Some improvements in background worker but we terminate late

src/garage/admin_rpc.rs

@@ -193,7 +193,12 @@ impl AdminRpcHandler {
 				let key_ids = self
 					.garage
 					.key_table
-					.get_range(&EmptyKey, None, Some(KeyFilter::Deleted(DeletedFilter::NotDeleted)), 10000)
+					.get_range(
+						&EmptyKey,
+						None,
+						Some(KeyFilter::Deleted(DeletedFilter::NotDeleted)),
+						10000,
+					)
 					.await?
 					.iter()
 					.map(|k| (k.key_id.to_string(), k.name.get().clone()))
@@ -257,15 +262,24 @@ impl AdminRpcHandler {
 	}
 
 	async fn get_existing_key(&self, pattern: &str) -> Result<Key, Error> {
-		let candidates = self.garage
+		let candidates = self
+			.garage
 			.key_table
-			.get_range(&EmptyKey, None, Some(KeyFilter::Matches(pattern.to_string())), 10)
+			.get_range(
+				&EmptyKey,
+				None,
+				Some(KeyFilter::Matches(pattern.to_string())),
+				10,
+			)
 			.await?
 			.into_iter()
 			.filter(|k| !k.deleted.get())
 			.collect::<Vec<_>>();
 		if candidates.len() != 1 {
-			Err(Error::Message(format!("{} matching keys", candidates.len())))
+			Err(Error::Message(format!(
+				"{} matching keys",
+				candidates.len()
+			)))
 		} else {
 			Ok(candidates.into_iter().next().unwrap())
 		}
@@ -469,12 +483,7 @@ impl AdminRpcHandler {
 			t.data.merkle_updater.merkle_tree_len()
 		)
 		.unwrap();
-		writeln!(
-			to,
-			"  GC todo queue length: {}",
-			t.data.gc_todo_len()
-		)
-		.unwrap();
+		writeln!(to, "  GC todo queue length: {}", t.data.gc_todo_len()).unwrap();
 		Ok(())
 	}
 }

src/garage/repair.rs

@@ -16,11 +16,7 @@ pub struct Repair {
 }
 
 impl Repair {
-	pub async fn repair_worker(
-		&self,
-		opt: RepairOpt,
-		must_exit: watch::Receiver<bool>,
-	) {
+	pub async fn repair_worker(&self, opt: RepairOpt, must_exit: watch::Receiver<bool>) {
 		if let Err(e) = self.repair_worker_aux(opt, must_exit).await {
 			warn!("Repair worker failed with error: {}", e);
 		}

src/garage/server.rs

@@ -47,10 +47,15 @@ pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
 
 	info!("Initializing background runner...");
 	let (send_cancel, watch_cancel) = watch::channel(false);
-	let background = BackgroundRunner::new(16, watch_cancel.clone());
+	let (background, await_background_done) = BackgroundRunner::new(16, watch_cancel.clone());
 
 	info!("Initializing Garage main data store...");
-	let garage = Garage::new(config, db, background.clone(), &mut rpc_server);
+	let garage = Garage::new(config.clone(), db, background, &mut rpc_server);
+	let bootstrap = garage.system.clone().bootstrap(
+		&config.bootstrap_peers[..],
+		config.consul_host,
+		config.consul_service_name,
+	);
 
 	info!("Crate admin RPC handler...");
 	AdminRpcHandler::new(garage.clone()).register_handler(&mut rpc_server);
@@ -58,21 +63,13 @@ pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
 	info!("Initializing RPC and API servers...");
 	let run_rpc_server = Arc::new(rpc_server).run(wait_from(watch_cancel.clone()));
 	let api_server = api_server::run_api_server(garage.clone(), wait_from(watch_cancel.clone()));
-	let web_server = web_server::run_web_server(garage.clone(), wait_from(watch_cancel.clone()));
+	let web_server = web_server::run_web_server(garage, wait_from(watch_cancel.clone()));
 
