Background task manager (#332)

- [x] New background worker trait
- [x] Adapt all current workers to use new API
- [x] Command to list currently running workers, and whether they are active, idle, or dead
- [x] Error reporting
- Optimizations
  - [x] Merkle updater: several items per iteration
  - [ ] Use `tokio::task::spawn_blocking` where appropriate so that CPU-intensive tasks don't block other things going on
- scrub:
  - [x] have only one worker with a channel to start/pause/cancel
  - [x] automatic scrub
  - [x] ability to view and change tranquility from CLI
  - [x] persistence of a few info
- [ ] Testing

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/332
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

6 files changed, 276 insertions, 98 deletions

diff --git a/src/garage/Cargo.toml b/src/garage/Cargo.toml
index 640e6975..8948e750 100644
--- a/src/garage/Cargo.toml
+++ b/src/garage/Cargo.toml
@@ -23,6 +23,7 @@ path = "tests/lib.rs"
 [dependencies]
 garage_db = { version = "0.8.0", path = "../db" }
 garage_api = { version = "0.7.0", path = "../api" }
+garage_block = { version = "0.7.0", path = "../block" }
 garage_model = { version = "0.7.0", path = "../model" }
 garage_rpc = { version = "0.7.0", path = "../rpc" }
 garage_table = { version = "0.7.0", path = "../table" }
@@ -31,6 +32,7 @@ garage_web = { version = "0.7.0", path = "../web" }
 
 bytes = "1.0"
 bytesize = "1.1"
+timeago = "0.3"
 hex = "0.4"
 tracing = { version = "0.1.30", features = ["log-always"] }
 pretty_env_logger = "0.4"
diff --git a/src/garage/admin.rs b/src/garage/admin.rs
index 48914655..71ee608c 100644
--- a/src/garage/admin.rs
+++ b/src/garage/admin.rs
@@ -24,7 +24,7 @@ use garage_model::migrate::Migrate;
 use garage_model::permission::*;
 
 use crate::cli::*;
-use crate::repair::online::OnlineRepair;
+use crate::repair::online::launch_online_repair;
 
 pub const ADMIN_RPC_PATH: &str = "garage/admin_rpc.rs/Rpc";
 
@@ -36,6 +36,7 @@ pub enum AdminRpc {
 	LaunchRepair(RepairOpt),
 	Migrate(MigrateOpt),
 	Stats(StatsOpt),
+	Worker(WorkerOpt),
 
 	// Replies
 	Ok(String),
@@ -47,6 +48,10 @@ pub enum AdminRpc {
 	},
 	KeyList(Vec<(String, String)>),
 	KeyInfo(Key, HashMap<Uuid, Bucket>),
+	WorkerList(
+		HashMap<usize, garage_util::background::WorkerInfo>,
+		WorkerListOpt,
+	),
 }
 
 impl Rpc for AdminRpc {
@@ -693,15 +698,7 @@ impl AdminRpcHandler {
 				)))
 			}
 		} else {
-			let repair = OnlineRepair {
-				garage: self.garage.clone(),
-			};
-			self.garage
-				.system
-				.background
-				.spawn_worker("Repair worker".into(), move |must_exit| async move {
-					repair.repair_worker(opt, must_exit).await
-				});
+			launch_online_repair(self.garage.clone(), opt).await;
 			Ok(AdminRpc::Ok(format!(
 				"Repair launched on {:?}",
 				self.garage.system.id
@@ -830,6 +827,17 @@ impl AdminRpcHandler {
 
 		Ok(())
 	}
+
+	// ----
+
+	async fn handle_worker_cmd(&self, opt: WorkerOpt) -> Result<AdminRpc, Error> {
+		match opt.cmd {
+			WorkerCmd::List { opt } => {
+				let workers = self.garage.background.get_worker_info();
+				Ok(AdminRpc::WorkerList(workers, opt))
+			}
+		}
+	}
 }
 
