refactor: restart notifications and panel when the other exits

src/main.rs

@@ -8,7 +8,10 @@ mod process;
 mod service;
 mod systemd;
 
-use std::os::fd::AsRawFd;
+use std::{
+	os::fd::AsRawFd,
+	sync::{Arc, Mutex},
+};
 
 use async_signals::Signals;
 use color_eyre::{eyre::WrapErr, Result};
@@ -24,6 +27,8 @@ use tracing::{metadata::LevelFilter, Instrument};
 use tracing_subscriber::{fmt, prelude::*, EnvFilter};
 use zbus::ConnectionBuilder;
 
+use crate::notifications::notifications_process;
+
 #[tokio::main(flavor = "current_thread")]
 async fn main() -> Result<()> {
 	color_eyre::install().wrap_err("failed to install color_eyre error handler")?;
@@ -74,72 +79,63 @@ async fn main() -> Result<()> {
 
 	let (panel_notifications_fd, daemon_notifications_fd) =
 		notifications::create_socket().expect("Failed to create notification socket");
-	let mut panel_env_vars = env_vars.clone();
-
-	panel_env_vars.push((
-		PANEL_NOTIFICATIONS_FD.to_string(),
-		panel_notifications_fd.as_raw_fd().to_string(),
-	));
-
-	let span = info_span!(parent: None, "cosmic-panel");
-	let stdout_span = span.clone();
-	let stderr_span = span;
-	process_manager
-		.start(
-			Process::new()
-				.with_executable("cosmic-panel")
-				.with_fds(move || vec![panel_notifications_fd.as_raw_fd()])
-				.with_on_stdout(move |_, _, line| {
-					let stdout_span = stdout_span.clone();
-					async move {
-						info!("{}", line);
-					}
-					.instrument(stdout_span)
-				})
-				.with_on_stderr(move |_, _, line| {
-					let stderr_span = stderr_span.clone();
-					async move {
-						warn!("{}", line);
-					}
-					.instrument(stderr_span)
-				})
-				.with_env(panel_env_vars.clone()),
-		)
-		.await
-		.expect("failed to start panel");
 
 	let mut daemon_env_vars = env_vars.clone();
 	daemon_env_vars.push((
 		DAEMON_NOTIFICATIONS_FD.to_string(),
 		daemon_notifications_fd.as_raw_fd().to_string(),
 	));
-	let span = info_span!(parent: None, "cosmic-notifications");
-	let stdout_span = span.clone();
-	let stderr_span = span;
+	let mut panel_env_vars = env_vars.clone();
+	panel_env_vars.push((
+		PANEL_NOTIFICATIONS_FD.to_string(),
+		panel_notifications_fd.as_raw_fd().to_string(),
+	));
 
-	process_manager
-		.start(
-			Process::new()
-				.with_executable("cosmic-notifications")
-				.with_fds(move || vec![daemon_notifications_fd.as_raw_fd()])
-				.with_on_stdout(move |_, _, line| {
-					let stdout_span = stdout_span.clone();
-					async move {
-						info!("{}", line);
-					}
-					.instrument(stdout_span)
-				})
-				.with_on_stderr(move |_, _, line| {
-					let stderr_span = stderr_span.clone();
-					async move {
-						warn!("{}", line);
-					}
-					.instrument(stderr_span)
-				})
-				.with_env(daemon_env_vars.clone()),
-		)
-		.await
-		.expect("failed to start notifications daemon");
+	let panel_key = Arc::new(Mutex::new(None));
+	let notif_key = Arc::new(Mutex::new(None));
+
+	let notifications_span = info_span!(parent: None, "cosmic-notifications");
+	let panel_span = info_span!(parent: None, "cosmic-panel");
+
+	let mut guard = notif_key.lock().unwrap();
+	*guard = Some(
+		process_manager
+			.start(notifications_process(
+				notifications_span.clone(),
+				"cosmic-notifications",
+				notif_key.clone(),
+				daemon_env_vars.clone(),
+				daemon_notifications_fd.as_raw_fd(),
+				panel_span.clone(),
+				"cosmic-panel",
+				panel_key.clone(),
+				panel_env_vars.clone(),
+				panel_notifications_fd.as_raw_fd(),
+			))
+			.await
+			.expect("failed to start notifications daemon"),
+	);
+	drop(guard);
+
+	let mut guard = panel_key.lock().unwrap();
+	*guard = Some(
+		process_manager
+			.start(notifications_process(
+				panel_span,
+				"cosmic-panel",
+				panel_key.clone(),
+				panel_env_vars,
+				panel_notifications_fd.as_raw_fd(),
+				notifications_span,
+				"cosmic-notifications",
+				notif_key,
+				daemon_env_vars,
+				daemon_notifications_fd.as_raw_fd(),
+			))
+			.await
+			.expect("failed to start panel"),
+	);
+	drop(guard);
 
