WIP

TODOs:
- ensure sync goes both way
- finish sending blocks to other nodes when they need them before deleting

src/block.rs

@@ -6,6 +6,7 @@ use futures::stream::*;
 use tokio::fs;
 use tokio::prelude::*;
 use tokio::sync::{watch, Mutex};
+use arc_swap::ArcSwapOption;
 
 use crate::data;
 use crate::data::*;
@@ -13,6 +14,7 @@ use crate::error::Error;
 use crate::membership::System;
 use crate::proto::*;
 use crate::rpc_client::*;
+use crate::server::Garage;
 
 pub struct BlockManager {
 	pub data_dir: PathBuf,
@@ -20,10 +22,11 @@ pub struct BlockManager {
 	pub resync_queue: sled::Tree,
 	pub lock: Mutex<()>,
 	pub system: Arc<System>,
+	pub garage: ArcSwapOption<Garage>,
 }
 
 impl BlockManager {
-	pub async fn new(db: &sled::Db, data_dir: PathBuf, system: Arc<System>) -> Arc<Self> {
+	pub fn new(db: &sled::Db, data_dir: PathBuf, system: Arc<System>) -> Arc<Self> {
 		let rc = db
 			.open_tree("block_local_rc")
 			.expect("Unable to open block_local_rc tree");
@@ -33,20 +36,23 @@ impl BlockManager {
 			.open_tree("block_local_resync_queue")
 			.expect("Unable to open block_local_resync_queue tree");
 
-		let block_manager = Arc::new(Self {
+		Arc::new(Self {
 			rc,
 			resync_queue,
 			data_dir,
 			lock: Mutex::new(()),
 			system,
-		});
-		let bm2 = block_manager.clone();
-		block_manager
+			garage: ArcSwapOption::from(None),
+		})
+	}
+
+	pub async fn spawn_background_worker(self: Arc<Self>) {
+		let bm2 = self.clone();
+		self
 			.system
 			.background
 			.spawn_worker(move |must_exit| bm2.resync_loop(must_exit))
 			.await;
-		block_manager
 	}
 
 	pub async fn write_block(&self, hash: &Hash, data: &[u8]) -> Result<Message, Error> {
@@ -80,7 +86,7 @@ impl BlockManager {
 			let _lock = self.lock.lock().await;
 			eprintln!("Block {:?} is corrupted. Deleting and resyncing.", hash);
 			fs::remove_file(path).await?;
-			self.resync_queue.insert(hash.to_vec(), vec![1u8])?;
+			self.put_to_resync(&hash, 0)?;
 			return Err(Error::CorruptData(hash.clone()));
 		}
 
@@ -98,38 +104,55 @@ impl BlockManager {
 	}
 
 	pub fn block_incref(&self, hash: &Hash) -> Result<(), Error> {
-		self.rc.merge(&hash, vec![1])?;
+		let new_rc = self.rc.merge(&hash, vec![1])?;
+		if new_rc.map(|x| u64_from_bytes(&x[..]) == 0).unwrap_or(true) {
+			self.put_to_resync(&hash, BLOCK_RW_TIMEOUT.as_millis() as u64)?;
+		}
 		Ok(())
 	}
 
 	pub fn block_decref(&self, hash: &Hash) -> Result<(), Error> {
-		if self.rc.merge(&hash, vec![0])?.is_none() {
-			self.resync_queue.insert(hash.to_vec(), vec![1u8])?;
+		let new_rc = self.rc.merge(&hash, vec![0])?;
+		if new_rc.is_none() {
+			self.put_to_resync(&hash, 2 * BLOCK_RW_TIMEOUT.as_millis() as u64)?;
 		}
 		Ok(())
 	}
 
