remove Ring and use ClusterLayout everywhere

5 files changed, 100 insertions, 206 deletions

diff --git a/src/rpc/layout.rs b/src/rpc/layout.rs
index 368a9d2c..2b5b6606 100644
--- a/src/rpc/layout.rs
+++ b/src/rpc/layout.rs
@@ -13,17 +13,39 @@ use garage_util::error::*;
 
 use crate::graph_algo::*;
 
-use crate::ring::*;
-
 use std::convert::TryInto;
 
+// ---- defines: partitions ----
+
+/// A partition id, which is stored on 16 bits
+/// i.e. we have up to 2**16 partitions.
+/// (in practice we have exactly 2**PARTITION_BITS partitions)
+pub type Partition = u16;
+
+// TODO: make this constant parametrizable in the config file
+// For deployments with many nodes it might make sense to bump
+// it up to 10.
+// Maximum value : 16
+/// How many bits from the hash are used to make partitions. Higher numbers means more fairness in
+/// presence of numerous nodes, but exponentially bigger ring. Max 16
+pub const PARTITION_BITS: usize = 8;
+
 const NB_PARTITIONS: usize = 1usize << PARTITION_BITS;
 
+// ---- defines: nodes ----
+
+// Type to store compactly the id of a node in the system
+// Change this to u16 the day we want to have more than 256 nodes in a cluster
+pub type CompactNodeType = u8;
+pub const MAX_NODE_NUMBER: usize = 256;
+
+// ---- defines: other ----
+
 // The Message type will be used to collect information on the algorithm.
-type Message = Vec<String>;
+pub type Message = Vec<String>;
 
 mod v08 {
-	use crate::ring::CompactNodeType;
+	use super::CompactNodeType;
 	use garage_util::crdt::LwwMap;
 	use garage_util::data::{Hash, Uuid};
 	use serde::{Deserialize, Serialize};
@@ -76,7 +98,7 @@ mod v08 {
 
 mod v09 {
 	use super::v08;
-	use crate::ring::CompactNodeType;
+	use super::CompactNodeType;
 	use garage_util::crdt::{Lww, LwwMap};
 	use garage_util::data::{Hash, Uuid};
 	use serde::{Deserialize, Serialize};
@@ -334,6 +356,46 @@ impl ClusterLayout {
 		))
 	}
 
+	/// Get the partition in which data would fall on
+	pub fn partition_of(&self, position: &Hash) -> Partition {
+		let top = u16::from_be_bytes(position.as_slice()[0..2].try_into().unwrap());
+		top >> (16 - PARTITION_BITS)
+	}
+
+	/// Get the list of partitions and the first hash of a partition key that would fall in it
+	pub fn partitions(&self) -> Vec<(Partition, Hash)> {
+		(0..(1 << PARTITION_BITS))
+			.map(|i| {
+				let top = (i as u16) << (16 - PARTITION_BITS);
+				let mut location = [0u8; 32];
+				location[..2].copy_from_slice(&u16::to_be_bytes(top)[..]);
+				(i as u16, Hash::from(location))
+			})
+			.collect::<Vec<_>>()
+	}
+
+	/// Walk the ring to find the n servers in which data should be replicated
+	pub fn nodes_of(&self, position: &Hash, n: usize) -> Vec<Uuid> {
+		assert_eq!(n, self.replication_factor);
+
+		let data = &self.ring_assignment_data;
+
+		if data.len() != self.replication_factor * (1 << PARTITION_BITS) {
+			warn!("Ring not yet ready, read/writes will be lost!");
+			return vec![];
+		}
+
+		let partition_idx = self.partition_of(position) as usize;
+		let partition_start = partition_idx * self.replication_factor;
+		let partition_end = (partition_idx + 1) * self.replication_factor;
+		let partition_nodes = &data[partition_start..partition_end];
+
+		partition_nodes
+			.iter()
+			.map(|i| self.node_id_vec[*i as usize])
+			.collect::<Vec<_>>()
+	}
+
 	// ===================== internal information extractors ======================
 
