Background task runner that replaces tokio::spawn

src/api_server.rs

@@ -23,7 +23,7 @@ type BodyType = Box<dyn HttpBody<Data = Bytes, Error = Error> + Send + Unpin>;
 pub async fn run_api_server(
 	garage: Arc<Garage>,
 	shutdown_signal: impl Future<Output = ()>,
-) -> Result<(), hyper::Error> {
+) -> Result<(), Error> {
 	let addr = ([0, 0, 0, 0], garage.system.config.api_port).into();
 
 	let service = make_service_fn(|conn: &AddrStream| {
@@ -42,7 +42,8 @@ pub async fn run_api_server(
 	let graceful = server.with_graceful_shutdown(shutdown_signal);
 	println!("API server listening on http://{}", addr);
 
-	graceful.await
+	graceful.await?;
+	Ok(())
 }
 
 async fn handler(
@@ -92,6 +93,13 @@ async fn handler_inner(
 				version_uuid
 			)))))
 		}
+		&Method::DELETE => {
+			let version_uuid = handle_delete(garage, &bucket, &key).await?;
+			Ok(Response::new(Box::new(BytesBody::from(format!(
+				"{:?}\n",
+				version_uuid
+			)))))
+		}
 		_ => Err(Error::BadRequest(format!("Invalid method"))),
 	}
 }
@@ -257,6 +265,27 @@ impl BodyChunker {
 	}
 }
 
+async fn handle_delete(garage: Arc<Garage>, bucket: &str, key: &str) -> Result<UUID, Error> {
+	let version_uuid = gen_uuid();
+
+	let mut object = Object {
+		bucket: bucket.into(),
+		key: key.into(),
+		versions: Vec::new(),
+	};
+	object.versions.push(Box::new(ObjectVersion {
+		uuid: version_uuid.clone(),
+		timestamp: now_msec(),
+		mime_type: "application/x-delete-marker".into(),
+		size: 0,
+		is_complete: true,
+		data: ObjectVersionData::DeleteMarker,
+	}));
+
+	garage.object_table.insert(&object).await?;
+	return Ok(version_uuid);
+}
+
 async fn handle_get(
 	garage: Arc<Garage>,
 	bucket: &str,

src/background.rs

@@ -0,0 +1,113 @@
+use core::future::Future;
+use std::pin::Pin;
+
+use futures::future::join_all;
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::Mutex;
+use tokio::sync::{mpsc, watch};
+
+use crate::error::Error;
+
+type JobOutput = Result<(), Error>;
+type Job = Pin<Box<dyn Future<Output = JobOutput> + Send>>;
+
+pub struct BackgroundRunner {
+	n_runners: usize,
+	stop_signal: watch::Receiver<bool>,
+
+	queue_in: mpsc::UnboundedSender<(Job, bool)>,
+	queue_out: Mutex<mpsc::UnboundedReceiver<(Job, bool)>>,
+
+	workers: Mutex<Vec<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();
+		Arc::new(Self {
+			n_runners,
+			stop_signal,
+			queue_in,
+			queue_out: Mutex::new(queue_out),
+			workers: Mutex::new(Vec::new()),
+		})
+	}
+
+	pub async fn run(self: Arc<Self>) {
+		let mut workers = self.workers.lock().await;
+		for _i in 0..self.n_runners {
+			workers.push(tokio::spawn(self.clone().runner()));
+		}
+		drop(workers);
+
+		let mut stop_signal = self.stop_signal.clone();
+		while let Some(exit_now) = stop_signal.recv().await {
+			if exit_now {
+				let mut workers = self.workers.lock().await;
+				let workers_vec = workers.drain(..).collect::<Vec<_>>();
+				join_all(workers_vec).await;
+				return;
+			}
+		}
+	}
+
+	pub fn spawn<T>(&self, job: T)
+	where
+		T: Future<Output = JobOutput> + Send + 'static,
+	{
+		let boxed: Job = Box::pin(job);
+		let _: Result<_, _> = self.queue_in.clone().send((boxed, false));
+	}
+
+	pub fn spawn_cancellable<T>(&self, job: T)
+	where
+		T: Future<Output = JobOutput> + Send + 'static,
+	{
+		let boxed: Job = Box::pin(job);
+		let _: Result<_, _> = self.queue_in.clone().send((boxed, true));
+	}
+
+	pub async fn spawn_worker<F, T>(self: Arc<Self>, worker: F)
+	where
+		F: FnOnce(watch::Receiver<bool>) -> T + Send + 'static,
+		T: Future<Output = JobOutput> + Send + 'static,
+	{
+		let mut workers = self.workers.lock().await;
+		let stop_signal = self.stop_signal.clone();
+		workers.push(tokio::spawn(async move {
+			if let Err(e) = worker(stop_signal).await {
+				eprintln!("Worker stopped with error: {}", e);
+			}
+		}));
+	}
+
+	async fn runner(self: Arc<Self>) {
+		let stop_signal = self.stop_signal.clone();
+		loop {
+			let must_exit: bool = *stop_signal.borrow();
+			if let Some(job) = self.dequeue_job(must_exit).await {
+				if let Err(e) = job.await {
+					eprintln!("Job failed: {}", e)
+				}
+			} else {
+				if must_exit {
+					return;
+				}
+				tokio::time::delay_for(Duration::from_secs(1)).await;
+			}
+		}
+	}
+
+	async fn dequeue_job(&self, must_exit: bool) -> Option<Job> {
+		let mut queue = self.queue_out.lock().await;
+		while let Ok((job, cancellable)) = queue.try_recv() {
+			if cancellable && must_exit {
+				continue;
+			} else {
+				return Some(job);
+			}
+		}
+		None
+	}
+}