+	fn put_to_resync(&self, hash: &Hash, delay_millis: u64) -> Result<(), Error> {
+		let when = now_msec() + delay_millis;
+		eprintln!("Put resync_queue: {} {:?}", when, hash);
+		let mut key = u64::to_be_bytes(when).to_vec();
+		key.extend(hash.as_ref());
+		self.resync_queue.insert(key, hash.as_ref())?;
+		Ok(())
+	}
+
 	async fn resync_loop(self: Arc<Self>, must_exit: watch::Receiver<bool>) -> Result<(), Error> {
 		while !*must_exit.borrow() {
-			if let Some((hash_bytes, _v)) = self.resync_queue.get_gt(&[])? {
-				let mut hash = [0u8; 32];
-				hash.copy_from_slice(hash_bytes.as_ref());
-				let hash = Hash::from(hash);
+			if let Some((time_bytes, hash_bytes)) = self.resync_queue.get_gt(&[])? {
+				let time_msec = u64_from_bytes(&time_bytes[0..8]);
+				eprintln!("First in resync queue: {} (now = {})", time_msec, now_msec());
+				if now_msec() >= time_msec {
+					let mut hash = [0u8; 32];
+					hash.copy_from_slice(hash_bytes.as_ref());
+					let hash = Hash::from(hash);
 
-				match self.resync_iter(&hash).await {
-					Ok(_) => {
-						self.resync_queue.remove(&hash_bytes)?;
-					}
-					Err(e) => {
-						eprintln!(
-							"Failed to resync hash {:?}, leaving it in queue: {}",
-							hash, e
-						);
+					match self.resync_iter(&hash).await {
+						Ok(_) => {
+							self.resync_queue.remove(&hash_bytes)?;
+						}
+						Err(e) => {
+							eprintln!(
+								"Failed to resync hash {:?}, leaving it in queue: {}",
+								hash, e
+							);
+						}
 					}
+					continue;
 				}
-			} else {
-				tokio::time::delay_for(Duration::from_secs(1)).await;
 			}
+			tokio::time::delay_for(Duration::from_secs(1)).await;
 		}
 		Ok(())
 	}
@@ -145,14 +168,23 @@ impl BlockManager {
 			.map(|x| u64_from_bytes(x.as_ref()) > 0)
 			.unwrap_or(false);
 
+		eprintln!("Resync block {:?}: exists {}, needed {}", hash, exists, needed);
+
 		if exists && !needed {
-			// TODO: verify that other nodes that might need it have it ?
+			let garage = self.garage.load_full().unwrap();
+			let active_refs = garage.block_ref_table.get_range(&hash, &[0u8; 32].into(), Some(()), 1).await?;
+			let needed_by_others = !active_refs.is_empty();
+			if needed_by_others {
+				// TODO check they have it and send it if not
+			}
 			fs::remove_file(path).await?;
 			self.resync_queue.remove(&hash)?;
 		}
 
 		if needed && !exists {
 			// TODO find a way to not do this if they are sending it to us
+			// Let's suppose this isn't an issue for now with the BLOCK_RW_TIMEOUT delay
+			// between the RC being incremented and this part being called.
 			let block_data = rpc_get_block(&self.system, &hash).await?;
 			self.write_block(hash, &block_data[..]).await?;
 		}
@@ -190,11 +222,8 @@ fn rc_merge(_key: &[u8], old: Option<&[u8]>, new: &[u8]) -> Option<Vec<u8>> {
 }
 
 pub async fn rpc_get_block(system: &Arc<System>, hash: &Hash) -> Result<Vec<u8>, Error> {
-	let who = system
-		.ring
-		.borrow()
-		.clone()
-		.walk_ring(&hash, system.config.data_replication_factor);
+	let ring = system.ring.borrow().clone();
+	let who = ring.walk_ring(&hash, system.config.data_replication_factor);
 	let msg = Message::GetBlock(hash.clone());
 	let mut resp_stream = who
 		.iter()
@@ -215,11 +244,8 @@ pub async fn rpc_get_block(system: &Arc<System>, hash: &Hash) -> Result<Vec<u8>,
 }
 
 pub async fn rpc_put_block(system: &Arc<System>, hash: Hash, data: Vec<u8>) -> Result<(), Error> {
-	let who = system
-		.ring
-		.borrow()
-		.clone()
-		.walk_ring(&hash, system.config.data_replication_factor);
+	let ring = system.ring.borrow().clone();
+	let who = ring.walk_ring(&hash, system.config.data_replication_factor);
 	rpc_try_call_many(
 		system.clone(),
 		&who[..],