From 7c86ff6c37cc93cca030bde060c41b8184b2cd61 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Thu, 14 Mar 2024 16:49:14 +0100
Subject: [PATCH] [disable-scrub] implement a `disable_scrub` configuration
 option

---
 src/block/manager.rs | 68 ++++++++++++++++++++++++--------------------
 src/model/garage.rs  |  9 +-----
 src/util/config.rs   |  4 +++
 3 files changed, 42 insertions(+), 39 deletions(-)

diff --git a/src/block/manager.rs b/src/block/manager.rs
index 890ea8b7..ef7279e9 100644
--- a/src/block/manager.rs
+++ b/src/block/manager.rs
@@ -22,7 +22,7 @@ use garage_net::stream::{read_stream_to_end, stream_asyncread, ByteStream};
 use garage_db as db;
 
 use garage_util::background::{vars, BackgroundRunner};
-use garage_util::config::DataDirEnum;
+use garage_util::config::Config;
 use garage_util::data::*;
 use garage_util::error::*;
 use garage_util::metrics::RecordDuration;
@@ -84,6 +84,7 @@ pub struct BlockManager {
 
 	data_fsync: bool,
 	compression_level: Option<i32>,
+	disable_scrub: bool,
 
 	mutation_lock: Vec<Mutex<BlockManagerLocked>>,
 
@@ -119,9 +120,7 @@ struct BlockManagerLocked();
 impl BlockManager {
 	pub fn new(
 		db: &db::Db,
-		data_dir: DataDirEnum,
-		data_fsync: bool,
-		compression_level: Option<i32>,
+		config: &Config,
 		replication: TableShardedReplication,
 		system: Arc<System>,
 	) -> Result<Arc<Self>, Error> {
@@ -131,11 +130,13 @@ impl BlockManager {
 		let data_layout = match data_layout_persister.load() {
 			Ok(mut layout) => {
 				layout
-					.update(&data_dir)
+					.update(&config.data_dir)
 					.ok_or_message("invalid data_dir config")?;
 				layout
 			}
-			Err(_) => DataLayout::initialize(&data_dir).ok_or_message("invalid data_dir config")?,
+			Err(_) => {
+				DataLayout::initialize(&config.data_dir).ok_or_message("invalid data_dir config")?
+			}
 		};
 		data_layout_persister
 			.save(&data_layout)
@@ -154,7 +155,7 @@ impl BlockManager {
 			.endpoint("garage_block/manager.rs/Rpc".to_string());
 
 		let metrics = BlockManagerMetrics::new(
-			compression_level,
+			config.compression_level,
 			rc.rc.clone(),
 			resync.queue.clone(),
 			resync.errors.clone(),
@@ -166,8 +167,9 @@ impl BlockManager {
 			replication,
 			data_layout: ArcSwap::new(Arc::new(data_layout)),
 			data_layout_persister,
-			data_fsync,
-			compression_level,
+			data_fsync: config.data_fsync,
+			disable_scrub: config.disable_scrub,
+			compression_level: config.compression_level,
 			mutation_lock: vec![(); MUTEX_COUNT]
 				.iter()
 				.map(|_| Mutex::new(BlockManagerLocked()))
@@ -194,33 +196,37 @@ impl BlockManager {
 		}
 
 		// Spawn scrub worker
-		let (scrub_tx, scrub_rx) = mpsc::channel(1);
-		self.tx_scrub_command.store(Some(Arc::new(scrub_tx)));
-		bg.spawn_worker(ScrubWorker::new(
-			self.clone(),
-			scrub_rx,
-			self.scrub_persister.clone(),
-		));
+		if !self.disable_scrub {
+			let (scrub_tx, scrub_rx) = mpsc::channel(1);
+			self.tx_scrub_command.store(Some(Arc::new(scrub_tx)));
+			bg.spawn_worker(ScrubWorker::new(
+				self.clone(),
+				scrub_rx,
+				self.scrub_persister.clone(),
+			));
+		}
 	}
 
 	pub fn register_bg_vars(&self, vars: &mut vars::BgVars) {
 		self.resync.register_bg_vars(vars);
 
-		vars.register_rw(
-			&self.scrub_persister,
-			"scrub-tranquility",
-			|p| p.get_with(|x| x.tranquility),
-			|p, tranquility| p.set_with(|x| x.tranquility = tranquility),
-		);
-		vars.register_ro(&self.scrub_persister, "scrub-last-completed", |p| {
-			p.get_with(|x| msec_to_rfc3339(x.time_last_complete_scrub))
-		});
-		vars.register_ro(&self.scrub_persister, "scrub-next-run", |p| {
-			p.get_with(|x| msec_to_rfc3339(x.time_next_run_scrub))
-		});
-		vars.register_ro(&self.scrub_persister, "scrub-corruptions_detected", |p| {
-			p.get_with(|x| x.corruptions_detected)
-		});
+		if !self.disable_scrub {
+			vars.register_rw(
+				&self.scrub_persister,
+				"scrub-tranquility",
+				|p| p.get_with(|x| x.tranquility),
+				|p, tranquility| p.set_with(|x| x.tranquility = tranquility),
+			);
+			vars.register_ro(&self.scrub_persister, "scrub-last-completed", |p| {
+				p.get_with(|x| msec_to_rfc3339(x.time_last_complete_scrub))
+			});
+			vars.register_ro(&self.scrub_persister, "scrub-next-run", |p| {
+				p.get_with(|x| msec_to_rfc3339(x.time_next_run_scrub))
+			});
+			vars.register_ro(&self.scrub_persister, "scrub-corruptions_detected", |p| {
+				p.get_with(|x| x.corruptions_detected)
+			});
+		}
 	}
 
 	/// Ask nodes that might have a (possibly compressed) block for it
diff --git a/src/model/garage.rs b/src/model/garage.rs
index 18421ca3..acf943f6 100644
--- a/src/model/garage.rs
+++ b/src/model/garage.rs
@@ -177,14 +177,7 @@ impl Garage {
 		};
 
 		info!("Initialize block manager...");
-		let block_manager = BlockManager::new(
-			&db,
-			config.data_dir.clone(),
-			config.data_fsync,
-			config.compression_level,
-			data_rep_param,
-			system.clone(),
-		)?;
+		let block_manager = BlockManager::new(&db, &config, data_rep_param, system.clone())?;
 		block_manager.register_bg_vars(&mut bg_vars);
 
 		// ---- admin tables ----
diff --git a/src/util/config.rs b/src/util/config.rs
index 056c625d..7338a506 100644
--- a/src/util/config.rs
+++ b/src/util/config.rs
@@ -23,6 +23,10 @@ pub struct Config {
 	#[serde(default)]
 	pub data_fsync: bool,
 
+	/// Disable automatic scrubbing of the data directory
+	#[serde(default)]
+	pub disable_scrub: bool,
+
 	/// Size of data blocks to save to disk
 	#[serde(
 		deserialize_with = "deserialize_capacity",