Make sync send data both ways

src/data.rs

@@ -25,7 +25,7 @@ impl Eq for FixedBytes32 {}
 
 impl fmt::Debug for FixedBytes32 {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-		write!(f, "{}", hex::encode(self.0))
+		write!(f, "{}…", hex::encode(&self.0[..8]))
 	}
 }
 

src/table.rs

@@ -6,7 +6,7 @@ use async_trait::async_trait;
 use futures::stream::*;
 use serde::{Deserialize, Serialize};
 use serde_bytes::ByteBuf;
-use tokio::sync::RwLock;
+use arc_swap::ArcSwapOption;
 
 use crate::data::*;
 use crate::error::Error;
@@ -22,7 +22,7 @@ pub struct Table<F: TableSchema> {
 
 	pub system: Arc<System>,
 	pub store: sled::Tree,
-	pub syncer: RwLock<Option<Arc<TableSyncer<F>>>>,
+	pub syncer: ArcSwapOption<TableSyncer<F>>,
 
 	pub param: TableReplicationParams,
 }
@@ -142,10 +142,10 @@ impl<F: TableSchema + 'static> Table<F> {
 			system,
 			store,
 			param,
-			syncer: RwLock::new(None),
+			syncer: ArcSwapOption::from(None),
 		});
 		let syncer = TableSyncer::launch(table.clone()).await;
-		*table.syncer.write().await = Some(syncer);
+		table.syncer.swap(Some(syncer));
 		table
 	}
 
@@ -389,7 +389,7 @@ impl<F: TableSchema + 'static> Table<F> {
 				Ok(TableRPC::Ok)
 			}
 			TableRPC::SyncRPC(rpc) => {
-				let syncer = self.syncer.read().await.as_ref().unwrap().clone();
+				let syncer = self.syncer.load_full().unwrap();
 				let response = syncer
 					.handle_rpc(&rpc, self.system.background.stop_signal.clone())
 					.await?;
@@ -408,7 +408,7 @@ impl<F: TableSchema + 'static> Table<F> {
 		}
 	}
 
-	async fn handle_update(self: &Arc<Self>, mut entries: Vec<Arc<ByteBuf>>) -> Result<(), Error> {
+	pub async fn handle_update(self: &Arc<Self>, mut entries: Vec<Arc<ByteBuf>>) -> Result<(), Error> {
 		for update_bytes in entries.drain(..) {
 			let update = rmp_serde::decode::from_read_ref::<_, F::E>(update_bytes.as_slice())?;
 
@@ -437,7 +437,7 @@ impl<F: TableSchema + 'static> Table<F> {
 			if old_entry != new_entry {
 				self.instance.updated(old_entry, new_entry).await;
 
-				let syncer = self.syncer.read().await.as_ref().unwrap().clone();
+				let syncer = self.syncer.load_full().unwrap();
 				self.system.background.spawn(syncer.invalidate(tree_key));
 			}
 		}

src/table_sync.rs

@@ -30,7 +30,7 @@ pub struct TableSyncer<F: TableSchema> {
 #[derive(Serialize, Deserialize)]
 pub enum SyncRPC {
 	Checksums(Vec<RangeChecksum>),
-	DifferentSet(Vec<SyncRange>),
+	Difference(Vec<SyncRange>, Vec<Arc<ByteBuf>>),
 }
 
 pub struct SyncTodo {
@@ -172,10 +172,12 @@ impl<F: TableSchema + 'static> TableSyncer<F> {
 			.root_checksum(&partition.begin, &partition.end, must_exit)
 			.await?;
 
