garage/src/table_sync.rs

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Rust
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use rand::Rng;
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use std::collections::{BTreeSet, BTreeMap, VecDeque};
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use std::sync::Arc;
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use std::time::{Duration, Instant};
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use futures::{pin_mut, select};
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use futures::future::BoxFuture;
use futures_util::stream::*;
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use futures_util::future::*;
use tokio::sync::watch;
use tokio::sync::Mutex;
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use serde::{Serialize, Deserialize};
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use serde_bytes::ByteBuf;
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use crate::data::*;
use crate::error::Error;
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use crate::membership::Ring;
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use crate::table::*;
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const MAX_DEPTH: usize = 16;
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const SCAN_INTERVAL: Duration = Duration::from_secs(3600);
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const CHECKSUM_CACHE_TIMEOUT: Duration = Duration::from_secs(1800);
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pub struct TableSyncer<F: TableSchema> {
pub table: Arc<Table<F>>,
pub todo: Mutex<SyncTodo>,
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pub cache: Vec<Mutex<BTreeMap<SyncRange, RangeChecksum>>>,
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}
pub struct SyncTodo {
pub todo: Vec<Partition>,
}
#[derive(Debug, Clone)]
pub struct Partition {
pub begin: Hash,
pub end: Hash,
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pub retain: bool,
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}
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#[derive(Hash, PartialEq, Eq, Debug, Clone, Serialize, Deserialize)]
pub struct SyncRange {
pub begin: Vec<u8>,
pub end: Vec<u8>,
pub level: usize,
}
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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)
}
}
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#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RangeChecksum {
pub bounds: SyncRange,
pub children: Vec<(SyncRange, Hash)>,
pub found_limit: Option<Vec<u8>>,
#[serde(skip, default="std::time::Instant::now")]
pub time: Instant,
}
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impl<F: TableSchema + 'static> TableSyncer<F> {
pub async fn launch(table: Arc<Table<F>>) -> Arc<Self> {
let todo = SyncTodo { todo: Vec::new() };
let syncer = Arc::new(TableSyncer {
table: table.clone(),
todo: Mutex::new(todo),
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cache: (0..MAX_DEPTH).map(|_| Mutex::new(BTreeMap::new())).collect::<Vec<_>>(),
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});
let s1 = syncer.clone();
table
.system
.background
.spawn_worker(move |must_exit: watch::Receiver<bool>| s1.watcher_task(must_exit))
.await;
let s2 = syncer.clone();
table
.system
.background
.spawn_worker(move |must_exit: watch::Receiver<bool>| s2.syncer_task(must_exit))
.await;
syncer
}
async fn watcher_task(
self: Arc<Self>,
mut must_exit: watch::Receiver<bool>,
) -> Result<(), Error> {
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tokio::time::delay_for(Duration::from_secs(10)).await;
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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<Ring> = self.table.system.ring.borrow().clone();
let mut ring_recv: watch::Receiver<Arc<Ring>> = self.table.system.ring.clone();
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while !*must_exit.borrow() {
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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();
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eprintln!("({}) Adding full scan to syncer todo list", self.table.name);
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self.todo.lock().await.add_full_scan(&self.table);
}
new_ring_r = s_ring_recv => {
if let Some(new_ring) = new_ring_r {
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eprintln!("({}) Adding ring difference to syncer todo list", self.table.name);
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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) {
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break;
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}
}
}
}
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Ok(())
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}
async fn syncer_task(
self: Arc<Self>,
mut must_exit: watch::Receiver<bool>,
) -> Result<(), Error> {
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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 {
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eprintln!("({}) Error while syncing {:?}: {}", self.table.name, partition, e);
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}
} else {
tokio::time::delay_for(Duration::from_secs(1)).await;
}
}
Ok(())
}
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async fn sync_partition(self: Arc<Self>, partition: &Partition, must_exit: &mut watch::Receiver<bool>) -> Result<(), Error> {
eprintln!("({}) Preparing to sync {:?}...", self.table.name, partition);
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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::<FuturesUnordered<_>>();
while let Some(r) = sync_futures.next().await {
if let Err(e) = r {
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eprintln!("({}) Sync error: {}", self.table.name, e);
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}
}
if !partition.retain {
self.table.delete_range(&partition.begin, &partition.end).await?;
}
Ok(())
}
async fn root_checksum(self: &Arc<Self>, begin: &Hash, end: &Hash, must_exit: &mut watch::Receiver<bool>) -> Result<RangeChecksum, Error> {
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for i in 1..MAX_DEPTH {
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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<Self>, range: &'a SyncRange, must_exit: &'a mut watch::Receiver<bool>) -> BoxFuture<'a, Result<RangeChecksum, Error>> {
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());
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}
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}
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());
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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<Self>, range: &SyncRange, must_exit: &mut watch::Receiver<bool>) -> Result<RangeChecksum, Error> {
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;
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}
}
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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;
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}
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Err(Error::Message(format!("Exiting.")))
