maolan_engine/workers/

worker.rs

use crate::{
    executor::NodeJob,
    message::{
        Action, Message, OfflineAutomationLane, OfflineAutomationTarget, OfflineBounceWork,
        ProcessTask,
    },
    midi::io::MidiEvent,
    render_plan::Op,
};
#[cfg(unix)]
use nix::libc;
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::mpsc::{Receiver, Sender};

pub(crate) struct NodeJobResult {
    pub(crate) worker_id: usize,
    pub(crate) epoch: u64,
    pub(crate) node: u32,
    pub(crate) output_linear: Vec<f32>,
    pub(crate) parameter_updates: Vec<Action>,
    pub(crate) latency_changed: bool,
}

#[derive(Debug)]
pub struct Worker {
    id: usize,
    rx: Receiver<Message>,
    tx: Sender<Message>,
    realtime_priority: i32,
}

impl Worker {
    fn apply_freeze_automation_at_sample(
        track: &mut crate::track::TrackData,
        sample: usize,
        lanes: &[OfflineAutomationLane],
    ) {
        for lane in lanes {
            if matches!(
                lane.target,
                OfflineAutomationTarget::Volume | OfflineAutomationTarget::Balance
            ) {
                continue;
            }
            let Some(value) = lane.value_at(sample) else {
                continue;
            };
            match lane.target {
                OfflineAutomationTarget::Volume | OfflineAutomationTarget::Balance => {}
                OfflineAutomationTarget::MidiCc { channel, cc } => {
                    let cc_value = (value * 127.0).round() as u8;
                    track.rt.pending_automation_midi_events.push(MidiEvent::new(
                        0,
                        vec![0xB0 | channel.min(15), cc.min(127), cc_value],
                    ));
                }
                #[cfg(unix)]
                OfflineAutomationTarget::Lv2Parameter {
                    instance_id,
                    index,
                    min,
                    max,
                } => {
                    let lo = min.min(max);
                    let hi = max.max(min);
                    let param_value = (lo + value * (hi - lo)).clamp(lo, hi);
                    let _ = track.set_lv2_control_value(
                        instance_id,
                        index as usize,
                        param_value as f64,
                    );
                }
                OfflineAutomationTarget::Vst3Parameter {
                    instance_id,
                    param_id,
                } => {
                    let _ = track.set_vst3_parameter(instance_id, param_id, value.clamp(0.0, 1.0));
                }
                OfflineAutomationTarget::ClapParameter {
                    instance_id,
                    param_id,
                    min,
                    max,
                } => {
                    let lo = min.min(max);
                    let hi = max.max(min);
                    let param_value = (lo + value as f64 * (hi - lo)).clamp(lo, hi);
                    let _ = track.set_clap_parameter_at(instance_id, param_id, param_value, 0);
                }
                OfflineAutomationTarget::MixOsc { .. } => {
                    // MixOSC values are sent to external hardware in real time,
                    // not rendered into frozen audio.
                }
            }
        }
    }

    fn prepare_track_for_freeze_render(track: &mut crate::track::TrackData) -> (f32, f32) {
        let original_level = track.level();
        let original_balance = track.balance();
        track.set_level(0.0);
        track.set_balance(0.0);
        (original_level, original_balance)
    }

    fn restore_track_after_freeze_render(
        track: &mut crate::track::TrackData,
        original_level: f32,
        original_balance: f32,
    ) {
        track.set_level(original_level);
        track.set_balance(original_balance);
    }

    async fn process_offline_bounce(&self, job: OfflineBounceWork) {
        let track_handle = job.state.tracks.get(&job.track_name).cloned();
        let Some(target_track) = track_handle else {
            let _ = self
                .tx
                .send(Message::OfflineBounceFinished {
                    result: Err(format!("Track not found: {}", job.track_name)),
                })
                .await;
            let _ = self.tx.send(Message::Ready(self.id)).await;
            return;
        };
        let (channels, block_size, sample_rate) = {
            let t = target_track.lock();
            let block_size = t
                .audio
                .outs
                .first()
                .map(|io| io.buffer_size())
                .or_else(|| t.audio.ins.first().map(|io| io.buffer_size()))
                .unwrap_or(0)
                .max(1);
            (
                t.audio.outs.len().max(1),
                block_size,
                t.sample_rate.round().max(1.0) as i32,
            )
        };
        let freeze_state = if job.apply_fader {
            None
        } else {
            let mut t = target_track.lock();
            Some(Self::prepare_track_for_freeze_render(&mut t))
        };

        let all_tracks: Vec<_> = job.state.tracks.values().cloned().collect();
        let plan_collector = basedrop::Collector::new();
        let render_plan = crate::render_plan::RenderPlan::compile(&job.state, &[], &[], block_size);
        let render_plan = Arc::new(basedrop::Owned::new(&plan_collector.handle(), render_plan));

