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-rw-r--r--src/rpc/layout.rs1462
1 files changed, 1013 insertions, 449 deletions
diff --git a/src/rpc/layout.rs b/src/rpc/layout.rs
index 1030e3a6..c2655e59 100644
--- a/src/rpc/layout.rs
+++ b/src/rpc/layout.rs
@@ -1,87 +1,260 @@
use std::cmp::Ordering;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
+use std::collections::HashSet;
-use serde::{Deserialize, Serialize};
+use bytesize::ByteSize;
+use itertools::Itertools;
-use garage_util::crdt::{AutoCrdt, Crdt, LwwMap};
+use garage_util::crdt::{AutoCrdt, Crdt, Lww, LwwMap};
use garage_util::data::*;
use garage_util::encode::nonversioned_encode;
use garage_util::error::*;
+use crate::graph_algo::*;
+
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,
+use std::convert::TryInto;
+
+const NB_PARTITIONS: usize = 1usize << PARTITION_BITS;
+
+// The Message type will be used to collect information on the algorithm.
+type Message = Vec<String>;
+
+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 {}
}
-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,
+
+ /// This attribute is only used to retain the previously computed partition size,
+ /// to know to what extent does it change with the layout update.
+ pub partition_size: u64,
+ /// Parameters used to compute the assignment currently given by
+ /// ring_assignment_data
+ pub parameters: LayoutParameters,
+
+ pub roles: LwwMap<Uuid, NodeRoleV>,
+
+ /// see comment in v08::ClusterLayout
+ pub node_id_vec: Vec<Uuid>,
+ /// see comment in v08::ClusterLayout
+ #[serde(with = "serde_bytes")]
+ pub ring_assignment_data: Vec<CompactNodeType>,
+
+ /// Parameters to be used in the next partition assignment computation.
+ pub staging_parameters: Lww<LayoutParameters>,
+ /// Role changes which are staged for the next version of the layout
+ pub staging_roles: LwwMap<Uuid, NodeRoleV>,
+ pub staging_hash: Hash,
+ }
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
-pub struct NodeRoleV(pub Option<NodeRole>);
+ /// 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 AutoCrdt for NodeRoleV {
+ impl garage_util::migrate::Migrate for ClusterLayout {
+ const VERSION_MARKER: &'static [u8] = b"G09layout";
+
+ 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;
}
-/// 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 AutoCrdt for NodeRoleV {
+ const WARN_IF_DIFFERENT: bool = true;
}
impl NodeRole {
pub fn capacity_string(&self) -> String {
match self.capacity {
- Some(c) => format!("{}", c),
+ Some(c) => ByteSize::b(c).to_string_as(false),
None => "gateway".to_string(),
}
}
+
+ pub fn tags_string(&self) -> String {
+ self.tags.join(",")
+ }
}
+// Implementation of the ClusterLayout methods unrelated to the assignment algorithm.
impl ClusterLayout {
pub fn new(replication_factor: usize) -> Self {
+ // We set the default zone redundancy to be equal to the replication factor,
+ // i.e. as strict as possible.
+ let parameters = LayoutParameters {
+ zone_redundancy: replication_factor,
+ };
+ let staging_parameters = Lww::<LayoutParameters>::new(parameters.clone());
+
let empty_lwwmap = LwwMap::new();
- let empty_lwwmap_hash = blake2sum(&nonversioned_encode(&empty_lwwmap).unwrap()[..]);
- ClusterLayout {
+ let mut ret = ClusterLayout {
version: 0,
replication_factor,
+ partition_size: 0,
roles: LwwMap::new(),
node_id_vec: Vec::new(),
- ring_assignation_data: Vec::new(),
- staging: empty_lwwmap,
- staging_hash: empty_lwwmap_hash,
- }
+ ring_assignment_data: Vec::new(),
+ parameters,
+ staging_parameters,
+ staging_roles: empty_lwwmap,
+ staging_hash: [0u8; 32].into(),
+ };
+ ret.staging_hash = ret.calculate_staging_hash();
+ ret
+ }
+
+ fn calculate_staging_hash(&self) -> Hash {
+ let hashed_tuple = (&self.staging_roles, &self.staging_parameters);
+ blake2sum(&nonversioned_encode(&hashed_tuple).unwrap()[..])
