Gracefully terminate deltachat-rpc-server on ctrl-c and SIGTERM (#4323)

CHANGELOG.md

@@ -11,7 +11,7 @@
 - maybe_add_time_based_warnings(): Use release date instead of the provider DB update one
 - Remove confusing log line "ignoring unsolicited response Recent(…)" #3934
 - Cleanly terminate deltachat-rpc-server.
-  Also terminate on ctrl-c.
+  I.e. on EOF in stdin.
 - Refactorings #4317
 - Add JSON-RPC API `can_send()`.
 - New `dc_get_next_msgs()` and `dc_wait_next_msgs()` C APIs.
@@ -24,6 +24,7 @@
 - New Python bindings APIs `Message.is_from_self()` and `Message.is_from_device()`.
 - Remove metadata from avatars and JPEG images before sending #4037
 - Reduce + recode images to JPEG if they are > 500K in size #4037
+- Gracefully terminate deltachat-rpc-server on ctrl-c and SIGTERM.
 
 ### Fixes
 - Fix python bindings README documentation on installing the bindings from source.

deltachat-rpc-server/src/main.rs

@@ -11,13 +11,26 @@ use deltachat_jsonrpc::api::events::event_to_json_rpc_notification;
 use deltachat_jsonrpc::api::{Accounts, CommandApi};
 use futures_lite::stream::StreamExt;
 use tokio::io::{self, AsyncBufReadExt, BufReader};
+
+#[cfg(target_family = "unix")]
+use tokio::signal::unix as signal_unix;
+
 use tokio::sync::RwLock;
 use tokio::task::JoinHandle;
 use tokio_util::sync::CancellationToken;
 use yerpc::{RpcClient, RpcSession};
 
 #[tokio::main(flavor = "multi_thread")]
-async fn main() -> Result<()> {
+async fn main() {
+    let r = main_impl().await;
+    // From tokio documentation:
+    // "For technical reasons, stdin is implemented by using an ordinary blocking read on a separate
+    // thread, and it is impossible to cancel that read. This can make shutdown of the runtime hang
+    // until the user presses enter."
+    std::process::exit(if r.is_ok() { 0 } else { 1 });
+}
+
+async fn main_impl() -> Result<()> {
     let mut args = env::args_os();
     let _program_name = args.next().context("no command line arguments found")?;
     if let Some(first_arg) = args.next() {
@@ -35,6 +48,11 @@ async fn main() -> Result<()> {
         return Err(anyhow!("Unrecognized argument {:?}", arg));
     }
 
+    // Install signal handlers early so that the shutdown is graceful starting from here.
+    let _ctrl_c = tokio::signal::ctrl_c();
+    #[cfg(target_family = "unix")]
+    let mut sigterm = signal_unix::signal(signal_unix::SignalKind::terminate())?;
+
     env_logger::Builder::from_env(env_logger::Env::default().default_filter_or("info")).init();
 
     let path = std::env::var("DC_ACCOUNTS_PATH").unwrap_or_else(|_| "accounts".to_string());
@@ -48,10 +66,12 @@ async fn main() -> Result<()> {
 
     let (client, mut out_receiver) = RpcClient::new();
     let session = RpcSession::new(client.clone(), state.clone());
-    let canceler = CancellationToken::new();
+    let main_cancel = CancellationToken::new();
 
     // Events task converts core events to JSON-RPC notifications.
+    let cancel = main_cancel.clone();
     let events_task: JoinHandle<Result<()>> = tokio::spawn(async move {
+        let _cancel_guard = cancel.clone().drop_guard();
         let mut r = Ok(());
         while let Some(event) = events.recv().await {
             if r.is_err() {
@@ -60,16 +80,16 @@ async fn main() -> Result<()> {
             let event = event_to_json_rpc_notification(event);
             r = client.send_notification("event", Some(event)).await;
         }
-        r?;
         Ok(())
     });
 
     // Send task prints JSON responses to stdout.
-    let cancelable = canceler.clone();
+    let cancel = main_cancel.clone();
     let send_task: JoinHandle<anyhow::Result<()>> = tokio::spawn(async move {
+        let _cancel_guard = cancel.clone().drop_guard();
         loop {
             let message = tokio::select! {
-                _ = cancelable.cancelled() => break,
+                _ = cancel.cancelled() => break,
                 message = out_receiver.next() => match message {
                     None => break,
                     Some(message) => serde_json::to_string(&message)?,
@@ -81,12 +101,32 @@ async fn main() -> Result<()> {
         Ok(())
     });
 
+    let cancel = main_cancel.clone();
+    let sigterm_task: JoinHandle<anyhow::Result<()>> = tokio::spawn(async move {
+        #[cfg(target_family = "unix")]
+        {
+            let _cancel_guard = cancel.clone().drop_guard();
+            tokio::select! {
+                _ = cancel.cancelled() => (),
+                _ = sigterm.recv() => {
+                    log::info!("got SIGTERM");
+                }
+            }
+        }
+        let _ = cancel;
+        Ok(())
+    });
+
     // Receiver task reads JSON requests from stdin.
+    let cancel = main_cancel.clone();
     let recv_task: JoinHandle<anyhow::Result<()>> = tokio::spawn(async move {
+        let _cancel_guard = cancel.clone().drop_guard();
         let stdin = io::stdin();
         let mut lines = BufReader::new(stdin).lines();
+
         loop {
             let message = tokio::select! {
+                _ = cancel.cancelled() => break,
                 _ = tokio::signal::ctrl_c() => {
                     log::info!("got ctrl-c event");
                     break;
@@ -108,17 +148,14 @@ async fn main() -> Result<()> {
         Ok(())
     });
 
-    // Wait for the end of stdin / ctrl-c.
-    recv_task.await?.ok();
-
     // See "Thread safety" section in deltachat-ffi/deltachat.h for explanation.
     // NB: Events are drained by events_task.
-    canceler.cancel();
+    main_cancel.cancelled().await;
     accounts.read().await.stop_io().await;
     drop(accounts);
     drop(state);
-    let (r0, r1) = tokio::join!(events_task, send_task);
-    for r in [r0, r1] {
+    let (r0, r1, r2, r3) = tokio::join!(events_task, send_task, sigterm_task, recv_task);
+    for r in [r0, r1, r2, r3] {
         r??;
     }