        let mut output_samples =
            Vec::<f32>::with_capacity(job.length_samples.saturating_mul(channels.max(1)));

        let mut cursor = 0usize;
        let mut last_reported_progress = 0.0_f32;
        let mut total_process_time = Duration::ZERO;
        let mut total_write_time = Duration::ZERO;
        while cursor < job.length_samples {
            if job.cancel.load(std::sync::atomic::Ordering::Relaxed) {
                let _ = std::fs::remove_file(&job.output_path);
                if let Some((original_level, original_balance)) = freeze_state {
                    let mut t = target_track.lock();
                    Self::restore_track_after_freeze_render(
                        &mut t,
                        original_level,
                        original_balance,
                    );
                }
                let _ = self
                    .tx
                    .send(Message::OfflineBounceFinished {
                        result: Ok(Action::TrackOfflineBounceCanceled {
                            track_name: job.track_name.clone(),
                        }),
                    })
                    .await;
                let _ = self.tx.send(Message::Ready(self.id)).await;
                return;
            }

            let step = (job.length_samples - cursor).min(block_size);
            for handle in &all_tracks {
                let mut t = handle.lock();
                t.audio.set_finished(false);
                t.audio.set_processing(false);
                t.set_transport_sample(job.start_sample.saturating_add(cursor));
                t.set_loop_config(false, None);
                t.set_transport_timing(job.tempo_bpm, job.tsig_num, job.tsig_denom);
                t.set_clip_playback_enabled(true);
                t.set_record_tap_enabled(false);
            }
            {
                let mut t = target_track.lock();
                Self::apply_freeze_automation_at_sample(
                    &mut t,
                    job.start_sample.saturating_add(cursor),
                    &job.automation_lanes,
                );
            }

            let p_start = Instant::now();
            for node in 0..render_plan.nodes.len() as crate::render_plan::NodeId {
                let _ = Self::process_node_job_result(
                    self.id,
                    NodeJob {
                        epoch: 0,
                        plan: render_plan.clone(),
                        node,
                    },
                );
            }
            total_process_time += p_start.elapsed();

            let write_start = Instant::now();
            {
                let t = target_track.lock();
                let outs = t.last_audio_outputs();
                for i in 0..step {
                    for ch in 0..channels {
                        let sample = outs
                            .get(ch)
                            .and_then(|out| out.get(i))
                            .copied()
                            .unwrap_or(0.0);
                        output_samples.push(sample);
                    }
                }
            }
            total_write_time += write_start.elapsed();

            cursor = cursor.saturating_add(step);
            let progress = (cursor as f32 / job.length_samples as f32).clamp(0.0, 1.0);

            if progress - last_reported_progress >= 0.01 || cursor >= job.length_samples {
                last_reported_progress = progress;
                let _ = self
                    .tx
                    .send(Message::OfflineBounceFinished {
                        result: Ok(Action::TrackOfflineBounceProgress {
                            track_name: job.track_name.clone(),
                            progress,
                            operation: Some("Rendering freeze".to_string()),
                        }),
                    })
                    .await;
            }
        }

        if let Err(e) = crate::audio_codec::write_wav_f32(
            std::path::Path::new(&job.output_path),
            &output_samples,
            channels,
            sample_rate as u32,
        ) {
            let _ = std::fs::remove_file(&job.output_path);
            if let Some((original_level, original_balance)) = freeze_state {
                let mut t = target_track.lock();
                Self::restore_track_after_freeze_render(&mut t, original_level, original_balance);
            }
            let _ = self
                .tx
                .send(Message::OfflineBounceFinished {
                    result: Err(format!(
                        "Failed to write offline bounce '{}': {e}",
                        job.output_path
                    )),
                })
                .await;
            let _ = self.tx.send(Message::Ready(self.id)).await;
            return;
        }

        if let Some((original_level, original_balance)) = freeze_state {
            let mut t = target_track.lock();
            Self::restore_track_after_freeze_render(&mut t, original_level, original_balance);
        }

        let _ = self
            .tx
            .send(Message::OfflineBounceFinished {
                result: Ok(Action::TrackOfflineBounce {
                    track_name: job.track_name,
                    output_path: job.output_path,
                    start_sample: job.start_sample,
                    length_samples: job.length_samples,
                    automation_lanes: vec![],
                    apply_fader: job.apply_fader,
                }),
            })
            .await;
        let _ = self.tx.send(Message::Ready(self.id)).await;
    }

    #[cfg(unix)]
    pub(crate) fn try_enable_realtime(priority: i32) -> Result<(), String> {
        let thread = unsafe { libc::pthread_self() };
        let policy = libc::SCHED_FIFO;
        let param = unsafe {
            let mut p = std::mem::zeroed::<libc::sched_param>();
            p.sched_priority = priority;
            p
        };
        let rc = unsafe { libc::pthread_setschedparam(thread, policy, &param) };
        if rc == 0 {
            Ok(())
        } else {
            Err(format!("pthread_setschedparam failed with errno {}", rc))
        }
    }