 	futures::try_join!(
-		garage
-			.system
-			.clone()
-			.bootstrap(
-				&garage.config.bootstrap_peers[..],
-				garage.config.consul_host.clone(),
-				garage.config.consul_service_name.clone()
-			)
-			.map(|rv| {
-				info!("Bootstrap done");
-				Ok(rv)
-			}),
+		bootstrap.map(|rv| {
+			info!("Bootstrap done");
+			Ok(rv)
+		}),
 		run_rpc_server.map(|rv| {
 			info!("RPC server exited");
 			rv
@@ -85,9 +82,9 @@ pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
 			info!("Web server exited");
 			rv
 		}),
-		background.run().map(|rv| {
-			info!("Background runner exited");
-			Ok(rv)
+		await_background_done.map(|rv| {
+			info!("Background runner exited: {:?}", rv);
+			Ok(())
 		}),
 		shutdown_signal(send_cancel),
 	)?;

src/model/block.rs

@@ -254,19 +254,18 @@ impl BlockManager {
 		Ok(())
 	}
 
-	async fn resync_loop(
-		self: Arc<Self>,
-		mut must_exit: watch::Receiver<bool>,
-	) {
+	async fn resync_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) {
 		while !*must_exit.borrow() {
 			if let Err(e) = self.resync_iter(&mut must_exit).await {
 				warn!("Error in block resync loop: {}", e);
-				tokio::time::sleep(Duration::from_secs(10)).await;
+				select! {
+					_ = tokio::time::sleep(Duration::from_secs(10)).fuse() => (),
+					_ = must_exit.changed().fuse() => (),
+				}
 			}
 		}
 	}
 
-
 	async fn resync_iter(&self, must_exit: &mut watch::Receiver<bool>) -> Result<(), Error> {
 		if let Some(first_item) = self.resync_queue.iter().next() {
 			let (time_bytes, hash_bytes) = first_item?;
@@ -280,7 +279,7 @@ impl BlockManager {
 					self.put_to_resync(&hash, RESYNC_RETRY_TIMEOUT)?;
 				}
 				self.resync_queue.remove(&time_bytes)?;
-				res?;	// propagate error to delay main loop
+				res?; // propagate error to delay main loop
 			} else {
 				let delay = tokio::time::sleep(Duration::from_millis(time_msec - now));
 				select! {

src/model/key_table.rs

@@ -109,7 +109,8 @@ impl TableSchema for KeyTable {
 			KeyFilter::Deleted(df) => df.apply(entry.deleted.get()),
 			KeyFilter::Matches(pat) => {
 				let pat = pat.to_lowercase();
-				entry.key_id.to_lowercase().starts_with(&pat) || entry.name.get().to_lowercase() == pat
+				entry.key_id.to_lowercase().starts_with(&pat)
+					|| entry.name.get().to_lowercase() == pat
 			}
 		}
 	}

src/model/object_table.rs

@@ -195,8 +195,7 @@ impl TableSchema for ObjectTable {
 
 	fn updated(&self, old: Option<Self::E>, new: Option<Self::E>) {
 		let version_table = self.version_table.clone();
-		// TODO not cancellable
-		self.background.spawn_cancellable(async move {
+		self.background.spawn(async move {
 			if let (Some(old_v), Some(new_v)) = (old, new) {
 				// Propagate deletion of old versions
 				for v in old_v.versions.iter() {

src/model/version_table.rs

@@ -110,8 +110,7 @@ impl TableSchema for VersionTable {
 
 	fn updated(&self, old: Option<Self::E>, new: Option<Self::E>) {
 		let block_ref_table = self.block_ref_table.clone();
-		// TODO not cancellable
-		self.background.spawn_cancellable(async move {
+		self.background.spawn(async move {
 			if let (Some(old_v), Some(new_v)) = (old, new) {
 				// Propagate deletion of version blocks
 				if new_v.deleted.get() && !old_v.deleted.get() {

src/rpc/membership.rs

@@ -11,9 +11,9 @@ use futures::future::join_all;
 use futures::select;
 use futures_util::future::*;
 use serde::{Deserialize, Serialize};
+use tokio::io::AsyncWriteExt;
 use tokio::sync::watch;
 use tokio::sync::Mutex;
-use tokio::io::AsyncWriteExt;
 
