(not well tested) use merkle tree for sync

1 files changed, 0 insertions, 898 deletions

diff --git a/src/table/table_sync.rs b/src/table/table_sync.rs
deleted file mode 100644
index 7394be1b..00000000
--- a/src/table/table_sync.rs
+++ /dev/null
@@ -1,898 +0,0 @@
-use rand::Rng;
-use std::collections::{BTreeMap, VecDeque};
-use std::sync::{Arc, Mutex};
-use std::time::{Duration, Instant};
-
-use futures::future::join_all;
-use futures::{pin_mut, select};
-use futures_util::future::*;
-use futures_util::stream::*;
-use serde::{Deserialize, Serialize};
-use serde_bytes::ByteBuf;
-use tokio::sync::{mpsc, watch};
-
-use garage_rpc::ring::Ring;
-use garage_util::data::*;
-use garage_util::error::Error;
-
-use crate::*;
-use crate::data::*;
-use crate::replication::*;
-
-const MAX_DEPTH: usize = 16;
-
-const TABLE_SYNC_RPC_TIMEOUT: Duration = Duration::from_secs(30);
-
-// Do anti-entropy every 10 minutes
-const SCAN_INTERVAL: Duration = Duration::from_secs(10 * 60);
-
-const CHECKSUM_CACHE_TIMEOUT: Duration = Duration::from_secs(10 * 60);
-
-pub struct TableSyncer<F: TableSchema, R: TableReplication> {
-	data: Arc<TableData<F>>,
-	aux: Arc<TableAux<F, R>>,
-
-	todo: Mutex<SyncTodo>,
-	cache: Vec<Mutex<BTreeMap<SyncRange, RangeChecksumCache>>>,
-}
-
-#[derive(Serialize, Deserialize)]
-pub(crate) enum SyncRPC {
-	GetRootChecksumRange(Hash, Hash),
-	RootChecksumRange(SyncRange),
-	Checksums(Vec<RangeChecksum>),
-	Difference(Vec<SyncRange>, Vec<Arc<ByteBuf>>),
-}
-
-struct SyncTodo {
-	todo: Vec<TodoPartition>,
-}
-
-#[derive(Debug, Clone)]
-struct TodoPartition {
-	// Partition consists in hashes between begin included and end excluded
-	begin: Hash,
-	end: Hash,
-
-	// Are we a node that stores this partition or not?
-	retain: bool,
-}
-
-// A SyncRange defines a query on the dataset stored by a node, in the following way:
-// - all items whose key are >= `begin`
-// - stopping at the first item whose key hash has at least `level` leading zero bytes (excluded)
-// - except if the first item of the range has such many leading zero bytes
-// - and stopping at `end` (excluded) if such an item is not found
-// The checksum itself does not store all of the items in the database, only the hashes of the "sub-ranges"
-// i.e. of ranges of level `level-1` that cover the same range
-// (ranges of level 0 do not exist and their hash is simply the hash of the first item >= begin)
-// See RangeChecksum for the struct that stores this information.
