Wait for remote worktree to catch up with host before mutating entries

This ensures that entries don't randomly re-appear on remote worktrees
due to observing an update too late. In fact, it ensures that the remote
worktree has the same starting state of the host before preemptively applying
the fs operation locally.

crates/collab/src/rpc.rs

@@ -448,6 +448,7 @@ impl Server {
                                 .cloned()
                                 .collect(),
                             visible: worktree.visible,
+                            scan_id: shared_worktree.scan_id,
                         })
                     })
                     .collect();
@@ -578,6 +579,7 @@ impl Server {
             request.payload.worktree_id,
             &request.payload.removed_entries,
             &request.payload.updated_entries,
+            request.payload.scan_id,
         )?;
 
         broadcast(request.sender_id, connection_ids, |connection_id| {
@@ -5804,6 +5806,7 @@ mod tests {
                     guest_client.username,
                     id
                 );
+                assert_eq!(guest_snapshot.scan_id(), host_snapshot.scan_id());
             }
 
             guest_client

crates/collab/src/rpc/store.rs

@@ -46,6 +46,7 @@ pub struct ProjectShare {
 pub struct WorktreeShare {
     pub entries: HashMap<u64, proto::Entry>,
     pub diagnostic_summaries: BTreeMap<PathBuf, proto::DiagnosticSummary>,
+    pub scan_id: u64,
 }
 
 #[derive(Default)]
@@ -561,6 +562,7 @@ impl Store {
         worktree_id: u64,
         removed_entries: &[u64],
         updated_entries: &[proto::Entry],
+        scan_id: u64,
     ) -> Result<Vec<ConnectionId>> {
         let project = self.write_project(project_id, connection_id)?;
         let worktree = project
@@ -574,6 +576,7 @@ impl Store {
         for entry in updated_entries {
             worktree.entries.insert(entry.id, entry.clone());
         }
+        worktree.scan_id = scan_id;
         let connection_ids = project.connection_ids();
         Ok(connection_ids)
     }

crates/project/src/project.rs

@@ -723,7 +723,11 @@ impl Project {
                     .ok_or_else(|| anyhow!("missing entry in response"))?;
                 worktree
                     .update(&mut cx, |worktree, cx| {
-                        worktree.as_remote().unwrap().insert_entry(entry, cx)
+                        worktree.as_remote().unwrap().insert_entry(
+                            entry,
+                            response.worktree_scan_id as usize,
+                            cx,
+                        )
                     })
                     .await
             }))
@@ -762,7 +766,11 @@ impl Project {
                     .ok_or_else(|| anyhow!("missing entry in response"))?;
                 worktree
                     .update(&mut cx, |worktree, cx| {
-                        worktree.as_remote().unwrap().insert_entry(entry, cx)
+                        worktree.as_remote().unwrap().insert_entry(
+                            entry,
+                            response.worktree_scan_id as usize,
+                            cx,
+                        )
                     })
                     .await
             }))
@@ -783,7 +791,7 @@ impl Project {
             let client = self.client.clone();
             let project_id = self.remote_id().unwrap();
             Some(cx.spawn_weak(|_, mut cx| async move {
-                client
+                let response = client
                     .request(proto::DeleteProjectEntry {
                         project_id,
                         entry_id: entry_id.to_proto(),
@@ -791,7 +799,11 @@ impl Project {
                     .await?;
                 worktree
                     .update(&mut cx, move |worktree, cx| {
-                        worktree.as_remote().unwrap().delete_entry(entry_id, cx)
+                        worktree.as_remote().unwrap().delete_entry(
+                            entry_id,
+                            response.worktree_scan_id as usize,
+                            cx,
+                        )
                     })
                     .await
             }))
@@ -3805,6 +3817,7 @@ impl Project {
                 entries: Default::default(),
                 diagnostic_summaries: Default::default(),
                 visible: envelope.payload.visible,
+                scan_id: 0,
             };
             let (worktree, load_task) =
                 Worktree::remote(remote_id, replica_id, worktree, client, cx);
@@ -3851,21 +3864,22 @@ impl Project {
         _: Arc<Client>,
         mut cx: AsyncAppContext,
     ) -> Result<proto::ProjectEntryResponse> {
-        let entry = this
+        let worktree = this.update(&mut cx, |this, cx| {
-            .update(&mut cx, |this, cx| {
+            let worktree_id = WorktreeId::from_proto(envelope.payload.worktree_id);
-                let worktree_id = WorktreeId::from_proto(envelope.payload.worktree_id);
+            this.worktree_for_id(worktree_id, cx)
-                let worktree = this
+                .ok_or_else(|| anyhow!("worktree not found"))
-                    .worktree_for_id(worktree_id, cx)
+        })?;
-                    .ok_or_else(|| anyhow!("worktree not found"))?;
+        let worktree_scan_id = worktree.read_with(&cx, |worktree, _| worktree.scan_id());
-                worktree.update(cx, |worktree, cx| {
+        let entry = worktree
-                    let worktree = worktree.as_local_mut().unwrap();
+            .update(&mut cx, |worktree, cx| {
-                    let path = PathBuf::from(OsString::from_vec(envelope.payload.path));
+                let worktree = worktree.as_local_mut().unwrap();
-                    anyhow::Ok(worktree.create_entry(path, envelope.payload.is_directory, cx))
+                let path = PathBuf::from(OsString::from_vec(envelope.payload.path));
-                })
+                worktree.create_entry(path, envelope.payload.is_directory, cx)
-            })?
+            })
             .await?;
         Ok(proto::ProjectEntryResponse {
             entry: Some((&entry).into()),
+            worktree_scan_id: worktree_scan_id as u64,
         })
     }
 