}
pub fn merge(&mut self, other: &ClusterLayout) -> bool {
@@ -91,9 +264,10 @@ impl ClusterLayout {
true
}
Ordering::Equal => {
- self.staging.merge(&other.staging);
+ self.staging_parameters.merge(&other.staging_parameters);
+ self.staging_roles.merge(&other.staging_roles);
- let new_staging_hash = blake2sum(&nonversioned_encode(&self.staging).unwrap()[..]);
+ let new_staging_hash = self.calculate_staging_hash();
let changed = new_staging_hash != self.staging_hash;
self.staging_hash = new_staging_hash;
@@ -104,7 +278,7 @@ impl ClusterLayout {
}
}
- pub fn apply_staged_changes(mut self, version: Option<u64>) -> Result<Self, Error> {
+ pub fn apply_staged_changes(mut self, version: Option<u64>) -> Result<(Self, Message), Error> {
match version {
None => {
let error = r#"
@@ -120,19 +294,18 @@ To know the correct value of the new layout version, invoke `garage layout show`
}
}
- self.roles.merge(&self.staging);
+ self.roles.merge(&self.staging_roles);
self.roles.retain(|(_, _, v)| v.0.is_some());
+ self.parameters = self.staging_parameters.get().clone();
- if !self.calculate_partition_assignation() {
- return Err(Error::Message("Could not calculate new assignation of partitions to nodes. This can happen if there are less nodes than the desired number of copies of your data (see the replication_mode configuration parameter).".into()));
- }
+ self.staging_roles.clear();
+ self.staging_hash = self.calculate_staging_hash();
- self.staging.clear();
- self.staging_hash = blake2sum(&nonversioned_encode(&self.staging).unwrap()[..]);
+ let msg = self.calculate_partition_assignment()?;
self.version += 1;
- Ok(self)
+ Ok((self, msg))
}
pub fn revert_staged_changes(mut self, version: Option<u64>) -> Result<Self, Error> {
@@ -151,8 +324,9 @@ To know the correct value of the new layout version, invoke `garage layout show`
}
}
- self.staging.clear();
- self.staging_hash = blake2sum(&nonversioned_encode(&self.staging).unwrap()[..]);
+ self.staging_roles.clear();
+ self.staging_parameters.update(self.parameters.clone());
+ self.staging_hash = self.calculate_staging_hash();
self.version += 1;
@@ -177,13 +351,81 @@ To know the correct value of the new layout version, invoke `garage layout show`
}
}
+ /// Returns the uuids of the non_gateway nodes in self.node_id_vec.
+ fn nongateway_nodes(&self) -> Vec<Uuid> {
+ let mut result = Vec::<Uuid>::new();
+ for uuid in self.node_id_vec.iter() {
+ match self.node_role(uuid) {
+ Some(role) if role.capacity != None => result.push(*uuid),
+ _ => (),
+ }
+ }
+ result
+ }
+
+ /// Given a node uuids, this function returns the label of its zone
+ fn get_node_zone(&self, uuid: &Uuid) -> Result<String, Error> {
+ match self.node_role(uuid) {
+ Some(role) => Ok(role.zone.clone()),
+ _ => Err(Error::Message(
+ "The Uuid does not correspond to a node present in the cluster.".into(),
+ )),
+ }
+ }
+
+ /// Given a node uuids, this function returns its capacity or fails if it does not have any
+ pub fn get_node_capacity(&self, uuid: &Uuid) -> Result<u64, Error> {
+ match self.node_role(uuid) {
+ Some(NodeRole {
+ capacity: Some(cap),
+ zone: _,
+ tags: _,
+ }) => Ok(*cap),
+ _ => Err(Error::Message(
+ "The Uuid does not correspond to a node present in the \
+ cluster or this node does not have a positive capacity."