+		let my_id = self.table.system.id.clone();
 		let ring = self.table.system.ring.borrow().clone();
 		let nodes = ring.walk_ring(&partition.begin, self.table.param.replication_factor);
 		let mut sync_futures = nodes
 			.iter()
+			.filter(|node| **node != my_id)
 			.map(|node| {
 				self.clone()
 					.do_sync_with(root_cks.clone(), node.clone(), must_exit.clone())
@@ -364,21 +366,25 @@ impl<F: TableSchema + 'static> TableSyncer<F> {
 				.table
 				.rpc_call(&who, &TableRPC::<F>::SyncRPC(SyncRPC::Checksums(step)))
 				.await?;
-			if let TableRPC::<F>::SyncRPC(SyncRPC::DifferentSet(mut s)) = rpc_resp {
-				let mut items = vec![];
-				for differing in s.drain(..) {
+			if let TableRPC::<F>::SyncRPC(SyncRPC::Difference(mut diff_ranges, diff_items)) = rpc_resp {
+				eprintln!("({}) Sync with {:?}: difference {} ranges, {} items", self.table.name, who, diff_ranges.len(), diff_items.len());
+				let mut items_to_send = vec![];
+				for differing in diff_ranges.drain(..) {
 					if differing.level == 0 {
-						items.push(differing.begin);
+						items_to_send.push(differing.begin);
 					} else {
 						let checksum = self.range_checksum(&differing, &mut must_exit).await?;
 						todo.push_back(checksum);
 					}
 				}
-				if items.len() > 0 {
+				if diff_items.len() > 0 {
+					self.table.handle_update(diff_items).await?;
+				}
+				if items_to_send.len() > 0 {
 					self.table
 						.system
 						.background
-						.spawn(self.clone().send_items(who.clone(), items));
+						.spawn(self.clone().send_items(who.clone(), items_to_send));
 				}
 			} else {
 				return Err(Error::Message(format!(
@@ -424,20 +430,47 @@ impl<F: TableSchema + 'static> TableSyncer<F> {
 		mut must_exit: watch::Receiver<bool>,
 	) -> Result<SyncRPC, Error> {
 		if let SyncRPC::Checksums(checksums) = message {
-			let mut ret = vec![];
+			let mut ret_ranges = vec![];
+			let mut ret_items = vec![];
 			for ckr in checksums.iter() {
 				let our_ckr = self.range_checksum(&ckr.bounds, &mut must_exit).await?;
 				for (range, hash) in ckr.children.iter() {
-					match our_ckr
+					// Only consider items that are in the intersection of the two ranges
+					// (other ranges will be exchanged at some point)
+					if our_ckr.found_limit.as_ref().map(|x| range.begin.as_slice() >= x.as_slice()).unwrap_or(false) {
+						break;
+					}
+
+					let differs = match our_ckr
 						.children
 						.binary_search_by(|(our_range, _)| our_range.begin.cmp(&range.begin))
 					{
-						Err(_) => {
-							ret.push(range.clone());
+						Err(_) => true,
+						Ok(i) => our_ckr.children[i].1 != *hash,
+					};
+					if differs {
+						ret_ranges.push(range.clone());
+						if range.level == 0 {
+							if let Some(item_bytes) = self.table.store.get(range.begin.as_slice())? {
+								ret_items.push(Arc::new(ByteBuf::from(item_bytes.to_vec())));
+							}
 						}
-						Ok(i) => {
-							if our_ckr.children[i].1 != *hash {
-								ret.push(range.clone());
+					}
+				}
+				for (range, _hash) in our_ckr.children.iter() {
+					if ckr.found_limit.as_ref().map(|x| range.begin.as_slice() >= x.as_slice()).unwrap_or(false) {
+						break;
+					}
+
+					let not_present = ckr
+						.children
+						.binary_search_by(|(their_range, _)| their_range.begin.cmp(&range.begin))
+						.is_err();
+					if not_present {
+						ret_ranges.push(range.clone());
+						if range.level == 0 {
+							if let Some(item_bytes) = self.table.store.get(range.begin.as_slice())? {
+								ret_items.push(Arc::new(ByteBuf::from(item_bytes.to_vec())));
 							}
 						}
 					}
@@ -448,12 +481,13 @@ impl<F: TableSchema + 'static> TableSyncer<F> {
 				.map(|x| x.children.len())
 				.fold(0, |x, y| x + y);
 			eprintln!(
-				"({}) Checksum comparison RPC: {} different out of {}",
+				"({}) Checksum comparison RPC: {} different + {} items for {} received",
 				self.table.name,
-				ret.len(),
+				ret_ranges.len(),
+				ret_items.len(),
 				n_checksums
 			);
-			return Ok(SyncRPC::DifferentSet(ret));
+			return Ok(SyncRPC::Difference(ret_ranges, ret_items));
 		}
 		Err(Error::Message(format!("Unexpected sync RPC")))
 	}