@@ -3875,16 +3889,25 @@ impl Project {
         _: Arc<Client>,
         mut cx: AsyncAppContext,
     ) -> Result<proto::ProjectEntryResponse> {
-        let entry = this
+        let entry_id = ProjectEntryId::from_proto(envelope.payload.entry_id);
-            .update(&mut cx, |this, cx| {
+        let worktree = this.read_with(&cx, |this, cx| {
-                let entry_id = ProjectEntryId::from_proto(envelope.payload.entry_id);
+            this.worktree_for_entry(entry_id, cx)
+                .ok_or_else(|| anyhow!("worktree not found"))
+        })?;
+        let worktree_scan_id = worktree.read_with(&cx, |worktree, _| worktree.scan_id());
+        let entry = worktree
+            .update(&mut cx, |worktree, cx| {
                 let new_path = PathBuf::from(OsString::from_vec(envelope.payload.new_path));
-                this.rename_entry(entry_id, new_path, cx)
+                worktree
+                    .as_local_mut()
+                    .unwrap()
+                    .rename_entry(entry_id, new_path, cx)
                     .ok_or_else(|| anyhow!("invalid entry"))
             })?
             .await?;
         Ok(proto::ProjectEntryResponse {
             entry: Some((&entry).into()),
+            worktree_scan_id: worktree_scan_id as u64,
         })
     }
 
@@ -3893,14 +3916,26 @@ impl Project {
         envelope: TypedEnvelope<proto::DeleteProjectEntry>,
         _: Arc<Client>,
         mut cx: AsyncAppContext,
-    ) -> Result<proto::Ack> {
+    ) -> Result<proto::ProjectEntryResponse> {
-        this.update(&mut cx, |this, cx| {
+        let entry_id = ProjectEntryId::from_proto(envelope.payload.entry_id);
-            let entry_id = ProjectEntryId::from_proto(envelope.payload.entry_id);
+        let worktree = this.read_with(&cx, |this, cx| {
-            this.delete_entry(entry_id, cx)
+            this.worktree_for_entry(entry_id, cx)
-                .ok_or_else(|| anyhow!("invalid entry"))
+                .ok_or_else(|| anyhow!("worktree not found"))
-        })?
+        })?;
-        .await?;
+        let worktree_scan_id = worktree.read_with(&cx, |worktree, _| worktree.scan_id());
-        Ok(proto::Ack {})
+        worktree
+            .update(&mut cx, |worktree, cx| {
+                worktree
+                    .as_local_mut()
+                    .unwrap()
+                    .delete_entry(entry_id, cx)
+                    .ok_or_else(|| anyhow!("invalid entry"))
+            })?
+            .await?;
+        Ok(proto::ProjectEntryResponse {
+            entry: None,
+            worktree_scan_id: worktree_scan_id as u64,
+        })
     }
 
