use rand::Rng; use std::collections::{BTreeMap, BTreeSet, VecDeque}; use std::sync::Arc; use std::time::{Duration, Instant}; use futures::future::BoxFuture; use futures::{pin_mut, select}; use futures_util::future::*; use futures_util::stream::*; use serde::{Deserialize, Serialize}; use serde_bytes::ByteBuf; use tokio::sync::watch; use tokio::sync::Mutex; use crate::data::*; use crate::error::Error; use crate::membership::Ring; use crate::table::*; const MAX_DEPTH: usize = 16; const SCAN_INTERVAL: Duration = Duration::from_secs(3600); const CHECKSUM_CACHE_TIMEOUT: Duration = Duration::from_secs(1800); pub struct TableSyncer { pub table: Arc>, pub todo: Mutex, pub cache: Vec>>, } pub struct SyncTodo { pub todo: Vec, } #[derive(Debug, Clone)] pub struct Partition { pub begin: Hash, pub end: Hash, pub retain: bool, } #[derive(Hash, PartialEq, Eq, Debug, Clone, Serialize, Deserialize)] pub struct SyncRange { pub begin: Vec, pub end: Vec, pub level: usize, } impl std::cmp::PartialOrd for SyncRange { fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } } impl std::cmp::Ord for SyncRange { fn cmp(&self, other: &Self) -> std::cmp::Ordering { self.begin.cmp(&other.begin) } } #[derive(Debug, Clone, Serialize, Deserialize)] pub struct RangeChecksum { pub bounds: SyncRange, pub children: Vec<(SyncRange, Hash)>, pub found_limit: Option>, #[serde(skip, default = "std::time::Instant::now")] pub time: Instant, } impl TableSyncer { pub async fn launch(table: Arc>) -> Arc { let todo = SyncTodo { todo: Vec::new() }; let syncer = Arc::new(TableSyncer { table: table.clone(), todo: Mutex::new(todo), cache: (0..MAX_DEPTH) .map(|_| Mutex::new(BTreeMap::new())) .collect::>(), }); let s1 = syncer.clone(); table .system .background .spawn_worker(move |must_exit: watch::Receiver| s1.watcher_task(must_exit)) .await; let s2 = syncer.clone(); table .system .background .spawn_worker(move |must_exit: watch::Receiver| s2.syncer_task(must_exit)) .await; syncer } async fn watcher_task( self: Arc, mut must_exit: watch::Receiver, ) -> Result<(), Error> { tokio::time::delay_for(Duration::from_secs(10)).await; self.todo.lock().await.add_full_scan(&self.table); let mut next_full_scan = tokio::time::delay_for(SCAN_INTERVAL).fuse(); let mut prev_ring: Arc = self.table.system.ring.borrow().clone(); let mut ring_recv: watch::Receiver> = self.table.system.ring.clone(); while !*must_exit.borrow() { let s_ring_recv = ring_recv.recv().fuse(); let s_must_exit = must_exit.recv().fuse(); pin_mut!(s_ring_recv, s_must_exit); select! { _ = next_full_scan => { next_full_scan = tokio::time::delay_for(SCAN_INTERVAL).fuse(); eprintln!("({}) Adding full scan to syncer todo list", self.table.name); self.todo.lock().await.add_full_scan(&self.table); } new_ring_r = s_ring_recv => { if let Some(new_ring) = new_ring_r { eprintln!("({}) Adding ring difference to syncer todo list", self.table.name); self.todo.lock().await.add_ring_difference(&self.table, &prev_ring, &new_ring); prev_ring = new_ring; } } must_exit_v = s_must_exit => { if must_exit_v.unwrap_or(false) { break; } } } } Ok(()) } async fn syncer_task( self: Arc, mut must_exit: watch::Receiver, ) -> Result<(), Error> { while !*must_exit.borrow() { if let Some(partition) = self.todo.lock().await.pop_task() { let res = self .clone() .sync_partition(&partition, &mut must_exit) .await; if let Err(e) = res { eprintln!( "({}) Error while syncing {:?}: {}", self.table.name, partition, e ); } } else { tokio::time::delay_for(Duration::from_secs(1)).await; } } Ok(()) } async fn sync_partition( self: Arc, partition: &Partition, must_exit: &mut watch::Receiver, ) -> Result<(), Error> { eprintln!("({}) Preparing to sync {:?