 use garage_util::background::BackgroundRunner;
 use garage_util::data::*;
@@ -316,17 +316,16 @@ impl System {
 		self.clone().ping_nodes(bootstrap_peers).await;
 
 		let self2 = self.clone();
-		self.clone()
-			.background
-			.spawn_worker(format!("ping loop"), |stop_signal| self2.ping_loop(stop_signal));
+		self.background
+			.spawn_worker(format!("ping loop"), |stop_signal| {
+				self2.ping_loop(stop_signal)
+			});
 
 		if let (Some(consul_host), Some(consul_service_name)) = (consul_host, consul_service_name) {
 			let self2 = self.clone();
-			self.clone()
-				.background
+			self.background
 				.spawn_worker(format!("Consul loop"), |stop_signal| {
-					self2
-						.consul_loop(stop_signal, consul_host, consul_service_name)
+					self2.consul_loop(stop_signal, consul_host, consul_service_name)
 				});
 		}
 	}
@@ -531,7 +530,7 @@ impl System {
 					.broadcast(Message::AdvertiseConfig(adv.clone()), PING_TIMEOUT)
 					.map(Ok),
 			);
-			self.background.spawn(self.clone().save_network_config()).await;
+			self.background.spawn(self.clone().save_network_config());
 		}
 
 		Ok(Message::Ok)
@@ -568,7 +567,7 @@ impl System {
 		consul_host: String,
 		consul_service_name: String,
 	) {
-		loop {
+		while !*stop_signal.borrow() {
 			let restart_at = tokio::time::sleep(CONSUL_INTERVAL);
 
 			match get_consul_nodes(&consul_host, &consul_service_name).await {
@@ -583,11 +582,7 @@ impl System {
 
 			select! {
 				_ = restart_at.fuse() => (),
-				_ = stop_signal.changed().fuse() => {
-					if *stop_signal.borrow() {
-						return;
-					}
-				}
+				_ = stop_signal.changed().fuse() => (),
 			}
 		}
 	}

src/rpc/ring.rs

@@ -161,11 +161,11 @@ impl Ring {
 			})
 			.collect::<Vec<_>>();
 
-		eprintln!("RING: --");
-		for e in ring.iter() {
-			eprintln!("{:?}", e);
-		}
-		eprintln!("END --");
+		// eprintln!("RING: --");
+		// for e in ring.iter() {
+		// 	eprintln!("{:?}", e);
+		// }
+		// eprintln!("END --");
 
 		Self { config, ring }
 	}

src/rpc/rpc_client.rs

@@ -198,7 +198,7 @@ impl<M: RpcMessage + 'static> RpcClient<M> {
 				let wait_finished_fut = tokio::spawn(async move {
 					resp_stream.collect::<Vec<_>>().await;
 				});
-				self.background.spawn(wait_finished_fut.map(|_| Ok(()))).await;
+				self.background.spawn(wait_finished_fut.map(|_| Ok(())));
 			}
 
 			Ok(results)

src/rpc/rpc_server.rs

@@ -13,9 +13,9 @@ use hyper::service::{make_service_fn, service_fn};
 use hyper::{Body, Method, Request, Response, Server, StatusCode};
 use serde::{Deserialize, Serialize};
 use tokio::net::{TcpListener, TcpStream};
-use tokio_stream::wrappers::TcpListenerStream;
 use tokio_rustls::server::TlsStream;
 use tokio_rustls::TlsAcceptor;
+use tokio_stream::wrappers::TcpListenerStream;
 
 use garage_util::config::TlsConfig;
 use garage_util::data::*;
@@ -52,7 +52,11 @@ where
 
 	trace!(
 		"Request message: {}",
-		serde_json::to_string(&msg).unwrap_or("<json error>".into()).chars().take(100).collect::<String>()
+		serde_json::to_string(&msg)
+			.unwrap_or("<json error>".into())
+			.chars()
+			.take(100)
+			.collect::<String>()
 	);
 
 	match handler(msg, sockaddr).await {

src/table/merkle.rs

@@ -101,10 +101,7 @@ impl MerkleUpdater {
 		ret
 	}
 
-	async fn updater_loop(
-		self: Arc<Self>,
-		mut must_exit: watch::Receiver<bool>,
-	) {
+	async fn updater_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) {
 		while !*must_exit.borrow() {
 			if let Some(x) = self.todo.iter().next() {
 				match x {

src/table/sync.rs

@@ -3,7 +3,7 @@ use std::convert::TryInto;
 use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
 