-#[derive(Hash, PartialEq, Eq, Debug, Clone, Serialize, Deserialize)]
-pub(crate) struct SyncRange {
-	begin: Vec<u8>,
-	end: Vec<u8>,
-	level: usize,
-}
-
-impl std::cmp::PartialOrd for SyncRange {
-	fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-		Some(self.cmp(other))
-	}
-}
-impl std::cmp::Ord for SyncRange {
-	fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-		self.begin
-			.cmp(&other.begin)
-			.then(self.level.cmp(&other.level))
-			.then(self.end.cmp(&other.end))
-	}
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub(crate) struct RangeChecksum {
-	bounds: SyncRange,
-	children: Vec<(SyncRange, Hash)>,
-	found_limit: Option<Vec<u8>>,
-
-	#[serde(skip, default = "std::time::Instant::now")]
-	time: Instant,
-}
-
-#[derive(Debug, Clone)]
-struct RangeChecksumCache {
-	hash: Option<Hash>, // None if no children
-	found_limit: Option<Vec<u8>>,
-	time: Instant,
-}
-
-impl<F, R> TableSyncer<F, R>
-where
-	F: TableSchema + 'static,
-	R: TableReplication + 'static,
-{
-	pub(crate) fn launch(data: Arc<TableData<F>>,
-					  aux: Arc<TableAux<F, R>>) -> Arc<Self> {
-		let todo = SyncTodo{ todo: vec![] };
-
-		let syncer = Arc::new(Self {
-			data: data.clone(),
-			aux: aux.clone(),
-			todo: Mutex::new(todo),
-			cache: (0..MAX_DEPTH)
-				.map(|_| Mutex::new(BTreeMap::new()))
-				.collect::<Vec<_>>(),
-		});
-
-		let (busy_tx, busy_rx) = mpsc::unbounded_channel();
-
-		let s1 = syncer.clone();
-		aux.system.background.spawn_worker(
-			format!("table sync watcher for {}", data.name),
-			move |must_exit: watch::Receiver<bool>| s1.watcher_task(must_exit, busy_rx),
-		);
-
-		let s2 = syncer.clone();
-		aux.system.background.spawn_worker(
-			format!("table syncer for {}", data.name),
-			move |must_exit: watch::Receiver<bool>| s2.syncer_task(must_exit, busy_tx),
-		);
-
-		let s3 = syncer.clone();
-		tokio::spawn(async move {
-			tokio::time::delay_for(Duration::from_secs(20)).await;
-			s3.add_full_scan();
-		});
-
-		syncer
-	}
-
-	async fn watcher_task(
-		self: Arc<Self>,
-		mut must_exit: watch::Receiver<bool>,
-		mut busy_rx: mpsc::UnboundedReceiver<bool>,
-	) -> Result<(), Error> {
-		let mut prev_ring: Arc<Ring> = self.aux.system.ring.borrow().clone();
-		let mut ring_recv: watch::Receiver<Arc<Ring>> = self.aux.system.ring.clone();
-		let mut nothing_to_do_since = Some(Instant::now());
-
-		while !*must_exit.borrow() {
-			let s_ring_recv = ring_recv.recv().fuse();
-			let s_busy = busy_rx.recv().fuse();
-			let s_must_exit = must_exit.recv().fuse();
-			let s_timeout = tokio::time::delay_for(Duration::from_secs(1)).fuse();
-			pin_mut!(s_ring_recv, s_busy, s_must_exit, s_timeout);
-
-			select! {
-				new_ring_r = s_ring_recv => {
-					if let Some(new_ring) = new_ring_r {
-						debug!("({}) Adding ring difference to syncer todo list", self.data.name);
-						self.todo.lock().unwrap().add_ring_difference(&prev_ring, &new_ring, &self.data, &self.aux);
-						prev_ring = new_ring;
-					}
-				}
-				busy_opt = s_busy => {
-					if let Some(busy) = busy_opt {
-						if busy {
-							nothing_to_do_since = None;
-						} else {
-							if nothing_to_do_since.is_none() {
-								nothing_to_do_since = Some(Instant::now());
-							}
-						}
-					}
-				}
-				must_exit_v = s_must_exit => {
-					if must_exit_v.unwrap_or(false) {
-						break;
-					}
-				}
-				_ = s_timeout => {
-					if nothing_to_do_since.map(|t| Instant::now() - t >= SCAN_INTERVAL).unwrap_or(false) {
-						nothing_to_do_since = None;
-						debug!("({}) Adding full scan to syncer todo list", self.data.name);
-						self.add_full_scan();
-					}
-				}
-			}
-		}
-		Ok(())
-	}
-
-	pub fn add_full_scan(&self) {
-		self.todo.lock().unwrap().add_full_scan(&self.data, &self.aux);