}...", self.table.name, partition); let root_cks = self .root_checksum(&partition.begin, &partition.end, must_exit) .await?; let nodes = self .table .system .ring .borrow() .clone() .walk_ring(&partition.begin, self.table.param.replication_factor); let mut sync_futures = nodes .iter() .map(|node| { self.clone() .do_sync_with(root_cks.clone(), node.clone(), must_exit.clone()) }) .collect::>(); while let Some(r) = sync_futures.next().await { if let Err(e) = r { eprintln!("({}) Sync error: {}", self.table.name, e); } } if !partition.retain { self.table .delete_range(&partition.begin, &partition.end) .await?; } Ok(()) } async fn root_checksum( self: &Arc, begin: &Hash, end: &Hash, must_exit: &mut watch::Receiver, ) -> Result { for i in 1..MAX_DEPTH { let rc = self .range_checksum( &SyncRange { begin: begin.to_vec(), end: end.to_vec(), level: i, }, must_exit, ) .await?; 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<'a>( self: &'a Arc, range: &'a SyncRange, must_exit: &'a mut watch::Receiver, ) -> BoxFuture<'a, Result> { async move { let mut cache = self.cache[range.level].lock().await; if let Some(v) = cache.get(&range) { if Instant::now() - v.time < CHECKSUM_CACHE_TIMEOUT { return Ok(v.clone()); } } cache.remove(&range); drop(cache); let v = self.range_checksum_inner(&range, must_exit).await?; eprintln!( "({}) New checksum calculated for {}-{}/{}, {} children", self.table.name, hex::encode(&range.begin[..]), hex::encode(&range.end[..]), range.level, v.children.len() ); let mut cache = self.cache[range.level].lock().await; cache.insert(range.clone(), v.clone()); Ok(v) } .boxed() } async fn range_checksum_inner( self: &Arc, range: &SyncRange, must_exit: &mut watch::Receiver, ) -> Result { if range.level == 1 { let mut children = vec![]; for item in self .table .store .range(range.begin.clone()..range.end.clone()) { let (key, value) = item?; let key_hash = hash(&key[..]); if key != range.begin && key_hash.as_slice()[0..range.level].iter().all(|x| *x == 0) { 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, hash(&value[..]))); } 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(&sub_range, must_exit).await?; if sub_ck.children.len() > 0 { let sub_ck_hash = hash(&rmp_to_vec_all_named(&sub_ck)?[..]); children.push((sub_range.clone(), sub_ck_hash)); if sub_ck.time < time { time = sub_ck.time; } } if sub_ck.found_limit.is_none() || sub_ck.children.len() == 0 { return Ok(RangeChecksum { bounds: range.clone(), children, found_limit: None, time, }); } let found_limit = sub_ck.found_limit.unwrap(); let actual_limit_hash = hash(&found_limit[..]); if actual_limit_hash.as_slice()[0..range.level] .iter() .all(|x| *x == 0) { return Ok(RangeChecksum { bounds: range.clone(), children, found_limit: Some(found_limit.clone()), time, }); } sub_range.begin = found_limit; } Err(Error::Message(format!("Exiting."))) } } async fn do_sync_with( self: Arc, root_ck: RangeChecksum, who: UUID, mut must_exit: watch::Receiver, ) -> Result<(), Error> { let mut todo = VecDeque::new(); todo.push_back(root_ck); while !todo.is_empty() && !*must_exit.borrow() { let total_children = todo.iter().map(|x| x.children.len()).fold(0, |x, y| x + y); eprintln!( "({}) Sync with {:?}: {} ({}) remaining", self.table.name, who, todo.len(), total_children ); let end = std::cmp::min(16, todo.len()); let step = todo.drain(..end).collect::>(); let rpc_resp = self .table .rpc_call(&who, &TableRPC::::SyncChecksums(step)) .await?; if let TableRPC::::SyncDifferentSet(mut s) = rpc_resp { let mut items = vec![]; for differing in s.drain(..) { if differing.level == 0 { items.push(differing.begin); } else { let checksum = self.range_checksum(&differing, &mut must_exit).await?; todo.push_back(checksum); } } if items.len() > 0 { self.table .system .background .spawn(self.clone().send_items(who.clone(), items)); } } else { return Err(Error::Message(format!( "Unexpected response to RPC SyncChecksums: {}", debug_serialize(&rpc_resp) ))); } } Ok(()) } async fn send_items(self: Arc, who: UUID, item_list: Vec>) -> Result<(), Error> { eprintln!( "({}) Sending {} items to {:?