src/error.rs

@@ -63,3 +63,9 @@ impl From<sled::TransactionError<Error>> for Error {
 		}
 	}
 }
+
+impl<T> From<tokio::sync::watch::error::SendError<T>> for Error {
+	fn from(_e: tokio::sync::watch::error::SendError<T>) -> Error {
+		Error::Message(format!("Watch send error"))
+	}
+}

src/main.rs

@@ -2,6 +2,7 @@ mod data;
 mod error;
 mod proto;
 
+mod background;
 mod membership;
 mod table;
 

src/membership.rs

@@ -8,10 +8,14 @@ use std::sync::Arc;
 use std::time::Duration;
 
 use futures::future::join_all;
+use futures::select;
+use futures_util::future::*;
 use sha2::{Digest, Sha256};
 use tokio::prelude::*;
+use tokio::sync::watch;
 use tokio::sync::RwLock;
 
+use crate::background::BackgroundRunner;
 use crate::data::*;
 use crate::error::Error;
 use crate::proto::*;
@@ -29,6 +33,8 @@ pub struct System {
 	pub rpc_client: RpcClient,
 
 	pub members: RwLock<Members>,
+
+	pub background: Arc<BackgroundRunner>,
 }
 
 pub struct Members {
@@ -181,7 +187,7 @@ fn read_network_config(metadata_dir: &PathBuf) -> Result<NetworkConfig, Error> {
 }
 
 impl System {
-	pub fn new(config: Config, id: UUID) -> Self {
+	pub fn new(config: Config, id: UUID, background: Arc<BackgroundRunner>) -> Self {
 		let net_config = match read_network_config(&config.metadata_dir) {
 			Ok(x) => x,
 			Err(e) => {
@@ -209,24 +215,24 @@ impl System {
 			id,
 			rpc_client: RpcClient::new(),
 			members: RwLock::new(members),
+			background,
 		}
 	}
 
-	async fn save_network_config(self: Arc<Self>) {
+	async fn save_network_config(self: Arc<Self>) -> Result<(), Error> {
 		let mut path = self.config.metadata_dir.clone();
 		path.push("network_config");
 
 		let members = self.members.read().await;
 		let data =
-			rmp_to_vec_all_named(&members.config).expect("Error while encoding network config");
+			rmp_to_vec_all_named(&members.config)?;
 		drop(members);
 
 		let mut f = tokio::fs::File::create(path.as_path())
-			.await
-			.expect("Could not create network_config");
+			.await?;
 		f.write_all(&data[..])
-			.await
-			.expect("Could not write network_config");
+			.await?;
+		Ok(())
 	}
 
 	pub async fn make_ping(&self) -> Message {
@@ -260,7 +266,10 @@ impl System {
 			.collect::<Vec<_>>();
 		self.clone().ping_nodes(bootstrap_peers).await;
 
