It turns out that the CRDT formed by the union of Git DAGs
is enough to guarantee everything we need for COBs.
This changes the following things:
* COB operations no longer need to be commutative
* COB histories are traversed in the same deterministic order on all
replicas
* It's now possible to implement RSMs on top of COBs, eg. scripting
* Lamport clocks have been removed
* `radicle-crdt` is no longer a dependency of `radicle`
* COBs are no longer instances of `Semilattice`
* The `Ops` type was removed in favor of having `Op` contain multiple
actions
The additional flexibility in choosing a backend for the COB store will
allow things like "draft" COBs that are stored in a different location,
without changing much of the logic.
We test to make sure that in the event of concurrent operations,
traversal order is deterministic.
This required some changes to the testing infrastructure. We're also
able to simplify the `Actor` type that now has redundant functionality.
Simplify graph traversal and evaluation by building in some of the
functionality into `radicle-dag`, namely the pruning fold.
We avoid building vectors of graph nodes this way, and simply iterate
over the graph in one go.
Allows patches to have their state updated to `Merged` with a `git push`
to the default branch.
Currently, due to the limitations of the COB store, this requires a
linear search through all patches. This will eventually become a problem
when projects have thousands of patches, so we should look into
long-term solutions.
This commit addresses the issue of recursion in the TryFrom
call of Reference by resolving the parent in a lazy way.
Due to constraints posed by the need to access `git2::Repository`
or `git2::Commit` to resolve the parent, this commit decides to
pull out the parent resolution logic from the `cob::object::Commit`
module and move it inside the `cob::store::Store` implementation by adding
a new method `parents_of`.
Suggested-by: Fintan Halpenny <fintan.halpenny@gmail.com>
Tested-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
This change updates to the latest radicle-git-ext, which required a
few changes within the radicle family of crates.
One set of changes is that the radicle-git-ext crate subsumes
git-commit, git-trailers, and git-ref-format -- so all those imports
go through radicle-git-ext.
The commit code requires that parent `Oid`s point to commits, which
made some tests fail. One of the reasons for these failures is that
the patch tests used fabricated `Oid`s and so the verification would
fail. This is fixed by allowing the test context code to create
`PatchRequest`s that create valid commits.
The other reason for failure was that the identity `Action` passed an
`Oid` that pointed to a blob. This is fixed by removing that code and
making a note of it in documentation.
The final major change was moving the Refspec type into git-ref-format
and removing the AsRefspecs trait. The trait was not required and
could its usage could be replaced by simpler code.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
This change ensures that we include as a parent to the initial commit
of a patch COB, the head of the branch we are proposing as a patch.
This was already happening for patch updates, but we forgot to also
include it for the initial patch revision.
This ensures that the code is always fetched alongside the patch.
This allows change commits to have more than one parent that isn't
part of the DAG.
We can use this to create dependencies towards git objects such as
commits, in the case of patch actions.
Revision IDs are globally unique. Users will be able to use the
Revision ID in place of its patch ID.
Make `rad merge` refuse to merge an older revision unless the `--force`
option is given.
By introducing a small limitation: only allowing entries in the change
graph to be addressable, instead of individual operations; we
drastically simplify the CRDT implementation.
There are four advantages:
1. Op ids are just regular SHA-1s
2. There's no need for relative IDs, ops never refer to other ops within the
same commit
3. There's no need for a nonce, since commits can't collide, and neither can op IDs
4. `OpId` can just be an alias of `EntryId`
The disadvantage of course, is that we have to be mindful of how we
create op transactions, since each transaction creates an addressable
unit. For example, we must not include multiple patch revisions in the
same transaction.
Before this change, the identity document would be loaded for the
COB signer. This meant that a fork would be needed for that signer.
After this change, it's no longer necessary, since the identity doc
head is computed from available remotes.
While making those changes, it was also apparent that some of the
identity-related functions had bad names and error types, this
was fixed as well.