    #[cfg(target_os = "windows")]
    pub(crate) fn try_enable_realtime(_priority: i32) -> Result<(), String> {
        use std::{cell::Cell, ffi::OsStr, os::windows::ffi::OsStrExt};

        #[link(name = "avrt")]
        unsafe extern "system" {
            fn AvSetMmThreadCharacteristicsW(task_name: *const u16, task_index: *mut u32) -> isize;
        }

        thread_local! {
            static MMCSS_TASK_HANDLE: Cell<isize> = const { Cell::new(0) };
        }

        MMCSS_TASK_HANDLE.with(|handle| {
            if handle.get() != 0 {
                return Ok(());
            }

            let task_name: Vec<u16> = OsStr::new("Pro Audio")
                .encode_wide()
                .chain(Some(0))
                .collect();
            let mut task_index = 0_u32;
            let mmcss_handle =
                unsafe { AvSetMmThreadCharacteristicsW(task_name.as_ptr(), &mut task_index) };
            if mmcss_handle == 0 {
                Err(format!(
                    "AvSetMmThreadCharacteristicsW(Pro Audio) failed: {}",
                    std::io::Error::last_os_error()
                ))
            } else {
                handle.set(mmcss_handle);
                Ok(())
            }
        })
    }

    #[cfg(all(not(unix), not(target_os = "windows")))]
    pub(crate) fn try_enable_realtime(_priority: i32) -> Result<(), String> {
        Err("Realtime thread priority is not supported on this platform".to_string())
    }

    pub async fn new(
        id: usize,
        rx: Receiver<Message>,
        tx: Sender<Message>,
        realtime_priority: i32,
    ) -> Worker {
        let worker = Worker {
            id,
            rx,
            tx,
            realtime_priority,
        };
        worker.send(Message::Ready(id)).await;
        worker
    }

    pub async fn send(&self, message: Message) {
        self.tx
            .send(message)
            .await
            .expect("Failed to send message from worker");
    }

    fn arena_input_slices<'a>(
        plan: &'a crate::render_plan::RenderPlan,
        ins: &[crate::render_plan::BufferId],
    ) -> Vec<&'a [f32]> {
        ins.iter()
            .map(|&buf| {
                // Safety: the plan dispatched this task only after every
                // producer of the input buffer completed.
                unsafe { plan.buffer(buf) }
            })
            .collect()
    }

    fn arena_source_slices<'a>(
        plan: &'a crate::render_plan::RenderPlan,
        writable: &[crate::render_plan::BufferId],
    ) -> Vec<(usize, &'a [f32], usize)> {
        plan.port_map
            .iter()
            .filter_map(|(&key, &buf)| {
                if writable.contains(&buf) {
                    return None;
                }
                // Safety: every returned buffer is excluded from this node's
                // writable outputs. Its producer completed before this task
                // because the plan routes folder-output dependencies from
                // child and plugin producer nodes.
                Some((key, unsafe { plan.buffer(buf) }, plan.buffer_latency(buf)))
            })
            .collect()
    }

    fn metronome_output_buffer(
        plan: &crate::render_plan::RenderPlan,
        t: &crate::track::TrackData,
        outs: &[crate::render_plan::BufferId],
    ) -> Option<crate::render_plan::BufferId> {
        let source = t.metronome_source()?;
        let key = Arc::as_ptr(&source) as usize;
        let &buf = plan.port_map.get(&key)?;
        outs.contains(&buf).then_some(buf)
    }