 	/// Returns the uuids of the non_gateway nodes in self.node_id_vec.
diff --git a/src/rpc/lib.rs b/src/rpc/lib.rs
index a5f8fc6e..1af8b78e 100644
--- a/src/rpc/lib.rs
+++ b/src/rpc/lib.rs
@@ -14,7 +14,6 @@ mod kubernetes;
 pub mod graph_algo;
 pub mod layout;
 pub mod replication_mode;
-pub mod ring;
 pub mod system;
 
 pub mod rpc_helper;
diff --git a/src/rpc/ring.rs b/src/rpc/ring.rs
deleted file mode 100644
index 6a2e5c72..00000000
--- a/src/rpc/ring.rs
+++ /dev/null
@@ -1,164 +0,0 @@
-//! Module containing types related to computing nodes which should receive a copy of data blocks
-//! and metadata
-use std::convert::TryInto;
-
-use garage_util::data::*;
-
-use crate::layout::ClusterLayout;
-
-/// A partition id, which is stored on 16 bits
-/// i.e. we have up to 2**16 partitions.
-/// (in practice we have exactly 2**PARTITION_BITS partitions)
-pub type Partition = u16;
-
-// TODO: make this constant parametrizable in the config file
-// For deployments with many nodes it might make sense to bump
-// it up to 10.
-// Maximum value : 16
-/// How many bits from the hash are used to make partitions. Higher numbers means more fairness in
-/// presence of numerous nodes, but exponentially bigger ring. Max 16
-pub const PARTITION_BITS: usize = 8;
-
-const PARTITION_MASK_U16: u16 = ((1 << PARTITION_BITS) - 1) << (16 - PARTITION_BITS);
-
-/// A ring distributing fairly objects to nodes
-#[derive(Clone)]
-pub struct Ring {
-	/// The replication factor for this ring
-	pub replication_factor: usize,
-
-	/// The network configuration used to generate this ring
-	pub layout: ClusterLayout,
-
-	// Internal order of nodes used to make a more compact representation of the ring
-	nodes: Vec<Uuid>,
-
-	// The list of entries in the ring
-	ring: Vec<RingEntry>,
-}
-
-// Type to store compactly the id of a node in the system
-// Change this to u16 the day we want to have more than 256 nodes in a cluster
-pub type CompactNodeType = u8;
-pub const MAX_NODE_NUMBER: usize = 256;
-
-// The maximum number of times an object might get replicated
-// This must be at least 3 because Garage supports 3-way replication
-// Here we use 6 so that the size of a ring entry is 8 bytes
-// (2 bytes partition id, 6 bytes node numbers as u8s)
-const MAX_REPLICATION: usize = 6;
-
-/// An entry in the ring
-#[derive(Clone, Debug)]
-struct RingEntry {
-	// The two first bytes of the first hash that goes in this partition
-	// (the next bytes are zeroes)
-	hash_prefix: u16,
-	// The nodes that store this partition, stored as a list of positions in the `nodes`
-	// field of the Ring structure
-	// Only items 0 up to ring.replication_factor - 1 are used, others are zeros
-	nodes_buf: [CompactNodeType; MAX_REPLICATION],
-}
-
-impl Ring {
-	pub(crate) fn new(layout: ClusterLayout, replication_factor: usize) -> Self {
-		if replication_factor != layout.replication_factor {
-			warn!("Could not build ring: replication factor does not match between local configuration and network role assignment.");