 #[async_trait]
@@ -845,6 +853,7 @@ impl EndpointHandler<AdminRpc> for AdminRpcHandler {
 			AdminRpc::Migrate(opt) => self.handle_migrate(opt.clone()).await,
 			AdminRpc::LaunchRepair(opt) => self.handle_launch_repair(opt.clone()).await,
 			AdminRpc::Stats(opt) => self.handle_stats(opt.clone()).await,
+			AdminRpc::Worker(opt) => self.handle_worker_cmd(opt.clone()).await,
 			m => Err(GarageError::unexpected_rpc_message(m).into()),
 		}
 	}
diff --git a/src/garage/cli/cmd.rs b/src/garage/cli/cmd.rs
index 3a0bd956..1aa2c2ff 100644
--- a/src/garage/cli/cmd.rs
+++ b/src/garage/cli/cmd.rs
@@ -1,4 +1,5 @@
 use std::collections::HashSet;
+use std::time::Duration;
 
 use garage_util::error::*;
 use garage_util::formater::format_table;
@@ -39,6 +40,7 @@ pub async fn cli_command_dispatch(
 			cmd_admin(admin_rpc_endpoint, rpc_host, AdminRpc::LaunchRepair(ro)).await
 		}
 		Command::Stats(so) => cmd_admin(admin_rpc_endpoint, rpc_host, AdminRpc::Stats(so)).await,
+		Command::Worker(wo) => cmd_admin(admin_rpc_endpoint, rpc_host, AdminRpc::Worker(wo)).await,
 		_ => unreachable!(),
 	}
 }
@@ -100,6 +102,7 @@ pub async fn cmd_status(rpc_cli: &Endpoint<SystemRpc, ()>, rpc_host: NodeID) ->
 			vec!["ID\tHostname\tAddress\tTags\tZone\tCapacity\tLast seen".to_string()];
 		for adv in status.iter().filter(|adv| !adv.is_up) {
 			if let Some(NodeRoleV(Some(cfg))) = layout.roles.get(&adv.id) {
+				let tf = timeago::Formatter::new();
 				failed_nodes.push(format!(
 					"{id:?}\t{host}\t{addr}\t[{tags}]\t{zone}\t{capacity}\t{last_seen}",
 					id = adv.id,
@@ -110,7 +113,7 @@ pub async fn cmd_status(rpc_cli: &Endpoint<SystemRpc, ()>, rpc_host: NodeID) ->
 					capacity = cfg.capacity_string(),
 					last_seen = adv
 						.last_seen_secs_ago
-						.map(|s| format!("{}s ago", s))
+						.map(|s| tf.convert(Duration::from_secs(s)))
 						.unwrap_or_else(|| "never seen".into()),
 				));
 			}
@@ -182,6 +185,9 @@ pub async fn cmd_admin(
 		AdminRpc::KeyInfo(key, rb) => {
 			print_key_info(&key, &rb);
 		}
+		AdminRpc::WorkerList(wi, wlo) => {
+			print_worker_info(wi, wlo);
+		}
 		r => {
 			error!("Unexpected response: {:?}", r);
 		}
diff --git a/src/garage/cli/structs.rs b/src/garage/cli/structs.rs
index 4f2efe19..bc44b5ef 100644
--- a/src/garage/cli/structs.rs
+++ b/src/garage/cli/structs.rs
@@ -45,6 +45,10 @@ pub enum Command {
 	/// Gather node statistics
 	#[structopt(name = "stats")]
 	Stats(StatsOpt),
+
+	/// Manage background workers
+	#[structopt(name = "worker")]
+	Worker(WorkerOpt),
 }
 