    /// Execute one node of a render plan (Phase 2, see `LOCKLESS.md`).
    ///
    /// `Sum`/`Zero` are pure arena ops. Task nodes run the legacy track body
    /// (it still re-sums its inputs from the port graph — identical to the
    /// plan's `Sum` result) and then copy their output ports into the arena
    /// so downstream `Sum` nodes and the hardware drain see the result.
    pub(crate) fn process_node_job_result(worker_id: usize, job: NodeJob) -> NodeJobResult {
        let NodeJob { epoch, plan, node } = job;
        let (output_linear, parameter_updates, latency_changed) = match &plan.nodes[node as usize] {
            Op::Zero { output } => {
                // Safety: this worker executes this node; the plan's
                // single-producer-chain invariant guarantees exclusive
                // access to the output buffer.
                unsafe { &mut *plan.buffer_ptr(*output) }.fill(0.0);
                plan.set_buffer_latency(*output, 0);
                (Vec::new(), Vec::new(), false)
            }
            Op::Sum {
                inputs,
                delays,
                output,
            } => {
                // Safety: see `Op::Zero`; additionally, every input buffer's
                // producer completed before this node was dispatched.
                let out = unsafe { &mut *plan.buffer_ptr(*output) };
                out.fill(0.0);
                let max_latency = inputs
                    .iter()
                    .map(|&input| plan.buffer_latency(input))
                    .max()
                    .unwrap_or(0);
                for (idx, &input) in inputs.iter().enumerate() {
                    let src = unsafe { plan.buffer(input) };
                    let delay = max_latency.saturating_sub(plan.buffer_latency(input));
                    // Safety: this Sum node is the only writer of its delay
                    // lines during this cycle, and the executor never
                    // dispatches the same node concurrently.
                    let line = unsafe { &mut *delays[idx].get() };
                    line.process(src, delay, out, idx != 0);
                }
                plan.set_buffer_latency(*output, max_latency);
                (Vec::new(), Vec::new(), false)
            }
            Op::HwInput { output, .. } => {
                // The hardware driver wrote this buffer before the cycle
                // started; nothing to do.
                plan.set_buffer_latency(*output, 0);
                (Vec::new(), Vec::new(), false)
            }
            Op::Task { task, ins, outs } => {
                let track = match task {
                    ProcessTask::Track(t)
                    | ProcessTask::FolderInput(t)
                    | ProcessTask::FolderOutput(t) => t,
                    ProcessTask::Plugin { track, .. } => track,
                };
                let mut t = track.lock();
                match task {
                    ProcessTask::Track(_) => {
                        let audio_out_count = t.audio.outs.len();
                        let metronome_output = Self::metronome_output_buffer(&plan, &t, outs);
                        let input_ptrs = ins
                            .iter()
                            .map(|&buf| {
                                // Safety: track tasks are registered as
                                // in-place writers for their input buffers.
                                unsafe { plan.buffer_ptr(buf) }
                            })
                            .collect::<Vec<_>>();
                        let mut inputs = input_ptrs
                            .iter()
                            .map(|&ptr| {
                                // Safety: each pointer came from a task input
                                // buffer this node owns in-place.
                                unsafe { (&mut *ptr).as_mut_slice() }
                            })
                            .collect::<Vec<_>>();
                        let source_buffers = Self::arena_source_slices(&plan, outs);
                        let output_ptrs = outs
                            .iter()
                            .take(audio_out_count)
                            .map(|&buf| {
                                // Safety: this worker executes the unique
                                // producer node for each output buffer.
                                unsafe { plan.buffer_ptr(buf) }
                            })
                            .collect::<Vec<_>>();
                        let mut outputs = output_ptrs
                            .iter()
                            .map(|&ptr| {
                                // Safety: each pointer came from a distinct
                                // task output buffer owned by this node.
                                unsafe { (&mut *ptr).as_mut_slice() }
                            })
                            .collect::<Vec<_>>();
                        let metronome_output_ptr = metronome_output.map(|buf| {
                            // Safety: the track task is the registered
                            // producer of the metronome side-output buffer.
                            unsafe { plan.buffer_ptr(buf) }
                        });
                        let metronome_output = metronome_output_ptr.map(|ptr| {
                            // Safety: the side-output buffer is excluded from
                            // the normal audio output slice above.
                            unsafe { (&mut *ptr).as_mut_slice() }
                        });
                        t.process_render_block_with_audio_buffers_and_metronome(
                            &mut inputs,
                            &mut outputs,
                            &source_buffers,
                            metronome_output,
                        );
                        for &out in outs.iter().take(audio_out_count) {
                            plan.set_buffer_latency(out, t.plugin_graph_latency_samples());
                        }
                    }
                    ProcessTask::FolderInput(_) => {
                        let metronome_output = Self::metronome_output_buffer(&plan, &t, outs);
                        let input_ptrs = ins
                            .iter()
                            .map(|&buf| {
                                // Safety: folder-input tasks are registered
                                // as in-place writers for their input buffers.
                                unsafe { plan.buffer_ptr(buf) }
                            })
                            .collect::<Vec<_>>();
                        let mut inputs = input_ptrs
                            .iter()
                            .map(|&ptr| {
                                // Safety: each pointer came from a task input
                                // buffer this node owns in-place.
                                unsafe { (&mut *ptr).as_mut_slice() }
                            })
                            .collect::<Vec<_>>();
                        let metronome_output_ptr = metronome_output.map(|buf| {
                            // Safety: the folder-input task is the registered
                            // producer of the metronome side-output buffer.
                            unsafe { plan.buffer_ptr(buf) }
                        });
                        let metronome_output = metronome_output_ptr.map(|ptr| {
                            // Safety: this buffer is a side output, distinct
                            // from the folder input buffers.
                            unsafe { (&mut *ptr).as_mut_slice() }
                        });
                        t.process_folder_input_with_audio_buffers_and_metronome(
                            &mut inputs,
                            metronome_output,
                        );
                        for &input in ins {
                            plan.set_buffer_latency(input, 0);
                        }
                    }
                    ProcessTask::FolderOutput(_) => {
                        let source_buffers = Self::arena_source_slices(&plan, outs);
                        let output_ptrs = outs
                            .iter()
                            .map(|&buf| {
                                // Safety: this worker executes the unique
                                // producer node for each output buffer.
                                unsafe { plan.buffer_ptr(buf) }
                            })
                            .collect::<Vec<_>>();
                        let mut outputs = output_ptrs
                            .iter()
                            .map(|&ptr| {
                                // Safety: each pointer came from a distinct
                                // task output buffer owned by this node.
                                unsafe { (&mut *ptr).as_mut_slice() }
                            })
                            .collect::<Vec<_>>();
                        t.process_folder_output_with_audio_buffers(&mut outputs, &source_buffers);
                        for &out in outs {
                            plan.set_buffer_latency(out, t.plugin_graph_latency_samples());
                        }
                    }
                    ProcessTask::Plugin { kind, index, .. } => {
                        let input_latency = ins
                            .iter()
                            .map(|&input| plan.buffer_latency(input))
                            .max()
                            .unwrap_or(0);
                        let inputs = Self::arena_input_slices(&plan, ins);
                        let output_ptrs = outs
                            .iter()
                            .map(|&buf| {
                                // Safety: this worker executes the unique
                                // producer node for each output buffer.
                                unsafe { plan.buffer_ptr(buf) }
                            })
                            .collect::<Vec<_>>();
                        let mut outputs = output_ptrs
                            .iter()
                            .map(|&ptr| {
                                // Safety: each pointer came from a distinct
                                // task output buffer owned by this node.
                                unsafe { (&mut *ptr).as_mut_slice() }
                            })
                            .collect::<Vec<_>>();
                        t.process_plugin_with_audio_buffers(*kind, *index, &inputs, &mut outputs);
                        let latency =
                            input_latency.saturating_add(t.plugin_latency_samples(*kind, *index));
                        for &out in outs {
                            plan.set_buffer_latency(out, latency);
                        }
                    }
                }
                t.audio.set_processing(false);
                let latency_changed = t.take_plugin_latency_changed();
                let updates = std::mem::take(&mut t.rt.echoed_parameter_updates);
                let meter = t.output_meter_linear();
                {
                    static TRACK_OUTPUT_PEAK_LOG_COUNT: std::sync::atomic::AtomicUsize =
                        std::sync::atomic::AtomicUsize::new(0);
                    let peak = meter.iter().copied().fold(0.0_f32, f32::max);
                    let count = TRACK_OUTPUT_PEAK_LOG_COUNT
                        .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
                    if count < 64 || peak > 0.0 {
                        let task_kind = match task {
                            ProcessTask::Track(_) => "track",
                            ProcessTask::FolderInput(_) => "folder_input",
                            ProcessTask::FolderOutput(_) => "folder_output",
                            ProcessTask::Plugin { .. } => "plugin",
                        };
                        tracing::debug!(
                            worker_id,
                            node,
                            track = %t.name,
                            task_kind,
                            peak,
                            meter = ?meter,
                            "track output meter peak"
                        );
                    }
                }
                (meter, updates, latency_changed)
            }
        };
        NodeJobResult {
            worker_id,
            epoch,
            node,
            output_linear,
            parameter_updates,
            latency_changed,
        }
    }