-		tokio::spawn(self.ping_loop());
+		self.background
+			.clone()
+			.spawn_worker(|stop_signal| self.ping_loop(stop_signal).map(Ok))
+			.await;
 	}
 
 	pub async fn ping_nodes(self: Arc<Self>, peers: Vec<(SocketAddr, Option<UUID>)>) {
@@ -294,10 +303,12 @@ impl System {
 					});
 				}
 				if is_new || members.status_hash != info.status_hash {
-					tokio::spawn(self.clone().pull_status(info.id.clone()));
+					self.background
+						.spawn_cancellable(self.clone().pull_status(info.id.clone()).map(Ok));
 				}
 				if is_new || members.config.version < info.config_version {
-					tokio::spawn(self.clone().pull_config(info.id.clone()));
+					self.background
+						.spawn_cancellable(self.clone().pull_config(info.id.clone()).map(Ok));
 				}
 			} else if let Some(id) = id_option {
 				let remaining_attempts = members
@@ -345,10 +356,10 @@ impl System {
 		drop(members);
 
 		if is_new || status_hash != ping.status_hash {
-			tokio::spawn(self.clone().pull_status(ping.id.clone()));
+			self.background.spawn_cancellable(self.clone().pull_status(ping.id.clone()).map(Ok));
 		}
 		if is_new || config_version < ping.config_version {
-			tokio::spawn(self.clone().pull_config(ping.id.clone()));
+			self.background.spawn_cancellable(self.clone().pull_config(ping.id.clone()).map(Ok));
 		}
 
 		Ok(self.make_ping().await)
@@ -405,7 +416,7 @@ impl System {
 		drop(members);
 
 		if to_ping.len() > 0 {
-			tokio::spawn(self.clone().ping_nodes(to_ping));
+			self.background.spawn_cancellable(self.clone().ping_nodes(to_ping).map(Ok));
 		}
 
 		Ok(Message::Ok)
@@ -420,17 +431,18 @@ impl System {
 			members.config = adv.clone();
 			members.rebuild_ring();
 
-			tokio::spawn(
+			self.background.spawn_cancellable(
 				self.clone()
-					.broadcast(Message::AdvertiseConfig(adv.clone()), PING_TIMEOUT),
+					.broadcast(Message::AdvertiseConfig(adv.clone()), PING_TIMEOUT)
+					.map(Ok),
 			);
-			tokio::spawn(self.clone().save_network_config());
+			self.background.spawn(self.clone().save_network_config());
 		}
 
 		Ok(Message::Ok)
 	}
 
-	pub async fn ping_loop(self: Arc<Self>) {
+	pub async fn ping_loop(self: Arc<Self>, mut stop_signal: watch::Receiver<bool>) {
 		loop {
 			let restart_at = tokio::time::delay_for(PING_INTERVAL);
 
@@ -445,7 +457,15 @@ impl System {
 
 			self.clone().ping_nodes(ping_addrs).await;
 
-			restart_at.await
+			select! {
+				_ = restart_at.fuse() => (),
+				must_exit = stop_signal.recv().fuse() => {
+					match must_exit {
+						None | Some(true) => return,
+						_ => (),
+					}
+				}
+			}
 		}
 	}
 

src/object_table.rs

@@ -38,6 +38,12 @@ pub enum ObjectVersionData {
 	FirstBlock(Hash),
 }
 
+impl ObjectVersion {
+	fn cmp_key(&self) -> (u64, &UUID) {
+		(self.timestamp, &self.uuid)
+	}
+}
+
 impl Entry<String, String> for Object {
 	fn partition_key(&self) -> &String {
 		&self.bucket
@@ -48,9 +54,10 @@ impl Entry<String, String> for Object {
 
 	fn merge(&mut self, other: &Self) {
 		for other_v in other.versions.iter() {
-			match self.versions.binary_search_by(|v| {
-				(v.timestamp, &v.uuid).cmp(&(other_v.timestamp, &other_v.uuid))
-			}) {
+			match self
+				.versions
+				.binary_search_by(|v| v.cmp_key().cmp(&other_v.cmp_key()))
+			{
 				Ok(i) => {
 					let mut v = &mut self.versions[i];
 					if other_v.size > v.size {
@@ -91,7 +98,30 @@ impl TableFormat for ObjectTable {
 	type E = Object;
 