 #[derive(StructOpt, Debug)]
@@ -423,8 +427,29 @@ pub enum RepairWhat {
 	/// Verify integrity of all blocks on disc (extremely slow, i/o intensive)
 	#[structopt(name = "scrub")]
 	Scrub {
-		/// Tranquility factor (see tranquilizer documentation)
-		#[structopt(name = "tranquility", default_value = "2")]
+		#[structopt(subcommand)]
+		cmd: ScrubCmd,
+	},
+}
+
+#[derive(Serialize, Deserialize, StructOpt, Debug, Eq, PartialEq, Clone)]
+pub enum ScrubCmd {
+	/// Start scrub
+	#[structopt(name = "start")]
+	Start,
+	/// Pause scrub (it will resume automatically after 24 hours)
+	#[structopt(name = "pause")]
+	Pause,
+	/// Resume paused scrub
+	#[structopt(name = "resume")]
+	Resume,
+	/// Cancel scrub in progress
+	#[structopt(name = "cancel")]
+	Cancel,
+	/// Set tranquility level for in-progress and future scrubs
+	#[structopt(name = "set-tranquility")]
+	SetTranquility {
+		#[structopt()]
 		tranquility: u32,
 	},
 }
@@ -460,3 +485,29 @@ pub struct StatsOpt {
 	#[structopt(short = "d", long = "detailed")]
 	pub detailed: bool,
 }
+
+#[derive(Serialize, Deserialize, StructOpt, Debug, Clone)]
+pub struct WorkerOpt {
+	#[structopt(subcommand)]
+	pub cmd: WorkerCmd,
+}
+
+#[derive(Serialize, Deserialize, StructOpt, Debug, Eq, PartialEq, Clone)]
+pub enum WorkerCmd {
+	/// List all workers on Garage node
+	#[structopt(name = "list")]
+	List {
+		#[structopt(flatten)]
+		opt: WorkerListOpt,
+	},
+}
+
+#[derive(Serialize, Deserialize, StructOpt, Debug, Eq, PartialEq, Clone, Copy)]
+pub struct WorkerListOpt {
+	/// Show only busy workers
+	#[structopt(short = "b", long = "busy")]
+	pub busy: bool,
+	/// Show only workers with errors
+	#[structopt(short = "e", long = "errors")]
+	pub errors: bool,
+}
diff --git a/src/garage/cli/util.rs b/src/garage/cli/util.rs
index 329e8a3e..396938ae 100644
--- a/src/garage/cli/util.rs
+++ b/src/garage/cli/util.rs
@@ -1,14 +1,19 @@
 use std::collections::HashMap;
+use std::time::Duration;
 
+use garage_util::background::*;
 use garage_util::crdt::*;
 use garage_util::data::Uuid;
 use garage_util::error::*;
 use garage_util::formater::format_table;
+use garage_util::time::*;
 
 use garage_model::bucket_table::*;
 use garage_model::key_table::*;
 use garage_model::s3::object_table::{BYTES, OBJECTS, UNFINISHED_UPLOADS};
 
+use crate::cli::structs::WorkerListOpt;
+
 pub fn print_bucket_list(bl: Vec<Bucket>) {
 	println!("List of buckets:");
 
@@ -235,3 +240,56 @@ pub fn find_matching_node(
 		Ok(candidates[0])
 	}
 }
+
+pub fn print_worker_info(wi: HashMap<usize, WorkerInfo>, wlo: WorkerListOpt) {
+	let mut wi = wi.into_iter().collect::<Vec<_>>();
+	wi.sort_by_key(|(tid, info)| {
+		(
+			match info.state {
+				WorkerState::Busy | WorkerState::Throttled(_) => 0,
+				WorkerState::Idle => 1,
+				WorkerState::Done => 2,
+			},
+			*tid,
+		)
+	});
+
+	let mut table = vec![];
+	for (tid, info) in wi.iter() {
+		if wlo.busy && !matches!(info.state, WorkerState::Busy | WorkerState::Throttled(_)) {
+			continue;
+		}
+		if wlo.errors && info.errors == 0 {
+			continue;
+		}
+
+		table.push(format!("{}\t{}\t{}", tid, info.state, info.name));
+		if let Some(i) = &info.info {
+			table.push(format!("\t\t  {}", i));
+		}
+		let tf = timeago::Formatter::new();
+		let (err_ago, err_msg) = info
+			.last_error
+			.as_ref()
+			.map(|(m, t)| {
+				(
+					tf.convert(Duration::from_millis(now_msec() - t)),
+					m.as_str(),
+				)
+			})
+			.unwrap_or(("(?) ago".into(), "(?)"));
+		if info.consecutive_errors > 0 {
+			table.push(format!(
+				"\t\t  {} consecutive errors ({} total), last {}",
+				info.consecutive_errors, info.errors, err_ago,
+			));
+			table.push(format!("\t\t  {}", err_msg));
+		} else if info.errors > 0 {
+			table.push(format!("\t\t  ({} errors, last {})", info.errors, err_ago,));
+			if wlo.errors {
+				table.push(format!("\t\t  {}", err_msg));
+			}
+		}
+	}
+	format_table(table);
+}
diff --git a/src/garage/repair/online.rs b/src/garage/repair/online.rs
index d6a71742..e33cf097 100644
--- a/src/garage/repair/online.rs
+++ b/src/garage/repair/online.rs
@@ -1,89 +1,110 @@
 use std::sync::Arc;
+use std::time::Duration;
 