    async fn process_node_job(&self, job: NodeJob) {
        let result = Self::process_node_job_result(self.id, job);
        let _ = self.tx.send(result.into()).await;
    }

    pub async fn work(&mut self) {
        crate::enable_flush_denormals_to_zero();
        if let Err(e) = Self::try_enable_realtime(self.realtime_priority) {
            tracing::warn!(
                "Worker {} realtime priority {} not enabled: {}",
                self.id,
                self.realtime_priority,
                e
            );
        }
        while let Some(message) = self.rx.recv().await {
            match message {
                Message::Request(Action::Quit) => {
                    return;
                }
                Message::ProcessOfflineBounce(job) => {
                    self.process_offline_bounce(job).await;
                }
                Message::NodeJob(job) => {
                    self.process_node_job(job).await;
                }
                _ => {}
            }
        }
    }
}

impl From<NodeJobResult> for Message {
    fn from(result: NodeJobResult) -> Self {
        Message::NodeDone {
            worker_id: result.worker_id,
            epoch: result.epoch,
            node: result.node,
            output_linear: result.output_linear,
            parameter_updates: result.parameter_updates,
            latency_changed: result.latency_changed,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::Worker;
    use crate::message::{
        Action, Message, OfflineAutomationLane, OfflineAutomationPoint, OfflineAutomationTarget,
        OfflineBounceWork,
    };
    use crate::state::State;
    use crate::track::Track;
    use std::path::PathBuf;
    use std::sync::{Arc, atomic::AtomicBool};
    use std::time::{SystemTime, UNIX_EPOCH};
    use tokio::sync::mpsc::channel;

    fn make_state_with_track(track: Track) -> State {
        let mut state = State::default();
        state.tracks.insert(track.name.clone(), Arc::new(track));
        state
    }

    fn unique_temp_wav(name: &str) -> PathBuf {
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .expect("clock")
            .as_nanos();
        std::env::temp_dir().join(format!("maolan_{name}_{nanos}.wav"))
    }

