[pbs-devel] [PATCH proxmox-backup] rest-server/daemon: use sd_notify_barrier for service reloading
Dominik Csapak
d.csapak at proxmox.com
Thu Sep 30 09:18:58 CEST 2021
until now, we manually polled the systemd service state during a reload
so that the sd_notify messages get processed in the correct order
(RELOAD(old) -> MAINPID(old) -> READY(new))
with systemd >= 246 there is now 'sd_notify_barrier' which
blocks until systemd processed all prior messages
with that change, the daemon does not need to know the service name anymore
Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
debian/control | 2 +-
.../examples/minimal-rest-server.rs | 1 -
proxmox-rest-server/src/daemon.rs | 61 +++++++------------
src/bin/proxmox-backup-api.rs | 1 -
src/bin/proxmox-backup-proxy.rs | 1 -
5 files changed, 22 insertions(+), 44 deletions(-)
diff --git a/debian/control b/debian/control
index 02b094bd..8aec88cf 100644
--- a/debian/control
+++ b/debian/control
@@ -89,7 +89,7 @@ Build-Depends: debhelper (>= 12),
librust-zstd-0.6+default-dev,
libacl1-dev,
libfuse3-dev,
- libsystemd-dev,
+ libsystemd-dev (>= 246-~~),
uuid-dev,
libsgutils2-dev,
bash-completion,
diff --git a/proxmox-rest-server/examples/minimal-rest-server.rs b/proxmox-rest-server/examples/minimal-rest-server.rs
index 22477039..2b6a40a1 100644
--- a/proxmox-rest-server/examples/minimal-rest-server.rs
+++ b/proxmox-rest-server/examples/minimal-rest-server.rs
@@ -207,7 +207,6 @@ async fn run() -> Result<(), Error> {
Ok(())
})
},
- "example_server",
).await?;
Ok(())
diff --git a/proxmox-rest-server/src/daemon.rs b/proxmox-rest-server/src/daemon.rs
index 9d48ecd2..5d59fce2 100644
--- a/proxmox-rest-server/src/daemon.rs
+++ b/proxmox-rest-server/src/daemon.rs
@@ -186,6 +186,9 @@ impl Reloader {
if let Err(e) = systemd_notify(SystemdNotify::MainPid(child)) {
log::error!("failed to notify systemd about the new main pid: {}", e);
}
+ if let Err(e) = systemd_notify_barrier() {
+ log::error!("failed to wait on systemd-processing: {}", e);
+ }
// notify child that it is now the new main process:
if let Err(e) = pold.write_all(&[1u8]) {
@@ -248,7 +251,6 @@ impl Reloadable for tokio::net::TcpListener {
pub async fn create_daemon<F, S>(
address: std::net::SocketAddr,
create_service: F,
- service_name: &str,
) -> Result<(), Error>
where
F: FnOnce(tokio::net::TcpListener) -> Result<S, Error>,
@@ -289,7 +291,10 @@ 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) = systemd_notify_barrier() {
+ log::error!("failed to wait on systemd-processing: {}", e);
+ }
+
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()));
@@ -302,51 +307,14 @@ where
future.await;
}
- // FIXME: this is a hack, replace with sd_notify_barrier when available
- if crate::is_reload_request() {
- wait_service_is_not_state(service_name, "reloading").await?;
- }
-
log::info!("daemon shut down.");
Ok(())
}
-// hack, do not use if unsure!
-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::sleep(std::time::Duration::new(1, 0)).await;
- while get_service_state(service).await? != state {
- tokio::time::sleep(std::time::Duration::new(5, 0)).await;
- }
- Ok(())
-}
-
-async fn wait_service_is_not_state(service: &str, state: &str) -> Result<(), Error> {
- tokio::time::sleep(std::time::Duration::new(1, 0)).await;
- while get_service_state(service).await? == state {
- tokio::time::sleep(std::time::Duration::new(5, 0)).await;
- }
- Ok(())
-}
-
#[link(name = "systemd")]
extern "C" {
fn sd_notify(unset_environment: c_int, state: *const c_char) -> c_int;
+ fn sd_notify_barrier(unset_environment: c_int, timeout: u64) -> c_int;
}
/// Systemd sercice startup states (see: ``man sd_notify``)
@@ -358,6 +326,19 @@ pub enum SystemdNotify {
MainPid(nix::unistd::Pid),
}
+/// Waits until all previously sent messages with sd_notify are processed
+pub fn systemd_notify_barrier() -> Result<(), Error> {
+ let rc = unsafe { sd_notify_barrier(0, u64::MAX) }; // infinite timeout
+ if rc < 0 {
+ bail!(
+ "systemd_notify_barrier failed: {}",
+ std::io::Error::from_raw_os_error(-rc),
+ );
+ }
+
+ Ok(())
+}
+
/// Tells systemd the startup state of the service (see: ``man sd_notify``)
pub fn systemd_notify(state: SystemdNotify) -> Result<(), Error> {
diff --git a/src/bin/proxmox-backup-api.rs b/src/bin/proxmox-backup-api.rs
index 35cfc5f0..97b7a5e8 100644
--- a/src/bin/proxmox-backup-api.rs
+++ b/src/bin/proxmox-backup-api.rs
@@ -119,7 +119,6 @@ async fn run() -> Result<(), Error> {
.await
})
},
- "proxmox-backup.service",
);
proxmox_rest_server::write_pid(pbs_buildcfg::PROXMOX_BACKUP_API_PID_FN)?;
diff --git a/src/bin/proxmox-backup-proxy.rs b/src/bin/proxmox-backup-proxy.rs
index a98d4c1f..a548b535 100644
--- a/src/bin/proxmox-backup-proxy.rs
+++ b/src/bin/proxmox-backup-proxy.rs
@@ -262,7 +262,6 @@ async fn run() -> Result<(), Error> {
.await
})
},
- "proxmox-backup-proxy.service",
);
proxmox_rest_server::write_pid(pbs_buildcfg::PROXMOX_BACKUP_PROXY_PID_FN)?;
--
2.30.2
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