feat: remove old DKG sessions

src/consensus/dkg.rs

@@ -105,16 +105,17 @@ impl DkgVoter {
         keypair: &Keypair,
         dkg_key: DkgKey,
         elders_info: EldersInfo,
+        key_index: u64,
     ) -> Vec<DkgCommand> {
         if let Some(session) = self.sessions.get(&dkg_key) {
-            if !session.complete {
+            if !session.complete && session.key_index >= key_index {
                 trace!("DKG for {} already in progress", elders_info);
                 return vec![];
             }
         }
 
         let name = crypto::name(&keypair.public);
-        let index = if let Some(index) = elders_info.position(&name) {
+        let participant_index = if let Some(index) = elders_info.position(&name) {
             index
         } else {
             error!(
@@ -132,7 +133,7 @@ impl DkgVoter {
                 elders_info,
                 outcome: SectionKeyShare {
                     public_key_set: secret_key_set.public_keys(),
-                    index,
+                    index: participant_index,
                     secret_key_share: secret_key_set.secret_key_share(0),
                 },
             }];
@@ -153,7 +154,8 @@ impl DkgVoter {
                 let mut session = Session {
                     key_gen,
                     elders_info,
-                    index,
+                    key_index,
+                    participant_index,
                     timer_token: 0,
                     failures: Default::default(),
                     complete: false,
@@ -169,6 +171,8 @@ impl DkgVoter {
                 );
 
                 let _ = self.sessions.insert(dkg_key, session);
+                self.sessions
+                    .retain(|_, session| session.key_index >= key_index);
 
                 commands
             }
@@ -222,8 +226,10 @@ impl DkgVoter {
 // Data for a DKG participant.
 struct Session {
     elders_info: EldersInfo,
+    // Section chain index of the key to be generated.
+    key_index: u64,
     // Our participant index.
-    index: usize,
+    participant_index: usize,
     key_gen: KeyGen,
     timer_token: u64,
     failures: DkgFailureProofSet,
@@ -266,7 +272,7 @@ impl Session {
         self.elders_info
             .peers()
             .enumerate()
-            .filter(|(index, _)| *index != self.index)
+            .filter(|(index, _)| *index != self.participant_index)
             .map(|(_, peer)| peer.addr())
             .copied()
             .collect()
@@ -345,7 +351,7 @@ impl Session {
 
             let outcome = SectionKeyShare {
                 public_key_set: outcome.public_key_set,
-                index: self.index,
+                index: self.participant_index,
                 secret_key_share: outcome.secret_key_share,
             };
 
@@ -672,7 +678,7 @@ mod tests {
         let elders_info = EldersInfo::new(iter::once(node.peer()), Prefix::default());
         let dkg_key = DkgKey::new(&elders_info);
 
-        let commands = voter.start(&node.keypair, dkg_key, elders_info);
+        let commands = voter.start(&node.keypair, dkg_key, elders_info, 0);
         assert_matches!(&commands[..], &[DkgCommand::HandleOutcome { .. }]);
     }
 
@@ -702,7 +708,7 @@ mod tests {
         for actor in actors.values_mut() {
             let commands = actor
                 .voter
-                .start(&actor.node.keypair, dkg_key, elders_info.clone());
+                .start(&actor.node.keypair, dkg_key, elders_info.clone(), 0);
 
             for command in commands {
                 messages.extend(actor.handle(command, &dkg_key))

src/messages/variant.rs

@@ -86,6 +86,8 @@ pub(crate) enum Variant {
         dkg_key: DkgKey,
         /// The DKG particpants.
         elders_info: EldersInfo,
+        /// The section chain index of the key to be generated.
+        key_index: u64,
     },
     /// Message exchanged for DKG process.
     DKGMessage {
@@ -199,10 +201,12 @@ impl Debug for Variant {
             Self::DKGStart {
                 dkg_key,
                 elders_info,
+                key_index,
             } => f
                 .debug_struct("DKGStart")
                 .field("dkg_key", dkg_key)
                 .field("elders_info", elders_info)
+                .field("key_index", key_index)
                 .finish(),
             Self::DKGMessage { dkg_key, message } => f
                 .debug_struct("DKGMessage")

src/routing/approved.rs

@@ -532,7 +532,8 @@ impl Approved {
             Variant::DKGStart {
                 dkg_key,
                 elders_info,
-            } => self.handle_dkg_start(*dkg_key, elders_info.clone()),
+                key_index,
+            } => self.handle_dkg_start(*dkg_key, elders_info.clone(), *key_index),
             Variant::DKGMessage { dkg_key, message } => {
                 self.handle_dkg_message(*dkg_key, message.clone(), msg.src().to_node_name()?)
             }
@@ -1097,10 +1098,11 @@ impl Approved {
         &mut self,
         dkg_key: DkgKey,
         new_elders_info: EldersInfo,
+        key_index: u64,
     ) -> Result<Vec<Command>> {
         trace!("Received DKGStart for {}", new_elders_info);
         self.dkg_voter
-            .start(&self.node.keypair, dkg_key, new_elders_info)
+            .start(&self.node.keypair, dkg_key, new_elders_info, key_index)
             .into_commands(&self.node)
     }
 
@@ -1742,6 +1744,7 @@ impl Approved {
         let variant = Variant::DKGStart {
             dkg_key,
             elders_info,
+            key_index: self.section.chain().last_key_index() + 1,
         };
         let vote = self.create_send_message_vote(DstLocation::Direct, variant, None)?;
         self.send_vote(recipients, vote)