-use futures::{select};
+use futures::select;
 use futures_util::future::*;
 use futures_util::stream::*;
 use rand::Rng;

src/util/background.rs

@@ -1,10 +1,11 @@
 use core::future::Future;
 use std::pin::Pin;
-use std::sync::Mutex;
-
-use arc_swap::ArcSwapOption;
 use std::sync::Arc;
-use tokio::sync::{mpsc, watch};
+use std::time::Duration;
+
+use futures::future::*;
+use futures::select;
+use tokio::sync::{mpsc, watch, Mutex};
 
 use crate::error::Error;
 
@@ -14,99 +15,115 @@ type Job = Pin<Box<dyn Future<Output = JobOutput> + Send>>;
 pub struct BackgroundRunner {
 	pub stop_signal: watch::Receiver<bool>,
 
-	queue_in: ArcSwapOption<mpsc::UnboundedSender<(Job, bool)>>,
-
-	workers: Mutex<Vec<tokio::task::JoinHandle<()>>>,
+	queue_in: mpsc::UnboundedSender<(Job, bool)>,
+	worker_in: mpsc::UnboundedSender<tokio::task::JoinHandle<()>>,
 }
 
 impl BackgroundRunner {
-	pub fn new(n_runners: usize, stop_signal: watch::Receiver<bool>) -> Arc<Self> {
-		let (queue_in, queue_out) = mpsc::unbounded_channel();
+	pub fn new(
+		n_runners: usize,
+		stop_signal: watch::Receiver<bool>,
+	) -> (Arc<Self>, tokio::task::JoinHandle<()>) {
+		let (worker_in, mut worker_out) = mpsc::unbounded_channel();
 
-		let mut workers = vec![];
-		let queue_out = Arc::new(tokio::sync::Mutex::new(queue_out));
+		let stop_signal_2 = stop_signal.clone();
+		let await_all_done = tokio::spawn(async move {
+			loop {
+				let wkr = {
+					select! {
+						item = worker_out.recv().fuse() => {
+							match item {
+								Some(x) => x,
+								None => break,
+							}
+						}
+						_ = tokio::time::sleep(Duration::from_secs(10)).fuse() => {
+							if *stop_signal_2.borrow() {
+								break;
+							} else {
+								continue;
+							}
+						}
+					}
+				};
+				if let Err(e) = wkr.await {
+					error!("Error while awaiting for worker: {}", e);
+				}
+			}
+		});
+
+		let (queue_in, queue_out) = mpsc::unbounded_channel();
+		let queue_out = Arc::new(Mutex::new(queue_out));
 
 		for i in 0..n_runners {
 			let queue_out = queue_out.clone();
 			let stop_signal = stop_signal.clone();
 
-			workers.push(tokio::spawn(async move {
-				while let Some((job, cancellable)) = queue_out.lock().await.recv().await {
-					if cancellable && *stop_signal.borrow() {
-						continue;
+			worker_in
+				.send(tokio::spawn(async move {
+					loop {
+						let (job, cancellable) = {
+							select! {
+								item = wait_job(&queue_out).fuse() => match item {
+									// We received a task, process it
+									Some(x) => x,
+									// We received a signal that no more tasks will ever be sent
+									// because the sending side was dropped. Exit now.
+									None => break,
+								},
+								_ = tokio::time::sleep(Duration::from_secs(10)).fuse() => {
+									if *stop_signal.borrow() {
+										// Nothing has been going on for 10 secs, and we are shutting
+										// down. Exit now.
+										break;
+									} else {
+										// Nothing is going on but we don't want to exit.
+										continue;
+									}
+								}
+							}
+						};
+						if cancellable && *stop_signal.borrow() {
+							continue;
+						}
+						if let Err(e) = job.await {
+							error!("Job failed: {}", e)
+						}
 					}
-					if let Err(e) = job.await {
-						error!("Job failed: {}", e)
-					}
-				}
-				info!("Worker {} exiting", i);
-			}));
+					info!("Background worker {} exiting", i);
+				}))
+				.unwrap();
 		}
 
