tools/daemon: improve reload behaviour

it seems that sometimes, the child process signal gets handled
before the parent process signal. Systemd then ignores the
childs signal (finished reloading) and only after going into
reloading state because of the parent. this will never finish.

Instead, wait for the state to change to 'reloading' after sending
that signal in the parent, an only fork afterwards. This way
we ensure that systemd knows about the reloading before actually trying
to do it.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Tested-By: Fabian Ebner <f.ebner@proxmox.com>

diff --git a/src/tools/daemon.rs b/src/tools/daemon.rs
index 6bb4a41bce5a90246b6ddda5943f1cae020e4dee..0e3a174a9fe22147014ef0438e431512dc95d97e 100644 (file)
--- a/src/tools/daemon.rs
+++ b/src/tools/daemon.rs
@@ -291,6 +291,7 @@ where
         if let Err(e) = systemd_notify(SystemdNotify::Reloading) {
             log::error!("failed to notify systemd about the state change: {}", e);
         }
+        wait_service_is_state(service_name, "reloading").await?;
         if let Err(e) = reloader.take().unwrap().fork_restart() {
             log::error!("error during reload: {}", e);
             let _ = systemd_notify(SystemdNotify::Status("error during reload".to_string()));
@@ -305,7 +306,7 @@ where
 
     // FIXME: this is a hack, replace with sd_notify_barrier when available
     if server::is_reload_request() {
-        wait_service_is_active(service_name).await?;
+        wait_service_is_not_state(service_name, "reloading").await?;
     }
 
     log::info!("daemon shut down...");
@@ -313,26 +314,36 @@ where
 }
 
 // hack, do not use if unsure!
-async fn wait_service_is_active(service: &str) -> Result<(), Error> {
+async fn get_service_state(service: &str) -> Result<String, Error> {
+    let text = match tokio::process::Command::new("systemctl")
+        .args(&["is-active", service])
+        .output()
+        .await
+    {
+        Ok(output) => match String::from_utf8(output.stdout) {
+            Ok(text) => text,
+            Err(err) => bail!("output of 'systemctl is-active' not valid UTF-8 - {}", err),
+        },
+        Err(err) => bail!("executing 'systemctl is-active' failed - {}", err),
+    };
+
+    Ok(text.trim().trim_start().to_string())
+}
+
+async fn wait_service_is_state(service: &str, state: &str) -> Result<(), Error> {
     tokio::time::delay_for(std::time::Duration::new(1, 0)).await;
-    loop {
-        let text = match tokio::process::Command::new("systemctl")
-            .args(&["is-active", service])
-            .output()
-            .await
-        {
-            Ok(output) => match String::from_utf8(output.stdout) {
-                Ok(text) => text,
-                Err(err) => bail!("output of 'systemctl is-active' not valid UTF-8 - {}", err),
-            },
-            Err(err) => bail!("executing 'systemctl is-active' failed - {}", err),
-        };
+    while get_service_state(service).await? != state {
+        tokio::time::delay_for(std::time::Duration::new(5, 0)).await;
+    }
+    Ok(())
+}
 
-        if text.trim().trim_start() != "reloading" {
-            return Ok(());
-        }
+async fn wait_service_is_not_state(service: &str, state: &str) -> Result<(), Error> {
+    tokio::time::delay_for(std::time::Duration::new(1, 0)).await;
+    while get_service_state(service).await? == state {
         tokio::time::delay_for(std::time::Duration::new(5, 0)).await;
     }
+    Ok(())
 }
 
 #[link(name = "systemd")]