mentat/tolstoy-traits/errors.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

115 lines
3.3 KiB
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.
use std;
use std::error::Error;
use rusqlite;
use uuid;
use hyper;
use serde_json;
use db_traits::errors::{
DbError,
};
#[derive(Debug, Fail)]
pub enum TolstoyError {
#[fail(display = "Received bad response from the remote: {}", _0)]
BadRemoteResponse(String),
// TODO expand this into concrete error types
#[fail(display = "Received bad remote state: {}", _0)]
BadRemoteState(String),
#[fail(display = "encountered more than one metadata value for key: {}", _0)]
DuplicateMetadata(String),
#[fail(display = "transaction processor didn't say it was done")]
TxProcessorUnfinished,
#[fail(display = "expected one, found {} uuid mappings for tx", _0)]
TxIncorrectlyMapped(usize),
#[fail(display = "encountered unexpected state: {}", _0)]
UnexpectedState(String),
#[fail(display = "not yet implemented: {}", _0)]
NotYetImplemented(String),
#[fail(display = "{}", _0)]
DbError(#[cause] DbError),
#[fail(display = "{}", _0)]
SerializationError(#[cause] serde_json::Error),
// It would be better to capture the underlying `rusqlite::Error`, but that type doesn't
// implement many useful traits, including `Clone`, `Eq`, and `PartialEq`.
#[fail(display = "SQL error: {}, cause: {}", _0, _1)]
RusqliteError(String, String),
#[fail(display = "{}", _0)]
IoError(#[cause] std::io::Error),
#[fail(display = "{}", _0)]
UuidError(#[cause] uuid::ParseError),
#[fail(display = "{}", _0)]
NetworkError(#[cause] hyper::Error),
#[fail(display = "{}", _0)]
UriError(#[cause] hyper::error::UriError),
}
impl From<DbError> for TolstoyError {
fn from(error: DbError) -> TolstoyError {
TolstoyError::DbError(error)
}
}
impl From<serde_json::Error> for TolstoyError {
fn from(error: serde_json::Error) -> TolstoyError {
TolstoyError::SerializationError(error)
}
}
impl From<rusqlite::Error> for TolstoyError {
fn from(error: rusqlite::Error) -> TolstoyError {
let cause = match error.cause() {
Some(e) => e.to_string(),
None => "".to_string()
};
TolstoyError::RusqliteError(error.to_string(), cause)
}
}
impl From<std::io::Error> for TolstoyError {
fn from(error: std::io::Error) -> TolstoyError {
TolstoyError::IoError(error)
}
}
impl From<uuid::ParseError> for TolstoyError {
fn from(error: uuid::ParseError) -> TolstoyError {
TolstoyError::UuidError(error)
}
}
impl From<hyper::Error> for TolstoyError {
fn from(error: hyper::Error) -> TolstoyError {
TolstoyError::NetworkError(error)
}
}
impl From<hyper::error::UriError> for TolstoyError {
fn from(error: hyper::error::UriError) -> TolstoyError {
TolstoyError::UriError(error)
}
}