* 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
* Part 1: Extract low-level test framework into mentat_db::debug for re-use.
* Part 2: Improve assert_matches!.
This corrects an incorrect pattern: a conversion method taking &self
but returning an owned value should be named like `to_FOO(&self) -> FOO`. (A
reference-to-reference conversion should be named like `as_FOO(&self)
-> &FOO`. A consuming conversion should be named like `into_FOO(self)
-> FOO`.)
In addition, this pushes the conversion via `to_edn` into the
`assert_matches!` macro, which lets consumers get a real data
structure (say, `Datoms`) and use it directly before or after
`assert_matches!`. (Currently, consumers get back `edn::Value`
instances, which aren't nearly as pleasant to use as real data
structures.)
Co-authored-by: Grisha Kruglov <gkruglov@mozilla.com>
* Part 3: Use mentat_db::debug framework in Tolstoy crate.
The advantage of this approach is that compiling Tolstoy (or anything
that's not db, really) can be quite a bit faster than compiling db.
