Refactor block resync loop; make workers infaillible

src/garage/repair.rs

@@ -20,6 +20,16 @@ impl Repair {
 		&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);
+		}
+	}
+
+	async fn repair_worker_aux(
+		&self,
+		opt: RepairOpt,
+		must_exit: watch::Receiver<bool>,
 	) -> Result<(), Error> {
 		let todo = |x| opt.what.as_ref().map(|y| *y == x).unwrap_or(true);
 

src/model/block.rs

@@ -258,46 +258,48 @@ impl BlockManager {
 	async fn resync_loop(
 		self: Arc<Self>,
 		mut must_exit: watch::Receiver<bool>,
-	) -> Result<(), Error> {
-		let mut n_failures = 0usize;
+	) {
 		while !*must_exit.borrow() {
-			if let Some((time_bytes, hash_bytes)) = self.resync_queue.pop_min()? {
-				let time_msec = u64_from_be_bytes(&time_bytes[0..8]);
-				let now = now_msec();
-				if now >= time_msec {
-					let hash = Hash::try_from(&hash_bytes[..]).unwrap();
+			if let Err(e) = self.resync_iter(&mut must_exit).await {
+				warn!("Error in block resync loop: {}", e);
+				tokio::time::delay_for(Duration::from_secs(10)).await;
+			}
+		}
+	}
 
-					if let Err(e) = self.resync_iter(&hash).await {
-						warn!("Failed to resync block {:?}, retrying later: {}", hash, e);
-						self.put_to_resync(&hash, RESYNC_RETRY_TIMEOUT)?;
-						n_failures += 1;
-						if n_failures >= 10 {
-							warn!("Too many resync failures, throttling.");
-							tokio::time::delay_for(Duration::from_secs(1)).await;
-						}
-					} else {
-						n_failures = 0;
-					}
-				} else {
-					self.resync_queue.insert(time_bytes, hash_bytes)?;
-					let delay = tokio::time::delay_for(Duration::from_millis(time_msec - now));
-					select! {
-						_ = delay.fuse() => (),
-						_ = self.resync_notify.notified().fuse() => (),
-						_ = must_exit.recv().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?;
+			let time_msec = u64_from_be_bytes(&time_bytes[0..8]);
+			let now = now_msec();
+			if now >= time_msec {
+				let hash = Hash::try_from(&hash_bytes[..]).unwrap();
+				let res = self.resync_block(&hash).await;
+				if let Err(e) = &res {
+					warn!("Error when resyncing {:?}: {}", hash, e);
+					self.put_to_resync(&hash, RESYNC_RETRY_TIMEOUT)?;
 				}
+				self.resync_queue.remove(&time_bytes)?;
+				res?;	// propagate error to delay main loop
 			} else {
+				let delay = tokio::time::delay_for(Duration::from_millis(time_msec - now));
 				select! {
+					_ = delay.fuse() => (),
 					_ = self.resync_notify.notified().fuse() => (),
 					_ = must_exit.recv().fuse() => (),
 				}
 			}
+		} else {
+			select! {
+				_ = self.resync_notify.notified().fuse() => (),
+				_ = must_exit.recv().fuse() => (),
+			}
 		}
 		Ok(())
 	}
 
-	async fn resync_iter(&self, hash: &Hash) -> Result<(), Error> {
+	async fn resync_block(&self, hash: &Hash) -> Result<(), Error> {
 		let lock = self.data_dir_lock.lock().await;
 
 		let path = self.block_path(hash);

src/rpc/membership.rs

@@ -318,9 +318,7 @@ impl System {
 		let self2 = self.clone();
 		self.clone()
 			.background
-			.spawn_worker(format!("ping loop"), |stop_signal| {
-				self2.ping_loop(stop_signal).map(Ok)
-			});
+			.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();
@@ -329,7 +327,6 @@ impl System {
 				.spawn_worker(format!("Consul loop"), |stop_signal| {
 					self2
 						.consul_loop(stop_signal, consul_host, consul_service_name)
-						.map(Ok)
 				});
 		}
 	}

src/table/gc.rs

@@ -70,7 +70,7 @@ where
 		gc
 	}
 
-	async fn gc_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) -> Result<(), Error> {
+	async fn gc_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) {
 		while !*must_exit.borrow() {
 			match self.gc_loop_iter().await {
 				Ok(true) => {
@@ -89,7 +89,6 @@ where
 				_ = must_exit.recv().fuse() => (),
 			}
 		}
-		Ok(())
 	}
 
 	async fn gc_loop_iter(&self) -> Result<bool, Error> {

src/table/merkle.rs

@@ -104,7 +104,7 @@ impl MerkleUpdater {
 	async fn updater_loop(
 		self: Arc<Self>,
 		mut must_exit: watch::Receiver<bool>,
-	) -> Result<(), Error> {
+	) {
 		while !*must_exit.borrow() {
 			if let Some(x) = self.todo.iter().next() {
 				match x {
@@ -131,7 +131,6 @@ impl MerkleUpdater {
 				}
 			}
 		}
-		Ok(())
 	}
 
 	fn update_item(&self, k: &[u8], vhash_by: &[u8]) -> Result<(), Error> {

src/table/sync.rs

@@ -136,7 +136,7 @@ where
 		self: Arc<Self>,
 		mut must_exit: watch::Receiver<bool>,
 		mut busy_rx: mpsc::UnboundedReceiver<bool>,
-	) -> Result<(), Error> {
+	) {
 		let mut prev_ring: Arc<Ring> = self.aux.system.ring.borrow().clone();
 		let mut ring_recv: watch::Receiver<Arc<Ring>> = self.aux.system.ring.clone();
 		let mut nothing_to_do_since = Some(Instant::now());
@@ -183,7 +183,6 @@ where
 				}
 			}
 		}
-		Ok(())
 	}
 
 	pub fn add_full_sync(&self) {
@@ -197,11 +196,11 @@ where
 		self: Arc<Self>,
 		mut must_exit: watch::Receiver<bool>,
 		busy_tx: mpsc::UnboundedSender<bool>,
-	) -> Result<(), Error> {
+	) {
 		while !*must_exit.borrow() {
 			let task = self.todo.lock().unwrap().pop_task();
 			if let Some(partition) = task {
-				busy_tx.send(true)?;
+				busy_tx.send(true).unwrap();
 				let res = self
 					.clone()
 					.sync_partition(&partition, &mut must_exit)
@@ -213,11 +212,10 @@ where
 					);
 				}
 			} else {
-				busy_tx.send(false)?;
+				busy_tx.send(false).unwrap();
 				tokio::time::delay_for(Duration::from_secs(1)).await;
 			}
 		}
-		Ok(())
 	}
 
 	async fn sync_partition(

src/util/background.rs

@@ -76,16 +76,13 @@ impl BackgroundRunner {
 	pub fn spawn_worker<F, T>(&self, name: String, worker: F)
 	where
 		F: FnOnce(watch::Receiver<bool>) -> T + Send + 'static,
-		T: Future<Output = JobOutput> + 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 {
-			if let Err(e) = worker(stop_signal).await {
-				error!("Worker stopped with error: {}, error: {}", name, e);
-			} else {
-				info!("Worker exited successfully: {}", name);
-			}
+			worker(stop_signal).await;
+			info!("Worker exited: {}", name);
 		}));
 	}