanup 'datoms' table after a timeline move
Since timeline move operations use a transactor, they generate a
"phantom" 'tx' and a 'txInstant' assertion. It is "phantom" in a sense
that it was never present in the 'transactions' table, and is entirely
synthetic as far as our database is concerned.
It's an implementational artifact, and we were not cleaning it up.
It becomes a problem when we start inserting transactions after a move.
Once the transactor clashes with the phantom 'tx', it will retract the
phantom 'txInstant' value, leaving the transactions log in an incorrect state.
This patch adds a test for this scenario and elects the easy way out: simply
remove the offending 'txInstant' datom.
* Part 1: Sync without support for side-effects
A "side-effect" is defined here as a mutation of a remote state as part
of the sync.
If, during a sync we determine that a remote state needs to be changed, bail out.
This generally supports different variations of "baton-passing" syncing, where clients
will succeed syncing if each change is non-conflicting.
* Part 2: Support basic "side-effects" syncing
This patch introduces a concept of a follow-up sync. If a sync generated
a "merge transaction" (a regular transaction that contains assertions
necessary for local and remote transaction logs to converge), then
this transaction needs to be uploaded in a follow-up sync.
Generated SyncReport indicates if a follow-up sync is required.
Follow-up sync itself is just a regular sync. If remote state did not change,
it will result in a simple RemoteFastForward. Otherwise, we'll continue
merging and requesting a follow-up.
Schema alterations are explicitly not supported.
As local transactions are rebased on top of remote, following changes happen:
- entids are changed into tempids, letting transactor upsert :db/unique values
- entids for retractions are changed into lookup-refs if we're confident they'll succeed
-- otherwise, retractions are dropped on the floor
* Post: use a macro for more readable tests
* Tolstoy README
Sync needs to operate over a "mentat transaction", not just a "db transaction".
This shuffle allows internal mentat crates to consume InProgress, which models
the concept of a "mentat transaction".
This was a work-around for Tolstoy, which couldn't gracefully handle
syncing a store with a bootstrap transaction. Tolstoy now handles
that single transaction, so this is no longer necessary.
* Add a top-level "syncable" feature.
Tested with:
cargo test --all
cargo test --all --no-default-features
cargo build --manifest-path tools/cli/Cargo.toml --no-default-features
cargo run --manifest-path tools/cli/Cargo.toml --no-default-features debugcli
Co-authored-by: Nick Alexander <nalexander@mozilla.com>
* Add 'syncable' feature to 'db' crate to conditionally derive serialization for Partition*
This is leading up to syncing with partition support.
There are a few tricky details to call out here. The first is the
`TransactableValueMarker` trait. This is strictly a marker (like
`Sized`, for example) to give some control over what types can be used
as value types in `Entity` instances. This expression is needed due
to the network of `Into` and `From` relations between the parts of
valid `Entity` instances. This allows to drop the `IntoThing`
work-around trait and use the established patterns. (Observe that
`KnownEntid` makes this a little harder, due to the cross-crate
consistency restrictions.)
The second is that we can get rid `{add,retract}_kw`, since the
network of relations expresses the coercions directly.
The third is that this commit doesn't change the name `TermBuilder`,
even though it is now building `Entity` instances. This is because
there's _already_ an `EntityBuilder` which fixes the `EntityPlace`.
It's not clear whether the existing entity building interface should
be removed or whether both should be renamed. That can be follow-up.
With the transition toward parsing with `rust-peg` and away from
`combine`, we're not using some of the many helpers we built to
support our unusual `combine` usage. They can just go!
I elected to keep Tolstoy using `failure::Error`, because Tolstoy
looks rather more like a high-level application (and will continue to
do so for a while) than a production-ready mid- or low-level API.
