From 5c63193d1de909cdecc501b482f5dc269a84874d Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Thu, 8 Feb 2024 23:43:59 +0100
Subject: [dep-upgrade-202402] fix shutdown issue introduced when upgrading
 hyper

---
 src/api/generic_server.rs | 88 ++++++++++++++++++++++++++++-------------------
 1 file changed, 52 insertions(+), 36 deletions(-)

(limited to 'src/api/generic_server.rs')

diff --git a/src/api/generic_server.rs b/src/api/generic_server.rs
index 7b37417e..9c49fdf3 100644
--- a/src/api/generic_server.rs
+++ b/src/api/generic_server.rs
@@ -18,6 +18,7 @@ use hyper_util::rt::TokioIo;
 
 use tokio::io::{AsyncRead, AsyncWrite};
 use tokio::net::{TcpListener, TcpStream, UnixListener, UnixStream};
+use tokio::sync::watch;
 
 use opentelemetry::{
 	global,
@@ -104,20 +105,17 @@ impl<A: ApiHandler> ApiServer<A> {
 		self: Arc<Self>,
 		bind_addr: UnixOrTCPSocketAddress,
 		unix_bind_addr_mode: Option<u32>,
-		shutdown_signal: impl Future<Output = ()>,
+		must_exit: watch::Receiver<bool>,
 	) -> Result<(), GarageError> {
-		info!(
-			"{} API server listening on {}",
-			A::API_NAME_DISPLAY,
-			bind_addr
-		);
+		let server_name = format!("{} API", A::API_NAME_DISPLAY);
+		info!("{} server listening on {}", server_name, bind_addr);
 
 		match bind_addr {
 			UnixOrTCPSocketAddress::TCPSocket(addr) => {
 				let listener = TcpListener::bind(addr).await?;
 
 				let handler = move |request, socketaddr| self.clone().handler(request, socketaddr);
-				server_loop(listener, handler, shutdown_signal).await
+				server_loop(server_name, listener, handler, must_exit).await
 			}
 			UnixOrTCPSocketAddress::UnixSocket(ref path) => {
 				if path.exists() {
@@ -133,7 +131,7 @@ impl<A: ApiHandler> ApiServer<A> {
 				)?;
 
 				let handler = move |request, socketaddr| self.clone().handler(request, socketaddr);
-				server_loop(listener, handler, shutdown_signal).await
+				server_loop(server_name, listener, handler, must_exit).await
 			}
 		}
 	}
@@ -278,9 +276,10 @@ impl Accept for UnixListenerOn {
 }
 
 pub async fn server_loop<A, H, F, E>(
+	server_name: String,
 	listener: A,
 	handler: H,
-	shutdown_signal: impl Future<Output = ()>,
+	mut must_exit: watch::Receiver<bool>,
 ) -> Result<(), GarageError>
 where
 	A: Accept,
@@ -288,42 +287,57 @@ where
 	F: Future<Output = Result<Response<BoxBody<E>>, http::Error>> + Send + 'static,
 	E: Send + Sync + std::error::Error + 'static,
 {
-	tokio::pin!(shutdown_signal);
-
 	let (conn_in, mut conn_out) = tokio::sync::mpsc::unbounded_channel();
-	let connection_collector = tokio::spawn(async move {
-		let mut collection = FuturesUnordered::new();
-		loop {
-			let collect_next = async {
-				if collection.is_empty() {
-					futures::future::pending().await
-				} else {
-					collection.next().await
-				}
-			};
-			tokio::select! {
-				result = collect_next => {
-					trace!("HTTP connection finished: {:?}", result);
-				}
-				new_fut = conn_out.recv() => {
-					match new_fut {
-						Some(f) => collection.push(f),
-						None => break,
+	let connection_collector = tokio::spawn({
+		let server_name = server_name.clone();
+		async move {
+			let mut connections = FuturesUnordered::new();
+			loop {
+				let collect_next = async {
+					if connections.is_empty() {
+						futures::future::pending().await
+					} else {
+						connections.next().await
+					}
+				};
+				tokio::select! {
+					result = collect_next => {
+						trace!("{} server: HTTP connection finished: {:?}", server_name, result);
+					}
+					new_fut = conn_out.recv() => {
+						match new_fut {
+							Some(f) => connections.push(f),
+							None => break,
+						}
 					}
 				}
 			}
+			if !connections.is_empty() {
+				info!(
+					"{} server: {} connections still open",
+					server_name,
+					connections.len()
+				);
+				while let Some(conn_res) = connections.next().await {
+					trace!(
+						"{} server: HTTP connection finished: {:?}",
+						server_name,
+						conn_res
+					);
+					info!(
+						"{} server: {} connections still open",
+						server_name,
+						connections.len()
+					);
+				}
+			}
 		}
-		debug!("Collecting last open HTTP connections.");
-		while let Some(conn_res) = collection.next().await {
-			trace!("HTTP connection finished: {:?}", conn_res);
-		}
-		debug!("No more HTTP connections to collect");
 	});
 
-	loop {
+	while !*must_exit.borrow() {
 		let (stream, client_addr) = tokio::select! {
 			acc = listener.accept() => acc?,
-			_ = &mut shutdown_signal => break,
+			_ = must_exit.changed() => continue,
 		};
 
 		let io = TokioIo::new(stream);
@@ -343,6 +357,8 @@ where
 		conn_in.send(fut)?;
 	}
 
+	info!("{} server exiting", server_name);
+	drop(conn_in);
 	connection_collector.await?;
 
 	Ok(())
-- 
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