-		Arc::new(Self {
+		let bgrunner = Arc::new(Self {
 			stop_signal,
-			queue_in: ArcSwapOption::new(Some(Arc::new(queue_in))),
-			workers: Mutex::new(workers),
-		})
-	}
-
-	pub async fn run(self: Arc<Self>) {
-		let mut stop_signal = self.stop_signal.clone();
-
-		loop {
-			let exit_now = match stop_signal.changed().await {
-				Ok(()) => *stop_signal.borrow(),
-				Err(e) => {
-					error!("Watch .changed() error: {}", e);
-					true
-				}
-			};
-			if exit_now {
-				break;
-			}
-		}
-
-		info!("Closing background job queue_in...");
-		drop(self.queue_in.swap(None));
-
-		info!("Waiting for all workers to terminate...");
-		while let Some(task) = self.workers.lock().unwrap().pop() {
-			if let Err(e) = task.await {
-				warn!("Error awaiting task: {}", e);
-			}
-		}
+			queue_in,
+			worker_in,
+		});
+		(bgrunner, await_all_done)
 	}
 
 	// Spawn a task to be run in background
-	pub async fn spawn<T>(&self, job: T)
+	pub fn spawn<T>(&self, job: T)
 	where
 		T: Future<Output = JobOutput> + Send + 'static,
 	{
-		match self.queue_in.load().as_ref() {
-			Some(chan) => {
-				let boxed: Job = Box::pin(job);
-				chan.send((boxed, false)).map_err(|_| "send error").unwrap();
-			}
-			None => {
-				warn!("Doing background job now because we are exiting...");
-				if let Err(e) = job.await {
-					warn!("Task failed: {}", e);
-				}
-			}
-		}
+		let boxed: Job = Box::pin(job);
+		self.queue_in
+			.send((boxed, false))
+			.map_err(|_| "could not put job in queue")
+			.unwrap();
 	}
 
 	pub fn spawn_cancellable<T>(&self, job: T)
 	where
 		T: Future<Output = JobOutput> + Send + 'static,
 	{
-		match self.queue_in.load().as_ref() {
-			Some(chan) => {
-				let boxed: Job = Box::pin(job);
-				chan.send((boxed, false)).map_err(|_| "send error").unwrap();
-			}
-			None => (), // drop job if we are exiting
-		}
+		let boxed: Job = Box::pin(job);
+		self.queue_in
+			.send((boxed, true))
+			.map_err(|_| "could not put job in queue")
+			.unwrap();
 	}
 
 	pub fn spawn_worker<F, T>(&self, name: String, worker: F)
@@ -114,11 +131,19 @@ impl BackgroundRunner {
 		F: FnOnce(watch::Receiver<bool>) -> T + Send + 'static,
 		T: Future<Output = ()> + Send + 'static,
 	{
-		let mut workers = self.workers.lock().unwrap();
 		let stop_signal = self.stop_signal.clone();
-		workers.push(tokio::spawn(async move {
+		let task = tokio::spawn(async move {
+			info!("Worker started: {}", name);
 			worker(stop_signal).await;
 			info!("Worker exited: {}", name);
-		}));
+		});
+		self.worker_in
+			.send(task)
+			.map_err(|_| "could not put job in queue")
+			.unwrap();
 	}
 }
+
+async fn wait_job(q: &Mutex<mpsc::UnboundedReceiver<(Job, bool)>>) -> Option<(Job, bool)> {
+	q.lock().await.recv().await
+}