Trait BackgroundTasks

Source

pub trait BackgroundTasks {
    type Params: Params;
    type Task: Send + 'static;

    // Required method
    fn run_task(task: Self::Task, params: &Self::Params);
}

Expand description

Opt-in managed background work. A plugin implements this in addition to its leaf trait to declare a Send task type and a handler the framework runs on a shared background-thread pool, then wires it in with the tasks: key on the truce::plugin! macro. Nothing changes for a plugin that doesn’t implement it.

run_task runs off the audio thread and reaches shared state through params (its #[skip] channels / atomics), exactly like the editor: it must never touch DspState, which is audio-thread-exclusive. Feedback to the audio thread stays the plugin’s job through those #[skip] channels.

Keep handlers short and non-blocking. The pool is shared by every truce plugin in the host and small (available_parallelism() - 1 threads, as few as one), so a handler that blocks on I/O (reading a sample off disk) or waits on a lock stalls background work for every other instance too, not just its own. Allocation and CPU-bound bursts are fine - that is what the pool is for. For work that genuinely blocks or runs long, give the plugin its own thread with AudioTap::spawn_worker rather than the shared pool.

Schedule tasks with ctx.tasks::<Task>() from process (wait-free), the editor’s PluginContext, or the InitContext passed to init.

impl BackgroundTasks for Reverb {
    type Params = ReverbParams;
    type Task = Rebuild;
    fn run_task(task: Rebuild, params: &ReverbParams) {
        let graph = build_graph(task.sample_rate, task.time_s);
        let _ = params.ready.force_push(graph);   // #[skip] handoff
    }
}