table sync: adapt to new layout history

1 files changed, 72 insertions, 106 deletions

diff --git a/src/table/sync.rs b/src/table/sync.rs
index 4355bd9e..43636faa 100644
--- a/src/table/sync.rs
+++ b/src/table/sync.rs
@@ -6,7 +6,7 @@ use arc_swap::ArcSwapOption;
 use async_trait::async_trait;
 use futures_util::stream::*;
 use opentelemetry::KeyValue;
-use rand::Rng;
+use rand::prelude::*;
 use serde::{Deserialize, Serialize};
 use serde_bytes::ByteBuf;
 use tokio::select;
@@ -52,16 +52,6 @@ impl Rpc for SyncRpc {
 	type Response = Result<SyncRpc, Error>;
 }
 
-#[derive(Debug, Clone)]
-struct TodoPartition {
-	partition: Partition,
-	begin: Hash,
-	end: Hash,
-
-	// Are we a node that stores this partition or not?
-	retain: bool,
-}
-
 impl<F: TableSchema, R: TableReplication> TableSyncer<F, R> {
 	pub(crate) fn new(
 		system: Arc<System>,
@@ -92,9 +82,9 @@ impl<F: TableSchema, R: TableReplication> TableSyncer<F, R> {
 		bg.spawn_worker(SyncWorker {
 			syncer: self.clone(),
 			layout_notify: self.system.layout_notify(),
-			layout_version: self.system.cluster_layout().current().version,
+			layout_versions: self.system.cluster_layout().sync_versions(),
 			add_full_sync_rx,
-			todo: vec![],
+			todo: None,
 			next_full_sync: Instant::now() + Duration::from_secs(20),
 		});
 	}
@@ -112,31 +102,26 @@ impl<F: TableSchema, R: TableReplication> TableSyncer<F, R> {
 
 	async fn sync_partition(
 		self: &Arc<Self>,
-		partition: &TodoPartition,
+		partition: &SyncPartition,
 		must_exit: &mut watch::Receiver<bool>,
 	) -> Result<(), Error> {
-		if partition.retain {
-			let my_id = self.system.id;
-
-			let nodes = self
-				.data
-				.replication
-				.write_nodes(&partition.begin)
-				.into_iter()
-				.filter(|node| *node != my_id)
-				.collect::<Vec<_>>();
+		let my_id = self.system.id;
+		let retain = partition.storage_nodes.contains(&my_id);
 
+		if retain {
 			debug!(
 				"({}) Syncing {:?} with {:?}...",
 				F::TABLE_NAME,
 				partition,
-				nodes
+				partition.storage_nodes
 			);
-			let mut sync_futures = nodes
+			let mut sync_futures = partition
+				.storage_nodes
 				.iter()
+				.filter(|node| **node != my_id)
 				.map(|node| {
 					self.clone()
-						.do_sync_with(partition.clone(), *node, must_exit.clone())
+						.do_sync_with(&partition, *node, must_exit.clone())
 				})
 				.collect::<FuturesUnordered<_>>();
 
@@ -147,14 +132,14 @@ impl<F: TableSchema, R: TableReplication> TableSyncer<F, R> {
 					warn!("({}) Sync error: {}", F::TABLE_NAME, e);
 				}
 			}
-			if n_errors > self.data.replication.max_write_errors() {
+			if n_errors > 0 {
 				return Err(Error::Message(format!(
-					"Sync failed with too many nodes (should have been: {:?}).",
-					nodes
+					"Sync failed with {} nodes.",
+					n_errors
 				)));
 			}
 		} else {
-			self.offload_partition(&partition.begin, &partition.end, must_exit)
+			self.offload_partition(&partition.first_hash, &partition.last_hash, must_exit)
 				.await?;
 		}
 
@@ -285,7 +270,7 @@ impl<F: TableSchema, R: TableReplication> TableSyncer<F, R> {
 
 	async fn do_sync_with(
 		self: Arc<Self>,
-		partition: TodoPartition,
+		partition: &SyncPartition,
 		who: Uuid,
 		must_exit: watch::Receiver<bool>,
 	) -> Result<(), Error> {
@@ -492,76 +477,23 @@ impl<F: TableSchema, R: TableReplication> EndpointHandler<SyncRpc> for TableSync
 
 struct SyncWorker<F: TableSchema, R: TableReplication> {
 	syncer: Arc<TableSyncer<F, R>>,
+
 	layout_notify: Arc<Notify>,
-	layout_version: u64,
+	layout_versions: (u64, u64, u64),
+
 	add_full_sync_rx: mpsc::UnboundedReceiver<()>,
-	todo: Vec<TodoPartition>,
 	next_full_sync: Instant,
+
+	todo: Option<SyncPartitions>,
 }
 
