Track open buffers when handling sync requests

When a host sends a buffer to a guest for the first time, they record that
they have done so in a set tied to that guest's peer id. When the guest
reconnects and syncs buffers, they do so under a different peer id, so we
need to be sure we track which buffers we have sent them to avoid sending
them the same buffer twice, which violates the guest's assumptions.

crates/fs/src/fs.rs

@@ -23,7 +23,7 @@ use std::{
     time::{Duration, SystemTime},
 };
 use tempfile::NamedTempFile;
-use util::{post_inc, ResultExt};
+use util::ResultExt;
 
 #[cfg(any(test, feature = "test-support"))]
 use collections::{btree_map, BTreeMap};
@@ -840,7 +840,7 @@ impl Fs for FakeFs {
         let target = normalize_path(target);
         let mut state = self.state.lock().await;
         let mtime = state.next_mtime;
-        let inode = post_inc(&mut state.next_inode);
+        let inode = util::post_inc(&mut state.next_inode);
         state.next_mtime += Duration::from_nanos(1);
         let source_entry = state.read_path(&source).await?;
         let content = source_entry.lock().await.file_content(&source)?.clone();

crates/gpui/src/executor.rs

@@ -4,7 +4,7 @@ use futures::channel::mpsc;
 use smol::{channel, prelude::*, Executor};
 use std::{
     any::Any,
-    fmt::{self, Display, Write as _},
+    fmt::{self, Display},
     marker::PhantomData,
     mem,
     pin::Pin,
@@ -17,8 +17,7 @@ use std::{
 
 use crate::{
     platform::{self, Dispatcher},
-    util::{self, CwdBacktrace},
+    util, MutableAppContext,
-    MutableAppContext,
 };
 
 pub enum Foreground {
@@ -549,6 +548,8 @@ impl Future for Timer {
 #[cfg(any(test, feature = "test-support"))]
 impl DeterministicState {
     fn push_to_history(&mut self, event: ExecutorEvent) {
+        use std::fmt::Write as _;
+
         self.poll_history.push(event);
         if let Some(prev_history) = &self.previous_poll_history {
             let ix = self.poll_history.len() - 1;
@@ -560,7 +561,7 @@ impl DeterministicState {
                     "current runnable backtrace:\n{:?}",
                     self.runnable_backtraces.get_mut(&event.id()).map(|trace| {
                         trace.resolve();
-                        CwdBacktrace(trace)
+                        util::CwdBacktrace(trace)
                     })
                 )
                 .unwrap();
@@ -571,7 +572,7 @@ impl DeterministicState {
                         .get_mut(&prev_event.id())
                         .map(|trace| {
                             trace.resolve();
-                            CwdBacktrace(trace)
+                            util::CwdBacktrace(trace)
                         })
                 )
                 .unwrap();

crates/project/src/project.rs

@@ -62,7 +62,7 @@ use std::{
     time::Instant,
 };
 use terminal::{Terminal, TerminalBuilder};
-use util::{defer, post_inc, ResultExt, TryFutureExt as _};
+use util::{debug_panic, defer, post_inc, ResultExt, TryFutureExt as _};
 
 pub use fs::*;
 pub use worktree::*;
@@ -1501,16 +1501,20 @@ impl Project {
             }
             Some(OpenBuffer::Weak(existing_handle)) => {
                 if existing_handle.upgrade(cx).is_some() {
+                    debug_panic!("already registered buffer with remote id {}", remote_id);
                     Err(anyhow!(
                         "already registered buffer with remote id {}",
                         remote_id
                     ))?
                 }
             }
-            Some(OpenBuffer::Strong(_)) => Err(anyhow!(
+            Some(OpenBuffer::Strong(_)) => {
+                debug_panic!("already registered buffer with remote id {}", remote_id);
+                Err(anyhow!(
                     "already registered buffer with remote id {}",
                     remote_id
-            ))?,
+                ))?
+            }
         }
         cx.subscribe(buffer, |this, buffer, event, cx| {
             this.on_buffer_event(buffer, event, cx);
@@ -5150,18 +5154,28 @@ impl Project {
         this: ModelHandle<Self>,
         envelope: TypedEnvelope<proto::SynchronizeBuffers>,
         _: Arc<Client>,
-        cx: AsyncAppContext,
+        mut cx: AsyncAppContext,
     ) -> Result<proto::SynchronizeBuffersResponse> {
         let project_id = envelope.payload.project_id;
         let mut response = proto::SynchronizeBuffersResponse {
             buffers: Default::default(),
         };
 
-        this.read_with(&cx, |this, cx| {
+        this.update(&mut cx, |this, cx| {
+            let Some(guest_id) = envelope.original_sender_id else {
+                log::error!("missing original_sender_id on SynchronizeBuffers request");
+                return;
+            };
+
             for buffer in envelope.payload.buffers {
                 let buffer_id = buffer.id;
                 let remote_version = language::proto::deserialize_version(buffer.version);
                 if let Some(buffer) = this.buffer_for_id(buffer_id, cx) {
+                    this.shared_buffers
+                        .entry(guest_id)
+                        .or_default()
+                        .insert(buffer_id);
+
                     let buffer = buffer.read(cx);
                     response.buffers.push(proto::BufferVersion {
                         id: buffer_id,