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-rw-r--r--src/rpc/layout.rs579
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diff --git a/src/rpc/layout.rs b/src/rpc/layout.rs
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+use std::cmp::Ordering;
+use std::collections::{HashMap, HashSet};
+
+use serde::{Deserialize, Serialize};
+
+use garage_util::crdt::{AutoCrdt, Crdt, LwwMap};
+use garage_util::data::*;
+
+use crate::ring::*;
+
+/// 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>);
+
+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 might be used to perform a better
+ /// geodistribution
+ pub zone: String,
+ /// The (relative) 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<u32>,
+ /// A set of tags to recognize the node
+ pub tags: Vec<String>,
+}
+
+impl NodeRole {
+ pub fn capacity_string(&self) -> String {
+ match self.capacity {
+ Some(c) => format!("{}", c),
+ None => "gateway".to_string(),
+ }
+ }
+}
+
+impl ClusterLayout {
+ pub fn new(replication_factor: usize) -> Self {
+ let empty_lwwmap = LwwMap::new();
+ let empty_lwwmap_hash = blake2sum(&rmp_to_vec_all_named(&empty_lwwmap).unwrap()[..]);
+
+ ClusterLayout {
+ version: 0,
+ replication_factor,
+ roles: LwwMap::new(),
+ node_id_vec: Vec::new(),
+ ring_assignation_data: Vec::new(),
+ staging: empty_lwwmap,
+ staging_hash: empty_lwwmap_hash,
+ }
+ }
+
+ pub fn merge(&mut self, other: &ClusterLayout) -> bool {
+ match other.version.cmp(&self.version) {
+ Ordering::Greater => {
+ *self = other.clone();
+ true
+ }
+ Ordering::Equal => {
+ self.staging.merge(&other.staging);
+
+ let new_staging_hash = blake2sum(&rmp_to_vec_all_named(&self.staging).unwrap()[..]);
+ let changed = new_staging_hash != self.staging_hash;
+
+ self.staging_hash = new_staging_hash;
+
+ changed
+ }
+ Ordering::Less => false,
+ }
+ }
+
+ /// Returns a list of IDs of nodes that currently have
+ /// a role in the cluster
+ pub fn node_ids(&self) -> &[Uuid] {
+ &self.node_id_vec[..]
+ }
+
+ pub fn num_nodes(&self) -> usize {
+ self.node_id_vec.len()
+ }
+
+ /// Returns the role of a node in the layout
+ pub fn node_role(&self, node: &Uuid) -> Option<&NodeRole> {
+ match self.roles.get(node) {
+ Some(NodeRoleV(Some(v))) => Some(v),
+ _ => None,
+ }
+ }
+
+ /// Check a cluster layout for internal consistency
+ /// returns true if consistent, false if error
+ pub fn check(&self) -> bool {
+ // Check that the hash of the staging data is correct
+ let staging_hash = blake2sum(&rmp_to_vec_all_named(&self.staging).unwrap()[..]);
+ if staging_hash != self.staging_hash {
+ return false;
+ }
+
+ // Check that node_id_vec contains the correct list of nodes
+ let mut expected_nodes = self
+ .roles
+ .items()
+ .iter()
+ .filter(|(_, _, v)| v.0.is_some())
+ .map(|(id, _, _)| *id)
+ .collect::<Vec<_>>();
+ expected_nodes.sort();
+ let mut node_id_vec = self.node_id_vec.clone();
+ node_id_vec.sort();
+ if expected_nodes != node_id_vec {
+ return false;
+ }
+
+ // Check that the assignation data has the correct length
+ if self.ring_assignation_data.len() != (1 << PARTITION_BITS) * self.replication_factor {
+ return false;
+ }
+
+ // Check that the assigned nodes are correct identifiers
+ // of nodes that are assigned a role
+ // and that role is not the role of a gateway nodes
+ for x in self.ring_assignation_data.iter() {
+ if *x as usize >= self.node_id_vec.len() {
+ return false;
+ }
+ let node = self.node_id_vec[*x as usize];
+ match self.roles.get(&node) {
+ Some(NodeRoleV(Some(x))) if x.capacity.is_some() => (),
+ _ => return false,
+ }
+ }
+
+ true
+ }
+
+ /// Calculate an assignation of partitions to nodes
+ pub fn calculate_partition_assignation(&mut self) -> bool {
+ let (configured_nodes, zones) = self.configured_nodes_and_zones();
+ let n_zones = zones.len();
+
+ println!("Calculating updated partition assignation, this may take some time...");
+ println!();
+
+ let old_partitions = self.parse_assignation_data();
+
+ let mut partitions = old_partitions.clone();
+ for part in partitions.iter_mut() {
+ part.nodes
+ .retain(|(_, info)| info.map(|x| x.capacity.is_some()).unwrap_or(false));
+ }
+
+ // When nodes are removed, or when bootstraping an assignation from
+ // scratch for a new cluster, the old partitions will have holes (or be empty).
