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watcher: Refactor tests to not use threads

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Fixes flakiness, removes unnecessary waiting.
This commit is contained in:
Ivan Molodetskikh
2025-08-15 08:08:55 +03:00
parent 8b4517a87b
commit 6d0505e684
1 changed files with 96 additions and 124 deletions
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src/utils/watcher.rs
+96 -124
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@@ -10,94 +10,73 @@ use smithay::reexports::calloop::channel::SyncSender;
use crate::niri::State;
const POLLING_INTERVAL: Duration = Duration::from_millis(500);
pub struct Watcher {
load_config: mpsc::Sender<()>,
}
struct WatcherInner {
/// The paths we're watching.
path: ConfigPath,
/// Last observed props of the watched file.
///
/// Equality on this means the file did not change.
///
/// We store the absolute path in addition to mtime to account for symlinked configs where the
/// symlink target may change without mtime. This is common on nix where everything is a
/// symlink to /nix/store, which keeps no mtime (= 1970-01-01).
last_props: Option<(SystemTime, PathBuf)>,
}
#[derive(Debug, PartialEq, Eq)]
enum CheckResult {
Missing,
Unchanged,
Changed,
}
impl Watcher {
pub fn new<T: Send + 'static>(
path: ConfigPath,
process: impl FnMut(&ConfigPath) -> T + Send + 'static,
changed: SyncSender<T>,
) -> Self {
let interval = Duration::from_millis(500);
Self::with_start_notification(path, process, changed, None, interval)
}
pub fn with_start_notification<T: Send + 'static>(
config_path: ConfigPath,
mut process: impl FnMut(&ConfigPath) -> T + Send + 'static,
changed: SyncSender<T>,
started: Option<mpsc::SyncSender<()>>,
polling_interval: Duration,
) -> Self {
let (load_config, load_config_rx) = mpsc::channel();
thread::Builder::new()
.name(format!("Filesystem Watcher for {config_path:?}"))
.name(format!("Filesystem Watcher for {path:?}"))
.spawn(move || {
// this "should" be as simple as storing the last seen mtime,
// and if the contents change without updating mtime, we ignore it.
//
// but that breaks if the config is a symlink, and its target
// changes but the new target and old target have identical mtimes.
// in which case we should *not* ignore it; this is an entirely different file.
//
// in practice, this edge case does not occur on systems other than nix.
// because, on nix, everything is a symlink to /nix/store
// and /nix/store keeps no mtime (= 1970-01-01)
// so, symlink targets change frequently when mtime doesn't.
//
// therefore, we must also store the canonical path, along with its mtime
fn see_path(path: &Path) -> io::Result<(SystemTime, PathBuf)> {
let canon = path.canonicalize()?;
let mtime = canon.metadata()?.modified()?;
Ok((mtime, canon))
}
fn see(config_path: &ConfigPath) -> io::Result<(SystemTime, PathBuf)> {
match config_path {
ConfigPath::Explicit(path) => see_path(path),
ConfigPath::Regular {
user_path,
system_path,
} => see_path(user_path).or_else(|_| see_path(system_path)),
}
}
let mut last_props = see(&config_path).ok();
if let Some(started) = started {
let _ = started.send(());
}
let mut inner = WatcherInner::new(path);
loop {
let mut should_load = match load_config_rx.recv_timeout(polling_interval) {
let mut should_load = match load_config_rx.recv_timeout(POLLING_INTERVAL) {
Ok(()) => true,
Err(mpsc::RecvTimeoutError::Disconnected) => break,
Err(mpsc::RecvTimeoutError::Timeout) => false,
};
if let Ok(new_props) = see(&config_path) {
if last_props.as_ref() != Some(&new_props) {
last_props = Some(new_props);
match inner.check() {
CheckResult::Missing => continue,
CheckResult::Unchanged => (),
CheckResult::Changed => {
trace!("config file changed");
should_load = true;
}
}
if should_load {
let rv = process(&config_path);
if should_load {
let rv = process(&inner.path);
if let Err(err) = changed.send(rv) {
warn!("error sending change notification: {err:?}");
break;
}
if let Err(err) = changed.send(rv) {
warn!("error sending change notification: {err:?}");
break;
}
}
}
debug!("exiting watcher thread for {config_path:?}");
debug!("exiting watcher thread for {:?}", inner.path);
})
.unwrap();
@@ -109,6 +88,42 @@ impl Watcher {
}
}
fn see_path(path: &Path) -> io::Result<(SystemTime, PathBuf)> {
let canon = path.canonicalize()?;
let mtime = canon.metadata()?.modified()?;
Ok((mtime, canon))
}
fn see(config_path: &ConfigPath) -> io::Result<(SystemTime, PathBuf)> {
match config_path {
ConfigPath::Explicit(path) => see_path(path),
ConfigPath::Regular {
user_path,
system_path,
} => see_path(user_path).or_else(|_| see_path(system_path)),
}
}
impl WatcherInner {
pub fn new(path: ConfigPath) -> Self {
let last_props = see(&path).ok();
Self { path, last_props }
}
pub fn check(&mut self) -> CheckResult {
if let Ok(new_props) = see(&self.path) {
if self.last_props.as_ref() != Some(&new_props) {
self.last_props = Some(new_props);
CheckResult::Changed
} else {
CheckResult::Unchanged
}
} else {
CheckResult::Missing
}
}
}
pub fn setup(state: &mut State, config_path: &ConfigPath) {
// Parsing the config actually takes > 20 ms on my beefy machine, so let's do it on the
// watcher thread.