-	}
-
-	async fn syncer_task(
-		self: Arc<Self>,
-		mut must_exit: watch::Receiver<bool>,
-		busy_tx: mpsc::UnboundedSender<bool>,
-	) -> Result<(), Error> {
-		while !*must_exit.borrow() {
-			let task = self.todo.lock().unwrap().pop_task();
-			if let Some(partition) = task {
-				busy_tx.send(true)?;
-				let res = self
-					.clone()
-					.sync_partition(&partition, &mut must_exit)
-					.await;
-				if let Err(e) = res {
-					warn!(
-						"({}) Error while syncing {:?}: {}",
-						self.data.name, partition, e
-					);
-				}
-			} else {
-				busy_tx.send(false)?;
-				tokio::time::delay_for(Duration::from_secs(1)).await;
-			}
-		}
-		Ok(())
-	}
-
-	async fn sync_partition(
-		self: Arc<Self>,
-		partition: &TodoPartition,
-		must_exit: &mut watch::Receiver<bool>,
-	) -> Result<(), Error> {
-		if partition.retain {
-			let my_id = self.aux.system.id;
-			let nodes = self
-				.aux
-				.replication
-				.write_nodes(&partition.begin, &self.aux.system)
-				.into_iter()
-				.filter(|node| *node != my_id)
-				.collect::<Vec<_>>();
-
-			debug!(
-				"({}) Preparing to sync {:?} with {:?}...",
-				self.data.name, partition, nodes
-			);
-			let root_cks = self.root_checksum(&partition.begin, &partition.end, must_exit)?;
-
-			let mut sync_futures = nodes
-				.iter()
-				.map(|node| {
-					self.clone().do_sync_with(
-						partition.clone(),
-						root_cks.clone(),
-						*node,
-						must_exit.clone(),
-					)
-				})
-				.collect::<FuturesUnordered<_>>();
-
-			let mut n_errors = 0;
-			while let Some(r) = sync_futures.next().await {
-				if let Err(e) = r {
-					n_errors += 1;
-					warn!("({}) Sync error: {}", self.data.name, e);
-				}
-			}
-			if n_errors > self.aux.replication.max_write_errors() {
-				return Err(Error::Message(format!(
-					"Sync failed with too many nodes (should have been: {:?}).",
-					nodes
-				)));
-			}
-		} else {
-			self.offload_partition(&partition.begin, &partition.end, must_exit)
-				.await?;
-		}
-
-		Ok(())
-	}
-
-	// Offload partition: this partition is not something we are storing,
-	// so send it out to all other nodes that store it and delete items locally.
-	// We don't bother checking if the remote nodes already have the items,
-	// we just batch-send everything. Offloading isn't supposed to happen very often.
-	// If any of the nodes that are supposed to store the items is unable to
-	// save them, we interrupt the process.
-	async fn offload_partition(
-		self: &Arc<Self>,
-		begin: &Hash,
-		end: &Hash,
-		must_exit: &mut watch::Receiver<bool>,
-	) -> Result<(), Error> {
-		let mut counter: usize = 0;
-
-		while !*must_exit.borrow() {
-			let mut items = Vec::new();
-
-			for item in self.data.store.range(begin.to_vec()..end.to_vec()) {
-				let (key, value) = item?;
-				items.push((key.to_vec(), Arc::new(ByteBuf::from(value.as_ref()))));
-
-				if items.len() >= 1024 {
-					break;
-				}
-			}
-
-			if items.len() > 0 {
-				let nodes = self
-					.aux
-					.replication
-					.write_nodes(&begin, &self.aux.system)
-					.into_iter()
-					.collect::<Vec<_>>();
-				if nodes.contains(&self.aux.system.id) {
-					warn!("Interrupting offload as partitions seem to have changed");
-					break;
-				}
-
-				counter += 1;
-				debug!(
-					"Offloading {} items from {:?}..{:?} ({})",
-					items.len(),
-					begin,
-					end,
-					counter
-				);
-				self.offload_items(&items, &nodes[..]).await?;
-			} else {
-				break;
-			}
-		}
-
-		Ok(())
-	}
-
-	async fn offload_items(
-		self: &Arc<Self>,
-		items: &Vec<(Vec<u8>, Arc<ByteBuf>)>,
-		nodes: &[UUID],
-	) -> Result<(), Error> {
-		let values = items.iter().map(|(_k, v)| v.clone()).collect::<Vec<_>>();
-		let update_msg = Arc::new(TableRPC::<F>::Update(values));