     async fn handle_update_diagnostic_summary(

crates/project/src/worktree.rs

@@ -29,7 +29,6 @@ use language::{
 use lazy_static::lazy_static;
 use parking_lot::Mutex;
 use postage::{
-    barrier,
     prelude::{Sink as _, Stream as _},
     watch,
 };
@@ -84,17 +83,13 @@ pub struct RemoteWorktree {
     pub(crate) background_snapshot: Arc<Mutex<Snapshot>>,
     project_id: u64,
     client: Arc<Client>,
-    updates_tx: UnboundedSender<BackgroundUpdate>,
+    updates_tx: UnboundedSender<proto::UpdateWorktree>,
+    last_scan_id_rx: watch::Receiver<usize>,
     replica_id: ReplicaId,
     diagnostic_summaries: TreeMap<PathKey, DiagnosticSummary>,
     visible: bool,
 }
 
-enum BackgroundUpdate {
-    Update(proto::UpdateWorktree),
-    Barrier(barrier::Sender),
-}
-
 #[derive(Clone)]
 pub struct Snapshot {
     id: WorktreeId,
@@ -102,12 +97,12 @@ pub struct Snapshot {
     root_char_bag: CharBag,
     entries_by_path: SumTree<Entry>,
     entries_by_id: SumTree<PathEntry>,
+    scan_id: usize,
 }
 
 #[derive(Clone)]
 pub struct LocalSnapshot {
     abs_path: Arc<Path>,
-    scan_id: usize,
     ignores: HashMap<Arc<Path>, (Arc<Gitignore>, usize)>,
     removed_entry_ids: HashMap<u64, ProjectEntryId>,
     next_entry_id: Arc<AtomicUsize>,
@@ -221,11 +216,13 @@ impl Worktree {
             root_char_bag,
             entries_by_path: Default::default(),
             entries_by_id: Default::default(),
+            scan_id: worktree.scan_id as usize,
         };
 
         let (updates_tx, mut updates_rx) = mpsc::unbounded();
         let background_snapshot = Arc::new(Mutex::new(snapshot.clone()));
         let (mut snapshot_updated_tx, mut snapshot_updated_rx) = watch::channel();
+        let (mut last_scan_id_tx, last_scan_id_rx) = watch::channel_with(worktree.scan_id as usize);
         let worktree_handle = cx.add_model(|_: &mut ModelContext<Worktree>| {
             Worktree::Remote(RemoteWorktree {
                 project_id: project_remote_id,
@@ -233,6 +230,7 @@ impl Worktree {
                 snapshot: snapshot.clone(),
                 background_snapshot: background_snapshot.clone(),
                 updates_tx,
+                last_scan_id_rx,
                 client: client.clone(),
                 diagnostic_summaries: TreeMap::from_ordered_entries(
                     worktree.diagnostic_summaries.into_iter().map(|summary| {
@@ -291,14 +289,12 @@ impl Worktree {
                 cx.background()
                     .spawn(async move {
                         while let Some(update) = updates_rx.next().await {
-                            if let BackgroundUpdate::Update(update) = update {
+                            if let Err(error) =
-                                if let Err(error) =
+                                background_snapshot.lock().apply_remote_update(update)
-                                    background_snapshot.lock().apply_remote_update(update)
+                            {
-                                {
+                                log::error!("error applying worktree update: {}", error);
-                                    log::error!("error applying worktree update: {}", error);
-                                }
-                                snapshot_updated_tx.send(()).await.ok();
                             }
+                            snapshot_updated_tx.send(()).await.ok();
                         }
                     })
                     .detach();
@@ -308,7 +304,11 @@ impl Worktree {
                     async move {
                         while let Some(_) = snapshot_updated_rx.recv().await {
                             if let Some(this) = this.upgrade(&cx) {
-                                this.update(&mut cx, |this, cx| this.poll_snapshot(cx));
+                                this.update(&mut cx, |this, cx| {
+                                    this.poll_snapshot(cx);
+                                    let this = this.as_remote_mut().unwrap();
+                                    *last_scan_id_tx.borrow_mut() = this.snapshot.scan_id;
+                                });
                             } else {
                                 break;
                             }
@@ -368,6 +368,13 @@ impl Worktree {
         }
     }
 