 impl<F: TableSchema, R: TableReplication> SyncWorker<F, R> {
 	fn add_full_sync(&mut self) {
-		let system = &self.syncer.system;
-		let data = &self.syncer.data;
-
-		let my_id = system.id;
-
-		self.todo.clear();
-
-		let partitions = data.replication.partitions();
-
-		for i in 0..partitions.len() {
-			let begin = partitions[i].1;
-
-			let end = if i + 1 < partitions.len() {
-				partitions[i + 1].1
-			} else {
-				[0xFFu8; 32].into()
-			};
-
-			let nodes = data.replication.write_nodes(&begin);
-
-			let retain = nodes.contains(&my_id);
-			if !retain {
-				// Check if we have some data to send, otherwise skip
-				match data.store.range(begin..end) {
-					Ok(mut iter) => {
-						if iter.next().is_none() {
-							continue;
-						}
-					}
-					Err(e) => {
-						warn!("DB error in add_full_sync: {}", e);
-						continue;
-					}
-				}
-			}
-
-			self.todo.push(TodoPartition {
-				partition: partitions[i].0,
-				begin,
-				end,
-				retain,
-			});
-		}
-
+		let mut partitions = self.syncer.data.replication.sync_partitions();
+		partitions.partitions.shuffle(&mut thread_rng());
+		self.todo = Some(partitions);
 		self.next_full_sync = Instant::now() + ANTI_ENTROPY_INTERVAL;
 	}
-
-	fn pop_task(&mut self) -> Option<TodoPartition> {
-		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)
-		}
-	}
 }
 
 #[async_trait]
@@ -572,18 +504,46 @@ impl<F: TableSchema, R: TableReplication> Worker for SyncWorker<F, R> {
 
 	fn status(&self) -> WorkerStatus {
 		WorkerStatus {
-			queue_length: Some(self.todo.len() as u64),
+			queue_length: Some(self.todo.as_ref().map(|x| x.partitions.len()).unwrap_or(0) as u64),
 			..Default::default()
 		}
 	}
 
 	async fn work(&mut self, must_exit: &mut watch::Receiver<bool>) -> Result<WorkerState, Error> {
-		if let Some(partition) = self.pop_task() {
-			self.syncer.sync_partition(&partition, must_exit).await?;
-			Ok(WorkerState::Busy)
-		} else {
-			Ok(WorkerState::Idle)
+		if let Some(todo) = &mut self.todo {
+			let partition = todo.partitions.pop().unwrap();
+
+			// process partition
+			if let Err(e) = self.syncer.sync_partition(&partition, must_exit).await {
+				error!(
+					"{}: Failed to sync partition {:?}: {}",
+					F::TABLE_NAME,
+					partition,
+					e
+				);
+				// if error, put partition back at the other side of the queue,
+				// so that other partitions will be tried in the meantime
+				todo.partitions.insert(0, partition);
+				// TODO: returning an error here will cause the background job worker
+				// to delay this task for some time, but maybe we don't want to
+				// delay it if there are lots of failures from nodes that are gone
+				// (we also don't want zero delays as that will cause lots of useless retries)
+				return Err(e);
+			}
+
+			// done
+			if !todo.partitions.is_empty() {
+				return Ok(WorkerState::Busy);
+			}
+
+			self.syncer
+				.system
+				.layout_manager
+				.sync_table_until(F::TABLE_NAME, todo.layout_version);
 		}
+
+		self.todo = None;
+		Ok(WorkerState::Idle)
 	}
 
 	async fn wait_for_work(&mut self) -> WorkerState {
@@ -594,10 +554,16 @@ impl<F: TableSchema, R: TableReplication> Worker for SyncWorker<F, R> {
 				}
 			},
 			_ = self.layout_notify.notified() => {
-				let new_version = self.syncer.system.cluster_layout().current().version;
-				if new_version > self.layout_version {
-					self.layout_version = new_version;
-					debug!("({}) Layout changed, adding full sync to syncer todo list", F::TABLE_NAME);
+				let layout_versions = self.syncer.system.cluster_layout().sync_versions();
+				if layout_versions != self.layout_versions {
+					self.layout_versions = layout_versions;
+					debug!(
+						"({}) Layout versions changed (max={}, ack={}, min stored={}), adding full sync to syncer todo list",
+						F::TABLE_NAME,
+						layout_versions.0,
+						layout_versions.1,
+						layout_versions.2
+					);
 					self.add_full_sync();
 				}
 			},
@@ -605,9 +571,9 @@ impl<F: TableSchema, R: TableReplication> Worker for SyncWorker<F, R> {
 				self.add_full_sync();
 			}
 		}
-		match self.todo.is_empty() {
-			false => WorkerState::Busy,
-			true => WorkerState::Idle,
+		match self.todo.is_some() {
+			true => WorkerState::Busy,
+			false => WorkerState::Idle,
 		}
 	}
 }