+ // Here we add more nodes to make a complete (sub-optimal) assignation,
+ // using an initial partition assignation that is calculated using the multi-dc maglev trick
+ match self.initial_partition_assignation() {
+ Some(initial_partitions) => {
+ for (part, ipart) in partitions.iter_mut().zip(initial_partitions.iter()) {
+ for (id, info) in ipart.nodes.iter() {
+ if part.nodes.len() < self.replication_factor {
+ part.add(part.nodes.len() + 1, n_zones, id, info.unwrap());
+ }
+ }
+ assert!(part.nodes.len() == self.replication_factor);
+ }
+ }
+ None => {
+ return false;
+ }
+ }
+
+ // Calculate how many partitions each node should ideally store,
+ // and how many partitions they are storing with the current assignation
+ // This defines our target for which we will optimize in the following loop.
+ let total_capacity = configured_nodes
+ .iter()
+ .map(|(_, info)| info.capacity.unwrap_or(0))
+ .sum::<u32>() as usize;
+ let total_partitions = self.replication_factor * (1 << PARTITION_BITS);
+ let target_partitions_per_node = configured_nodes
+ .iter()
+ .map(|(id, info)| {
+ (
+ *id,
+ info.capacity.unwrap_or(0) as usize * total_partitions / total_capacity,
+ )
+ })
+ .collect::<HashMap<&Uuid, usize>>();
+
+ let mut partitions_per_node = self.partitions_per_node(&partitions[..]);
+
+ println!("Target number of partitions per node:");
+ for (node, npart) in target_partitions_per_node.iter() {
+ println!("{:?}\t{}", node, npart);
+ }
+ println!();
+
+ // Shuffle partitions between nodes so that nodes will reach (or better approach)
+ // their target number of stored partitions
+ loop {
+ let mut option = None;
+ for (i, part) in partitions.iter_mut().enumerate() {
+ for (irm, (idrm, _)) in part.nodes.iter().enumerate() {
+ let suprm = partitions_per_node.get(*idrm).cloned().unwrap_or(0) as i32
+ - target_partitions_per_node.get(*idrm).cloned().unwrap_or(0) as i32;
+
+ for (idadd, infoadd) in configured_nodes.iter() {
+ // skip replacing a node by itself
+ // and skip replacing by gateway nodes
+ if idadd == idrm || infoadd.capacity.is_none() {
+ continue;
+ }
+
+ let supadd = partitions_per_node.get(*idadd).cloned().unwrap_or(0) as i32
+ - target_partitions_per_node.get(*idadd).cloned().unwrap_or(0) as i32;
+
+ // We want to try replacing node idrm by node idadd
+ // if that brings us close to our goal.
+ let square = |i: i32| i * i;
+ let oldcost = square(suprm) + square(supadd);
+ let newcost = square(suprm - 1) + square(supadd + 1);
+ if newcost >= oldcost {
+ // not closer to our goal
+ continue;
+ }
+ let gain = oldcost - newcost;
+
+ let mut newpart = part.clone();
+
+ newpart.nodes.remove(irm);
+ if !newpart.add(newpart.nodes.len() + 1, n_zones, idadd, infoadd) {
+ continue;
+ }
+ assert!(newpart.nodes.len() == self.replication_factor);
+
+ if !old_partitions[i]
+ .is_valid_transition_to(&newpart, self.replication_factor)
+ {
+ continue;
+ }
+
+ if option
+ .as_ref()
+ .map(|(old_gain, _, _, _, _)| gain > *old_gain)
+ .unwrap_or(true)
+ {
+ option = Some((gain, i, idadd, idrm, newpart));
+ }
+ }
+ }
+ }
+ if let Some((_gain, i, idadd, idrm, newpart)) = option {
+ *partitions_per_node.entry(idadd).or_insert(0) += 1;
+ *partitions_per_node.get_mut(idrm).unwrap() -= 1;
+ partitions[i] = newpart;
+ } else {
+ break;
+ }
+ }
+
+ // Check we completed the assignation correctly
+ // (this is a set of checks for the algorithm's consistency)
+ assert!(partitions.len() == (1 << PARTITION_BITS));
+ assert!(partitions
+ .iter()
+ .all(|p| p.nodes.len() == self.replication_factor));
+
+ let new_partitions_per_node = self.partitions_per_node(&partitions[..]);
+ assert!(new_partitions_per_node == partitions_per_node);