+    pub fn scan_id(&self) -> usize {
+        match self {
+            Worktree::Local(worktree) => worktree.snapshot.scan_id,
+            Worktree::Remote(worktree) => worktree.snapshot.scan_id,
+        }
+    }
+
     pub fn is_visible(&self) -> bool {
         match self {
             Worktree::Local(worktree) => worktree.visible,
@@ -465,7 +472,6 @@ impl LocalWorktree {
         let tree = cx.add_model(move |cx: &mut ModelContext<Worktree>| {
             let mut snapshot = LocalSnapshot {
                 abs_path,
-                scan_id: 0,
                 ignores: Default::default(),
                 removed_entry_ids: Default::default(),
                 next_entry_id,
@@ -475,6 +481,7 @@ impl LocalWorktree {
                     root_char_bag,
                     entries_by_path: Default::default(),
                     entries_by_id: Default::default(),
+                    scan_id: 0,
                 },
             };
             if let Some(metadata) = metadata {
@@ -505,24 +512,13 @@ impl LocalWorktree {
 
             cx.spawn_weak(|this, mut cx| async move {
                 while let Some(scan_state) = scan_states_rx.next().await {
-                    if let Some(handle) = this.upgrade(&cx) {
+                    if let Some(this) = this.upgrade(&cx) {
-                        let to_send = handle.update(&mut cx, |this, cx| {
+                        last_scan_state_tx.blocking_send(scan_state).ok();
-                            last_scan_state_tx.blocking_send(scan_state).ok();
+                        this.update(&mut cx, |this, cx| {
                             this.poll_snapshot(cx);
-                            let tree = this.as_local_mut().unwrap();
+                            this.as_local().unwrap().broadcast_snapshot()
-                            if !tree.is_scanning() {
+                        })
-                                if let Some(share) = tree.share.as_ref() {
+                        .await;
-                                    return Some((tree.snapshot(), share.snapshots_tx.clone()));
-                                }
-                            }
-                            None
-                        });
-
-                        if let Some((snapshot, snapshots_to_send_tx)) = to_send {
-                            if let Err(err) = snapshots_to_send_tx.send(snapshot).await {
-                                log::error!("error submitting snapshot to send {}", err);
-                            }
-                        }
                     } else {
                         break;
                     }
@@ -745,7 +741,11 @@ impl LocalWorktree {
                 let mut snapshot = this.background_snapshot.lock();
                 snapshot.delete_entry(entry_id);
             });
-            this.update(&mut cx, |this, cx| this.poll_snapshot(cx));
+            this.update(&mut cx, |this, cx| {
+                this.poll_snapshot(cx);
+                this.as_local().unwrap().broadcast_snapshot()
+            })
+            .await;
             Ok(())
         }))
     }
@@ -780,7 +780,11 @@ impl LocalWorktree {
                     )
                 })
                 .await?;
-            this.update(&mut cx, |this, cx| this.poll_snapshot(cx));
+            this.update(&mut cx, |this, cx| {
+                this.poll_snapshot(cx);
+                this.as_local().unwrap().broadcast_snapshot()
+            })
+            .await;
             Ok(entry)
         }))
     }
@@ -814,7 +818,11 @@ impl LocalWorktree {
                         .refresh_entry(path, abs_path, None)
                 })
                 .await?;
-            this.update(&mut cx, |this, cx| this.poll_snapshot(cx));
+            this.update(&mut cx, |this, cx| {
+                this.poll_snapshot(cx);
+                this.as_local().unwrap().broadcast_snapshot()
+            })
+            .await;
             Ok(entry)
         })
     }
@@ -923,6 +931,7 @@ impl LocalWorktree {
                                         .map(Into::into)
                                         .collect(),
                                     removed_entries: Default::default(),
+                                    scan_id: snapshot.scan_id as u64,
                                 })
                                 .await
                             {
@@ -991,6 +1000,23 @@ impl LocalWorktree {
     pub fn is_shared(&self) -> bool {
         self.share.is_some()
     }
+
+    fn broadcast_snapshot(&self) -> impl Future<Output = ()> {
+        let mut to_send = None;
+        if !self.is_scanning() {
+            if let Some(share) = self.share.as_ref() {
+                to_send = Some((self.snapshot(), share.snapshots_tx.clone()));
+            }
+        }
+
+        async move {
+            if let Some((snapshot, snapshots_to_send_tx)) = to_send {
+                if let Err(err) = snapshots_to_send_tx.send(snapshot).await {
+                    log::error!("error submitting snapshot to send {}", err);
+                }
+            }
+        }
+    }
 }
 