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}
}
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async fn do_sync_with(self: Arc<Self>, root_ck: RangeChecksum, who: UUID, mut must_exit: watch::Receiver<bool>) -> Result<(), Error> {
let mut todo = VecDeque::new();
todo.push_back(root_ck);
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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);
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let end = std::cmp::min(16, todo.len());
let step = todo.drain(..end).collect::<Vec<_>>();
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let rpc_resp = self.table.rpc_call(&who, &TableRPC::<F>::SyncChecksums(step)).await?;
if let TableRPC::<F>::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))));
}
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}
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Ok(())
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}
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async fn send_items(self: Arc<Self>, who: UUID, item_list: Vec<Vec<u8>>) -> Result<(), Error> {
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eprintln!("({}) Sending {} items to {:?}", self.table.name, item_list.len(), who);
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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::<F>::Update(values)).await?;
if let TableRPC::<F>::Ok = rpc_resp {
Ok(())
} else {
Err(Error::Message(format!("Unexpected response to RPC Update: {}", debug_serialize(&rpc_resp))))
}
}
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pub async fn handle_checksum_rpc(self: &Arc<Self>, checksums: &[RangeChecksum], mut must_exit: watch::Receiver<bool>) -> Result<Vec<SyncRange>, 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());
}
}
}
}
}
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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);
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Ok(ret)
}
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pub async fn invalidate(self: Arc<Self>, item_key: Vec<u8>) -> 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(())
}
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}
impl SyncTodo {
fn add_full_scan<F: TableSchema>(&mut self, table: &Table<F>) {
let my_id = table.system.id.clone();
self.todo.clear();
let ring: Arc<Ring> = table.system.ring.borrow().clone();
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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();
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if i == 0 {
self.add_full_scan_aux(table, [0u8; 32].into(), begin.clone(), &nodes[..], &my_id);
}
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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<F: TableSchema>(
&mut self,
table: &Table<F>,
begin: Hash,
end: Hash,
nodes: &[UUID],
my_id: &UUID,
) {
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let retain = nodes.contains(my_id);
if !retain {
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// Check if we have some data to send, otherwise skip
if table
.store
.range(begin.clone()..end.clone())
.next()
.is_none()
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{
return;
}
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}
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self.todo.push(Partition { begin, end, retain });
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}
fn add_ring_difference<F: TableSchema>(&mut self, table: &Table<F>, old: &Ring, new: &Ring) {
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let my_id = table.system.id.clone();
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let old_ring = ring_points(old);
let new_ring = ring_points(new);
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let both_ring = old_ring.union(&new_ring).cloned().collect::<BTreeSet<_>>();
let prev_todo_begin = self
.todo
.iter()
.map(|x| x.begin.clone())
.collect::<BTreeSet<_>>();
let prev_todo_end = self
.todo
.iter()
.map(|x| x.end.clone())
.collect::<BTreeSet<_>>();
let prev_todo = prev_todo_begin
.union(&prev_todo_end)
.cloned()
.collect::<BTreeSet<_>>();
let all_points = both_ring.union(&prev_todo).cloned().collect::<Vec<_>>();
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;
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}
fn pop_task(&mut self) -> Option<Partition> {
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)
}
}
}
fn ring_points(ring: &Ring) -> BTreeSet<Hash> {
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
}