perf: avoid eager diff loading and full-file typing work

src/session.rs

@@ -5,7 +5,7 @@ use std::{
     sync::{
         Arc,
         atomic::{AtomicBool, AtomicU64, Ordering},
-        mpsc::{self, Receiver, SyncSender},
+        mpsc::{self, Receiver, Sender},
     },
     thread::{self, JoinHandle},
 };
@@ -25,7 +25,7 @@ use crate::{
 type DiffResult = (u64, Result<DiffOutcome, String>);
 
 struct DiffWorker {
-    requests: Option<SyncSender<(u64, DiffOperation)>>,
+    requests: Option<Sender<(u64, DiffOperation)>>,
     results: Option<Receiver<DiffResult>>,
     cancelled: Arc<AtomicBool>,
     stopped: Arc<AtomicBool>,
@@ -36,7 +36,7 @@ struct DiffWorker {
 
 impl DiffWorker {
     fn start(root: PathBuf) -> Result<Self, String> {
-        let (requests, incoming) = mpsc::sync_channel::<(u64, DiffOperation)>(1);
+        let (requests, incoming) = mpsc::channel::<(u64, DiffOperation)>();
         let (outgoing, results) = mpsc::sync_channel(1);
         let cancelled = Arc::new(AtomicBool::new(false));
         let stopped = Arc::new(AtomicBool::new(false));
@@ -56,7 +56,7 @@ impl DiffWorker {
                     if stop.load(Ordering::Acquire) {
                         break;
                     }
-                    if cancelled_id.load(Ordering::Acquire) == id {
+                    if cancelled_id.load(Ordering::Acquire) >= id {
                         continue;
                     }
                     let result = (|| {
@@ -68,6 +68,9 @@ impl DiffWorker {
                             DiffOperation::Discover => {
                                 repository.catalog().map(DiffOutcome::Catalog)
                             }
+                            DiffOperation::ListRemote(remote) => {
+                                repository.list_remote(&remote).map(DiffOutcome::Catalog)
+                            }
                             DiffOperation::FetchRemote(remote) => {
                                 repository.fetch_remote(&remote).map(DiffOutcome::Catalog)
                             }
@@ -76,8 +79,18 @@ impl DiffWorker {
                                 after,
                                 buffers,
                             } => repository
-                                .compare(&before, &after, &buffers)
+                                .compare(id, &before, &after, &buffers)
                                 .map(DiffOutcome::Comparison),
+                            DiffOperation::LoadFile {
+                                comparison_id,
+                                file_index,
+                            } => repository.load_file(comparison_id, file_index).map(|file| {
+                                DiffOutcome::File {
+                                    comparison_id,
+                                    file_index,
+                                    file,
+                                }
+                            }),
                         }
                     })();
                     if stop.load(Ordering::Acquire) || outgoing.send((id, result)).is_err() {
@@ -98,16 +111,15 @@ impl DiffWorker {
     }
 
     fn request(&mut self, id: u64, operation: DiffOperation) -> Result<(), String> {
+        if let Some(previous) = self.pending.take() {
+            self.cancelled_request.store(previous, Ordering::Release);
+            self.cancelled.store(true, Ordering::Release);
+        }
         self.requests
             .as_ref()
             .expect("live diff worker has a sender")
-            .try_send((id, operation))
-            .map_err(|error| match error {
-                mpsc::TrySendError::Full(_) => "Diff worker is already busy".to_owned(),
-                mpsc::TrySendError::Disconnected(_) => {
-                    "Diff worker stopped unexpectedly".to_owned()
-                }
-            })?;
+            .send((id, operation))
+            .map_err(|_| "Diff worker stopped unexpectedly".to_owned())?;
         self.pending = Some(id);
         Ok(())
     }
@@ -3387,6 +3399,7 @@ end
                     path: PathBuf::from("buffer.txt"),
                     old_path: None,
                     status: FileStatus::Modified,
+                    loaded: true,
                     before: vec!["base".into()],
                     after: vec!["base".into()],
                     before_eof: false,