 	async fn updated(&self, old: Option<&Self::E>, new: &Self::E) {
-		//unimplemented!()
-		// TODO
+		let old = old.cloned();
+		let new = new.clone();
+		let garage = self.garage.read().await.as_ref().cloned().unwrap();
+		garage.clone().background.spawn(async move {
+			// Propagate deletion of old versions
+			if let Some(old_v) = old {
+				for v in old_v.versions.iter() {
+					if new
+						.versions
+						.binary_search_by(|nv| nv.cmp_key().cmp(&v.cmp_key()))
+						.is_err()
+					{
+						let deleted_version = Version {
+							uuid: v.uuid.clone(),
+							deleted: true,
+							blocks: vec![],
+							bucket: old_v.bucket.clone(),
+							key: old_v.key.clone(),
+						};
+						garage.version_table.insert(&deleted_version).await?;
+					}
+				}
+			}
+			Ok(())
+		});
 	}
 }

src/rpc_server.rs

@@ -90,7 +90,7 @@ async fn handler(
 pub async fn run_rpc_server(
 	garage: Arc<Garage>,
 	shutdown_signal: impl Future<Output = ()>,
-) -> Result<(), hyper::Error> {
+) -> Result<(), Error> {
 	let bind_addr = ([0, 0, 0, 0], garage.system.config.rpc_port).into();
 
 	let service = make_service_fn(|conn: &AddrStream| {
@@ -112,5 +112,6 @@ pub async fn run_rpc_server(
 	let graceful = server.with_graceful_shutdown(shutdown_signal);
 	println!("RPC server listening on http://{}", bind_addr);
 
-	graceful.await
+	graceful.await?;
+	Ok(())
 }

src/server.rs

@@ -1,13 +1,15 @@
-use futures::channel::oneshot;
+use futures_util::future::FutureExt;
 use serde::Deserialize;
 use std::collections::HashMap;
 use std::io::{Read, Write};
 use std::net::SocketAddr;
 use std::path::PathBuf;
 use std::sync::Arc;
+use tokio::sync::watch;
 use tokio::sync::{Mutex, RwLock};
 
 use crate::api_server;
+use crate::background::*;
 use crate::data::*;
 use crate::error::Error;
 use crate::membership::System;
@@ -15,10 +17,31 @@ use crate::proto::*;
 use crate::rpc_server;
 use crate::table::*;
 
+#[derive(Deserialize, Debug)]
+pub struct Config {
+	pub metadata_dir: PathBuf,
+	pub data_dir: PathBuf,
+
+	pub api_port: u16,
+	pub rpc_port: u16,
+
+	pub bootstrap_peers: Vec<SocketAddr>,
+
+	#[serde(default = "default_block_size")]
+	pub block_size: usize,
+
+	#[serde(default = "default_meta_replication_factor")]
+	pub meta_replication_factor: usize,
+
+	#[serde(default = "default_data_replication_factor")]
+	pub data_replication_factor: usize,
+}
+
 pub struct Garage {
 	pub db: sled::Db,
 	pub system: Arc<System>,
 	pub fs_lock: Mutex<()>,
+	pub background: Arc<BackgroundRunner>,
 
 	pub table_rpc_handlers: HashMap<String, Box<dyn TableRpcHandler + Sync + Send>>,
 
@@ -28,8 +51,13 @@ pub struct Garage {
 }
 
 impl Garage {
-	pub async fn new(config: Config, id: UUID, db: sled::Db) -> Arc<Self> {
-		let system = Arc::new(System::new(config, id));
+	pub async fn new(
+		config: Config,
+		id: UUID,
+		db: sled::Db,
+		background: Arc<BackgroundRunner>,
+	) -> Arc<Self> {
+		let system = Arc::new(System::new(config, id, background.clone()));
 