 impl RemoteWorktree {
@@ -1003,18 +1029,19 @@ impl RemoteWorktree {
         envelope: TypedEnvelope<proto::UpdateWorktree>,
     ) -> Result<()> {
         self.updates_tx
-            .unbounded_send(BackgroundUpdate::Update(envelope.payload))
+            .unbounded_send(envelope.payload)
             .expect("consumer runs to completion");
         Ok(())
     }
 
-    pub fn finish_pending_remote_updates(&self) -> impl Future<Output = ()> {
+    fn wait_for_snapshot(&self, scan_id: usize) -> impl Future<Output = ()> {
-        let (tx, mut rx) = barrier::channel();
+        let mut rx = self.last_scan_id_rx.clone();
-        self.updates_tx
-            .unbounded_send(BackgroundUpdate::Barrier(tx))
-            .expect("consumer runs to completion");
         async move {
-            rx.recv().await;
+            while let Some(applied_scan_id) = rx.next().await {
+                if applied_scan_id >= scan_id {
+                    return;
+                }
+            }
         }
     }
 
@@ -1038,16 +1065,12 @@ impl RemoteWorktree {
     pub fn insert_entry(
         &self,
         entry: proto::Entry,
+        scan_id: usize,
         cx: &mut ModelContext<Worktree>,
     ) -> Task<Result<Entry>> {
+        let wait_for_snapshot = self.wait_for_snapshot(scan_id);
         cx.spawn(|this, mut cx| async move {
-            this.update(&mut cx, |worktree, _| {
+            wait_for_snapshot.await;
-                worktree
-                    .as_remote_mut()
-                    .unwrap()
-                    .finish_pending_remote_updates()
-            })
-            .await;
             this.update(&mut cx, |worktree, _| {
                 let worktree = worktree.as_remote_mut().unwrap();
                 let mut snapshot = worktree.background_snapshot.lock();
@@ -1061,16 +1084,12 @@ impl RemoteWorktree {
     pub(crate) fn delete_entry(
         &self,
         id: ProjectEntryId,
+        scan_id: usize,
         cx: &mut ModelContext<Worktree>,
     ) -> Task<Result<()>> {
+        let wait_for_snapshot = self.wait_for_snapshot(scan_id);
         cx.spawn(|this, mut cx| async move {
-            this.update(&mut cx, |worktree, _| {
+            wait_for_snapshot.await;
-                worktree
-                    .as_remote_mut()
-                    .unwrap()
-                    .finish_pending_remote_updates()
-            })
-            .await;
             this.update(&mut cx, |worktree, _| {
                 let worktree = worktree.as_remote_mut().unwrap();
                 let mut snapshot = worktree.background_snapshot.lock();
@@ -1145,6 +1164,7 @@ impl Snapshot {
 
         self.entries_by_path.edit(entries_by_path_edits, &());
         self.entries_by_id.edit(entries_by_id_edits, &());
+        self.scan_id = update.scan_id as usize;
 
