Instead of having two types, we simply have one, called `Entry`, which
we rename from `Change`.
There was no real benefit to having two almost identical types, but lots
of added complexity. This patch simplifies the crate by removing one of
the types.
> I'm going to be making a set of breaking changes to COBs in order to
stabilize the data formats. This is hopefully a one-time change that
bundles various breaking changes.
All COBs have been reworked: issue, patch, id.
The changes included are:
* Revise the assign and tag actions to take a single list of
assignees/tags to set, instead of an "add" and a "remove" list. This
makes API usage simpler when editing issues, and simplifies the apply
function
* Rename "tags" to "labels", and the tag action to label. This is
because tag is confusing in the context of git, as it could mean a git
tag. Using label removes that confusion.
* Use DIDs instead of PublicKeys for assignees -- this is more
future-proof
* Modify the manifest file format in the COB tree. Mainly, remove the
`history_type` key which is redundant, and use camelCase for keys
* Flatten the `Thread` actions into the parent action type
* Ensure that operations on redacted objects do not fail, since
redactions could have happened concurrently
* Use a consistent naming scheme for actions, using `.` as separator
* Consolidate comment types and remove `CodeComment`, by adding an
optional `location` field to `Comment`
* Add many placeholder actions that are not yet implemented
To preserve backwards compatibility, a `legacy` module is created with
the old `apply` function. When loading the manifest, we check whether it
is a legacy COB or a "stable" COB, and in the legacy case, use the
legacy code to materialize the state and then convert the object into
the stable type. Eventually, we'll delete the legacy code.
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
There were a few subtle issues with the apply logic of certain COBs
that should be fixed now.
Note that the underlying store guarantees exactly-once delivery, and so
it does not make sense to test idempotence at the patch level.
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.
Though these are perhaps not the final error types, we name them the same
across COBs and have them work the same way.
All COB modules now have a `Error` enum.
In a future change, we may want the `FromHistory` trait to support
multiple error types, eg. one for `apply` and one for `validate`.
Move `merges` from `Revision` to `Patch`, and key them by actor.
This ensures that only one merge is possible per actor. We also make
sure that only one revision can be merged at a time, and signal a
conflict if more than one revision is considered merged.
Finally, we make sure that merges have the same target-branch commit
to be considered equal.
When a merge is applied to a patch, we check whether the threshold
of delegates has been reached, at which point we set the patch status
to `merged`.
This requires threading the identity document oid through the "apply"
process.
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.
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.
cloudhead
Alexis Sellier