-
-		for res in join_all(nodes.iter().map(|to| {
-			self.aux
-				.rpc_client
-				.call_arc(*to, update_msg.clone(), TABLE_SYNC_RPC_TIMEOUT)
-		}))
-		.await
-		{
-			res?;
-		}
-
-		// All remote nodes have written those items, now we can delete them locally
-		let mut not_removed = 0;
-		for (k, v) in items.iter() {
-			if !self.data.delete_if_equal(&k[..], &v[..])? {
-				not_removed += 1;
-			}
-		}
-
-		if not_removed > 0 {
-			debug!("{} items not removed during offload because they changed in between (trying again...)", not_removed);
-		}
-
-		Ok(())
-	}
-
-	fn root_checksum(
-		self: &Arc<Self>,
-		begin: &Hash,
-		end: &Hash,
-		must_exit: &mut watch::Receiver<bool>,
-	) -> Result<RangeChecksum, Error> {
-		for i in 1..MAX_DEPTH {
-			let rc = self.range_checksum(
-				&SyncRange {
-					begin: begin.to_vec(),
-					end: end.to_vec(),
-					level: i,
-				},
-				must_exit,
-			)?;
-			if rc.found_limit.is_none() {
-				return Ok(rc);
-			}
-		}
-		Err(Error::Message(format!(
-			"Unable to compute root checksum (this should never happen)"
-		)))
-	}
-
-	fn range_checksum(
-		self: &Arc<Self>,
-		range: &SyncRange,
-		must_exit: &mut watch::Receiver<bool>,
-	) -> Result<RangeChecksum, Error> {
-		assert!(range.level != 0);
-		trace!("Call range_checksum {:?}", range);
-
-		if range.level == 1 {
-			let mut children = vec![];
-			for item in self
-				.data
-				.store
-				.range(range.begin.clone()..range.end.clone())
-			{
-				let (key, value) = item?;
-				let key_hash = blake2sum(&key[..]);
-				if children.len() > 0
-					&& key_hash.as_slice()[0..range.level]
-						.iter()
-						.all(|x| *x == 0u8)
-				{
-					trace!(
-						"range_checksum {:?} returning {} items",
-						range,
-						children.len()
-					);
-					return Ok(RangeChecksum {
-						bounds: range.clone(),
-						children,
-						found_limit: Some(key.to_vec()),
-						time: Instant::now(),
-					});
-				}
-				let item_range = SyncRange {
-					begin: key.to_vec(),
-					end: vec![],
-					level: 0,
-				};
-				children.push((item_range, blake2sum(&value[..])));
-			}
-			trace!(
-				"range_checksum {:?} returning {} items",
-				range,
-				children.len()
-			);
-			Ok(RangeChecksum {
-				bounds: range.clone(),
-				children,
-				found_limit: None,
-				time: Instant::now(),
-			})
-		} else {
-			let mut children = vec![];
-			let mut sub_range = SyncRange {
-				begin: range.begin.clone(),
-				end: range.end.clone(),
-				level: range.level - 1,
-			};
-			let mut time = Instant::now();
-			while !*must_exit.borrow() {
-				let sub_ck = self.range_checksum_cached_hash(&sub_range, must_exit)?;
-
-				if let Some(hash) = sub_ck.hash {
-					children.push((sub_range.clone(), hash));
-					if sub_ck.time < time {
-						time = sub_ck.time;
-					}
-				}
-
-				if sub_ck.found_limit.is_none() || sub_ck.hash.is_none() {
-					trace!(
-						"range_checksum {:?} returning {} items",
-						range,
-						children.len()
-					);
-					return Ok(RangeChecksum {
-						bounds: range.clone(),
-						children,
-						found_limit: None,
-						time,
-					});
-				}
-				let found_limit = sub_ck.found_limit.unwrap();
-
-				let actual_limit_hash = blake2sum(&found_limit[..]);
-				if actual_limit_hash.as_slice()[0..range.level]
-					.iter()
-					.all(|x| *x == 0u8)
-				{
-					trace!(
-						"range_checksum {:?} returning {} items",
-						range,
-						children.len()
-					);
-					return Ok(RangeChecksum {
-						bounds: range.clone(),
-						children,
-						found_limit: Some(found_limit.clone()),
-						time,
-					});
-				}
-
-				sub_range.begin = found_limit;
-			}
-			trace!("range_checksum {:?} exiting due to must_exit", range);
-			Err(Error::Message(format!("Exiting.")))
