[uniffi] Remove GroupState type from storage trait (#128)

This removes the `GroupState` type from the `GroupStateStorage` trait
in mls-rs-uniffi. This is done for two reasons:

- It makes all methods on the trait consistent in the way that they
  take a `group_id` as the first argument.

- Fewer types means less boiler-plate generated by the UniFFI bindings
  generator (`Vec<u8>` is a built-in type in UniFFI).

The `EpochRecord` type stays: I don’t think we have a different way of
passing in a vector of epochs IDs with their data.

I could apply this change to mls-rs too, but it doesn’t seem useful
there since it’s cheap and easy to create a new type in Rust.

mls-rs-uniffi/src/config.rs

@@ -42,7 +42,8 @@ impl mls_rs_core::group::GroupStateStorage for ClientGroupStorage {
         updates: Vec<mls_rs_core::group::EpochRecord>,
     ) -> Result<(), Self::Error> {
         self.0.write(
-            state.into(),
+            state.id,
+            state.data,
             inserts.into_iter().map(Into::into).collect(),
             updates.into_iter().map(Into::into).collect(),
         )

mls-rs-uniffi/src/config/group_state.rs

@@ -4,36 +4,18 @@ use std::sync::Mutex;
 
 use crate::Error;
 
-// TODO(mulmarta): we'd like to use GroupState and EpochRecord from mls-rs-core
-// but this breaks python tests because using 2 crates makes uniffi generate
-// a python module which must be in a subdirectory of the directory with test scripts
-// which is not supported by the script we use.
-#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, uniffi::Record)]
-pub struct GroupState {
-    /// A unique group identifier.
-    pub id: Vec<u8>,
-    pub data: Vec<u8>,
-}
-
+// TODO(mulmarta): we'd like to use EpochRecord from mls-rs-core but
+// this breaks the Python tests because using two crates makes UniFFI
+// generate a Python module which must be in a subdirectory of the
+// directory with test scripts which is not supported by the script we
+// use.
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, uniffi::Record)]
 pub struct EpochRecord {
     /// A unique epoch identifier within a particular group.
     pub id: u64,
     pub data: Vec<u8>,
 }
 
-impl From<mls_rs_core::group::GroupState> for GroupState {
-    fn from(mls_rs_core::group::GroupState { id, data }: mls_rs_core::group::GroupState) -> Self {
-        Self { id, data }
-    }
-}
-
-impl From<GroupState> for mls_rs_core::group::GroupState {
-    fn from(GroupState { id, data }: GroupState) -> Self {
-        Self { id, data }
-    }
-}
-
 impl From<mls_rs_core::group::EpochRecord> for EpochRecord {
     fn from(mls_rs_core::group::EpochRecord { id, data }: mls_rs_core::group::EpochRecord) -> Self {
         Self { id, data }
@@ -55,7 +37,8 @@ pub trait GroupStateStorage: Send + Sync + Debug {
 
     async fn write(
         &self,
-        state: GroupState,
+        group_id: Vec<u8>,
+        group_state: Vec<u8>,
         epoch_inserts: Vec<EpochRecord>,
         epoch_updates: Vec<EpochRecord>,
     ) -> Result<(), Error>;
@@ -102,13 +85,14 @@ where
 
     async fn write(
         &self,
-        state: GroupState,
+        id: Vec<u8>,
+        data: Vec<u8>,
         epoch_inserts: Vec<EpochRecord>,
         epoch_updates: Vec<EpochRecord>,
     ) -> Result<(), Error> {
         self.inner()
             .write(
-                state.into(),
+                mls_rs_core::group::GroupState { id, data },
                 epoch_inserts.into_iter().map(Into::into).collect(),
                 epoch_updates.into_iter().map(Into::into).collect(),
             )

mls-rs-uniffi/src/lib.rs

@@ -704,7 +704,7 @@ impl Group {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::config::group_state::{EpochRecord, GroupState, GroupStateStorage};
+    use crate::config::group_state::{EpochRecord, GroupStateStorage};
     use std::collections::HashMap;
 
     #[test]
@@ -754,14 +754,15 @@ mod tests {
 
             fn write(
                 &self,
-                state: GroupState,
+                group_id: Vec<u8>,
+                group_state: Vec<u8>,
                 epoch_inserts: Vec<EpochRecord>,
                 epoch_updates: Vec<EpochRecord>,
             ) -> Result<(), Error> {
                 let mut groups = self.lock();
 
-                let group = groups.entry(state.id).or_default();
-                group.state = state.data;
+                let group = groups.entry(group_id).or_default();
+                group.state = group_state;
                 for insert in epoch_inserts {
                     group.epoch_data.push(insert);
                 }

mls-rs-uniffi/tests/simple_scenario_sync.py

@@ -1,7 +1,7 @@
 from dataclasses import dataclass, field
 
 from mls_rs_uniffi import CipherSuite, generate_signature_keypair, Client, \
-    GroupStateStorage, GroupState, EpochRecord, ClientConfig, ProtocolVersion
+    GroupStateStorage, EpochRecord, ClientConfig, ProtocolVersion
 
 @dataclass
 class GroupStateData:
@@ -32,11 +32,11 @@ def epoch(self, group_id: bytes, epoch_id: int):
 
         return None
 
-    def write(self, state: GroupState, epoch_inserts: list[EpochRecord], epoch_updates: list[EpochRecord]):
-        if self.groups.get(state.id.hex()) == None:
-            self.groups[state.id.hex()] = GroupStateData(state.data)
+    def write(self, group_id: bytes, group_state: bytes, epoch_inserts: list[EpochRecord], epoch_updates: list[EpochRecord]):
+        if self.groups.get(group_id.hex()) == None:
+            self.groups[group_id.hex()] = GroupStateData(group_state)
 
-        group = self.groups[state.id.hex()]
+        group = self.groups[group_id.hex()]
 
         for insert in epoch_inserts:
             group.epoch_data.append(insert)