-			return Self::empty(layout, replication_factor);
-		}
-
-		if layout.ring_assignment_data.len() != replication_factor * (1 << PARTITION_BITS) {
-			warn!("Could not build ring: network role assignment data has invalid length");
-			return Self::empty(layout, replication_factor);
-		}
-
-		let nodes = layout.node_id_vec.clone();
-		let ring = (0..(1 << PARTITION_BITS))
-			.map(|i| {
-				let top = (i as u16) << (16 - PARTITION_BITS);
-				let mut nodes_buf = [0u8; MAX_REPLICATION];
-				nodes_buf[..replication_factor].copy_from_slice(
-					&layout.ring_assignment_data
-						[replication_factor * i..replication_factor * (i + 1)],
-				);
-				RingEntry {
-					hash_prefix: top,
-					nodes_buf,
-				}
-			})
-			.collect::<Vec<_>>();
-
-		Self {
-			replication_factor,
-			layout,
-			nodes,
-			ring,
-		}
-	}
-
-	fn empty(layout: ClusterLayout, replication_factor: usize) -> Self {
-		Self {
-			replication_factor,
-			layout,
-			nodes: vec![],
-			ring: vec![],
-		}
-	}
-
-	/// Get the partition in which data would fall on
-	pub fn partition_of(&self, position: &Hash) -> Partition {
-		let top = u16::from_be_bytes(position.as_slice()[0..2].try_into().unwrap());
-		top >> (16 - PARTITION_BITS)
-	}
-
-	/// Get the list of partitions and the first hash of a partition key that would fall in it
-	pub fn partitions(&self) -> Vec<(Partition, Hash)> {
-		let mut ret = vec![];
-
-		for (i, entry) in self.ring.iter().enumerate() {
-			let mut location = [0u8; 32];
-			location[..2].copy_from_slice(&u16::to_be_bytes(entry.hash_prefix)[..]);
-			ret.push((i as u16, location.into()));
-		}
-		if !ret.is_empty() {
-			assert_eq!(ret[0].1, [0u8; 32].into());
-		}
-
-		ret
-	}
-
-	/// Walk the ring to find the n servers in which data should be replicated
-	pub fn get_nodes(&self, position: &Hash, n: usize) -> Vec<Uuid> {
-		if self.ring.len() != 1 << PARTITION_BITS {
-			warn!("Ring not yet ready, read/writes will be lost!");
-			return vec![];
-		}
-
-		let partition_idx = self.partition_of(position) as usize;
-		let partition = &self.ring[partition_idx];
-
-		let top = u16::from_be_bytes(position.as_slice()[0..2].try_into().unwrap());
-		// Check that we haven't messed up our partition table, i.e. that this partition
-		// table entrey indeed corresponds to the item we are storing
-		assert_eq!(
-			partition.hash_prefix & PARTITION_MASK_U16,
-			top & PARTITION_MASK_U16
-		);
-
-		assert!(n <= self.replication_factor);
-		partition.nodes_buf[..n]
-			.iter()
-			.map(|i| self.nodes[*i as usize])
-			.collect::<Vec<_>>()
-	}
-}
-
-#[cfg(test)]
-mod tests {
-	use super::*;
-
-	#[test]
-	fn test_ring_entry_size() {
-		assert_eq!(std::mem::size_of::<RingEntry>(), 8);
-	}
-}
diff --git a/src/rpc/rpc_helper.rs b/src/rpc/rpc_helper.rs
index e59c372a..56bef2f3 100644
--- a/src/rpc/rpc_helper.rs
+++ b/src/rpc/rpc_helper.rs
@@ -26,8 +26,8 @@ use garage_util::data::*;
 use garage_util::error::Error;
 use garage_util::metrics::RecordDuration;
 
