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>

3 files changed, 118 insertions, 3 deletions

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);
+}