Jobs & Workers
Slow work (probing files, reading OTIO, scanning folders, exporting) runs off the host thread. Each start call returns a JobId. The outcome comes back as a SessionEvent from Session::tick(), which the host calls on its own thread, so results reach the project only there, as ordinary history steps.
Rules
- Waker. Workers call
Waker::wake()when there is something to collect. The host decides what that means: an egui repaint in the editor, an inbox wake for headless MCP. - Not inside an undo group.
tick()turns imports and relinks into history steps, so it must not run while the caller has an undo group open (for example mid-gesture), or the results would join the user's step. - Undoable imports. An import's media all land in one undo step that can keep growing (
join_import), for example with the timeline created for the first media.
Job kinds
| Job | Threads and behaviour |
|---|---|
| Media import | ImportWorker: one probe thread per core (probing a video takes ~100 ms). Results go into the pool in selection order, not completion order. Imports queue behind each other; files already in the pool are skipped (canonical paths). |
| OTIO import | One thread reads and probes. If imported media share a file name with pool media, the job waits for the host's decision (finish_otio_import: reuse, import all, or drop). |
| Relink | One thread, by name under a folder or with files already chosen. All relinks form one undo step. Cancellable. |
| Forced relink search | Started by the dialog (forced_relink::spawn_search). Matches files on the chosen criteria (duration, size, codec, waveform…) regardless of name. |
| Export | One thread on a clone of the project, so editing can go on; see Export Pipeline. Progress stays readable after it ends. |
Only one OTIO import, one relink and one export can run at a time; starting a second one returns None.
Worker<J>
vv_session::worker::Worker is the small building block for serial job queues: a thread reading an mpsc channel. Dropping it closes the queue and joins the thread. The app's proxy, waveform, thumbnail and mix-buffer workers are built on it.
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