         Ok(())
     }
@@ -1233,6 +1253,10 @@ impl Snapshot {
         &self.root_name
     }
 
+    pub fn scan_id(&self) -> usize {
+        self.scan_id
+    }
+
     pub fn entry_for_path(&self, path: impl AsRef<Path>) -> Option<&Entry> {
         let path = path.as_ref();
         self.traverse_from_path(true, true, path)
@@ -1282,6 +1306,7 @@ impl LocalSnapshot {
                 .map(|(path, summary)| summary.to_proto(&path.0))
                 .collect(),
             visible,
+            scan_id: self.scan_id as u64,
         }
     }
 
@@ -1347,6 +1372,7 @@ impl LocalSnapshot {
             root_name: self.root_name().to_string(),
             updated_entries,
             removed_entries,
+            scan_id: self.scan_id as u64,
         }
     }
 
@@ -1390,11 +1416,18 @@ impl LocalSnapshot {
         entries: impl IntoIterator<Item = Entry>,
         ignore: Option<Arc<Gitignore>>,
     ) {
-        let mut parent_entry = self
+        let mut parent_entry = if let Some(parent_entry) =
-            .entries_by_path
+            self.entries_by_path.get(&PathKey(parent_path.clone()), &())
-            .get(&PathKey(parent_path.clone()), &())
+        {
-            .unwrap()
+            parent_entry.clone()
-            .clone();
+        } else {
+            log::warn!(
+                "populating a directory {:?} that has been removed",
+                parent_path
+            );
+            return;
+        };
+
         if let Some(ignore) = ignore {
             self.ignores.insert(parent_path, (ignore, self.scan_id));
         }
@@ -1454,7 +1487,7 @@ impl LocalSnapshot {
 
         if path.file_name() == Some(&GITIGNORE) {
             if let Some((_, scan_id)) = self.ignores.get_mut(path.parent().unwrap()) {
-                *scan_id = self.scan_id;
+                *scan_id = self.snapshot.scan_id;
             }
         }
     }
@@ -2773,7 +2806,6 @@ mod tests {
         let next_entry_id = Arc::new(AtomicUsize::new(0));
         let mut initial_snapshot = LocalSnapshot {
             abs_path: root_dir.path().into(),
-            scan_id: 0,
             removed_entry_ids: Default::default(),
             ignores: Default::default(),
             next_entry_id: next_entry_id.clone(),
@@ -2783,6 +2815,7 @@ mod tests {
                 entries_by_id: Default::default(),
                 root_name: Default::default(),
                 root_char_bag: Default::default(),
+                scan_id: 0,
             },
         };
         initial_snapshot.insert_entry(

crates/rpc/proto/zed.proto

@@ -162,6 +162,7 @@ message UpdateWorktree {
     string root_name = 3;
     repeated Entry updated_entries = 4;
     repeated uint64 removed_entries = 5;
+    uint64 scan_id = 6;
 }
 
 message CreateProjectEntry {
@@ -184,6 +185,7 @@ message DeleteProjectEntry {
 
 message ProjectEntryResponse {
     Entry entry = 1;
+    uint64 worktree_scan_id = 2;
 }
 
 message AddProjectCollaborator {
@@ -658,6 +660,7 @@ message Worktree {
     repeated Entry entries = 3;
     repeated DiagnosticSummary diagnostic_summaries = 4;
     bool visible = 5;
+    uint64 scan_id = 6;
 }
 
 message File {

crates/rpc/src/proto.rs

@@ -225,7 +225,7 @@ request_messages!(
         ApplyCompletionAdditionalEditsResponse
     ),
     (CreateProjectEntry, ProjectEntryResponse),
-    (DeleteProjectEntry, Ack),
+    (DeleteProjectEntry, ProjectEntryResponse),
     (Follow, FollowResponse),
     (FormatBuffers, FormatBuffersResponse),
     (GetChannelMessages, GetChannelMessagesResponse),