 	let span = info_span!(parent: None, "cosmic-app-library");
 	start_component("cosmic-app-library", span, &process_manager, &env_vars).await;

src/notifications.rs

@@ -1,7 +1,11 @@
 use color_eyre::eyre::Context;
 use color_eyre::Result;
-use std::os::fd::OwnedFd;
+use launch_pad::process::Process;
+use launch_pad::ProcessKey;
+use std::os::fd::{OwnedFd, RawFd};
 use std::os::unix::net::UnixStream;
+use std::sync::{Arc, Mutex};
+use tracing::Instrument;
 
 pub fn create_socket() -> Result<(OwnedFd, OwnedFd)> {
 	// Create a new pair of unnamed Unix sockets
@@ -10,12 +14,77 @@ pub fn create_socket() -> Result<(OwnedFd, OwnedFd)> {
 	// Turn the sockets into non-blocking fd, which we can pass to the child
 	// process
 	sock_1
-		.set_nonblocking(false)
-		.wrap_err("failed to mark client socket as blocking")?;
+		.set_nonblocking(true)
+		.wrap_err("failed to mark client socket as non-blocking")?;
 
 	sock_2
-		.set_nonblocking(false)
-		.wrap_err("failed to mark client socket as blocking")?;
+		.set_nonblocking(true)
+		.wrap_err("failed to mark client socket as non-blocking")?;
 
 	Ok((OwnedFd::from(sock_1), OwnedFd::from(sock_2)))
 }
+
+pub fn notifications_process(
+	span: tracing::Span,
+	cmd: &'static str,
+	key: Arc<Mutex<Option<ProcessKey>>>,
+	env_vars: Vec<(String, String)>,
+	fd: RawFd,
+	restart_span: tracing::Span,
+	restart_cmd: &'static str,
+	restart_key: Arc<Mutex<Option<ProcessKey>>>,
+	restart_env_vars: Vec<(String, String)>,
+	restart_fd: RawFd,
+) -> Process {
+	let stdout_span = span.clone();
+	let stderr_span = span.clone();
+	let env_clone = env_vars.clone();
+	Process::new()
+		.with_executable(cmd)
+		.with_fds(move || vec![fd])
+		.with_on_stdout(move |_, _, line| {
+			let stdout_span = stdout_span.clone();
+			async move {
+				info!("{}", line);
+			}
+			.instrument(stdout_span)
+		})
+		.with_on_stderr(move |_, _, line| {
+			let stderr_span = stderr_span.clone();
+			async move {
+				warn!("{}", line);
+			}
+			.instrument(stderr_span)
+		})
+		.with_on_exit(move |pman, _, _, will_restart| {
+			// force restart of notifications / panel when the other exits
+			let new_process = notifications_process(
+				restart_span.clone(),
+				restart_cmd,
+				restart_key.clone(),
+				restart_env_vars.clone(),
+				restart_fd,
+				span.clone(),
+				cmd,
+				key.clone(),
+				env_clone.clone(),
+				fd,
+			);
+			let restart_key = restart_key.clone();
+			async move {
+				if will_restart {
+					let Some(old) = restart_key.lock().unwrap().clone() else {
+                        error!("Couldn't stop previous invocation of {}", cmd);
+                        return;
+					};
+					_ = pman.stop_process(old).await;
+
+					if let Ok(new) = pman.start(new_process).await {
+						let mut guard = restart_key.lock().unwrap();
+						*guard = Some(new);
+					}
+				}
+			}
+		})
+		.with_env(env_vars)
+}