1 files changed, 381 insertions, 0 deletions
diff --git a/src/rpc/layout/manager.rs b/src/rpc/layout/manager.rs
new file mode 100644
index 00000000..a0dcf50e
--- /dev/null
+++ b/src/rpc/layout/manager.rs
@@ -0,0 +1,381 @@
+use std::collections::HashMap;
+use std::sync::{atomic::Ordering, Arc, Mutex, RwLock, RwLockReadGuard};
+use std::time::Duration;
+
+use tokio::sync::Notify;
+
+use garage_net::endpoint::Endpoint;
+use garage_net::peering::PeeringManager;
+use garage_net::NodeID;
+
+use garage_util::config::Config;
+use garage_util::data::*;
+use garage_util::error::*;
+use garage_util::persister::Persister;
+
+use super::*;
+use crate::replication_mode::*;
+use crate::rpc_helper::*;
+use crate::system::*;
+
+pub struct LayoutManager {
+	node_id: Uuid,
+	replication_factor: ReplicationFactor,
+	persist_cluster_layout: Persister<LayoutHistory>,
+
+	layout: Arc<RwLock<LayoutHelper>>,
+	pub(crate) change_notify: Arc<Notify>,
+
+	table_sync_version: Mutex<HashMap<String, u64>>,
+
+	pub(crate) rpc_helper: RpcHelper,
+	system_endpoint: Arc<Endpoint<SystemRpc, System>>,
+}
+
+impl LayoutManager {
+	pub fn new(
+		config: &Config,
+		node_id: NodeID,
+		system_endpoint: Arc<Endpoint<SystemRpc, System>>,
+		peering: Arc<PeeringManager>,
+		replication_factor: ReplicationFactor,
+		consistency_mode: ConsistencyMode,
+	) -> Result<Arc<Self>, Error> {
+		let persist_cluster_layout: Persister<LayoutHistory> =
+			Persister::new(&config.metadata_dir, "cluster_layout");
+
+		let cluster_layout = match persist_cluster_layout.load() {
+			Ok(x) => {
+				if x.current().replication_factor != replication_factor.replication_factor() {
+					return Err(Error::Message(format!(
+						"Prevous cluster layout has replication factor {}, which is different than the one specified in the config file ({}). The previous cluster layout can be purged, if you know what you are doing, simply by deleting the `cluster_layout` file in your metadata directory.",
+						x.current().replication_factor,
+						replication_factor.replication_factor()
+					)));
+				}
+				x
+			}
+			Err(e) => {
+				info!(
+					"No valid previous cluster layout stored ({}), starting fresh.",
+					e
+				);
+				LayoutHistory::new(replication_factor)
+			}
+		};
+
+		let mut cluster_layout = LayoutHelper::new(
+			replication_factor,
+			consistency_mode,
+			cluster_layout,
+			Default::default(),
+		);
+		cluster_layout.update_update_trackers(node_id.into());
+
+		let layout = Arc::new(RwLock::new(cluster_layout));
+		let change_notify = Arc::new(Notify::new());
+
+		let rpc_helper = RpcHelper::new(
+			node_id.into(),
+			peering,
+			layout.clone(),
+			config.rpc_timeout_msec.map(Duration::from_millis),
+		);
+
+		Ok(Arc::new(Self {
+			node_id: node_id.into(),
+			replication_factor,
+			persist_cluster_layout,
+			layout,
+			change_notify,
+			table_sync_version: Mutex::new(HashMap::new()),
+			system_endpoint,
+			rpc_helper,
+		}))
+	}
+
+	// ---- PUBLIC INTERFACE ----
+
+	pub fn layout(&self) -> RwLockReadGuard<'_, LayoutHelper> {
+		self.layout.read().unwrap()
+	}
+
+	pub async fn update_cluster_layout(
+		self: &Arc<Self>,
+		layout: &LayoutHistory,
+	) -> Result<(), Error> {
+		self.handle_advertise_cluster_layout(layout).await?;
+		Ok(())
+	}
+
+	pub fn add_table(&self, table_name: &'static str) {
+		let first_version = self.layout().versions().first().unwrap().version;
+
+		self.table_sync_version
+			.lock()
+			.unwrap()
+			.insert(table_name.to_string(), first_version);
+	}
+
+	pub fn sync_table_until(self: &Arc<Self>, table_name: &'static str, version: u64) {
+		let mut table_sync_version = self.table_sync_version.lock().unwrap();
+		*table_sync_version.get_mut(table_name).unwrap() = version;
+		let sync_until = table_sync_version.iter().map(|(_, v)| *v).min().unwrap();