@@ -137,8 +152,6 @@ mod tests {
use std::fs::{self, File, FileTimes};
use std::io::Write;
use calloop::channel::{sync_channel, Event};
use calloop::EventLoop;
use xshell::{cmd, Shell, TempDir};
use super::*;
@@ -234,29 +247,9 @@ mod tests {
sh, config_path, ..
} = self;
let (tx, rx) = sync_channel(1);
let (started_tx, started_rx) = mpsc::sync_channel(1);
let _watcher = Watcher::with_start_notification(
config_path,
|config_path| canon(config_path).clone(),
tx,
Some(started_tx),
Duration::from_millis(100),
);
started_rx.recv()?;
let event_loop = EventLoop::try_new()?;
event_loop
.handle()
.insert_source(rx, |event, (), latest_path| {
if let Event::Msg(path) = event {
*latest_path = Some(path);
}
})?;
let mut test = TestUtil { event_loop };
let mut test = TestUtil {
watcher: WatcherInner::new(config_path),
};
// don't trigger before we start
test.assert_unchanged();
@@ -272,22 +265,23 @@ mod tests {
}
}
struct TestUtil<'a> {
event_loop: EventLoop<'a, Option<PathBuf>>,
struct TestUtil {
watcher: WatcherInner,
}
impl<'a> TestUtil<'a> {
impl TestUtil {
// Ensures that mtime is different between writes in the tests.
fn pass_time(&self) {
thread::sleep(Duration::from_millis(50));
}
fn assert_unchanged(&mut self) {
let mut new_path = None;
self.event_loop
.dispatch(Duration::from_millis(150), &mut new_path)
.unwrap();
assert_eq!(
new_path, None,
let res = self.watcher.check();
// This may be Missing or Unchanged, both are fine.
assert_ne!(
res,
CheckResult::Changed,
"watcher should not have noticed any changes"
);
@@ -295,29 +289,22 @@ mod tests {
}
fn assert_changed_to(&mut self, expected: &str) {
let mut new_path = None;
self.event_loop
.dispatch(Duration::from_millis(150), &mut new_path)
.unwrap();
let Some(new_path) = new_path else {
panic!("watcher should have noticed a change, but it didn't");
};
let actual = fs::read_to_string(&new_path).unwrap();
assert_eq!(actual, expected, "watcher gave the wrong file");
let res = self.watcher.check();
assert_eq!(
res,
CheckResult::Changed,
"watcher should have noticed a change, but it didn't"
);
let new_path = canon(&self.watcher.path);
let actual = fs::read_to_string(new_path).unwrap();
assert_eq!(actual, expected, "wrong file contents");
self.pass_time();
}
}
// All tests are currently ignored because they are flaky. Presumably, this is because the
// watcher thread sleeps can align with test thread runs in such a way that the watcher wakes
// up in the middle between operations and ends up reporting a change one more time than
// expected, leading to test failures on the final unchanged check.
//
// https://github.com/YaLTeR/niri/issues/2226
#[test]
#[ignore]
fn change_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -331,7 +318,6 @@ mod tests {
}
#[test]
#[ignore]
fn overwrite_but_dont_change_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -345,7 +331,6 @@ mod tests {
}
#[test]
#[ignore]
fn touch_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -359,7 +344,6 @@ mod tests {
}
#[test]
#[ignore]
fn create_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.create_dir("niri"))
@@ -373,7 +357,6 @@ mod tests {
}
#[test]
#[ignore]
fn create_dir_and_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.without_setup()
@@ -386,7 +369,6 @@ mod tests {
}
#[test]
#[ignore]
fn change_linked_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| {
@@ -403,7 +385,6 @@ mod tests {
}
#[test]
#[ignore]
fn change_file_in_linked_dir() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| {
@@ -420,7 +401,6 @@ mod tests {
}
#[test]
#[ignore]
fn remove_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -434,7 +414,6 @@ mod tests {
}
#[test]
#[ignore]
fn remove_dir() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -448,7 +427,6 @@ mod tests {
}
#[test]
#[ignore]
fn recreate_file() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -463,7 +441,6 @@ mod tests {
}
#[test]
#[ignore]
fn recreate_dir() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| {
@@ -481,7 +458,6 @@ mod tests {
}
#[test]
#[ignore]
fn swap_dir() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| sh.write_file("niri/config.kdl", "a"))
@@ -497,7 +473,6 @@ mod tests {
}
#[test]
#[ignore]
fn swap_dir_link() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup(|sh| {
@@ -530,7 +505,6 @@ mod tests {
}
#[test]
#[ignore]
fn swap_just_link() -> Result {
TestPath::Explicit("niri/config.kdl")
.setup_any(|sh| {
@@ -555,7 +529,6 @@ mod tests {
}
#[test]
#[ignore]
fn swap_many_regular() -> Result {
TestPath::Regular {
user_path: "user-niri/config.kdl",
@@ -590,7 +563,6 @@ mod tests {
}
#[test]
#[ignore]
fn swap_many_links_regular_like_nix() -> Result {
TestPath::Regular {
user_path: "user-niri/config.kdl",