Block manager with new worker

src/block/manager.rs

@@ -9,9 +9,9 @@ use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 
 use futures::future::*;
-use futures::select;
 use tokio::fs;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::select;
 use tokio::sync::{watch, Mutex, Notify};
 
 use opentelemetry::{
@@ -22,6 +22,7 @@ use opentelemetry::{
 use garage_db as db;
 use garage_db::counted_tree_hack::CountedTree;
 
+use garage_util::background::*;
 use garage_util::data::*;
 use garage_util::error::*;
 use garage_util::metrics::RecordDuration;
@@ -110,6 +111,12 @@ pub struct BlockManager {
 // it INSIDE a Mutex.
 struct BlockManagerLocked();
 
+enum BlockIterResult {
+	BusyDidSomething,
+	BusyDidNothing,
+	IdleFor(Duration),
+}
+
 impl BlockManager {
 	pub fn new(
 		db: &db::Db,
@@ -557,11 +564,14 @@ impl BlockManager {
 	fn spawn_background_worker(self: Arc<Self>) {
 		// Launch a background workers for background resync loop processing
 		let background = self.system.background.clone();
+		let worker = BlockResyncWorker {
+			manager: self,
+			tranquilizer: Tranquilizer::new(30),
+			next_delay: Duration::from_secs(10),
+		};
 		tokio::spawn(async move {
 			tokio::time::sleep(Duration::from_secs(10)).await;
-			background.spawn_worker("block resync worker".into(), move |must_exit| {
-				self.resync_loop(must_exit)
-			});
+			background.spawn_worker(worker);
 		});
 	}
 
@@ -579,37 +589,7 @@ impl BlockManager {
 		Ok(())
 	}
 
-	async fn resync_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) {
-		let mut tranquilizer = Tranquilizer::new(30);
-
-		while !*must_exit.borrow() {
-			match self.resync_iter(&mut must_exit).await {
-				Ok(true) => {
-					tranquilizer.tranquilize(self.background_tranquility).await;
-				}
-				Ok(false) => {
-					tranquilizer.reset();
-				}
-				Err(e) => {
-					// The errors that we have here are only Sled errors
-					// We don't really know how to handle them so just ¯\_(ツ)_/¯
-					// (there is kind of an assumption that Sled won't error on us,
-					// if it does there is not much we can do -- TODO should we just panic?)
-					error!(
-						"Could not do a resync iteration: {} (this is a very bad error)",
-						e
-					);
-					tranquilizer.reset();
-				}
-			}
-		}
-	}
-
-	// The result of resync_iter is:
-	// - Ok(true) -> a block was processed (successfully or not)
-	// - Ok(false) -> no block was processed, but we are ready for the next iteration
-	// - Err(_) -> a Sled error occurred when reading/writing from resync_queue/resync_errors
-	async fn resync_iter(&self, must_exit: &mut watch::Receiver<bool>) -> Result<bool, db::Error> {
+	async fn resync_iter(&self) -> Result<BlockIterResult, db::Error> {
 		if let Some((time_bytes, hash_bytes)) = self.resync_queue.first()? {
 			let time_msec = u64::from_be_bytes(time_bytes[0..8].try_into().unwrap());
 			let now = now_msec();
@@ -629,7 +609,7 @@ impl BlockManager {
 						// (we want to do the remove after the insert to ensure
 						// that the item is not lost if we crash in-between)
 						self.resync_queue.remove(time_bytes)?;
-						return Ok(false);
+						return Ok(BlockIterResult::BusyDidNothing);
 					}
 				}
 
@@ -676,15 +656,11 @@ impl BlockManager {
 					self.resync_queue.remove(time_bytes)?;
 				}
 
-				Ok(true)
+				Ok(BlockIterResult::BusyDidSomething)
 			} else {
-				let delay = tokio::time::sleep(Duration::from_millis(time_msec - now));
-				select! {
-					_ = delay.fuse() => {},
-					_ = self.resync_notify.notified().fuse() => {},
-					_ = must_exit.changed().fuse() => {},
-				}
-				Ok(false)
+				Ok(BlockIterResult::IdleFor(Duration::from_millis(
+					time_msec - now,
+				)))
 			}
 		} else {
 			// Here we wait either for a notification that an item has been
@@ -693,13 +669,7 @@ impl BlockManager {
 			// between the time we checked the queue and the first poll
 			// to resync_notify.notified(): if that happens, we'll just loop
 			// back 10 seconds later, which is fine.
-			let delay = tokio::time::sleep(Duration::from_secs(10));
-			select! {
-				_ = delay.fuse() => {},
-				_ = self.resync_notify.notified().fuse() => {},
-				_ = must_exit.changed().fuse() => {},
-			}
-			Ok(false)
+			Ok(BlockIterResult::IdleFor(Duration::from_secs(10)))
 		}
 	}
 
@@ -898,6 +868,58 @@ impl EndpointHandler<BlockRpc> for BlockManager {
 	}
 }
 
+struct BlockResyncWorker {
+	manager: Arc<BlockManager>,
+	tranquilizer: Tranquilizer,
+	next_delay: Duration,
+}
+
+#[async_trait]
+impl Worker for BlockResyncWorker {
+	fn name(&self) -> String {
+		"Block resync worker".into()
+	}
+
+	async fn work(
+		&mut self,
+		_must_exit: &mut watch::Receiver<bool>,
+	) -> Result<WorkerStatus, Error> {
+		self.tranquilizer.reset();
+		match self.manager.resync_iter().await {
+			Ok(BlockIterResult::BusyDidSomething) => {
+				self.tranquilizer
+					.tranquilize(self.manager.background_tranquility)
+					.await;
+				Ok(WorkerStatus::Busy)
+			}
+			Ok(BlockIterResult::BusyDidNothing) => Ok(WorkerStatus::Busy),
+			Ok(BlockIterResult::IdleFor(delay)) => {
+				self.next_delay = delay;
+				Ok(WorkerStatus::Idle)
+			}
+			Err(e) => {
+				// The errors that we have here are only Sled errors
+				// We don't really know how to handle them so just ¯\_(ツ)_/¯
+				// (there is kind of an assumption that Sled won't error on us,
+				// if it does there is not much we can do -- TODO should we just panic?)
+				error!(
+					"Could not do a resync iteration: {} (this is a very bad error)",
+					e
+				);
+				Err(e.into())
+			}
+		}
+	}
+
+	async fn wait_for_work(&mut self, _must_exit: &watch::Receiver<bool>) -> WorkerStatus {
+		select! {
+			_ = tokio::time::sleep(self.next_delay) => (),
+			_ = self.manager.resync_notify.notified() => (),
+		};
+		WorkerStatus::Busy
+	}
+}
+
 struct BlockStatus {
 	exists: bool,
 	needed: RcEntry,