Add the LoadConfigFile action (#2163)

* Add the `LoadConfigFile` action

* fixes

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

niri-config/src/lib.rs

@@ -1924,6 +1924,8 @@ pub enum Action {
     SetWindowUrgent(u64),
     #[knuffel(skip)]
     UnsetWindowUrgent(u64),
+    #[knuffel(skip)]
+    LoadConfigFile,
 }
 
 impl From<niri_ipc::Action> for Action {
@@ -2199,6 +2201,7 @@ impl From<niri_ipc::Action> for Action {
             niri_ipc::Action::ToggleWindowUrgent { id } => Self::ToggleWindowUrgent(id),
             niri_ipc::Action::SetWindowUrgent { id } => Self::SetWindowUrgent(id),
             niri_ipc::Action::UnsetWindowUrgent { id } => Self::UnsetWindowUrgent(id),
+            niri_ipc::Action::LoadConfigFile {} => Self::LoadConfigFile,
         }
     }
 }

niri-ipc/src/lib.rs

@@ -840,6 +840,11 @@ pub enum Action {
         #[cfg_attr(feature = "clap", arg(long))]
         id: u64,
     },
+    /// Reload the config file.
+    ///
+    /// Can be useful for scripts changing the config file, to avoid waiting the small duration for
+    /// niri's config file watcher to notice the changes.
+    LoadConfigFile {},
 }
 
 /// Change in window or column size.

src/input/mod.rs

@@ -2113,6 +2113,11 @@ impl State {
                 }
                 self.niri.queue_redraw_all();
             }
+            Action::LoadConfigFile => {
+                if let Some(watcher) = &self.niri.config_file_watcher {
+                    watcher.load_config();
+                }
+            }
         }
     }
 

src/main.rs

@@ -23,8 +23,7 @@ use niri::utils::spawning::{
     spawn, store_and_increase_nofile_rlimit, CHILD_DISPLAY, CHILD_ENV, REMOVE_ENV_RUST_BACKTRACE,
     REMOVE_ENV_RUST_LIB_BACKTRACE,
 };
-use niri::utils::watcher::Watcher;
-use niri::utils::{cause_panic, version, xwayland, IS_SYSTEMD_SERVICE};
+use niri::utils::{cause_panic, version, watcher, xwayland, IS_SYSTEMD_SERVICE};
 use niri_config::ConfigPath;
 use niri_ipc::socket::SOCKET_PATH_ENV;
 use portable_atomic::Ordering;
@@ -230,27 +229,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         }
     }
 
-    // Set up config file watcher.
-    let _watcher = {
-        // Parsing the config actually takes > 20 ms on my beefy machine, so let's do it on the
-        // watcher thread.
-        let process = |path: &ConfigPath| {
-            path.load().map_err(|err| {
-                warn!("{err:?}");
-            })
-        };
-
-        let (tx, rx) = calloop::channel::sync_channel(1);
-        let watcher = Watcher::new(config_path.clone(), process, tx);
-        event_loop
-            .handle()
-            .insert_source(rx, |event, _, state| match event {
-                calloop::channel::Event::Msg(config) => state.reload_config(config),
-                calloop::channel::Event::Closed => (),
-            })
-            .unwrap();
-        watcher
-    };
+    watcher::setup(&mut state, &config_path);
 
     // Spawn commands from cli and auto-start.
     spawn(cli.command, None);

src/niri.rs

@@ -164,6 +164,7 @@ use crate::ui::screen_transition::{self, ScreenTransition};
 use crate::ui::screenshot_ui::{OutputScreenshot, ScreenshotUi, ScreenshotUiRenderElement};
 use crate::utils::scale::{closest_representable_scale, guess_monitor_scale};
 use crate::utils::spawning::{CHILD_DISPLAY, CHILD_ENV};
+use crate::utils::watcher::Watcher;
 use crate::utils::xwayland::satellite::Satellite;
 use crate::utils::{
     center, center_f64, expand_home, get_monotonic_time, ipc_transform_to_smithay, is_mapped,
@@ -190,6 +191,8 @@ pub struct Niri {
     /// (and transient changes dropped).
     pub config_file_output_config: niri_config::Outputs,
 
+    pub config_file_watcher: Option<Watcher>,
+
     pub event_loop: LoopHandle<'static, State>,
     pub scheduler: Scheduler<()>,
     pub stop_signal: LoopSignal,
@@ -2528,6 +2531,7 @@ impl Niri {
         let mut niri = Self {
             config,
             config_file_output_config,
+            config_file_watcher: None,
 
             event_loop,
             scheduler,

src/utils/watcher.rs

@@ -1,22 +1,17 @@
 //! File modification watcher.
 
 use std::path::{Path, PathBuf};
-use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{mpsc, Arc};
+use std::sync::mpsc;
 use std::time::{Duration, SystemTime};
 use std::{io, thread};
 
 use niri_config::ConfigPath;
 use smithay::reexports::calloop::channel::SyncSender;
 
-pub struct Watcher {
-    should_stop: Arc<AtomicBool>,
-}
+use crate::niri::State;
 
-impl Drop for Watcher {
-    fn drop(&mut self) {
-        self.should_stop.store(true, Ordering::SeqCst);
-    }
+pub struct Watcher {
+    load_config: mpsc::Sender<()>,
 }
 
 impl Watcher {
@@ -36,10 +31,8 @@ impl Watcher {
         started: Option<mpsc::SyncSender<()>>,
         polling_interval: Duration,
     ) -> Self {
-        let should_stop = Arc::new(AtomicBool::new(false));
+        let (load_config, load_config_rx) = mpsc::channel();
 
-        {
-            let should_stop = should_stop.clone();
         thread::Builder::new()
             .name(format!("Filesystem Watcher for {config_path:?}"))
             .spawn(move || {
@@ -80,24 +73,26 @@ impl Watcher {
                 }
 
                 loop {
-                        thread::sleep(polling_interval);
-
-                        if should_stop.load(Ordering::SeqCst) {
-                            break;
-                        }
+                    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);
                             trace!("config file changed");
+                            should_load = true;
+                        }
 
+                        if should_load {
                             let rv = process(&config_path);
 
                             if let Err(err) = changed.send(rv) {
                                 warn!("error sending change notification: {err:?}");
                                 break;
                             }
-
-                                last_props = Some(new_props);
                         }
                     }
                 }
@@ -105,12 +100,37 @@ impl Watcher {
                 debug!("exiting watcher thread for {config_path:?}");
             })
             .unwrap();
+
+        Self { load_config }
     }
 
-        Self { should_stop }
+    pub fn load_config(&self) {
+        let _ = self.load_config.send(());
     }
 }
 
+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.
+    let process = |path: &ConfigPath| {
+        path.load().map_err(|err| {
+            warn!("{err:?}");
+        })
+    };
+
+    let (tx, rx) = calloop::channel::sync_channel(1);
+    state
+        .niri
+        .event_loop
+        .insert_source(rx, |event, _, state| match event {
+            calloop::channel::Event::Msg(config) => state.reload_config(config),
+            calloop::channel::Event::Closed => (),
+        })
+        .unwrap();
+
+    state.niri.config_file_watcher = Some(Watcher::new(config_path.clone(), process, tx));
+}
+
 #[cfg(test)]
 mod tests {
     use std::error::Error;