mentat/public-traits/lib.rs
Grisha Kruglov b22b29679b
Basic sync support (#563) r=nalexander
* 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
2018-09-07 19:18:20 -07:00

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Rust

// Copyright 2018 Mozilla
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
// this file except in compliance with the License. You may obtain a copy of the
// License at http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
extern crate failure;
#[macro_use]
extern crate failure_derive;
extern crate rusqlite;
extern crate edn;
extern crate core_traits;
extern crate db_traits;
extern crate query_pull_traits;
extern crate query_projector_traits;
extern crate query_algebrizer_traits;
extern crate sql_traits;
extern crate uuid;
#[cfg(feature = "syncable")]
extern crate tolstoy_traits;
#[cfg(feature = "syncable")]
extern crate hyper;
#[cfg(feature = "syncable")]
extern crate serde_json;
pub mod errors;