+use async_trait::async_trait;
 use tokio::sync::watch;
 
+use garage_block::repair::ScrubWorkerCommand;
 use garage_model::garage::Garage;
 use garage_model::s3::block_ref_table::*;
 use garage_model::s3::object_table::*;
 use garage_model::s3::version_table::*;
 use garage_table::*;
+use garage_util::background::*;
 use garage_util::error::Error;
 
 use crate::*;
 
-pub struct OnlineRepair {
-	pub garage: Arc<Garage>,
-}
-
-impl OnlineRepair {
-	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);
+pub async fn launch_online_repair(garage: Arc<Garage>, opt: RepairOpt) {
+	match opt.what {
+		RepairWhat::Tables => {
+			info!("Launching a full sync of tables");
+			garage.bucket_table.syncer.add_full_sync();
+			garage.object_table.syncer.add_full_sync();
+			garage.version_table.syncer.add_full_sync();
+			garage.block_ref_table.syncer.add_full_sync();
+			garage.key_table.syncer.add_full_sync();
+		}
+		RepairWhat::Versions => {
+			info!("Repairing the versions table");
+			garage
+				.background
+				.spawn_worker(RepairVersionsWorker::new(garage.clone()));
+		}
+		RepairWhat::BlockRefs => {
+			info!("Repairing the block refs table");
+			garage
+				.background
+				.spawn_worker(RepairBlockrefsWorker::new(garage.clone()));
+		}
+		RepairWhat::Blocks => {
+			info!("Repairing the stored blocks");
+			garage
+				.background
+				.spawn_worker(garage_block::repair::RepairWorker::new(
+					garage.block_manager.clone(),
+				));
+		}
+		RepairWhat::Scrub { cmd } => {
+			let cmd = match cmd {
+				ScrubCmd::Start => ScrubWorkerCommand::Start,
+				ScrubCmd::Pause => ScrubWorkerCommand::Pause(Duration::from_secs(3600 * 24)),
+				ScrubCmd::Resume => ScrubWorkerCommand::Resume,
+				ScrubCmd::Cancel => ScrubWorkerCommand::Cancel,
+				ScrubCmd::SetTranquility { tranquility } => {
+					ScrubWorkerCommand::SetTranquility(tranquility)
+				}
+			};
+			info!("Sending command to scrub worker: {:?}", cmd);
+			garage.block_manager.send_scrub_command(cmd).await;
 		}
 	}
+}
 
-	async fn repair_worker_aux(
-		&self,
-		opt: RepairOpt,
-		must_exit: watch::Receiver<bool>,
-	) -> Result<(), Error> {
-		match opt.what {
-			RepairWhat::Tables => {
-				info!("Launching a full sync of tables");
-				self.garage.bucket_table.syncer.add_full_sync();
-				self.garage.object_table.syncer.add_full_sync();
-				self.garage.version_table.syncer.add_full_sync();
-				self.garage.block_ref_table.syncer.add_full_sync();
-				self.garage.key_table.syncer.add_full_sync();
-			}
-			RepairWhat::Versions => {
-				info!("Repairing the versions table");
-				self.repair_versions(&must_exit).await?;
-			}
-			RepairWhat::BlockRefs => {
-				info!("Repairing the block refs table");
-				self.repair_block_ref(&must_exit).await?;
-			}
-			RepairWhat::Blocks => {
-				info!("Repairing the stored blocks");
-				self.garage
-					.block_manager
-					.repair_data_store(&must_exit)
-					.await?;
-			}
-			RepairWhat::Scrub { tranquility } => {
-				info!("Verifying integrity of stored blocks");
-				self.garage
-					.block_manager
-					.scrub_data_store(&must_exit, tranquility)
-					.await?;
-			}
+// ----
+
+struct RepairVersionsWorker {
+	garage: Arc<Garage>,
+	pos: Vec<u8>,
+	counter: usize,
+}
+
+impl RepairVersionsWorker {
+	fn new(garage: Arc<Garage>) -> Self {
+		Self {
+			garage,
+			pos: vec![],
+			counter: 0,
 		}
-		Ok(())
 	}
+}
 