    #[test]
    fn prepare_track_for_freeze_render_neutralizes_level_and_balance() {
        let mut track = Track::new("track".to_string(), 1, 2, 0, 0, 64, 48_000.0);
        track.set_level(-6.0);
        track.set_balance(0.35);

        let (level, balance) = Worker::prepare_track_for_freeze_render(&mut track);

        assert_eq!(level, -6.0);
        assert_eq!(balance, 0.35);
        assert_eq!(track.level(), 0.0);
        assert_eq!(track.balance(), 0.0);

        Worker::restore_track_after_freeze_render(&mut track, level, balance);
        assert_eq!(track.level(), -6.0);
        assert_eq!(track.balance(), 0.35);
    }

    #[test]
    fn freeze_automation_ignores_volume_and_balance_lanes() {
        let mut track = Track::new("track".to_string(), 1, 2, 0, 1, 64, 48_000.0);
        let lanes = vec![
            OfflineAutomationLane {
                target: OfflineAutomationTarget::Volume,
                visible: true,
                points: vec![OfflineAutomationPoint {
                    sample: 0,
                    value: 0.0,
                }],
            },
            OfflineAutomationLane {
                target: OfflineAutomationTarget::Balance,
                visible: true,
                points: vec![OfflineAutomationPoint {
                    sample: 0,
                    value: 1.0,
                }],
            },
            OfflineAutomationLane {
                target: OfflineAutomationTarget::MidiCc { channel: 0, cc: 7 },
                visible: true,
                points: vec![OfflineAutomationPoint {
                    sample: 0,
                    value: 1.0,
                }],
            },
        ];

        Worker::apply_freeze_automation_at_sample(&mut track, 0, &lanes);

        assert_eq!(track.level(), 0.0);
        assert_eq!(track.balance(), 0.0);
        assert_eq!(track.rt.pending_automation_midi_events.len(), 1);
        assert_eq!(
            track.rt.pending_automation_midi_events[0].data,
            vec![0xB0, 7, 127]
        );
    }

    #[test]
    fn automation_lane_value_at_interpolates_between_points() {
        let lane = OfflineAutomationLane {
            target: OfflineAutomationTarget::Volume,
            visible: true,
            points: vec![
                OfflineAutomationPoint {
                    sample: 10,
                    value: 0.25,
                },
                OfflineAutomationPoint {
                    sample: 20,
                    value: 0.75,
                },
            ],
        };
        let value = lane.value_at(15).expect("value");

        assert!((value - 0.5).abs() < 1.0e-6);
    }

    #[test]
    fn freeze_automation_applies_interpolated_midi_cc_lane() {
        let mut track = Track::new("track".to_string(), 1, 1, 0, 1, 64, 48_000.0);
        let lanes = vec![OfflineAutomationLane {
            target: OfflineAutomationTarget::MidiCc { channel: 0, cc: 7 },
            visible: true,
            points: vec![
                OfflineAutomationPoint {
                    sample: 0,
                    value: 0.0,
                },
                OfflineAutomationPoint {
                    sample: 10,
                    value: 1.0,
                },
            ],
        }];

        Worker::apply_freeze_automation_at_sample(&mut track, 5, &lanes);
        assert_eq!(track.rt.pending_automation_midi_events.len(), 1);
        assert_eq!(track.rt.pending_automation_midi_events[0].data[2], 64);

        track.rt.pending_automation_midi_events.clear();
        Worker::apply_freeze_automation_at_sample(&mut track, 2, &lanes);
        assert_eq!(track.rt.pending_automation_midi_events.len(), 1);
        assert_eq!(track.rt.pending_automation_midi_events[0].data[2], 25);
    }

    #[cfg_attr(
        all(miri, target_os = "freebsd"),
        ignore = "Tokio runtime uses kqueue, which Miri does not support on FreeBSD"
    )]
    #[tokio::test]
    async fn process_node_job_sums_arena_buffers() {
        use crate::render_plan::{Op, RenderPlan};
        use std::cell::UnsafeCell;
        use std::collections::HashMap;