It's fairly easy for a user to (by mistake or intentionally) create two
operations with the same OpId. This patch makes it much less likely,
and ensures that if the OpId is equal, it's because the operations
are identical.
The macro in the trailers module existed since there were multiple
trailers before the refactoring, so it minimised boilerplate code.
After the refactoring of the code there was only one trailer
left. Remove the macro generation code and replace it with just the
necessary code for the ResourceCommitTrailer.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
Rust 1.67 was announced[0]. Update the necessary files for running
1.67 and fix the clippy suggestions for string interpolation.
[0]: https://blog.rust-lang.org/2023/01/26/Rust-1.67.0.html
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
We were getting warnings in release mode, since the
debug code is not being run, and some vars are mutable
instead of immutable.
Signed-off-by: Alexis Sellier <alexis@radicle.xyz>
By using `0` as the clock value for an empty state (without operations),
we simplify transaction code. Previously, there was no clock value for
empty states, which meant that we had to sometimes use an `Option`.
* Move storage impl into `storage::cob`
* Rename `change::Create` to `change::Template`
* Rename `change::Storage::create` to `change::Storage::store`
Some of the renames are to further distinguish COBs from Changes, and
the different types of "create" operations within cobs.
Signed-off-by: Alexis Sellier <alexis@radicle.xyz>
We're using petgraph to encode an operation based CRDT (each graph node
is an operation) as a DAG, and one of the important things to ensure
is that the final state is not influenced by the order of concurrent
operations. In this case a concurrent operation would mean two potential
graph traversal orders, as there's no direct edge between the two
concurrent ops. This is essential a "partial order" of operations.
To be able to test this, we'd want some kind of control over how
neighbors are iterated over I guess, when there's more than one possible
sort order. Say we have a graph like this:
┌────────b◄─────┐
▼ │
a d
▲ │
└────────c◄─────┘
There are two possible topological traverse orders: [a, b, c, d] and [a,
c, b, d]. Having a way to go through these different orders would
be super handy.
One option would be to allow random order traversal. This would allow us
to test all orders by running the test enough times to likely test all
permutations.
Since petgraph doesn't support this, we implement our own simple DAG in
`radicle-dag`, which implements random-order topological orders.
For now, we don't make explicit use of these improvements, we simply
replace the underlying graph with our own.
Panic to clear to the operator something is wrong. Panic'ing like this
is ok in debug mode, but must be avoided in production.
Signed-off-by: Slack Coder <slackcoder@server.ky>
Collaborative object IDs are derived from their commit oid. These
IDs must be reproducible to support testing the client's example. All but
one of the parameters used to derive the Object ID is the commit's Author
and committer timestamp.
Introduce an environment variable 'RAD_COMMIT_TIME' to set both Author and
Committer timestamp when creating a commit in the cob module.
Use single variable, instead of Git's two (for author and committer), to
keep the changes simple. The function being modified returns a single
timestamp which is derived from the author's.
Signed-off-by: Slack Coder <slackcoder@server.ky>
We weren't accounting for batches ops in an entry.
This change should account for it by adding N-1
to the clock value of an entry, where N is the number
of entries.
Signed-off-by: Alexis Sellier <alexis@radicle.xyz>
Sometimes it is more efficient to perform multiple operations at once
and store those in the collaborative object graph together.
Change the contents to be a non-empty sequence of byte sequences,
i.e. NonEmpty<Vec<u8>>. These are stored as blobs in a git tree in
order by their index in the non-empty sequence. They are, in turn,
retrieved in order of their original index.
Change the conversion of an `EntryWithClock` to return a non-empty
sequence of `Op`s, which are in turn used to apply many changes in
each `from_history` implementation.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
The latter is a fork of the former, which adds const generics
and a bunch of other quality of life improvements that aren't
in the original crate due to it being unmaintained.
Signed-off-by: Alexis Sellier <alexis@radicle.xyz>
Alexis Sellier
Vincenzo Palazzo
Fintan Halpenny
Slack Coder
Alexis Sellier