-	async fn repair_versions(&self, must_exit: &watch::Receiver<bool>) -> Result<(), Error> {
-		let mut pos = vec![];
-		let mut i = 0;
+#[async_trait]
+impl Worker for RepairVersionsWorker {
+	fn name(&self) -> String {
+		"Version repair worker".into()
+	}
 
-		while !*must_exit.borrow() {
-			let item_bytes = match self.garage.version_table.data.store.get_gt(pos)? {
-				Some((k, v)) => {
-					pos = k;
-					v
-				}
-				None => break,
-			};
+	fn info(&self) -> Option<String> {
+		Some(format!("{} items done", self.counter))
+	}
 
-			i += 1;
-			if i % 1000 == 0 {
-				info!("repair_versions: {}", i);
+	async fn work(&mut self, _must_exit: &mut watch::Receiver<bool>) -> Result<WorkerState, Error> {
+		let item_bytes = match self.garage.version_table.data.store.get_gt(&self.pos)? {
+			Some((k, v)) => {
+				self.pos = k;
+				v
 			}
-
-			let version = rmp_serde::decode::from_read_ref::<_, Version>(&item_bytes)?;
-			if version.deleted.get() {
-				continue;
+			None => {
+				info!("repair_versions: finished, done {}", self.counter);
+				return Ok(WorkerState::Done);
 			}
+		};
+
+		self.counter += 1;
+
+		let version = rmp_serde::decode::from_read_ref::<_, Version>(&item_bytes)?;
+		if !version.deleted.get() {
 			let object = self
 				.garage
 				.object_table
@@ -109,32 +130,59 @@ impl OnlineRepair {
 					.await?;
 			}
 		}
-		info!("repair_versions: finished, done {}", i);
-		Ok(())
+
+		Ok(WorkerState::Busy)
 	}
 
-	async fn repair_block_ref(&self, must_exit: &watch::Receiver<bool>) -> Result<(), Error> {
-		let mut pos = vec![];
-		let mut i = 0;
+	async fn wait_for_work(&mut self, _must_exit: &watch::Receiver<bool>) -> WorkerState {
+		unreachable!()
+	}
+}
 
-		while !*must_exit.borrow() {
-			let item_bytes = match self.garage.block_ref_table.data.store.get_gt(pos)? {
-				Some((k, v)) => {
-					pos = k;
-					v
-				}
-				None => break,
-			};
+// ----
 
-			i += 1;
-			if i % 1000 == 0 {
-				info!("repair_block_ref: {}", i);
-			}
+struct RepairBlockrefsWorker {
+	garage: Arc<Garage>,
+	pos: Vec<u8>,
+	counter: usize,
+}
 
-			let block_ref = rmp_serde::decode::from_read_ref::<_, BlockRef>(&item_bytes)?;
-			if block_ref.deleted.get() {
-				continue;
+impl RepairBlockrefsWorker {
+	fn new(garage: Arc<Garage>) -> Self {
+		Self {
+			garage,
+			pos: vec![],
+			counter: 0,
+		}
+	}
+}
+
+#[async_trait]
+impl Worker for RepairBlockrefsWorker {
+	fn name(&self) -> String {
+		"Block refs repair worker".into()
+	}
+
+	fn info(&self) -> Option<String> {
+		Some(format!("{} items done", self.counter))
+	}
+
+	async fn work(&mut self, _must_exit: &mut watch::Receiver<bool>) -> Result<WorkerState, Error> {
+		let item_bytes = match self.garage.block_ref_table.data.store.get_gt(&self.pos)? {
+			Some((k, v)) => {
+				self.pos = k;
+				v
 			}
+			None => {
+				info!("repair_block_ref: finished, done {}", self.counter);
+				return Ok(WorkerState::Done);
+			}
+		};
+
+		self.counter += 1;
+
+		let block_ref = rmp_serde::decode::from_read_ref::<_, BlockRef>(&item_bytes)?;
+		if !block_ref.deleted.get() {
 			let version = self
 				.garage
 				.version_table
@@ -157,7 +205,11 @@ impl OnlineRepair {
 					.await?;
 			}
 		}
-		info!("repair_block_ref: finished, done {}", i);
-		Ok(())
+
+		Ok(WorkerState::Busy)
+	}
+
+	async fn wait_for_work(&mut self, _must_exit: &watch::Receiver<bool>) -> WorkerState {
+		unreachable!()
 	}
 }