+
+ // Show statistics
+ println!("New number of partitions per node:");
+ for (node, npart) in partitions_per_node.iter() {
+ println!("{:?}\t{}", node, npart);
+ }
+ println!();
+
+ let mut diffcount = HashMap::new();
+ for (oldpart, newpart) in old_partitions.iter().zip(partitions.iter()) {
+ let nminus = oldpart.txtplus(newpart);
+ let nplus = newpart.txtplus(oldpart);
+ if nminus != "[...]" || nplus != "[...]" {
+ let tup = (nminus, nplus);
+ *diffcount.entry(tup).or_insert(0) += 1;
+ }
+ }
+ if diffcount.is_empty() {
+ println!("No data will be moved between nodes.");
+ } else {
+ let mut diffcount = diffcount.into_iter().collect::<Vec<_>>();
+ diffcount.sort();
+ println!("Number of partitions that move:");
+ for ((nminus, nplus), npart) in diffcount {
+ println!("\t{}\t{} -> {}", npart, nminus, nplus);
+ }
+ }
+ println!();
+
+ // Calculate and save new assignation data
+ let (nodes, assignation_data) =
+ self.compute_assignation_data(&configured_nodes[..], &partitions[..]);
+
+ self.node_id_vec = nodes;
+ self.ring_assignation_data = assignation_data;
+
+ true
+ }
+
+ fn initial_partition_assignation(&self) -> Option<Vec<PartitionAss<'_>>> {
+ let (configured_nodes, zones) = self.configured_nodes_and_zones();
+ let n_zones = zones.len();
+
+ // Create a vector of partition indices (0 to 2**PARTITION_BITS-1)
+ let partitions_idx = (0usize..(1usize << PARTITION_BITS)).collect::<Vec<_>>();
+
+ // Prepare ring
+ let mut partitions: Vec<PartitionAss> = partitions_idx
+ .iter()
+ .map(|_i| PartitionAss::new())
+ .collect::<Vec<_>>();
+
+ // Create MagLev priority queues for each node
+ let mut queues = configured_nodes
+ .iter()
+ .filter(|(_id, info)| info.capacity.is_some())
+ .map(|(node_id, node_info)| {
+ let mut parts = partitions_idx
+ .iter()
+ .map(|i| {
+ let part_data =
+ [&u16::to_be_bytes(*i as u16)[..], node_id.as_slice()].concat();
+ (*i, fasthash(&part_data[..]))
+ })
+ .collect::<Vec<_>>();
+ parts.sort_by_key(|(_i, h)| *h);
+ let parts_i = parts.iter().map(|(i, _h)| *i).collect::<Vec<_>>();
+ (node_id, node_info, parts_i, 0)
+ })
+ .collect::<Vec<_>>();
+
+ let max_capacity = configured_nodes
+ .iter()
+ .filter_map(|(_, node_info)| node_info.capacity)
+ .fold(0, std::cmp::max);
+
+ // Fill up ring
+ for rep in 0..self.replication_factor {
+ queues.sort_by_key(|(ni, _np, _q, _p)| {
+ let queue_data = [&u16::to_be_bytes(rep as u16)[..], ni.as_slice()].concat();
+ fasthash(&queue_data[..])
+ });
+
+ for (_, _, _, pos) in queues.iter_mut() {
+ *pos = 0;
+ }
+
+ let mut remaining = partitions_idx.len();
+ while remaining > 0 {
+ let remaining0 = remaining;
+ for i_round in 0..max_capacity {
+ for (node_id, node_info, q, pos) in queues.iter_mut() {
+ if i_round >= node_info.capacity.unwrap() {
+ continue;
+ }
+ for (pos2, &qv) in q.iter().enumerate().skip(*pos) {
+ if partitions[qv].add(rep + 1, n_zones, node_id, node_info) {
+ remaining -= 1;
+ *pos = pos2 + 1;
+ break;
+ }
+ }
+ }
+ }
+ if remaining == remaining0 {
+ // No progress made, exit
+ return None;
+ }
+ }
+ }
+
+ Some(partitions)
+ }
+
+ fn configured_nodes_and_zones(&self) -> (Vec<(&Uuid, &NodeRole)>, HashSet<&str>) {
+ let configured_nodes = self
+ .roles
+ .items()
+ .iter()
+ .filter(|(_id, _, info)| info.0.is_some())
+ .map(|(id, _, info)| (id, info.0.as_ref().unwrap()))
+ .collect::<Vec<(&Uuid, &NodeRole)>>();
+
+ let zones = configured_nodes
+ .iter()
+ .filter(|(_id, info)| info.capacity.is_some())
+ .map(|(_id, info)| info.zone.as_str())
+ .collect::<HashSet<&str>>();
+
+ (configured_nodes, zones)
+ }
+
+ fn compute_assignation_data<'a>(
+ &self,
+ configured_nodes: &[(&'a Uuid, &'a NodeRole)],