+ .into(),
+ )),
+ }
+ }
+
+ /// Returns the number of partitions associated to this node in the ring
+ pub fn get_node_usage(&self, uuid: &Uuid) -> Result<usize, Error> {
+ for (i, id) in self.node_id_vec.iter().enumerate() {
+ if id == uuid {
+ let mut count = 0;
+ for nod in self.ring_assignment_data.iter() {
+ if i as u8 == *nod {
+ count += 1
+ }
+ }
+ return Ok(count);
+ }
+ }
+ Err(Error::Message(
+ "The Uuid does not correspond to a node present in the \
+ cluster or this node does not have a positive capacity."
+ .into(),
+ ))
+ }
+
+ /// Returns the sum of capacities of non gateway nodes in the cluster
+ fn get_total_capacity(&self) -> Result<u64, Error> {
+ let mut total_capacity = 0;
+ for uuid in self.nongateway_nodes().iter() {
+ total_capacity += self.get_node_capacity(uuid)?;
+ }
+ Ok(total_capacity)
+ }
+
/// Check a cluster layout for internal consistency
+ /// (assignment, roles, parameters, partition size)
/// returns true if consistent, false if error
- pub fn check(&self) -> bool {
+ pub fn check(&self) -> Result<(), String> {
// Check that the hash of the staging data is correct
- let staging_hash = blake2sum(&nonversioned_encode(&self.staging).unwrap()[..]);
+ let staging_hash = self.calculate_staging_hash();
if staging_hash != self.staging_hash {
- return false;
+ return Err("staging_hash is incorrect".into());
}
// Check that node_id_vec contains the correct list of nodes
@@ -198,472 +440,794 @@ To know the correct value of the new layout version, invoke `garage layout show`
let mut node_id_vec = self.node_id_vec.clone();
node_id_vec.sort();
if expected_nodes != node_id_vec {
- return false;
+ return Err(format!("node_id_vec does not contain the correct set of nodes\nnode_id_vec: {:?}\nexpected: {:?}", node_id_vec, expected_nodes));
}
- // 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 assignment data has the correct length
+ let expected_assignment_data_len = (1 << PARTITION_BITS) * self.replication_factor;
+ if self.ring_assignment_data.len() != expected_assignment_data_len {
+ return Err(format!(
+ "ring_assignment_data has incorrect length {} instead of {}",
+ self.ring_assignment_data.len(),
+ expected_assignment_data_len
+ ));
}
// 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() {
+ for x in self.ring_assignment_data.iter() {
if *x as usize >= self.node_id_vec.len() {
- return false;
+ return Err(format!(
+ "ring_assignment_data contains invalid node id {}",
+ *x
+ ));
}
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,
+ _ => return Err("ring_assignment_data contains id of a gateway node".into()),
}
}
- true
- }
+ // Check that every partition is associated to distinct nodes
+ let rf = self.replication_factor;
+ for p in 0..(1 << PARTITION_BITS) {
+ let nodes_of_p = self.ring_assignment_data[rf * p..rf * (p + 1)].to_vec();
+ if nodes_of_p.iter().unique().count() != rf {
+ return Err(format!("partition does not contain {} unique node ids", rf));
+ }
+ // Check that every partition is spread over at least zone_redundancy zones.
+ let zones_of_p = nodes_of_p
+ .iter()
+ .map(|n| {
+ self.get_node_zone(&self.node_id_vec[*n as usize])
+ .expect("Zone not found.")