}", self.table.name, item_list.len(), who ); let mut values = vec![]; for item in item_list.iter() { if let Some(v) = self.table.store.get(&item[..])? { values.push(Arc::new(ByteBuf::from(v.as_ref()))); } } let rpc_resp = self .table .rpc_call(&who, &TableRPC::::Update(values)) .await?; if let TableRPC::::Ok = rpc_resp { Ok(()) } else { Err(Error::Message(format!( "Unexpected response to RPC Update: {}", debug_serialize(&rpc_resp) ))) } } pub async fn handle_checksum_rpc( self: &Arc, checksums: &[RangeChecksum], mut must_exit: watch::Receiver, ) -> Result, Error> { let mut ret = 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 .children .binary_search_by(|(our_range, _)| our_range.begin.cmp(&range.begin)) { Err(_) => { ret.push(range.clone()); } Ok(i) => { if our_ckr.children[i].1 != *hash { ret.push(range.clone()); } } } } } let n_checksums = checksums .iter() .map(|x| x.children.len()) .fold(0, |x, y| x + y); eprintln!( "({}) Checksum comparison RPC: {} different out of {}", self.table.name, ret.len(), n_checksums ); Ok(ret) } pub async fn invalidate(self: Arc, item_key: Vec) -> Result<(), Error> { 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().await; 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); } } } Ok(()) } } impl SyncTodo { fn add_full_scan(&mut self, table: &Table) { let my_id = table.system.id.clone(); self.todo.clear(); let ring: Arc = table.system.ring.borrow().clone(); for i in 0..ring.ring.len() { let nodes = ring.walk_ring_from_pos(i, table.param.replication_factor); let begin = ring.ring[i].location.clone(); if i == 0 { self.add_full_scan_aux(table, [0u8; 32].into(), begin.clone(), &nodes[..], &my_id); } if i == ring.ring.len() - 1 { self.add_full_scan_aux(table, begin, [0xffu8; 32].into(), &nodes[..], &my_id); } else { let end = ring.ring[i + 1].location.clone(); self.add_full_scan_aux(table, begin, end, &nodes[..], &my_id); } } } fn add_full_scan_aux( &mut self, table: &Table, begin: Hash, end: Hash, nodes: &[UUID], my_id: &UUID, ) { let retain = nodes.contains(my_id); if !retain { // Check if we have some data to send, otherwise skip if table .store .range(begin.clone()..end.clone()) .next() .is_none() { return; } } self.todo.push(Partition { begin, end, retain }); } fn add_ring_difference(&mut self, table: &Table, old: &Ring, new: &Ring) { let my_id = table.system.id.clone(); let old_ring = ring_points(old); let new_ring = ring_points(new); let both_ring = old_ring.union(&new_ring).cloned().collect::>(); let prev_todo_begin = self .todo .iter() .map(|x| x.begin.clone()) .collect::>(); let prev_todo_end = self .todo .iter() .map(|x| x.end.clone()) .collect::>(); let prev_todo = prev_todo_begin .union(&prev_todo_end) .cloned() .collect::>(); let all_points = both_ring.union(&prev_todo).cloned().collect::>(); self.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].clone(); let end = all_points[i + 1].clone(); let was_ours = old .walk_ring(&begin, table.param.replication_factor) .contains(&my_id); let is_ours = new .walk_ring(&begin, table.param.replication_factor) .contains(&my_id); let was_todo = match self.todo.binary_search_by(|x| x.begin.cmp(&begin)) { Ok(_) => true, Err(j) => { (j > 0 && self.todo[j - 1].begin < end && begin < self.todo[j - 1].end) || (j < self.todo.len() && self.todo[j].begin < end && begin < self.todo[j].end) } }; if was_todo || (is_ours && !was_ours) || (was_ours && !is_ours) { new_todo.push(Partition { begin, end, retain: is_ours, }); } } self.todo = new_todo; } fn pop_task(&mut self) -> Option { if self.todo.is_empty() { return None; } let i = rand::thread_rng().gen_range::(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) } } } fn ring_points(ring: &Ring) -> BTreeSet { let mut ret = BTreeSet::new(); ret.insert([0u8; 32].into()); ret.insert([0xFFu8; 32].into()); for i in 0..ring.ring.len() { ret.insert(ring.ring[i].location.clone()); } ret }