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//! File modification watcher.
use std::path::PathBuf;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread;
use std::time::Duration;
use smithay::reexports::calloop::channel::SyncSender;
pub struct Watcher {
should_stop: Arc<AtomicBool>,
}
impl Drop for Watcher {
fn drop(&mut self) {
self.should_stop.store(true, Ordering::SeqCst);
}
}
impl Watcher {
pub fn new(path: PathBuf, changed: SyncSender<()>) -> Self {
let should_stop = Arc::new(AtomicBool::new(false));
{
let should_stop = should_stop.clone();
thread::Builder::new()
.name(format!("Filesystem Watcher for {}", path.to_string_lossy()))
.spawn(move || {
// this "should" be as simple as mtime, but it does not quite work in practice;
// it doesn't work if the config is a symlink, and its target changes but the
// new target and old target have identical mtimes.
//
// in practice, this does not occur on any systems other than nix.
// because, on nix practically everything is a symlink to /nix/store
// and due to reproducibility, /nix/store keeps no mtime (= 1970-01-01)
// so, symlink targets change frequently when mtime doesn't.
let mut last_props = path
.canonicalize()
.and_then(|canon| Ok((canon.metadata()?.modified()?, canon)))
.ok();
loop {
thread::sleep(Duration::from_millis(500));
if should_stop.load(Ordering::SeqCst) {
break;
}
if let Ok(new_props) = path
.canonicalize()
.and_then(|canon| Ok((canon.metadata()?.modified()?, canon)))
{
if last_props.as_ref() != Some(&new_props) {
trace!("file changed: {}", path.to_string_lossy());
if let Err(err) = changed.send(()) {
warn!("error sending change notification: {err:?}");
break;
}
last_props = Some(new_props);
}
}
}
debug!("exiting watcher thread for {}", path.to_string_lossy());
})
.unwrap();
}
Self { should_stop }
}
}
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