next.js

be3ee02b - turbo-tasks-backend: stability fixes for task cancellation and error handling (#92254)

turbo-tasks-backend: stability fixes for task cancellation and error handling (#92254) ### What? Bug fixes and a refactoring in `turbo-tasks-backend` targeting stability issues that surface when filesystem caching is enabled: 1. **Preserve `cell_type_max_index` on task error** — when a task fails partway through execution, `cell_counters` only reflects the partially-executed state. Previously, `cell_type_max_index` was updated from these incomplete counters, which removed entries for cell types not yet encountered. This caused `"Cell no longer exists"` hard errors for tasks that still held dependencies on those cells. The fix skips the `cell_type_max_index` update on error, keeping it consistent with the preserved cell data (which already wasn't cleared on error). This bug manifested specifically with `serialization = "hash"` cell types (e.g. `FileContent`), where cell data is transient and readers fall back to `cell_type_max_index` to decide whether to schedule recomputation. 2. **Fix shutdown hang and cache poisoning for cancelled tasks** — three related fixes for tasks cancelled during shutdown: - `task_execution_canceled` now drains and notifies all `InProgressCellState` events, preventing `stop_and_wait` from hanging on foreground jobs waiting on cells that will never be filled. - `try_read_task_cell` bails early (before calling `listen_to_cell`) when a task is in `Canceled` state, avoiding pointless listener registrations that would never resolve. - Cancelled tasks are marked as session-dependent dirty, preventing cache poisoning where `"was canceled"` errors get persisted as task output and break subsequent builds. The session-dependent dirty flag causes the task to re-execute in the next session, invalidating stale dependents. 3. **Extract `update_dirty_state` helper on `TaskGuard`** — the "read old dirty state → apply new state → propagate via `ComputeDirtyAndCleanUpdate`" pattern was duplicated between `task_execution_canceled` and `task_execution_completed_finish`. The new `update_dirty_state` default method on `TaskGuard` handles both transitions (to `SessionDependent` or to `None`) and returns the aggregation job + `ComputeDirtyAndCleanUpdateResult` for callers that need post-processing (e.g. firing the `all_clean_event`). ### Why? These bugs caused observable failures when using Turbopack with filesystem caching (`--cache` / persistent cache): - `"Cell no longer exists"` panics/errors on incremental rebuilds after a task error. - Hangs on `stop_and_wait` during dev server shutdown. - Stale `"was canceled"` errors persisted in the cache breaking subsequent builds until the cache is cleared. ### How? Changes are in `turbopack/crates/turbo-tasks-backend/src/backend/`: **`mod.rs`:** - Guard the `cell_type_max_index` update block inside `if result.is_ok()` to skip it on error, with a cross-reference comment to `task_execution_completed_cleanup` (which similarly skips cell data removal on error — the two must stay in sync). - Move the `is_cancelled` bail in `try_read_task_cell` before the `listen_to_cell` call to avoid inserting phantom `InProgressCellState` events that would never be notified. - In `task_execution_canceled`: switch to `TaskDataCategory::All` (needed for dirty state metadata access), notify all pending in-progress cell events, and mark the task as `SessionDependent` dirty via the new helper. - In `task_execution_completed_finish`: replace ~77 lines of inline dirty state logic with a call to `task.update_dirty_state(new_dirtyness)`, preserving the `all_clean_event` post-processing and the `dirty_changed` variable under `#[cfg(feature = "verify_determinism")]`. **`operation/mod.rs`:** - Add `update_dirty_state` default method on `TaskGuard` trait (~60 lines), co-located with the existing `dirty_state()` reader. Takes `Option<Dirtyness>`, applies the transition, builds `ComputeDirtyAndCleanUpdate`, and returns `(Option<AggregationUpdateJob>, ComputeDirtyAndCleanUpdateResult)`. - Add `ComputeDirtyAndCleanUpdateResult` to the public re-exports. --------- Co-authored-by: Tobias Koppers <sokra@users.noreply.github.com> Co-authored-by: Claude <noreply@anthropic.com>