diff options
Diffstat (limited to 'src/table/table_sync.rs')
-rw-r--r-- | src/table/table_sync.rs | 898 |
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) - } - } -} |