+ partitions: &[PartitionAss<'a>],
+ ) -> (Vec<Uuid>, Vec<CompactNodeType>) {
+ assert!(partitions.len() == (1 << PARTITION_BITS));
+
+ // Make a canonical order for nodes
+ let mut nodes = configured_nodes
+ .iter()
+ .filter(|(_id, info)| info.capacity.is_some())
+ .map(|(id, _)| **id)
+ .collect::<Vec<_>>();
+ let nodes_rev = nodes
+ .iter()
+ .enumerate()
+ .map(|(i, id)| (*id, i as CompactNodeType))
+ .collect::<HashMap<Uuid, CompactNodeType>>();
+
+ let mut assignation_data = vec![];
+ for partition in partitions.iter() {
+ assert!(partition.nodes.len() == self.replication_factor);
+ for (id, _) in partition.nodes.iter() {
+ assignation_data.push(*nodes_rev.get(id).unwrap());
+ }
+ }
+
+ nodes.extend(
+ configured_nodes
+ .iter()
+ .filter(|(_id, info)| info.capacity.is_none())
+ .map(|(id, _)| **id),
+ );
+
+ (nodes, assignation_data)
+ }
+
+ fn parse_assignation_data(&self) -> Vec<PartitionAss<'_>> {
+ if self.ring_assignation_data.len() == self.replication_factor * (1 << PARTITION_BITS) {
+ // If the previous assignation data is correct, use that
+ let mut partitions = vec![];
+ for i in 0..(1 << PARTITION_BITS) {
+ let mut part = PartitionAss::new();
+ for node_i in self.ring_assignation_data
+ [i * self.replication_factor..(i + 1) * self.replication_factor]
+ .iter()
+ {
+ let node_id = &self.node_id_vec[*node_i as usize];
+
+ if let Some(NodeRoleV(Some(info))) = self.roles.get(node_id) {
+ part.nodes.push((node_id, Some(info)));
+ } else {
+ part.nodes.push((node_id, None));
+ }
+ }
+ partitions.push(part);
+ }
+ partitions
+ } else {
+ // Otherwise start fresh
+ (0..(1 << PARTITION_BITS))
+ .map(|_| PartitionAss::new())
+ .collect()
+ }
+ }
+
+ fn partitions_per_node<'a>(&self, partitions: &[PartitionAss<'a>]) -> HashMap<&'a Uuid, usize> {
+ let mut partitions_per_node = HashMap::<&Uuid, usize>::new();
+ for p in partitions.iter() {
+ for (id, _) in p.nodes.iter() {
+ *partitions_per_node.entry(*id).or_insert(0) += 1;
+ }
+ }
+ partitions_per_node
+ }
+}
+
+// ---- Internal structs for partition assignation in layout ----
+
+#[derive(Clone)]
+struct PartitionAss<'a> {
+ nodes: Vec<(&'a Uuid, Option<&'a NodeRole>)>,
+}
+
+impl<'a> PartitionAss<'a> {
+ fn new() -> Self {
+ Self { nodes: Vec::new() }
+ }
+
+ fn nplus(&self, other: &PartitionAss<'a>) -> usize {
+ self.nodes
+ .iter()
+ .filter(|x| !other.nodes.contains(x))
+ .count()
+ }
+
+ fn txtplus(&self, other: &PartitionAss<'a>) -> String {
+ let mut nodes = self
+ .nodes
+ .iter()
+ .filter(|x| !other.nodes.contains(x))
+ .map(|x| format!("{:?}", x.0))
+ .collect::<Vec<_>>();
+ nodes.sort();
+ if self.nodes.iter().any(|x| other.nodes.contains(x)) {
+ nodes.push("...".into());
+ }
+ format!("[{}]", nodes.join(" "))
+ }
+
+ fn is_valid_transition_to(&self, other: &PartitionAss<'a>, replication_factor: usize) -> bool {
+ let min_keep_nodes_per_part = (replication_factor + 1) / 2;
+ let n_removed = self.nplus(other);
+
+ if self.nodes.len() <= min_keep_nodes_per_part {
+ n_removed == 0
+ } else {
+ n_removed <= self.nodes.len() - min_keep_nodes_per_part
+ }
+ }
+
+ fn add(
+ &mut self,
+ target_len: usize,
+ n_zones: usize,
+ node: &'a Uuid,
+ role: &'a NodeRole,
+ ) -> bool {
+ if self.nodes.len() != target_len - 1 {
+ return false;
+ }
+
+ let p_zns = self
+ .nodes
+ .iter()
+ .map(|(_id, info)| info.unwrap().zone.as_str())
+ .collect::<HashSet<&str>>();
+ if (p_zns.len() < n_zones && !p_zns.contains(&role.zone.as_str()))
+ || (p_zns.len() == n_zones && !self.nodes.iter().any(|(id, _)| *id == node))
+ {
+ self.nodes.push((node, Some(role)));
+ true
+ } else {
+ false
+ }
+ }
+}
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