+use crate::layout::ClusterLayout;
 use crate::metrics::RpcMetrics;
-use crate::ring::Ring;
 
 // Default RPC timeout = 5 minutes
 const DEFAULT_TIMEOUT: Duration = Duration::from_secs(300);
@@ -91,7 +91,7 @@ pub struct RpcHelper(Arc<RpcHelperInner>);
 struct RpcHelperInner {
 	our_node_id: Uuid,
 	fullmesh: Arc<FullMeshPeeringStrategy>,
-	ring: watch::Receiver<Arc<Ring>>,
+	layout_watch: watch::Receiver<Arc<ClusterLayout>>,
 	metrics: RpcMetrics,
 	rpc_timeout: Duration,
 }
@@ -100,7 +100,7 @@ impl RpcHelper {
 	pub(crate) fn new(
 		our_node_id: Uuid,
 		fullmesh: Arc<FullMeshPeeringStrategy>,
-		ring: watch::Receiver<Arc<Ring>>,
+		layout_watch: watch::Receiver<Arc<ClusterLayout>>,
 		rpc_timeout: Option<Duration>,
 	) -> Self {
 		let metrics = RpcMetrics::new();
@@ -108,7 +108,7 @@ impl RpcHelper {
 		Self(Arc::new(RpcHelperInner {
 			our_node_id,
 			fullmesh,
-			ring,
+			layout_watch,
 			metrics,
 			rpc_timeout: rpc_timeout.unwrap_or(DEFAULT_TIMEOUT),
 		}))
@@ -392,8 +392,8 @@ impl RpcHelper {
 	pub fn request_order(&self, nodes: &[Uuid]) -> Vec<Uuid> {
 		// Retrieve some status variables that we will use to sort requests
 		let peer_list = self.0.fullmesh.get_peer_list();
-		let ring: Arc<Ring> = self.0.ring.borrow().clone();
-		let our_zone = match ring.layout.node_role(&self.0.our_node_id) {
+		let layout: Arc<ClusterLayout> = self.0.layout_watch.borrow().clone();
+		let our_zone = match layout.node_role(&self.0.our_node_id) {
 			Some(pc) => &pc.zone,
 			None => "",
 		};
@@ -407,7 +407,7 @@ impl RpcHelper {
 		let mut nodes = nodes
 			.iter()
 			.map(|to| {
-				let peer_zone = match ring.layout.node_role(to) {
+				let peer_zone = match layout.node_role(to) {
 					Some(pc) => &pc.zone,
 					None => "",
 				};
diff --git a/src/rpc/system.rs b/src/rpc/system.rs
index 4b40bec4..106e9f8c 100644
--- a/src/rpc/system.rs
+++ b/src/rpc/system.rs
@@ -36,7 +36,6 @@ use crate::consul::ConsulDiscovery;
 use crate::kubernetes::*;
 use crate::layout::*;
 use crate::replication_mode::*;
-use crate::ring::*;
 use crate::rpc_helper::*;
 
 use crate::system_metrics::*;
@@ -112,9 +111,9 @@ pub struct System {
 	replication_mode: ReplicationMode,
 	replication_factor: usize,
 
-	/// The ring
-	pub ring: watch::Receiver<Arc<Ring>>,
-	update_ring: Mutex<watch::Sender<Arc<Ring>>>,
+	/// The layout
+	pub layout_watch: watch::Receiver<Arc<ClusterLayout>>,
+	update_layout: Mutex<watch::Sender<Arc<ClusterLayout>>>,
 
 	/// Path to metadata directory
 	pub metadata_dir: PathBuf,
@@ -286,8 +285,7 @@ impl System {
 		let mut local_status = NodeStatus::initial(replication_factor, &cluster_layout);
 		local_status.update_disk_usage(&config.metadata_dir, &config.data_dir, &metrics);
 
-		let ring = Ring::new(cluster_layout, replication_factor);
-		let (update_ring, ring) = watch::channel(Arc::new(ring));
+		let (update_layout, layout_watch) = watch::channel(Arc::new(cluster_layout));
 
 		let rpc_public_addr = match &config.rpc_public_addr {
 			Some(a_str) => {
@@ -362,7 +360,7 @@ impl System {
 			rpc: RpcHelper::new(
 				netapp.id.into(),
 				fullmesh,
-				ring.clone(),
+				layout_watch.clone(),
 				config.rpc_timeout_msec.map(Duration::from_millis),
 			),
 			system_endpoint,
@@ -378,8 +376,8 @@ impl System {
 			kubernetes_discovery: config.kubernetes_discovery.clone(),
 			metrics,
 
-			ring,
-			update_ring: Mutex::new(update_ring),
+			layout_watch,
+			update_layout: Mutex::new(update_layout),
 			metadata_dir: config.metadata_dir.clone(),
 			data_dir: config.data_dir.clone(),
 		});
@@ -426,7 +424,7 @@ impl System {
 	}
 
 	pub fn get_cluster_layout(&self) -> ClusterLayout {
-		self.ring.borrow().layout.clone()
+		self.layout_watch.borrow().as_ref().clone()
 	}
 
 	pub async fn update_cluster_layout(
@@ -466,7 +464,7 @@ impl System {
 	}
 
 	pub fn health(&self) -> ClusterHealth {
-		let ring: Arc<_> = self.ring.borrow().clone();
+		let layout: Arc<_> = self.layout_watch.borrow().clone();
 		let quorum = self.replication_mode.write_quorum();
 		let replication_factor = self.replication_factor;
 
