369fc76 cob: Use new `Immutable` lattice for merges — heartwood

Radicle Heartwood Protocol & Stack

cob: Use new `Immutable` lattice for merges

Alexis Sellier committed 2 years ago

commit 369fc7637cb7e68a02f115bc6dfd69be15058a09
parent 11b32725c8822ba78ac4387bf6b6ddc6b9d32e95

3 files changed +72 -10

added radicle-crdt/src/immutable.rs

@@ -0,0 +1,52 @@

 use crate::Semilattice;
 /// A [`Semilattice`] that panics when attempting to merge inequal elements.
 /// Use this for types that will never merge.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Immutable<T>(pub T);
 impl<T> Immutable<T> {
     /// Create a new immutable object.
     pub fn new(inner: T) -> Self {
         Self(inner)
     }
 }
 impl<T> std::ops::Deref for Immutable<T> {
     type Target = T;
     fn deref(&self) -> &Self::Target {
         &self.0
     }
 }
 impl<T: PartialEq> Semilattice for Immutable<T> {
     fn merge(&mut self, other: Self) {
         if self.0 != other.0 {
             panic!("Immutable::merge: Cannot merge inequal objects");
         }
     }
 }
 #[cfg(test)]
 mod test {
     use super::*;
     #[test]
     #[should_panic]
     fn test_merge_inequal() {
         let mut a = Immutable::new(0);
         let b = Immutable::new(1);
         a.merge(b);
     }
     #[test]
     fn test_merge_equal() {
         let mut a = Immutable::new(1);
         let b = Immutable::new(1);
         a.merge(b);
         assert_eq!(a, b);
     }
 }

modified radicle-crdt/src/lib.rs

@@ -5,6 +5,7 @@

 pub mod clock;
 pub mod gmap;
 pub mod gset;
 pub mod immutable;
 pub mod lwwmap;
 pub mod lwwreg;
 pub mod lwwset;

@@ -19,6 +20,7 @@ pub mod test;

 pub use clock::Lamport;
 pub use gmap::GMap;
 pub use gset::GSet;
 pub use immutable::Immutable;
 pub use lwwmap::LWWMap;
 pub use lwwreg::LWWReg;
 pub use lwwset::LWWSet;

modified radicle/src/cob/patch.rs

@@ -12,7 +12,9 @@ use serde::{Deserialize, Serialize};

 use thiserror::Error;
 use radicle_crdt::clock;
 use radicle_crdt::{GMap, GSet, LWWMap, LWWReg, LWWSet, Lamport, Max, Redactable, Semilattice};
 use radicle_crdt::{
     GMap, GSet, Immutable, LWWMap, LWWReg, LWWSet, Lamport, Max, Redactable, Semilattice,
 };
 use crate::cob;
 use crate::cob::common::{Author, Tag, Timestamp};

@@ -181,6 +183,7 @@ impl MergeTarget {

     }
 }
 /// Patch CRDT.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Patch {
     /// Title of the patch.

@@ -190,11 +193,20 @@ pub struct Patch {

     /// Target this patch is meant to be merged in.
     target: LWWReg<Max<MergeTarget>>,
     /// Associated tags.
     /// Tags can be added and removed at will.
     tags: LWWSet<Tag>,
     /// Patch merges.
     merges: LWWMap<ActorId, Redactable<Merge>>,
     ///
     /// Only one merge is allowed per user.
     ///
     /// Merges can be removed and replaced, but not modified. Generally, once a revision is merged,
     /// it stays that way. Being able to remove merges may be useful in case of force updates
     /// on the target branch.
     merges: LWWMap<ActorId, Immutable<Merge>>,
     /// List of patch revisions. The initial changeset is part of the
     /// first revision.
     ///
     /// Revisions can be redacted, but are otherwise immutable.
     revisions: GMap<RevisionId, Redactable<Revision>>,
     /// Users assigned to review this patch.
     reviewers: LWWSet<ActorId>,

@@ -304,9 +316,7 @@ impl Patch {

     /// Get the merges.
     pub fn merges(&self) -> impl Iterator<Item = (&ActorId, &Merge)> {
         self.merges
             .iter()
             .filter_map(|(a, m)| m.get().map(|m| (a, m)))
         self.merges.iter().map(|(a, m)| (a, m.deref()))
     }
     /// Reference to the Git object containing the code on the latest revision.

@@ -603,7 +613,7 @@ impl store::FromHistory for Patch {

                         }
                         self.merges.insert(
                             op.author,
                             Redactable::Present(Merge {
                             Immutable::new(Merge {
                                 revision,
                                 commit,
                                 timestamp,

@@ -614,9 +624,7 @@ impl store::FromHistory for Patch {

                         let mut merges = self.merges.iter().fold(
                             HashMap::<(RevisionId, git::Oid), usize>::new(),
                             |mut acc, (_, merge)| {
                                 if let Some(merge) = merge.get() {
                                     *acc.entry((merge.revision, merge.commit)).or_default() += 1;
                                 }
                                 *acc.entry((merge.revision, merge.commit)).or_default() += 1;
                                 acc
                             },
                         );

@@ -1799,7 +1807,7 @@ mod test {

         let (merger, merge) = merges.first().unwrap();
         assert_eq!(*merger, signer.public_key());
         assert_eq!(merge.get().unwrap().commit, pr.base);
         assert_eq!(merge.commit, pr.base);
     }
     #[test]