+		drop(table_sync_version);
+
+		let mut layout = self.layout.write().unwrap();
+		if layout.update(|l| l.update_trackers.sync_map.set_max(self.node_id, sync_until)) {
+			info!("sync_until updated to {}", sync_until);
+			self.broadcast_update(SystemRpc::AdvertiseClusterLayoutTrackers(
+				layout.inner().update_trackers.clone(),
+			));
+		}
+	}
+
+	fn ack_new_version(self: &Arc<Self>) {
+		let mut layout = self.layout.write().unwrap();
+		if layout.update_ack_to_max_free(self.node_id) {
+			self.broadcast_update(SystemRpc::AdvertiseClusterLayoutTrackers(
+				layout.inner().update_trackers.clone(),
+			));
+		}
+	}
+
+	// ---- ACK LOCKING ----
+
+	pub fn write_sets_of(self: &Arc<Self>, position: &Hash) -> WriteLock<Vec<Vec<Uuid>>> {
+		let layout = self.layout();
+		let version = layout.current().version;
+		let nodes = layout.storage_sets_of(position);
+		layout
+			.ack_lock
+			.get(&version)
+			.unwrap()
+			.fetch_add(1, Ordering::Relaxed);
+		WriteLock::new(version, self, nodes)
+	}
+
+	// ---- INTERNALS ---
+
+	fn merge_layout(&self, adv: &LayoutHistory) -> Option<LayoutHistory> {
+		let mut layout = self.layout.write().unwrap();
+		let prev_digest = layout.digest();
+		let prev_layout_check = layout.is_check_ok();
+
+		if !prev_layout_check || adv.check().is_ok() {
+			if layout.update(|l| l.merge(adv)) {
+				layout.update_update_trackers(self.node_id);
+				if prev_layout_check && !layout.is_check_ok() {
+					panic!("Merged two correct layouts and got an incorrect layout.");
+				}
+				assert!(layout.digest() != prev_digest);
+				return Some(layout.inner().clone());
+			}
+		}
+
+		None
+	}
+
+	fn merge_layout_trackers(&self, adv: &UpdateTrackers) -> Option<UpdateTrackers> {
+		let mut layout = self.layout.write().unwrap();
+		let prev_digest = layout.digest();
+
+		if layout.inner().update_trackers != *adv {
+			if layout.update(|l| l.update_trackers.merge(adv)) {
+				layout.update_update_trackers(self.node_id);
+				assert!(layout.digest() != prev_digest);
+				return Some(layout.inner().update_trackers.clone());
+			}
+		}
+
+		None
+	}
+
+	async fn pull_cluster_layout(self: &Arc<Self>, peer: Uuid) {
+		let resp = self
+			.rpc_helper
+			.call(
+				&self.system_endpoint,
+				peer,
+				SystemRpc::PullClusterLayout,
+				RequestStrategy::with_priority(PRIO_HIGH),
+			)
+			.await;
+		if let Ok(SystemRpc::AdvertiseClusterLayout(layout)) = resp {
+			if let Err(e) = self.handle_advertise_cluster_layout(&layout).await {
+				warn!("In pull_cluster_layout: {}", e);
+			}
+		}
+	}
+
+	async fn pull_cluster_layout_trackers(self: &Arc<Self>, peer: Uuid) {
+		let resp = self
+			.rpc_helper
+			.call(
+				&self.system_endpoint,
+				peer,
+				SystemRpc::PullClusterLayoutTrackers,
+				RequestStrategy::with_priority(PRIO_HIGH),
+			)
+			.await;
+		if let Ok(SystemRpc::AdvertiseClusterLayoutTrackers(trackers)) = resp {
+			if let Err(e) = self
+				.handle_advertise_cluster_layout_trackers(&trackers)
+				.await
+			{
+				warn!("In pull_cluster_layout_trackers: {}", e);
+			}
+		}
+	}
+
+	/// Save cluster layout data to disk
+	async fn save_cluster_layout(&self) -> Result<(), Error> {
+		let layout = self.layout.read().unwrap().inner().clone();
+		self.persist_cluster_layout
+			.save_async(&layout)
+			.await
+			.expect("Cannot save current cluster layout");
+		Ok(())
+	}
+
+	fn broadcast_update(self: &Arc<Self>, rpc: SystemRpc) {
+		tokio::spawn({
+			let this = self.clone();
+			async move {
+				if let Err(e) = this
+					.rpc_helper
+					.broadcast(
+						&this.system_endpoint,
+						rpc,
+						RequestStrategy::with_priority(PRIO_HIGH),
+					)
+					.await
+				{
+					warn!("Error while broadcasting new cluster layout: {}", e);
+				}
