fix(fuse): a stop wakes every drain worker (B180)

crates/pdfs-fuse/src/drain.rs

@@ -703,12 +703,11 @@ impl Core {
     /// Block until there is plausibly something to do: a new op, a reconnect, or
     /// the shortest outstanding backoff elapsing.
     pub(crate) fn wait_for_drain_work(&self) {
-        let (lock, cv) = &*self.drain_wake;
-        let mut woken = lock.lock();
-        if !*woken {
-            cv.wait_for(&mut woken, DRAIN_IDLE_POLL);
-        }
-        *woken = false;
+        sleep_for_drain_work(
+            &self.drain_wake,
+            || self.shutdown.is_stopping(),
+            DRAIN_IDLE_POLL,
+        );
     }
 
     /// Like [`wait_for_drain_work`](Self::wait_for_drain_work), but first
@@ -722,12 +721,7 @@ impl Core {
             }
             _ => DRAIN_IDLE_POLL,
         };
-        let (lock, cv) = &*self.drain_wake;
-        let mut woken = lock.lock();
-        if !*woken {
-            cv.wait_for(&mut woken, timeout);
-        }
-        *woken = false;
+        sleep_for_drain_work(&self.drain_wake, || self.shutdown.is_stopping(), timeout);
     }
 
     /// Perform one queued op and retire it.
@@ -2697,6 +2691,27 @@ fn keeps_landed_upload(pinned: bool, len: u64, budget: u64) -> bool {
 }
 
 /// Where `st` has `uid`: its name and parent.
+/// Sleep on the drain's `wake` for up to `timeout`, unless a wake-up came
+/// since a worker last took one, or the mount is `stopping`.
+///
+/// One wake-up wakes every worker, and the first to wake takes it. A worker
+/// that came to sleep after that slept out its timeout, the stop's included,
+/// and the stop gave up on it after 10 s (`docs/BUGS.md` B180). The stop sets
+/// its flag before it takes the lock, so a worker that finds it unset under
+/// the lock is asleep when the wake-up comes.
+fn sleep_for_drain_work(
+    wake: &(Mutex<bool>, parking_lot::Condvar),
+    stopping: impl Fn() -> bool,
+    timeout: Duration,
+) {
+    let (lock, cv) = wake;
+    let mut woken = lock.lock();
+    if !*woken && !stopping() {
+        cv.wait_for(&mut woken, timeout);
+    }
+    *woken = false;
+}
+
 fn placed_in(st: &crate::state::State, uid: &NodeUid) -> Option<(String, Option<NodeUid>)> {
     let entry = st.by_uid.get(uid).and_then(|ino| st.entries.get(ino))?;
     Some((entry.node.name.clone(), entry.node.parent_uid.clone()))
@@ -2712,6 +2727,16 @@ mod tests {
     use proton_drive_rs::proton_sdk::ids::{LinkId, VolumeId};
     use std::cell::Cell;
 
+    #[test]
+    fn a_drain_worker_that_missed_the_stop_wake_up_does_not_sleep() {
+        // Another worker took the stop's wake-up, and this one slept out its
+        // timeout, past the stop's deadline (B180).
+        let wake = (Mutex::new(false), parking_lot::Condvar::new());
+        let started = Instant::now();
+        sleep_for_drain_work(&wake, || true, Duration::from_secs(5));
+        assert!(started.elapsed() < Duration::from_secs(1));
+    }
+
     fn pending(kind: &str) -> PendingOp {
         PendingOp {
             id: 0,

docs/BUGS.md

@@ -12,6 +12,32 @@ Conventions:
 
 ---
 
+## B180 — A stop waits 10 s for a drain worker that slept through it
+
+**Status:** Fixed.
+**Found:** 2026-10-04, by the simulation suite on 0f3c06f: `a_stop_ends_a_mirror_pass_after_the_uploads_it_is_sending`
+found "background workers did not finish in time" in the log, left there by two earlier tests
+whose stops had given up on a drain worker. On its own,
+`a_folder_made_again_while_the_old_one_is_trashed_is_a_new_folder` took 11 s instead of 2 s in
+about one run in three.
+
+**Where:** `Core::wait_for_drain_work` and `Core::wait_for_drain_work_or_due` in
+`crates/pdfs-fuse/src/drain.rs`.
+
+**Cause.** The drain workers sleep on one flag and one condvar. A stop sets its flag, then
+raises the wake-up and wakes them all, and the first worker to wake takes the wake-up. A worker
+that was between its stop check and its sleep at that moment found no wake-up and slept its
+timeout, up to 30 s. The stop gave up on it after 10 s and shut down around it. With 16 workers
+since step 7 this was common.
+
+**Fix.** A worker checks the stop under the wake-up's lock before it sleeps. The stop sets its
+flag before it takes that lock, so a worker that finds it unset is asleep when the wake-up comes.
+
+**Test:** `a_drain_worker_that_missed_the_stop_wake_up_does_not_sleep` in
+`crates/pdfs-fuse/src/drain.rs`.
+
+---
+
 ## B179 — A file read just as its create lands reads empty
 
 **Status:** Fixed (unverified).

docs/CHANGELOG.md

@@ -84,6 +84,8 @@ by its local id, in the queue, the stored tree and pins alike.
 - **Deleting a folder while sync is paused no longer leaves a queued change behind** for a
   file in it that was never uploaded (B178).
 - **A file read just as it reaches Drive no longer reads empty** (B179).
+- **Stopping the daemon no longer takes 10 seconds more than it needs** when an idle upload
+  worker missed the stop (B180).
 - **A file renamed just as its upload finished keeps its new name.** The mount no longer showed
   the old name, and a second rename no longer failed with "No such file or directory" (B152,
   B172).

docs/MILESTONE-3.0.0-STATUS.md

@@ -9,7 +9,7 @@ Tracks `docs/MILESTONE-3.0.0.md`. Update it with every commit that moves a phase
 - **Phase 2**: local ids, inode = local id, one tree for every mount (2.10.0).
 - **Phase 3, first part**: mkdir, create, rename, unlink and rmdir on the mount are recorded
   locally and sent from the queue; `"local_first": false` brings back the old path (5e0f30c).
-- Fixes from the simulation and account runs since then: B127 and B141 to B179.
+- Fixes from the simulation and account runs since then: B127 and B141 to B180.
 - **Sync issues, first cut** (§6.2): refusals sorted into issues, shown at once in the app,
   tray and CLI; Export button and `pdfs sync export`; `pdfs sync issues`.
 
@@ -125,6 +125,8 @@ Tracks `docs/MILESTONE-3.0.0.md`. Update it with every commit that moves a phase
          its stand-in and answered `EIO` (B177, fixed). A folder trashed while sync was
          paused kept a create below it as a trash: a paused drain worker had claimed it
          (B178, fixed). A file read as its create landed read empty (B179, fixed).
+         The suite on 0f3c06f: a stop gave up on a drain worker that slept through its
+         wake-up (B180, fixed).
 5. **Release**: 2.10.0 is tagged; the 2.9.0 tag still waits for the user's go-ahead.
 
 ## After 3.0.0