[turbopack] Store TaskDirtyCause in Dirtyness and pass to NativeFunction::span#94057
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…ion::span
Track the cause of task invalidation in `Dirtyness::Dirty` (gated by a new
`task_dirty_cause` feature) and surface it to the tracing span when the
task executes, so traces can show why a task was re-run.
- Replace `Dirtyness::Dirty(TaskPriority)` with a struct variant
`Dirty { parent_priority, cause: TaskDirtyCause }` where `cause` is only
present under the `task_dirty_cause` feature.
- Move `TaskDirtyCause` from `turbo-tasks-backend` into `turbo-tasks` so the
span signature can reference it. Replace `OutputChange.task_description`
with `OutputChange { function: FunctionId }` and add a new
`ResolveOutputChange { function: FunctionId }` variant used when the
task's output is `OutputValue::Output(_)`.
- `NativeFunction::span` now takes a feature-gated
`cause: Option<&TaskDirtyCause>` argument and records it as a `cause`
field on `turbo_tasks::function`. The `cause` is read from the dirty
state in `try_start_task_execution` before execution starts.
- Split the `trace_task_dirty` feature: the new `task_dirty_cause`
feature owns the storage/parameter plumbing, and `trace_task_dirty`
now depends on it.
Contributor
Tests PassedCommit: bb70074 |
mischnic
approved these changes
May 26, 2026
Contributor
Stats skippedCommit: bb70074 |
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What?
Track the cause of task invalidation in turbo-tasks and surface it to the tracing span when a task executes, so traces can show why a task was re-run.
A new
task_dirty_causeCargo feature gates the storage and parameter plumbing for this information. The existingtrace_task_dirtyfeature now depends on it.Why?
When investigating Turbopack performance and incremental-recompute behavior, traces show which tasks ran but not what invalidated them. Recording the
TaskDirtyCauseon theturbo_tasks::functionspan makes it possible to attribute task re-runs to their triggering change (cell update, output change, collectible change, etc.) directly from a trace.How?
Dirtyness::Dirty(TaskPriority)with a struct variantDirty { parent_priority, cause: TaskDirtyCause }. Thecausefield is only present when thetask_dirty_causefeature is enabled.TaskDirtyCausefromturbo-tasks-backendintoturbo-tasksso the span signature inturbo-taskscan reference it.OutputChange { task_description }withOutputChange { function: FunctionId }, and add a newResolveOutputChange { function: FunctionId }variant used when the task's output isOutputValue::Output(_). This avoids constructing aStringfor the cause at invalidation time.NativeFunction::spannow accepts a feature-gatedcause: Option<&TaskDirtyCause>argument and records it as acausefield on theturbo_tasks::functionspan. The cause is read from the dirty state intry_start_task_executionbefore execution starts.trace_task_dirtyfeature: the newtask_dirty_causefeature owns the storage/parameter plumbing, andtrace_task_dirtynow depends on it. This lets consumers opt into the storage cost without the full tracing overhead, and keeps the default build unaffected.Closes PACK-