Migration of cluster layout from v0.8 to v0.9

src/rpc/layout.rs

@@ -5,8 +5,6 @@ use std::collections::HashSet;
 use bytesize::ByteSize;
 use itertools::Itertools;
 
-use serde::{Deserialize, Serialize};
-
 use garage_util::crdt::{AutoCrdt, Crdt, Lww, LwwMap};
 use garage_util::data::*;
 use garage_util::encode::nonversioned_encode;
@@ -23,10 +21,70 @@ const NB_PARTITIONS: usize = 1usize << PARTITION_BITS;
 // The Message type will be used to collect information on the algorithm.
 type Message = Vec<String>;
 
-/// The layout of the cluster, i.e. the list of roles
-/// which are assigned to each cluster node
-#[derive(Clone, Debug, Serialize, Deserialize)]
-pub struct ClusterLayout {
+mod v08 {
+	use crate::ring::CompactNodeType;
+	use garage_util::crdt::LwwMap;
+	use garage_util::data::{Hash, Uuid};
+	use serde::{Deserialize, Serialize};
+
+	/// The layout of the cluster, i.e. the list of roles
+	/// which are assigned to each cluster node
+	#[derive(Clone, Debug, Serialize, Deserialize)]
+	pub struct ClusterLayout {
+		pub version: u64,
+
+		pub replication_factor: usize,
+		pub roles: LwwMap<Uuid, NodeRoleV>,
+
+		/// node_id_vec: a vector of node IDs with a role assigned
+		/// in the system (this includes gateway nodes).
+		/// The order here is different than the vec stored by `roles`, because:
+		/// 1. non-gateway nodes are first so that they have lower numbers
+		/// 2. nodes that don't have a role are excluded (but they need to
+		///    stay in the CRDT as tombstones)
+		pub node_id_vec: Vec<Uuid>,
+		/// the assignation of data partitions to node, the values
+		/// are indices in node_id_vec
+		#[serde(with = "serde_bytes")]
+		pub ring_assignation_data: Vec<CompactNodeType>,
+
+		/// Role changes which are staged for the next version of the layout
+		pub staging: LwwMap<Uuid, NodeRoleV>,
+		pub staging_hash: Hash,
+	}
+
+	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
+	pub struct NodeRoleV(pub Option<NodeRole>);
+
+	/// The user-assigned roles of cluster nodes
+	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
+	pub struct NodeRole {
+		/// Datacenter at which this entry belong. This information is used to
+		/// perform a better geodistribution
+		pub zone: String,
+		/// The capacity of the node
+		/// If this is set to None, the node does not participate in storing data for the system
+		/// and is only active as an API gateway to other nodes
+		pub capacity: Option<u64>,
+		/// A set of tags to recognize the node
+		pub tags: Vec<String>,
+	}
+
+	impl garage_util::migrate::InitialFormat for ClusterLayout {}
+}
+
+mod v09 {
+	use super::v08;
+	use crate::ring::CompactNodeType;
+	use garage_util::crdt::{Lww, LwwMap};
+	use garage_util::data::{Hash, Uuid};
+	use serde::{Deserialize, Serialize};
+	pub use v08::{NodeRole, NodeRoleV};
+
+	/// The layout of the cluster, i.e. the list of roles
+	/// which are assigned to each cluster node
+	#[derive(Clone, Debug, Serialize, Deserialize)]
+	pub struct ClusterLayout {
 		pub version: u64,
 
 		pub replication_factor: usize,
@@ -40,16 +98,9 @@ pub struct ClusterLayout {
 
 		pub roles: LwwMap<Uuid, NodeRoleV>,
 
-	/// node_id_vec: a vector of node IDs with a role assigned
-	/// in the system (this includes gateway nodes).
-	/// The order here is different than the vec stored by `roles`, because:
-	/// 1. non-gateway nodes are first so that they have lower numbers holding
-	///     in u8 (the number of non-gateway nodes is at most 256).
-	/// 2. nodes that don't have a role are excluded (but they need to
-	///    stay in the CRDT as tombstones)
+		/// see comment in v08::ClusterLayout
 		pub node_id_vec: Vec<Uuid>,
-	/// the assignment of data partitions to node, the values
-	/// are indices in node_id_vec
+		/// see comment in v08::ClusterLayout
 		#[serde(with = "serde_bytes")]
 		pub ring_assignment_data: Vec<CompactNodeType>,
 
