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Fix shutdown of config monitor #7936

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merged 1 commit into from May 3, 2024
Merged

Fix shutdown of config monitor #7936

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240 changes: 134 additions & 106 deletions alacritty/src/config/monitor.rs
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@@ -1,9 +1,13 @@
use std::path::PathBuf;
use std::sync::mpsc::{self, RecvTimeoutError};
use std::sync::mpsc::{self, RecvTimeoutError, Sender};
use std::thread::JoinHandle;
use std::time::{Duration, Instant};

use log::{debug, error};
use notify::{Config, EventKind, RecommendedWatcher, RecursiveMode, Watcher};
use log::{debug, error, warn};
use notify::{
Config, Error as NotifyError, Event as NotifyEvent, EventKind, RecommendedWatcher,
RecursiveMode, Watcher,
};
use winit::event_loop::EventLoopProxy;

use alacritty_terminal::thread;
Expand All @@ -15,115 +19,139 @@ const DEBOUNCE_DELAY: Duration = Duration::from_millis(10);
/// The fallback for `RecommendedWatcher` polling.
const FALLBACK_POLLING_TIMEOUT: Duration = Duration::from_secs(1);

pub fn watch(mut paths: Vec<PathBuf>, event_proxy: EventLoopProxy<Event>) {
// Don't monitor config if there is no path to watch.
if paths.is_empty() {
return;
}
/// Config file update monitor.
pub struct ConfigMonitor {
thread: JoinHandle<()>,
shutdown_tx: Sender<Result<NotifyEvent, NotifyError>>,
}

// Exclude char devices like `/dev/null`, sockets, and so on, by checking that file type is a
// regular file.
paths.retain(|path| {
// Call `metadata` to resolve symbolic links.
path.metadata().map_or(false, |metadata| metadata.file_type().is_file())
});

// Canonicalize paths, keeping the base paths for symlinks.
for i in 0..paths.len() {
if let Ok(canonical_path) = paths[i].canonicalize() {
match paths[i].symlink_metadata() {
Ok(metadata) if metadata.file_type().is_symlink() => paths.push(canonical_path),
_ => paths[i] = canonical_path,
}
impl ConfigMonitor {
pub fn new(mut paths: Vec<PathBuf>, event_proxy: EventLoopProxy<Event>) -> Option<Self> {
// Don't monitor config if there is no path to watch.
if paths.is_empty() {
return None;
}
}

// The Duration argument is a debouncing period.
let (tx, rx) = mpsc::channel();
let mut watcher = match RecommendedWatcher::new(
tx,
Config::default().with_poll_interval(FALLBACK_POLLING_TIMEOUT),
) {
Ok(watcher) => watcher,
Err(err) => {
error!("Unable to watch config file: {}", err);
return;
},
};

thread::spawn_named("config watcher", move || {
// Get all unique parent directories.
let mut parents = paths
.iter()
.map(|path| {
let mut path = path.clone();
path.pop();
path
})
.collect::<Vec<PathBuf>>();
parents.sort_unstable();
parents.dedup();

// Watch all configuration file directories.
for parent in &parents {
if let Err(err) = watcher.watch(parent, RecursiveMode::NonRecursive) {
debug!("Unable to watch config directory {:?}: {}", parent, err);
// Exclude char devices like `/dev/null`, sockets, and so on, by checking that file type is
// a regular file.
paths.retain(|path| {
// Call `metadata` to resolve symbolic links.
path.metadata().map_or(false, |metadata| metadata.file_type().is_file())
});

// Canonicalize paths, keeping the base paths for symlinks.
for i in 0..paths.len() {
if let Ok(canonical_path) = paths[i].canonicalize() {
match paths[i].symlink_metadata() {
Ok(metadata) if metadata.file_type().is_symlink() => paths.push(canonical_path),
_ => paths[i] = canonical_path,
}
}
}

// The current debouncing time.
let mut debouncing_deadline: Option<Instant> = None;

// The events accumulated during the debounce period.
let mut received_events = Vec::new();

loop {
// We use `recv_timeout` to debounce the events coming from the watcher and reduce
// the amount of config reloads.
let event = match debouncing_deadline.as_ref() {
Some(debouncing_deadline) => {
rx.recv_timeout(debouncing_deadline.saturating_duration_since(Instant::now()))
},
None => {
let event = rx.recv().map_err(Into::into);
// Set the debouncing deadline after receiving the event.
debouncing_deadline = Some(Instant::now() + DEBOUNCE_DELAY);
event
},
};

match event {
Ok(Ok(event)) => match event.kind {
EventKind::Any
| EventKind::Create(_)
| EventKind::Modify(_)
| EventKind::Other => {
received_events.push(event);
// The Duration argument is a debouncing period.
let (tx, rx) = mpsc::channel();
let mut watcher = match RecommendedWatcher::new(
tx.clone(),
Config::default().with_poll_interval(FALLBACK_POLLING_TIMEOUT),
) {
Ok(watcher) => watcher,
Err(err) => {
error!("Unable to watch config file: {}", err);
return None;
},
};

let join_handle = thread::spawn_named("config watcher", move || {
// Get all unique parent directories.
let mut parents = paths
.iter()
.map(|path| {
let mut path = path.clone();
path.pop();
path
})
.collect::<Vec<PathBuf>>();
parents.sort_unstable();
parents.dedup();