-		}
-	}
-
-	fn range_checksum_cached_hash(
-		self: &Arc<Self>,
-		range: &SyncRange,
-		must_exit: &mut watch::Receiver<bool>,
-	) -> Result<RangeChecksumCache, Error> {
-		{
-			let mut cache = self.cache[range.level].lock().unwrap();
-			if let Some(v) = cache.get(&range) {
-				if Instant::now() - v.time < CHECKSUM_CACHE_TIMEOUT {
-					return Ok(v.clone());
-				}
-			}
-			cache.remove(&range);
-		}
-
-		let v = self.range_checksum(&range, must_exit)?;
-		trace!(
-			"({}) New checksum calculated for {}-{}/{}, {} children",
-			self.data.name,
-			hex::encode(&range.begin)
-				.chars()
-				.take(16)
-				.collect::<String>(),
-			hex::encode(&range.end).chars().take(16).collect::<String>(),
-			range.level,
-			v.children.len()
-		);
-
-		let hash = if v.children.len() > 0 {
-			Some(blake2sum(&rmp_to_vec_all_named(&v)?[..]))
-		} else {
-			None
-		};
-		let cache_entry = RangeChecksumCache {
-			hash,
-			found_limit: v.found_limit,
-			time: v.time,
-		};
-
-		let mut cache = self.cache[range.level].lock().unwrap();
-		cache.insert(range.clone(), cache_entry.clone());
-		Ok(cache_entry)
-	}
-
-	async fn do_sync_with(
-		self: Arc<Self>,
-		partition: TodoPartition,
-		root_ck: RangeChecksum,
-		who: UUID,
-		mut must_exit: watch::Receiver<bool>,
-	) -> Result<(), Error> {
-		let mut todo = VecDeque::new();
-
-		// If their root checksum has level > than us, use that as a reference
-		let root_cks_resp = self
-			.aux
-			.rpc_client
-			.call(
-				who,
-				TableRPC::<F>::SyncRPC(SyncRPC::GetRootChecksumRange(
-					partition.begin.clone(),
-					partition.end.clone(),
-				)),
-				TABLE_SYNC_RPC_TIMEOUT,
-			)
-			.await?;
-		if let TableRPC::<F>::SyncRPC(SyncRPC::RootChecksumRange(range)) = root_cks_resp {
-			if range.level > root_ck.bounds.level {
-				let their_root_range_ck = self.range_checksum(&range, &mut must_exit)?;
-				todo.push_back(their_root_range_ck);
-			} else {
-				todo.push_back(root_ck);
-			}
-		} else {
-			return Err(Error::Message(format!(
-				"Invalid respone to GetRootChecksumRange RPC: {}",
-				debug_serialize(root_cks_resp)
-			)));
-		}
-
-		while !todo.is_empty() && !*must_exit.borrow() {
-			let total_children = todo.iter().map(|x| x.children.len()).fold(0, |x, y| x + y);
-			trace!(
-				"({}) Sync with {:?}: {} ({}) remaining",
-				self.data.name,
-				who,
-				todo.len(),
-				total_children
-			);
-
-			let step_size = std::cmp::min(16, todo.len());
-			let step = todo.drain(..step_size).collect::<Vec<_>>();
-
-			let rpc_resp = self
-				.aux
-				.rpc_client
-				.call(
-					who,
-					TableRPC::<F>::SyncRPC(SyncRPC::Checksums(step)),
-					TABLE_SYNC_RPC_TIMEOUT,
-				)
-				.await?;
-			if let TableRPC::<F>::SyncRPC(SyncRPC::Difference(mut diff_ranges, diff_items)) =
-				rpc_resp
-			{
-				if diff_ranges.len() > 0 || diff_items.len() > 0 {
-					info!(
-						"({}) Sync with {:?}: difference {} ranges, {} items",
-						self.data.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_to_send.push(differing.begin);
-					} else {
-						let checksum = self.range_checksum(&differing, &mut must_exit)?;
-						todo.push_back(checksum);
-					}
-				}
-				if diff_items.len() > 0 {
-					self.data.update_many(&diff_items[..])?;
