Start work on rejoining channel buffers

crates/channel/src/channel_buffer.rs

@@ -17,6 +17,7 @@ pub struct ChannelBuffer {
     connected: bool,
     collaborators: Vec<proto::Collaborator>,
     buffer: ModelHandle<language::Buffer>,
+    buffer_epoch: u64,
     client: Arc<Client>,
     subscription: Option<client::Subscription>,
 }
@@ -73,6 +74,7 @@ impl ChannelBuffer {
 
             Self {
                 buffer,
+                buffer_epoch: response.epoch,
                 client,
                 connected: true,
                 collaborators,
@@ -82,6 +84,26 @@ impl ChannelBuffer {
         }))
     }
 
+    pub(crate) fn replace_collaborators(
+        &mut self,
+        collaborators: Vec<proto::Collaborator>,
+        cx: &mut ModelContext<Self>,
+    ) {
+        for old_collaborator in &self.collaborators {
+            if collaborators
+                .iter()
+                .any(|c| c.replica_id == old_collaborator.replica_id)
+            {
+                self.buffer.update(cx, |buffer, cx| {
+                    buffer.remove_peer(old_collaborator.replica_id as u16, cx)
+                });
+            }
+        }
+        self.collaborators = collaborators;
+        cx.emit(Event::CollaboratorsChanged);
+        cx.notify();
+    }
+
     async fn handle_update_channel_buffer(
         this: ModelHandle<Self>,
         update_channel_buffer: TypedEnvelope<proto::UpdateChannelBuffer>,
@@ -166,6 +188,10 @@ impl ChannelBuffer {
         }
     }
 
+    pub fn epoch(&self) -> u64 {
+        self.buffer_epoch
+    }
+
     pub fn buffer(&self) -> ModelHandle<language::Buffer> {
         self.buffer.clone()
     }
@@ -179,6 +205,7 @@ impl ChannelBuffer {
     }
 
     pub(crate) fn disconnect(&mut self, cx: &mut ModelContext<Self>) {
+        log::info!("channel buffer {} disconnected", self.channel.id);
         if self.connected {
             self.connected = false;
             self.subscription.take();