        let (_rx_unused_tx, rx_unused) = channel(1);
        let (tx, mut out_rx) = channel(8);
        let worker = Worker {
            id: 4,
            rx: rx_unused,
            tx,
            realtime_priority: 0,
        };
        let collector = basedrop::Collector::new();
        let plan = RenderPlan {
            buffer_size: 4,
            buffers: (0..3).map(|_| UnsafeCell::new(vec![0.0; 4])).collect(),
            buffer_latencies: (0..3)
                .map(|_| std::sync::atomic::AtomicUsize::new(0))
                .collect(),
            nodes: vec![Op::Sum {
                inputs: vec![0, 1],
                delays: vec![
                    UnsafeCell::new(crate::render_plan::DelayLine::new()),
                    UnsafeCell::new(crate::render_plan::DelayLine::new()),
                ],
                output: 2,
            }],
            indegree: vec![0],
            dependents: vec![vec![]],
            sources: vec![0],
            hw_in_map: vec![],
            hw_out_map: vec![],
            port_map: HashMap::new(),
            midi_edges: vec![],
            forced: vec![],
        };
        // Safety: test thread, no node is executing yet.
        unsafe {
            (&mut *plan.buffer_ptr(0)).copy_from_slice(&[0.25, 0.5, 0.75, 1.0]);
            (&mut *plan.buffer_ptr(1)).copy_from_slice(&[0.75, 0.5, 0.25, f32::NAN]);
        }
        let shared = std::sync::Arc::new(basedrop::Owned::new(&collector.handle(), plan));

        worker
            .process_node_job(crate::executor::NodeJob {
                epoch: 1,
                plan: shared.clone(),
                node: 0,
            })
            .await;

        // Safety: the job completed, so the Sum node's writes are done.
        // The NaN in the second source is sanitized to 0 before adding.
        unsafe {
            assert_eq!(
                &*shared.buffer_ptr(2),
                &vec![1.0, 1.0, 1.0, 1.0],
                "sanitized sum in the arena"
            );
        }
        match out_rx.recv().await.expect("message") {
            Message::NodeDone {
                worker_id,
                epoch,
                node,
                output_linear,
                ..
            } => {
                assert_eq!(worker_id, 4);
                assert_eq!(epoch, 1);
                assert_eq!(node, 0);
                assert!(output_linear.is_empty());
            }
            other => panic!("unexpected message: {other:?}"),
        }
    }

    #[cfg_attr(
        all(miri, target_os = "freebsd"),
        ignore = "Tokio runtime uses kqueue, which Miri does not support on FreeBSD"
    )]
    #[tokio::test]
    async fn process_offline_bounce_errors_when_track_is_missing() {
        let (_rx_unused_tx, rx_unused) = channel(1);
        let (tx, mut out_rx) = channel(8);
        let worker = Worker {
            id: 7,
            rx: rx_unused,
            tx,
            realtime_priority: 0,
        };
        let job = OfflineBounceWork {
            state: Arc::new(State::default().snapshot()),
            track_name: "missing".to_string(),
            output_path: unique_temp_wav("missing").to_string_lossy().to_string(),
            start_sample: 0,
            length_samples: 8,
            tempo_bpm: 120.0,
            tsig_num: 4,
            tsig_denom: 4,
            automation_lanes: vec![],
            cancel: Arc::new(AtomicBool::new(false)),
            apply_fader: false,
        };

        worker.process_offline_bounce(job).await;

        match out_rx.recv().await.expect("message") {
            Message::OfflineBounceFinished { result: Err(err) } => {
                assert!(err.contains("Track not found: missing"));
            }
            other => panic!("unexpected message: {other:?}"),
        }
    }

    #[cfg_attr(
        all(miri, target_os = "freebsd"),
        ignore = "Tokio runtime uses kqueue, which Miri does not support on FreeBSD"
    )]
    #[tokio::test]
    async fn process_offline_bounce_cancels_and_restores_track_state() {
        let (_rx_unused_tx, rx_unused) = channel(1);
        let (tx, mut out_rx) = channel(8);
        let worker = Worker {
            id: 5,
            rx: rx_unused,
            tx,
            realtime_priority: 0,
        };
        let track = Track::new("track".to_string(), 1, 2, 0, 0, 4, 48_000.0);
        track.set_level(-9.0);
        track.set_balance(-0.3);
        let state = make_state_with_track(track);
        let job = OfflineBounceWork {
            state: Arc::new(state.lock().snapshot()),
            track_name: "track".to_string(),
            output_path: unique_temp_wav("cancel").to_string_lossy().to_string(),
            start_sample: 0,
            length_samples: 8,
            tempo_bpm: 120.0,
            tsig_num: 4,
            tsig_denom: 4,
            automation_lanes: vec![],
            cancel: Arc::new(AtomicBool::new(true)),
            apply_fader: false,
        };

        worker.process_offline_bounce(job).await;

        match out_rx.recv().await.expect("message") {
            Message::OfflineBounceFinished {
                result: Ok(Action::TrackOfflineBounceCanceled { track_name }),
            } => assert_eq!(track_name, "track"),
            other => panic!("unexpected message: {other:?}"),
        }
        assert!(matches!(out_rx.recv().await, Some(Message::Ready(5))));
        let state_guard = state.lock();
        let track = state_guard.tracks.get("track").expect("track").lock();
        assert_eq!(track.level(), -9.0);
        assert_eq!(track.balance(), -0.3);
    }