-				}
-				if items_to_send.len() > 0 {
-					self.send_items(who, items_to_send).await?;
-				}
-			} else {
-				return Err(Error::Message(format!(
-					"Unexpected response to sync RPC checksums: {}",
-					debug_serialize(&rpc_resp)
-				)));
-			}
-		}
-		Ok(())
-	}
-
-	async fn send_items(&self, who: UUID, item_list: Vec<Vec<u8>>) -> Result<(), Error> {
-		info!(
-			"({}) Sending {} items to {:?}",
-			self.data.name,
-			item_list.len(),
-			who
-		);
-
-		let mut values = vec![];
-		for item in item_list.iter() {
-			if let Some(v) = self.data.store.get(&item[..])? {
-				values.push(Arc::new(ByteBuf::from(v.as_ref())));
-			}
-		}
-		let rpc_resp = self
-			.aux
-			.rpc_client
-			.call(who, TableRPC::<F>::Update(values), TABLE_SYNC_RPC_TIMEOUT)
-			.await?;
-		if let TableRPC::<F>::Ok = rpc_resp {
-			Ok(())
-		} else {
-			Err(Error::Message(format!(
-				"Unexpected response to RPC Update: {}",
-				debug_serialize(&rpc_resp)
-			)))
-		}
-	}
-
-	pub(crate) async fn handle_rpc(
-		self: &Arc<Self>,
-		message: &SyncRPC,
-		mut must_exit: watch::Receiver<bool>,
-	) -> Result<SyncRPC, Error> {
-		match message {
-			SyncRPC::GetRootChecksumRange(begin, end) => {
-				let root_cks = self.root_checksum(&begin, &end, &mut must_exit)?;
-				Ok(SyncRPC::RootChecksumRange(root_cks.bounds))
-			}
-			SyncRPC::Checksums(checksums) => {
-				self.handle_checksums_rpc(&checksums[..], &mut must_exit)
-					.await
-			}
-			_ => Err(Error::Message(format!("Unexpected sync RPC"))),
-		}
-	}
-
-	async fn handle_checksums_rpc(
-		self: &Arc<Self>,
-		checksums: &[RangeChecksum],
-		must_exit: &mut watch::Receiver<bool>,
-	) -> Result<SyncRPC, Error> {
-		let mut ret_ranges = vec![];
-		let mut ret_items = vec![];
-
-		for their_ckr in checksums.iter() {
-			let our_ckr = self.range_checksum(&their_ckr.bounds, must_exit)?;
-			for (their_range, their_hash) in their_ckr.children.iter() {
-				let differs = match our_ckr
-					.children
-					.binary_search_by(|(our_range, _)| our_range.cmp(&their_range))
-				{
-					Err(_) => {
-						if their_range.level >= 1 {
-							let cached_hash =
-								self.range_checksum_cached_hash(&their_range, must_exit)?;
-							cached_hash.hash.map(|h| h != *their_hash).unwrap_or(true)
-						} else {
-							true
-						}
-					}
-					Ok(i) => our_ckr.children[i].1 != *their_hash,
-				};
-				if differs {
-					ret_ranges.push(their_range.clone());
-					if their_range.level == 0 {
-						if let Some(item_bytes) =
-							self.data.store.get(their_range.begin.as_slice())?
-						{
-							ret_items.push(Arc::new(ByteBuf::from(item_bytes.to_vec())));
-						}
-					}
-				}
-			}
-			for (our_range, _hash) in our_ckr.children.iter() {
-				if let Some(their_found_limit) = &their_ckr.found_limit {
-					if our_range.begin.as_slice() > their_found_limit.as_slice() {
-						break;
-					}
-				}
-
-				let not_present = our_ckr
-					.children
-					.binary_search_by(|(their_range, _)| their_range.cmp(&our_range))
-					.is_err();
-				if not_present {
-					if our_range.level > 0 {
-						ret_ranges.push(our_range.clone());
-					}
-					if our_range.level == 0 {
-						if let Some(item_bytes) =
-							self.data.store.get(our_range.begin.as_slice())?
