monolith

//! Launch context. A window goes to the output and tag the user was on when

//! its launch began, found by matching its process or an ancestor against

//! the programs monolith spawned.

use monolith_layout::{OutputId, TagId};

use std::time::{Duration, Instant};

const KEEP: Duration = Duration::from_secs(120);

struct Launch {

    pid: u32,

    output: Option<OutputId>,

    tag: TagId,

    at: Instant,

}

#[derive(Default)]

pub struct Launches(Vec<Launch>);

impl Launches {

    pub fn record(&mut self, pid: u32, output: Option<OutputId>, tag: TagId) {

        self.0.retain(|l| l.at.elapsed() < KEEP);

        self.0.push(Launch {

            pid,

            output,

            tag,

            at: Instant::now(),

        });

    }

    pub fn find(&self, pid: u32) -> Option<(Option<OutputId>, TagId)> {

        let mut pid = pid;

        for _ in 0..32 {

            if let Some(l) = self.0.iter().find(|l| l.pid == pid) {

                return Some((l.output, l.tag));

            }

            pid = parent(pid).filter(|&p| p > 1)?;

        }

        None

    }

}

fn parent(pid: u32) -> Option<u32> {

    let stat = std::fs::read_to_string(format!("/proc/{pid}/stat")).ok()?;

    let rest = stat.get(stat.rfind(')')? + 2..)?;

    rest.split(' ').nth(1)?.parse().ok()

}