 		let meta_rep_param = TableReplicationParams {
 			replication_factor: system.config.meta_replication_factor,
@@ -56,6 +84,14 @@ impl Garage {
 			"version".to_string(),
 			meta_rep_param.clone(),
 		));
+
+		let data_rep_param = TableReplicationParams {
+			replication_factor: system.config.data_replication_factor,
+			write_quorum: (system.config.data_replication_factor + 1) / 2,
+			read_quorum: 1,
+			timeout: DEFAULT_TIMEOUT,
+		};
+
 		let block_ref_table = Arc::new(Table::new(
 			BlockRefTable {
 				garage: RwLock::new(None),
@@ -63,13 +99,14 @@ impl Garage {
 			system.clone(),
 			&db,
 			"block_ref".to_string(),
-			meta_rep_param.clone(),
+			data_rep_param.clone(),
 		));
 
 		let mut garage = Self {
 			db,
 			system: system.clone(),
 			fs_lock: Mutex::new(()),
+			background,
 			table_rpc_handlers: HashMap::new(),
 			object_table,
 			version_table,
@@ -105,22 +142,8 @@ fn default_block_size() -> usize {
 fn default_meta_replication_factor() -> usize {
 	3
 }
-
-#[derive(Deserialize, Debug)]
-pub struct Config {
-	pub metadata_dir: PathBuf,
-	pub data_dir: PathBuf,
-
-	pub api_port: u16,
-	pub rpc_port: u16,
-
-	pub bootstrap_peers: Vec<SocketAddr>,
-
-	#[serde(default = "default_block_size")]
-	pub block_size: usize,
-
-	#[serde(default = "default_meta_replication_factor")]
-	pub meta_replication_factor: usize,
+fn default_data_replication_factor() -> usize {
+	3
 }
 
 fn read_config(config_file: PathBuf) -> Result<Config, Error> {
@@ -157,19 +180,22 @@ fn gen_node_id(metadata_dir: &PathBuf) -> Result<UUID, Error> {
 	}
 }
 
-async fn shutdown_signal(chans: Vec<oneshot::Sender<()>>) {
+async fn shutdown_signal(send_cancel: watch::Sender<bool>) -> Result<(), Error> {
 	// Wait for the CTRL+C signal
 	tokio::signal::ctrl_c()
 		.await
 		.expect("failed to install CTRL+C signal handler");
 	println!("Received CTRL+C, shutting down.");
-	for ch in chans {
-		ch.send(()).unwrap();
-	}
+	send_cancel.broadcast(true)?;
+	Ok(())
 }
 
-async fn wait_from(chan: oneshot::Receiver<()>) -> () {
-	chan.await.unwrap()
+async fn wait_from(mut chan: watch::Receiver<bool>) -> () {
+	while let Some(exit_now) = chan.recv().await {
+		if exit_now {
+			return;
+		}
+	}
 }
 
 pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
@@ -182,17 +208,20 @@ pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
 	let id = gen_node_id(&config.metadata_dir).expect("Unable to read or generate node ID");
 	println!("Node ID: {}", hex::encode(&id));
 
-	let garage = Garage::new(config, id, db).await;
+	let (send_cancel, watch_cancel) = watch::channel(false);
 
-	let (tx1, rx1) = oneshot::channel();
-	let (tx2, rx2) = oneshot::channel();
+	let background = BackgroundRunner::new(8, watch_cancel.clone());
+	let garage = Garage::new(config, id, db, background.clone()).await;
 
-	let rpc_server = rpc_server::run_rpc_server(garage.clone(), wait_from(rx1));
-	let api_server = api_server::run_api_server(garage.clone(), wait_from(rx2));
+	let rpc_server = rpc_server::run_rpc_server(garage.clone(), wait_from(watch_cancel.clone()));
+	let api_server = api_server::run_api_server(garage.clone(), wait_from(watch_cancel.clone()));
 
-	tokio::spawn(shutdown_signal(vec![tx1, tx2]));
-	tokio::spawn(garage.system.clone().bootstrap());
-
-	futures::try_join!(rpc_server, api_server)?;
+	futures::try_join!(
+		garage.system.clone().bootstrap().map(Ok),
+		rpc_server,
+		api_server,
+		background.run().map(Ok),
+		shutdown_signal(send_cancel),
+	)?;
 	Ok(())
 }