@@ -58,41 +109,108 @@ pub struct ClusterLayout {
 		/// Role changes which are staged for the next version of the layout
 		pub staging_roles: LwwMap<Uuid, NodeRoleV>,
 		pub staging_hash: Hash,
-}
-impl garage_util::migrate::InitialFormat for ClusterLayout {}
+	}
 
-/// This struct is used to set the parameters to be used in the assignment computation
-/// algorithm. It is stored as a Crdt.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
-pub struct LayoutParameters {
+	/// This struct is used to set the parameters to be used in the assignment computation
+	/// algorithm. It is stored as a Crdt.
+	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Debug, Serialize, Deserialize)]
+	pub struct LayoutParameters {
 		pub zone_redundancy: usize,
+	}
+
+	impl garage_util::migrate::Migrate for ClusterLayout {
+		const VERSION_MARKER: &'static [u8] = b"Glayout09";
+
+		type Previous = v08::ClusterLayout;
+
+		fn migrate(previous: Self::Previous) -> Self {
+			use itertools::Itertools;
+			use std::collections::HashSet;
+
+			// In the old layout, capacities are in an arbitrary unit,
+			// but in the new layout they are in bytes.
+			// Here we arbitrarily multiply everything by 1G,
+			// such that 1 old capacity unit = 1GB in the new units.
+			// This is totally arbitrary and won't work for most users.
+			let cap_mul = 1024 * 1024 * 1024;
+			let roles = multiply_all_capacities(previous.roles, cap_mul);
+			let staging_roles = multiply_all_capacities(previous.staging, cap_mul);
+			let node_id_vec = previous.node_id_vec;
+
+			// Determine partition size
+			let mut tmp = previous.ring_assignation_data.clone();
+			tmp.sort();
+			let partition_size = tmp
+				.into_iter()
+				.dedup_with_count()
+				.map(|(npart, node)| {
+					roles
+						.get(&node_id_vec[node as usize])
+						.and_then(|p| p.0.as_ref().and_then(|r| r.capacity))
+						.unwrap_or(0) / npart as u64
+				})
+				.min()
+				.unwrap_or(0);
+
+			// Determine zone redundancy parameter
+			let zone_redundancy = std::cmp::min(
+				previous.replication_factor,
+				roles
+					.items()
+					.iter()
+					.filter_map(|(_, _, r)| r.0.as_ref().map(|p| p.zone.as_str()))
+					.collect::<HashSet<&str>>()
+					.len(),
+			);
+			let parameters = LayoutParameters { zone_redundancy };
+
+			let mut res = Self {
+				version: previous.version,
+				replication_factor: previous.replication_factor,
+				partition_size,
+				parameters,
+				roles,
+				node_id_vec,
+				ring_assignment_data: previous.ring_assignation_data,
+				staging_parameters: Lww::new(parameters),
+				staging_roles,
+				staging_hash: [0u8; 32].into(),
+			};
+			res.staging_hash = res.calculate_staging_hash();
+			res
+		}
+	}
+
+	fn multiply_all_capacities(
+		old_roles: LwwMap<Uuid, NodeRoleV>,
+		mul: u64,
+	) -> LwwMap<Uuid, NodeRoleV> {
+		let mut new_roles = LwwMap::new();
+		for (node, ts, role) in old_roles.items() {
+			let mut role = role.clone();
+			if let NodeRoleV(Some(NodeRole {
+				capacity: Some(ref mut cap),
+				..
+			})) = role
+			{
+				*cap = *cap * mul;
+			}
+			new_roles.merge_raw(node, *ts, &role);
+		}
+		new_roles
+	}
 }
 
+pub use v09::*;
+
 impl AutoCrdt for LayoutParameters {
 	const WARN_IF_DIFFERENT: bool = true;
 }
 
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
-pub struct NodeRoleV(pub Option<NodeRole>);
-
 impl AutoCrdt for NodeRoleV {
 	const WARN_IF_DIFFERENT: bool = true;
 }
 
-/// The user-assigned roles of cluster nodes
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
-pub struct NodeRole {
-	/// Datacenter at which this entry belong. This information is used to
-	/// perform a better geodistribution
-	pub zone: String,
-	/// The capacity of the node
-	/// If this is set to None, the node does not participate in storing data for the system
-	/// and is only active as an API gateway to other nodes
-	pub capacity: Option<u64>,
-	/// A set of tags to recognize the node
-	pub tags: Vec<String>,
-}
-
 impl NodeRole {
 	pub fn capacity_string(&self) -> String {
 		match self.capacity {