+			}
+		});
+	}
+
+	// ---- RPC HANDLERS ----
+
+	pub(crate) fn handle_advertise_status(self: &Arc<Self>, from: Uuid, remote: &RpcLayoutDigest) {
+		let local = self.layout().digest();
+		if remote.current_version > local.current_version
+			|| remote.active_versions != local.active_versions
+			|| remote.staging_hash != local.staging_hash
+		{
+			tokio::spawn({
+				let this = self.clone();
+				async move { this.pull_cluster_layout(from).await }
+			});
+		} else if remote.trackers_hash != local.trackers_hash {
+			tokio::spawn({
+				let this = self.clone();
+				async move { this.pull_cluster_layout_trackers(from).await }
+			});
+		}
+	}
+
+	pub(crate) fn handle_pull_cluster_layout(&self) -> SystemRpc {
+		let layout = self.layout.read().unwrap().inner().clone();
+		SystemRpc::AdvertiseClusterLayout(layout)
+	}
+
+	pub(crate) fn handle_pull_cluster_layout_trackers(&self) -> SystemRpc {
+		let layout = self.layout.read().unwrap();
+		SystemRpc::AdvertiseClusterLayoutTrackers(layout.inner().update_trackers.clone())
+	}
+
+	pub(crate) async fn handle_advertise_cluster_layout(
+		self: &Arc<Self>,
+		adv: &LayoutHistory,
+	) -> Result<SystemRpc, Error> {
+		debug!(
+			"handle_advertise_cluster_layout: {} versions, last={}, trackers={:?}",
+			adv.versions.len(),
+			adv.current().version,
+			adv.update_trackers
+		);
+
+		if adv.current().replication_factor != self.replication_factor.replication_factor() {
+			let msg = format!(
+				"Received a cluster layout from another node with replication factor {}, which is different from what we have in our configuration ({}). Discarding the cluster layout we received.",
+				adv.current().replication_factor,
+				self.replication_factor.replication_factor()
+			);
+			error!("{}", msg);
+			return Err(Error::Message(msg));
+		}
+
+		if let Some(new_layout) = self.merge_layout(adv) {
+			debug!("handle_advertise_cluster_layout: some changes were added to the current stuff");
+
+			self.change_notify.notify_waiters();
+			self.broadcast_update(SystemRpc::AdvertiseClusterLayout(new_layout));
+			self.save_cluster_layout().await?;
+		}
+
+		Ok(SystemRpc::Ok)
+	}
+
+	pub(crate) async fn handle_advertise_cluster_layout_trackers(
+		self: &Arc<Self>,
+		trackers: &UpdateTrackers,
+	) -> Result<SystemRpc, Error> {
+		debug!("handle_advertise_cluster_layout_trackers: {:?}", trackers);
+
+		if let Some(new_trackers) = self.merge_layout_trackers(trackers) {
+			self.change_notify.notify_waiters();
+			self.broadcast_update(SystemRpc::AdvertiseClusterLayoutTrackers(new_trackers));
+			self.save_cluster_layout().await?;
+		}
+
+		Ok(SystemRpc::Ok)
+	}
+}
+
+// ---- ack lock ----
+
+pub struct WriteLock<T> {
+	layout_version: u64,
+	layout_manager: Arc<LayoutManager>,
+	value: T,
+}
+
+impl<T> WriteLock<T> {
+	fn new(version: u64, layout_manager: &Arc<LayoutManager>, value: T) -> Self {
+		Self {
+			layout_version: version,
+			layout_manager: layout_manager.clone(),
+			value,
+		}
+	}
+}
+
+impl<T> AsRef<T> for WriteLock<T> {
+	fn as_ref(&self) -> &T {
+		&self.value
+	}
+}
+
+impl<T> AsMut<T> for WriteLock<T> {
+	fn as_mut(&mut self) -> &mut T {
+		&mut self.value
+	}
+}
+
+impl<T> Drop for WriteLock<T> {
+	fn drop(&mut self) {
+		let layout = self.layout_manager.layout(); // acquire read lock
+		if let Some(counter) = layout.ack_lock.get(&self.layout_version) {
+			let prev_lock = counter.fetch_sub(1, Ordering::Relaxed);
+			if prev_lock == 1 && layout.current().version > self.layout_version {
+				drop(layout); // release read lock, write lock will be acquired
+				self.layout_manager.ack_new_version();
+			}
+		} else {
+			error!("Could not find ack lock counter for layout version {}. This probably indicates a bug in Garage.", self.layout_version);
+		}
+	}
+}