@@ -477,8 +475,7 @@ impl System {
 			.collect::<HashMap<Uuid, _>>();
 		let connected_nodes = nodes.iter().filter(|(_, n)| n.is_up).count();
 
-		let storage_nodes = ring
-			.layout
+		let storage_nodes = layout
 			.roles
 			.items()
 			.iter()
@@ -489,11 +486,11 @@ impl System {
 			.filter(|(x, _, _)| nodes.get(x).map(|n| n.is_up).unwrap_or(false))
 			.count();
 
-		let partitions = ring.partitions();
+		let partitions = layout.partitions();
 		let partitions_n_up = partitions
 			.iter()
 			.map(|(_, h)| {
-				let pn = ring.get_nodes(h, ring.replication_factor);
+				let pn = layout.nodes_of(h, layout.replication_factor);
 				pn.iter()
 					.filter(|x| nodes.get(x).map(|n| n.is_up).unwrap_or(false))
 					.count()
@@ -584,9 +581,9 @@ impl System {
 
 	/// Save network configuration to disc
 	async fn save_cluster_layout(&self) -> Result<(), Error> {
-		let ring: Arc<Ring> = self.ring.borrow().clone();
+		let layout: Arc<ClusterLayout> = self.layout_watch.borrow().clone();
 		self.persist_cluster_layout
-			.save_async(&ring.layout)
+			.save_async(&layout)
 			.await
 			.expect("Cannot save current cluster layout");
 		Ok(())
@@ -595,9 +592,9 @@ impl System {
 	fn update_local_status(&self) {
 		let mut new_si: NodeStatus = self.local_status.load().as_ref().clone();
 
-		let ring = self.ring.borrow();
-		new_si.cluster_layout_version = ring.layout.version;
-		new_si.cluster_layout_staging_hash = ring.layout.staging_hash;
+		let layout = self.layout_watch.borrow();
+		new_si.cluster_layout_version = layout.version;
+		new_si.cluster_layout_staging_hash = layout.staging_hash;
 
 		new_si.update_disk_usage(&self.metadata_dir, &self.data_dir, &self.metrics);
 
@@ -612,8 +609,8 @@ impl System {
 	}
 
 	fn handle_pull_cluster_layout(&self) -> SystemRpc {
-		let ring = self.ring.borrow().clone();
-		SystemRpc::AdvertiseClusterLayout(ring.layout.clone())
+		let layout = self.layout_watch.borrow().as_ref().clone();
+		SystemRpc::AdvertiseClusterLayout(layout)
 	}
 
 	fn handle_get_known_nodes(&self) -> SystemRpc {
@@ -663,8 +660,9 @@ impl System {
 			return Err(Error::Message(msg));
 		}
 
-		let update_ring = self.update_ring.lock().await;
-		let mut layout: ClusterLayout = self.ring.borrow().layout.clone();
+		let update_layout = self.update_layout.lock().await;
+		// TODO: don't clone each time an AdvertiseClusterLayout is received
+		let mut layout: ClusterLayout = self.layout_watch.borrow().as_ref().clone();
 
 		let prev_layout_check = layout.check().is_ok();
 		if layout.merge(adv) {
@@ -675,9 +673,8 @@ impl System {
 				));
 			}
 
-			let ring = Ring::new(layout.clone(), self.replication_factor);
-			update_ring.send(Arc::new(ring))?;
-			drop(update_ring);
+			update_layout.send(Arc::new(layout.clone()))?;
+			drop(update_layout);
 
 			let self2 = self.clone();
 			tokio::spawn(async move {
@@ -725,9 +722,9 @@ impl System {
 
 	async fn discovery_loop(self: &Arc<Self>, mut stop_signal: watch::Receiver<bool>) {
 		while !*stop_signal.borrow() {
-			let not_configured = self.ring.borrow().layout.check().is_err();
+			let not_configured = self.layout_watch.borrow().check().is_err();
 			let no_peers = self.fullmesh.get_peer_list().len() < self.replication_factor;
-			let expected_n_nodes = self.ring.borrow().layout.num_nodes();
+			let expected_n_nodes = self.layout_watch.borrow().num_nodes();
 			let bad_peers = self
 				.fullmesh
 				.get_peer_list()