Begin work on sync...

src/table_sync.rs

@@ -0,0 +1,204 @@
+use rand::Rng;
+use std::sync::Arc;
+use std::time::Duration;
+use std::collections::BTreeSet;
+
+use futures::{pin_mut, select};
+use futures_util::future::*;
+use tokio::sync::watch;
+use tokio::sync::Mutex;
+
+use crate::data::*;
+use crate::error::Error;
+use crate::membership::{Ring, System};
+use crate::table::*;
+
+const SCAN_INTERVAL: Duration = Duration::from_secs(3600);
+
+pub struct TableSyncer<F: TableSchema> {
+	pub table: Arc<Table<F>>,
+
+	pub todo: Mutex<SyncTodo>,
+}
+
+pub struct SyncTodo {
+	pub todo: Vec<Partition>,
+}
+
+#[derive(Debug, Clone)]
+pub struct Partition {
+	pub begin: Hash,
+	pub end: Hash,
+}
+
+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),
+		});
+
+		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> {
+		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();
+
+		loop {
+			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();
+					self.todo.lock().await.add_full_scan(&self.table);
+				}
+				new_ring_r = s_ring_recv => {
+					if let Some(new_ring) = new_ring_r {
+						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) {
+						return Ok(())
+					}
+				}
+			}
+		}
+	}
+
+	async fn syncer_task(
+		self: Arc<Self>,
+		mut must_exit: watch::Receiver<bool>,
+	) -> Result<(), Error> {
+		loop {
+			let s_pop_task = self.pop_task().fuse();
+			let s_must_exit = must_exit.recv().fuse();
+			pin_mut!(s_must_exit, s_pop_task);
+
+			select! {
+				task = s_pop_task => {
+					if let Some(partition) = task {
+						let res = self.sync_partition(&partition).await;
+						if let Err(e) = res {
+							eprintln!("Error while syncing {:?}: {}", partition, e);
+						}
+					} else {
+						tokio::time::delay_for(Duration::from_secs(1)).await;
+					}
+				}
+				must_exit_v = s_must_exit => {
+					if must_exit_v.unwrap_or(false) {
+						return Ok(())
+					}
+				}
+			}
+		}
+	}
+
+	async fn pop_task(&self) -> Option<Partition> {
+		self.todo.lock().await.pop_task()
+	}
+
+	async fn sync_partition(self: &Arc<Self>, partition: &Partition) -> Result<(), Error> {
+		unimplemented!()
+	}
+}
+
+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 == ring.ring.len() - 1 {
+				let end = ring.ring[0].location.clone();
+				self.add_full_scan_aux(table, begin, [0xffu8; 32].into(), &nodes[..], &my_id);
+				self.add_full_scan_aux(table, [0u8; 32].into(), end, &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,
+	) {
+		if !nodes.contains(my_id) {
+			// Check if we have some data to send, otherwise skip
+			if table
+				.store
+				.range(begin.clone()..end.clone())
+				.next()
+				.is_none()
+			{}
+		}
+
+		self.todo.push(Partition { begin, end });
+	}
+
+	fn add_ring_difference<F: TableSchema>(&mut self, table: &Table<F>, old: &Ring, new: &Ring) {
+		let old_ring = ring_points(old);
+		let new_ring = ring_points(new);
+		unimplemented!()
+	}
+
+	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
+}