mirui 0.17.0

//! Per-frame perf reporting.
//!
//! Drains the thread-local span events from [`crate::perf`] each
//! frame, optionally writes them to a chrome-JSON ndjson file (open
//! in <https://ui.perfetto.dev>), and periodically prints a console
//! summary aggregating per-name count / total / avg / min / max.
//!
//! The plugin also surfaces the per-system timings the scheduler
//! writes into [`SystemPerfSnapshot`] so a single report combines
//! framework spans and user-registered systems.

use crate::app::{App, RendererFactory};
use crate::ecs::World;
#[cfg(feature = "std")]
use crate::perf::PerfEvent;
use crate::perf::StageStat;
use crate::plugin::Plugin;
use crate::surface::Surface;

/// Snapshot of per-system perf counters written by `App::run` after
/// every `systems.run_all`. Plugins read this without needing direct
/// scheduler access.
#[derive(Default, Clone)]
pub struct SystemPerfSnapshot {
    pub entries: alloc::vec::Vec<SystemStat>,
}

#[derive(Clone, Copy)]
pub struct SystemStat {
    pub name: &'static str,
    pub priority: i32,
    pub last_us: u32,
    pub avg_us: u32,
    pub call_count: u32,
}

/// `App::run` consumes this each frame: when `true`, the scheduler's
/// per-system perf counters reset before the next window begins.
#[derive(Default, Clone, Copy)]
pub struct PerfResetFlag(pub bool);

#[derive(Clone)]
pub struct PerfReport {
    pub frames: u32,
    pub stage_stats: alloc::vec::Vec<StageStat>,
    pub systems: alloc::vec::Vec<SystemStat>,
}

pub struct PerfReportPlugin {
    frames_per_report: u32,
    frame_count: u32,
    on_report: fn(report: &PerfReport),
    #[cfg(feature = "std")]
    perfetto_writer: Option<std::sync::Mutex<std::fs::File>>,
}

impl PerfReportPlugin {
    pub fn new(frames_per_report: u32) -> Self {
        Self {
            frames_per_report,
            frame_count: 0,
            on_report: default_sink,
            #[cfg(feature = "std")]
            perfetto_writer: None,
        }
    }

    pub fn with_sink(mut self, sink: fn(&PerfReport)) -> Self {
        self.on_report = sink;
        self
    }

    /// Write every drained span event to a chrome-JSON ndjson file.
    /// Open the result in <https://ui.perfetto.dev> for a timeline
    /// view. Truncates the file on creation.
    #[cfg(feature = "std")]
    pub fn with_perfetto_writer(mut self, path: impl AsRef<std::path::Path>) -> Self {
        let f = std::fs::File::create(path).expect("failed to create perfetto trace file");
        self.perfetto_writer = Some(std::sync::Mutex::new(f));
        self
    }
}

impl Default for PerfReportPlugin {
    fn default() -> Self {
        Self::new(60)
    }
}

impl<B, F> Plugin<B, F> for PerfReportPlugin
where
    B: Surface,
    F: RendererFactory<B>,
{
    fn build(&mut self, app: &mut App<B, F>) {
        app.world.insert_resource(PerfAccum::default());
    }

    fn post_render(&mut self, world: &mut World, _render_nanos: u64) {
        let events = crate::perf::drain_events();

        #[cfg(feature = "std")]
        if let Some(w) = self.perfetto_writer.as_ref() {
            write_perfetto_ndjson(w, &events);
        }

        if let Some(acc) = world.resource_mut::<PerfAccum>() {
            // Aggregate per-frame so events don't need to be retained
            // across the whole report window.
            for ev in &events {
                let dur = ev.end_ns.saturating_sub(ev.start_ns);
                if let Some(s) = acc.stage_stats.iter_mut().find(|s| s.name == ev.name) {
                    s.count += 1;
                    s.total_ns += dur;
                    s.last_ns = dur;
                    if dur < s.min_ns {
                        s.min_ns = dur;
                    }
                    if dur > s.max_ns {
                        s.max_ns = dur;
                    }
                } else {
                    acc.stage_stats.push(StageStat {
                        name: ev.name,
                        count: 1,
                        total_ns: dur,
                        last_ns: dur,
                        min_ns: dur,
                        max_ns: dur,
                    });
                }
            }
        }

        self.frame_count += 1;
        if self.frame_count < self.frames_per_report {
            return;
        }

        let stage_stats = world
            .resource::<PerfAccum>()
            .map(|a| a.stage_stats.clone())
            .unwrap_or_default();
        let report = PerfReport {
            frames: self.frame_count,
            stage_stats,
            systems: collect_system_stats(world),
        };
        (self.on_report)(&report);

        self.frame_count = 0;
        if let Some(a) = world.resource_mut::<PerfAccum>() {
            a.stage_stats.clear();
        }
        if let Some(snap) = world.resource_mut::<SystemPerfSnapshot>() {
            snap.entries.clear();
        }
        world.insert_resource(PerfResetFlag(true));
    }
}

#[derive(Default, Clone)]
struct PerfAccum {
    stage_stats: alloc::vec::Vec<StageStat>,
}

fn collect_system_stats(world: &World) -> alloc::vec::Vec<SystemStat> {
    world
        .resource::<SystemPerfSnapshot>()
        .map(|s| s.entries.clone())
        .unwrap_or_default()
}

#[cfg(feature = "std")]
fn write_perfetto_ndjson(w: &std::sync::Mutex<std::fs::File>, events: &[PerfEvent]) {
    use std::io::Write;
    let Ok(mut f) = w.lock() else { return };
    for ev in events {
        let dur_us = ev.end_ns.saturating_sub(ev.start_ns) / 1_000;
        let ts_us = ev.start_ns / 1_000;
        // ph: "X" — complete event with explicit duration, no
        // pairing required. cat is fixed since we don't have multi-
        // category traces yet.
        let _ = writeln!(
            f,
            r#"{{"name":"{}","cat":"mirui","ph":"X","pid":1,"tid":1,"ts":{},"dur":{}}}"#,
            ev.name, ts_us, dur_us,
        );
    }
}

#[cfg(feature = "std")]
fn default_sink(report: &PerfReport) {
    eprintln!("[perf] {} frames", report.frames);
    let mut sorted: alloc::vec::Vec<&StageStat> = report.stage_stats.iter().collect();
    sorted.sort_by_key(|s| core::cmp::Reverse(s.total_ns));
    for s in &sorted {
        let avg = if s.count == 0 {
            0
        } else {
            s.total_ns / s.count as u64
        };
        eprintln!(
            "[perf]   {:>26}  n={:<4} total {:>7}µs  avg {:>5}µs  min {:>5}µs  max {:>5}µs",
            s.name,
            s.count,
            s.total_ns / 1_000,
            avg / 1_000,
            s.min_ns / 1_000,
            s.max_ns / 1_000,
        );
    }
    for s in &report.systems {
        if s.avg_us == 0 && s.last_us == 0 {
            continue;
        }
        eprintln!(
            "[perf]   {:>26}  last {:>5}µs  avg {:>5}µs  n={}",
            s.name, s.last_us, s.avg_us, s.call_count
        );
    }
}

#[cfg(not(feature = "std"))]
fn default_sink(_report: &PerfReport) {}