// Watch all configuration file directories.
for parent in &parents {
if let Err(err) = watcher.watch(parent, RecursiveMode::NonRecursive) {
debug!("Unable to watch config directory {:?}: {}", parent, err);
}
}

// The current debouncing time.
let mut debouncing_deadline: Option<Instant> = None;

// The events accumulated during the debounce period.
let mut received_events = Vec::new();

loop {
// We use `recv_timeout` to debounce the events coming from the watcher and reduce
// the amount of config reloads.
let event = match debouncing_deadline.as_ref() {
Some(debouncing_deadline) => rx.recv_timeout(
debouncing_deadline.saturating_duration_since(Instant::now()),
),
None => {
let event = rx.recv().map_err(Into::into);
// Set the debouncing deadline after receiving the event.
debouncing_deadline = Some(Instant::now() + DEBOUNCE_DELAY);
event
},
};

match event {
Ok(Ok(event)) => match event.kind {
EventKind::Other if event.info() == Some("shutdown") => break,
EventKind::Any
| EventKind::Create(_)
| EventKind::Modify(_)
| EventKind::Other => {
received_events.push(event);
},
_ => (),
},
Err(RecvTimeoutError::Timeout) => {
// Go back to polling the events.
debouncing_deadline = None;

if received_events
.drain(..)
.flat_map(|event| event.paths.into_iter())
.any(|path| paths.contains(&path))
{
// Always reload the primary configuration file.
let event = Event::new(EventType::ConfigReload(paths[0].clone()), None);
let _ = event_proxy.send_event(event);
}
},
_ => (),
},
Err(RecvTimeoutError::Timeout) => {
// Go back to polling the events.
debouncing_deadline = None;

if received_events
.drain(..)
.flat_map(|event| event.paths.into_iter())
.any(|path| paths.contains(&path))
{
// Always reload the primary configuration file.
let event = Event::new(EventType::ConfigReload(paths[0].clone()), None);
let _ = event_proxy.send_event(event);
}
},
Ok(Err(err)) => {
debug!("Config watcher errors: {:?}", err);
},
Err(err) => {
debug!("Config watcher channel dropped unexpectedly: {}", err);
break;
},
};
Ok(Err(err)) => {
debug!("Config watcher errors: {:?}", err);
},
Err(err) => {
debug!("Config watcher channel dropped unexpectedly: {}", err);
break;
},
};
}
});

Some(Self { thread: join_handle, shutdown_tx: tx })
}

/// Synchronously shut down the monitor.
pub fn shutdown(self) {
// Request shutdown.
let mut event = NotifyEvent::new(EventKind::Other);
event = event.set_info("shutdown");
let _ = self.shutdown_tx.send(Ok(event));

// Wait for thread to terminate.
if let Err(err) = self.thread.join() {
warn!("config monitor shutdown failed: {err:?}");
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}
});
}
}
13 changes: 9 additions & 4 deletions alacritty/src/main.rs
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Expand Up @@ -56,7 +56,8 @@ mod gl {
#[cfg(unix)]
use crate::cli::MessageOptions;
use crate::cli::{Options, Subcommands};
use crate::config::{monitor, UiConfig};
use crate::config::monitor::ConfigMonitor;
use crate::config::UiConfig;
use crate::event::{Event, Processor};
#[cfg(target_os = "macos")]
use crate::macos::locale;
Expand Down Expand Up @@ -165,8 +166,10 @@ fn alacritty(mut options: Options) -> Result<(), Box<dyn Error>> {
//
// The monitor watches the config file for changes and reloads it. Pending
// config changes are processed in the main loop.
let mut config_monitor = None;
if config.live_config_reload {
monitor::watch(config.config_paths.clone(), window_event_loop.create_proxy());
config_monitor =
ConfigMonitor::new(config.config_paths.clone(), window_event_loop.create_proxy());
}

// Create the IPC socket listener.
Expand Down Expand Up @@ -205,8 +208,10 @@ fn alacritty(mut options: Options) -> Result<(), Box<dyn Error>> {
// FIXME: Change PTY API to enforce the correct drop order with the typesystem.
drop(processor);

// FIXME patch notify library to have a shutdown method.
// config_reloader.join().ok();
// Terminate the config monitor.
if let Some(config_monitor) = config_monitor.take() {
config_monitor.shutdown();
}

// Without explicitly detaching the console cmd won't redraw it's prompt.
#[cfg(windows)]
Expand Down