-						{
-							ret_items.push(Arc::new(ByteBuf::from(item_bytes.to_vec())));
-						}
-					}
-				}
-			}
-		}
-		let n_checksums = checksums
-			.iter()
-			.map(|x| x.children.len())
-			.fold(0, |x, y| x + y);
-		if ret_ranges.len() > 0 || ret_items.len() > 0 {
-			trace!(
-				"({}) Checksum comparison RPC: {} different + {} items for {} received",
-				self.data.name,
-				ret_ranges.len(),
-				ret_items.len(),
-				n_checksums
-			);
-		}
-		Ok(SyncRPC::Difference(ret_ranges, ret_items))
-	}
-
-	pub(crate) fn invalidate(self: &Arc<Self>, item_key: &[u8]) {
-		for i in 1..MAX_DEPTH {
-			let needle = SyncRange {
-				begin: item_key.to_vec(),
-				end: vec![],
-				level: i,
-			};
-			let mut cache = self.cache[i].lock().unwrap();
-			if let Some(cache_entry) = cache.range(..=needle).rev().next() {
-				if cache_entry.0.begin[..] <= *item_key && cache_entry.0.end[..] > *item_key {
-					let index = cache_entry.0.clone();
-					drop(cache_entry);
-					cache.remove(&index);
-				}
-			}
-		}
-	}
-}
-
-impl SyncTodo {
-	fn add_full_scan<F: TableSchema, R: TableReplication>(&mut self, data: &TableData<F>, aux: &TableAux<F, R>) {
-		let my_id = aux.system.id;
-
-		self.todo.clear();
-
-		let ring = aux.system.ring.borrow().clone();
-		let split_points = aux.replication.split_points(&ring);
-
-		for i in 0..split_points.len() - 1 {
-			let begin = split_points[i];
-			let end = split_points[i + 1];
-			if begin == end {
-				continue;
-			}
-
-			let nodes = aux.replication.replication_nodes(&begin, &ring);
-
-			let retain = nodes.contains(&my_id);
-			if !retain {
-				// Check if we have some data to send, otherwise skip
-				if data.store.range(begin..end).next().is_none() {
-					continue;
-				}
-			}
-
-			self.todo.push(TodoPartition { begin, end, retain });
-		}
-	}
-
-	fn add_ring_difference<F: TableSchema, R: TableReplication>(
-		&mut self,
-		old_ring: &Ring,
-		new_ring: &Ring,
-		data: &TableData<F>, aux: &TableAux<F, R>,
-	) {
-		let my_id = aux.system.id;
-
-		// If it is us who are entering or leaving the system,
-		// initiate a full sync instead of incremental sync
-		if old_ring.config.members.contains_key(&my_id)
-			!= new_ring.config.members.contains_key(&my_id)
-		{
-			self.add_full_scan(data, aux);
-			return;
-		}
-
-		let mut all_points = None
-			.into_iter()
-			.chain(aux.replication.split_points(old_ring).drain(..))
-			.chain(aux.replication.split_points(new_ring).drain(..))
-			.chain(self.todo.iter().map(|x| x.begin))
-			.chain(self.todo.iter().map(|x| x.end))
-			.collect::<Vec<_>>();
-		all_points.sort();
-		all_points.dedup();
-
-		let mut old_todo = std::mem::replace(&mut self.todo, vec![]);
-		old_todo.sort_by(|x, y| x.begin.cmp(&y.begin));
-		let mut new_todo = vec![];
-
-		for i in 0..all_points.len() - 1 {
-			let begin = all_points[i];
-			let end = all_points[i + 1];
-			let was_ours = aux
-				.replication
-				.replication_nodes(&begin, &old_ring)
-				.contains(&my_id);
-			let is_ours = aux
-				.replication
-				.replication_nodes(&begin, &new_ring)
-				.contains(&my_id);
-
-			let was_todo = match old_todo.binary_search_by(|x| x.begin.cmp(&begin)) {
-				Ok(_) => true,
-				Err(j) => {
-					(j > 0 && old_todo[j - 1].begin < end && begin < old_todo[j - 1].end)
-						|| (j < old_todo.len()
-							&& old_todo[j].begin < end && begin < old_todo[j].end)
-				}
-			};
-			if was_todo || (is_ours && !was_ours) || (was_ours && !is_ours) {
-				new_todo.push(TodoPartition {
-					begin,
-					end,
-					retain: is_ours,
-				});
-			}
-		}
-
-		self.todo = new_todo;
-	}
-
-	fn pop_task(&mut self) -> Option<TodoPartition> {
-		if self.todo.is_empty() {
-			return None;
-		}
-
-		let i = rand::thread_rng().gen_range::<usize, _, _>(0, self.todo.len());
-		if i == self.todo.len() - 1 {
-			self.todo.pop()
-		} else {
-			let replacement = self.todo.pop().unwrap();
-			let ret = std::mem::replace(&mut self.todo[i], replacement);
-			Some(ret)
-		}
-	}
-}