    #[cfg_attr(
        all(miri, target_os = "freebsd"),
        ignore = "Tokio runtime uses kqueue, which Miri does not support on FreeBSD"
    )]
    #[tokio::test]
    async fn process_offline_bounce_restores_track_state_on_write_failure() {
        let (_rx_unused_tx, rx_unused) = channel(1);
        let (tx, mut out_rx) = channel(8);
        let worker = Worker {
            id: 3,
            rx: rx_unused,
            tx,
            realtime_priority: 0,
        };
        let track = Track::new("track".to_string(), 1, 2, 0, 0, 4, 48_000.0);
        track.set_level(-4.0);
        track.set_balance(0.25);
        let state = make_state_with_track(track);
        let output_path = std::env::temp_dir().to_string_lossy().to_string();
        let job = OfflineBounceWork {
            state: Arc::new(state.lock().snapshot()),
            track_name: "track".to_string(),
            output_path,
            start_sample: 0,
            length_samples: 4,
            tempo_bpm: 120.0,
            tsig_num: 4,
            tsig_denom: 4,
            automation_lanes: vec![],
            cancel: Arc::new(AtomicBool::new(false)),
            apply_fader: false,
        };

        worker.process_offline_bounce(job).await;

        let mut saw_error = false;
        while let Some(message) = out_rx.recv().await {
            match message {
                Message::OfflineBounceFinished {
                    result: Ok(Action::TrackOfflineBounceProgress { .. }),
                } => {}
                Message::OfflineBounceFinished { result: Err(err) } => {
                    assert!(
                        err.contains("Failed to create offline bounce")
                            || err.contains("Failed to write offline bounce")
                            || err.contains("Failed to finalize offline bounce")
                    );
                    saw_error = true;
                }
                Message::Ready(3) => break,
                other => panic!("unexpected message: {other:?}"),
            }
        }
        assert!(saw_error);
        let state_guard = state.lock();
        let track = state_guard.tracks.get("track").expect("track").lock();
        assert_eq!(track.level(), -4.0);
        assert_eq!(track.balance(), 0.25);
    }

    #[cfg_attr(
        all(miri, target_os = "freebsd"),
        ignore = "Tokio runtime uses kqueue, which Miri does not support on FreeBSD"
    )]
    #[tokio::test]
    async fn process_offline_bounce_emits_progress_and_completion() {
        let (_rx_unused_tx, rx_unused) = channel(1);
        let (tx, mut out_rx) = channel(16);
        let worker = Worker {
            id: 2,
            rx: rx_unused,
            tx,
            realtime_priority: 0,
        };
        let track = Track::new("track".to_string(), 1, 1, 0, 0, 4, 48_000.0);
        track.set_level(-3.0);
        track.set_balance(0.4);
        let state = make_state_with_track(track);
        let output = unique_temp_wav("success");
        let job = OfflineBounceWork {
            state: Arc::new(state.lock().snapshot()),
            track_name: "track".to_string(),
            output_path: output.to_string_lossy().to_string(),
            start_sample: 0,
            length_samples: 8,
            tempo_bpm: 120.0,
            tsig_num: 4,
            tsig_denom: 4,
            automation_lanes: vec![],
            cancel: Arc::new(AtomicBool::new(false)),
            apply_fader: false,
        };

        worker.process_offline_bounce(job).await;

        let mut saw_progress = false;
        let mut saw_complete = false;
        let mut saw_ready = false;
        while let Some(message) = out_rx.recv().await {
            match message {
                Message::OfflineBounceFinished {
                    result:
                        Ok(Action::TrackOfflineBounceProgress {
                            track_name,
                            progress,
                            ..
                        }),
                } => {
                    assert_eq!(track_name, "track");
                    assert!(progress > 0.0);
                    saw_progress = true;
                }
                Message::OfflineBounceFinished {
                    result:
                        Ok(Action::TrackOfflineBounce {
                            track_name,
                            output_path,
                            ..
                        }),
                } => {
                    assert_eq!(track_name, "track");
                    assert_eq!(output_path, output.to_string_lossy());
                    saw_complete = true;
                }
                Message::Ready(2) => {
                    saw_ready = true;
                    break;
                }
                other => panic!("unexpected message: {other:?}"),
            }
        }

        assert!(saw_progress);
        assert!(saw_complete);
        assert!(saw_ready);
        assert!(output.exists());
        std::fs::remove_file(&output).expect("remove temp wav");
        let state_guard = state.lock();
        let track = state_guard.tracks.get("track").expect("track").lock();
        assert_eq!(track.level(), -3.0);
        assert_eq!(track.balance(), 0.4);
        assert!(!track.muted());
    }
}