garage/src/table_sync.rs
Alex Auvolat db1c4222ce Don't send items...
...if syncer doesn't need them because he's going to delete the partition anyway.
Also, fix block resync queue
2020-04-17 18:51:29 +02:00

675 lines
17 KiB
Rust

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<F: TableSchema> {
pub table: Arc<Table<F>>,
pub todo: Mutex<SyncTodo>,
pub cache: Vec<Mutex<BTreeMap<SyncRange, RangeChecksum>>>,
}
#[derive(Serialize, Deserialize)]
pub enum SyncRPC {
Checksums(Vec<RangeChecksum>, bool),
Difference(Vec<SyncRange>, Vec<Arc<ByteBuf>>),
}
pub struct SyncTodo {
pub todo: Vec<Partition>,
}
#[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<u8>,
pub end: Vec<u8>,
pub 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)
}
}
#[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,
}
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),
cache: (0..MAX_DEPTH)
.map(|_| Mutex::new(BTreeMap::new()))
.collect::<Vec<_>>(),
});
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> {
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<Ring> = self.table.system.ring.borrow().clone();
let mut ring_recv: watch::Receiver<Arc<Ring>> = 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<Self>,
mut must_exit: watch::Receiver<bool>,
) -> 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<Self>,
partition: &Partition,
must_exit: &mut watch::Receiver<bool>,
) -> Result<(), Error> {
eprintln!("({}) Preparing to sync {:?}...", self.table.name, partition);
let root_cks = self
.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(),
partition.retain,
must_exit.clone(),
)
})
.collect::<FuturesUnordered<_>>();
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<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,
)
.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());
}
}
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<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;
}
}
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<Self>,
root_ck: RangeChecksum,
who: UUID,
retain: bool,
mut must_exit: watch::Receiver<bool>,
) -> 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::<Vec<_>>();
let rpc_resp = self
.table
.rpc_call(
&who,
&TableRPC::<F>::SyncRPC(SyncRPC::Checksums(step, retain)),
)
.await?;
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_to_send.push(differing.begin);
} else {
let checksum = self.range_checksum(&differing, &mut must_exit).await?;
todo.push_back(checksum);
}
}
if retain && 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_to_send));
}
} else {
return Err(Error::Message(format!(
"Unexpected response to sync RPC checksums: {}",
debug_serialize(&rpc_resp)
)));
}
}
Ok(())
}
async fn send_items(self: Arc<Self>, who: UUID, item_list: Vec<Vec<u8>>) -> 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::<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)
)))
}
}
pub async fn handle_rpc(
self: &Arc<Self>,
message: &SyncRPC,
mut must_exit: watch::Receiver<bool>,
) -> Result<SyncRPC, Error> {
if let SyncRPC::Checksums(checksums, retain) = message {
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() {
// 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(_) => true,
Ok(i) => our_ckr.children[i].1 != *hash,
};
if differs {
ret_ranges.push(range.clone());
if *retain && 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())));
}
}
}
}
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 {
if range.level > 0 {
ret_ranges.push(range.clone());
}
if *retain && 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())));
}
}
}
}
}
let n_checksums = checksums
.iter()
.map(|x| x.children.len())
.fold(0, |x, y| x + y);
eprintln!(
"({}) Checksum comparison RPC: {} different + {} items for {} received",
self.table.name,
ret_ranges.len(),
ret_items.len(),
n_checksums
);
return Ok(SyncRPC::Difference(ret_ranges, ret_items));
}
Err(Error::Message(format!("Unexpected sync RPC")))
}
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(())
}
}
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();
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<F: TableSchema>(
&mut self,
table: &Table<F>,
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<F: TableSchema>(&mut self, table: &Table<F>, 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::<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;
}
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
}