+ })
+ .collect::<Vec<_>>();
+ let redundancy = self.parameters.zone_redundancy;
+ if zones_of_p.iter().unique().count() < redundancy {
+ return Err(format!(
+ "nodes of partition are in less than {} distinct zones",
+ redundancy
+ ));
+ }
+ }
- /// 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();
+ // Check that the nodes capacities is consistent with the stored partitions
+ let mut node_usage = vec![0; MAX_NODE_NUMBER];
+ for n in self.ring_assignment_data.iter() {
+ node_usage[*n as usize] += 1;
+ }
+ for (n, usage) in node_usage.iter().enumerate() {
+ if *usage > 0 {
+ let uuid = self.node_id_vec[n];
+ let partusage = usage * self.partition_size;
+ let nodecap = self.get_node_capacity(&uuid).unwrap();
+ if partusage > nodecap {
+ return Err(format!(
+ "node usage ({}) is bigger than node capacity ({})",
+ usage * self.partition_size,
+ nodecap
+ ));
+ }
+ }
+ }
- println!("Calculating updated partition assignation, this may take some time...");
- println!();
+ // Check that the partition size stored is the one computed by the asignation
+ // algorithm.
+ let cl2 = self.clone();
+ let (_, zone_to_id) = cl2.generate_nongateway_zone_ids().unwrap();
+ match cl2.compute_optimal_partition_size(&zone_to_id) {
+ Ok(s) if s != self.partition_size => {
+ return Err(format!(
+ "partition_size ({}) is different than optimal value ({})",
+ self.partition_size, s
+ ))
+ }
+ Err(e) => return Err(format!("could not calculate optimal partition size: {}", e)),
+ _ => (),
+ }
- // Get old partition assignation
- let old_partitions = self.parse_assignation_data();
+ Ok(())
+ }
+}
- // Start new partition assignation with nodes from old assignation where it is relevant
- let mut partitions = old_partitions
- .iter()
- .map(|old_part| {
- let mut new_part = PartitionAss::new();
- for node in old_part.nodes.iter() {
- if let Some(role) = node.1 {
- if role.capacity.is_some() {
- new_part.add(None, n_zones, node.0, role);
- }
- }
- }
- new_part
- })
- .collect::<Vec<_>>();
+// Implementation of the ClusterLayout methods related to the assignment algorithm.
+impl ClusterLayout {
+ /// This function calculates a new partition-to-node assignment.
+ /// The computed assignment respects the node replication factor
+ /// and the zone redundancy parameter It maximizes the capacity of a
+ /// partition (assuming all partitions have the same size).
+ /// Among such optimal assignment, it minimizes the distance to
+ /// the former assignment (if any) to minimize the amount of
+ /// data to be moved.
+ /// Staged role changes must be merged with nodes roles before calling this function,
+ /// hence it must only be called from apply_staged_changes() and hence is not public.
+ fn calculate_partition_assignment(&mut self) -> Result<Message, Error> {
+ // We update the node ids, since the node role list might have changed with the
+ // changes in the layout. We retrieve the old_assignment reframed with new ids
+ let old_assignment_opt = self.update_node_id_vec()?;
+
+ let mut msg = Message::new();
+ msg.push("==== COMPUTATION OF A NEW PARTITION ASSIGNATION ====".into());
+ msg.push("".into());
+ msg.push(format!(
+ "Partitions are \
+ replicated {} times on at least {} distinct zones.",
+ self.replication_factor, self.parameters.zone_redundancy
+ ));
+
+ // We generate for once numerical ids for the zones of non gateway nodes,
+ // to use them as indices in the flow graphs.
+ let (id_to_zone, zone_to_id) = self.generate_nongateway_zone_ids()?;
+
+ let nb_nongateway_nodes = self.nongateway_nodes().len();
+ if nb_nongateway_nodes < self.replication_factor {
+ return Err(Error::Message(format!(
+ "The number of nodes with positive \
+ capacity ({}) is smaller than the replication factor ({}).",
+ nb_nongateway_nodes, self.replication_factor
+ )));
+ }
+ if id_to_zone.len() < self.parameters.zone_redundancy {
+ return Err(Error::Message(format!(
+ "The number of zones with non-gateway \
+ nodes ({}) is smaller than the redundancy parameter ({})",
+ id_to_zone.len(),
+ self.parameters.zone_redundancy
+ )));
+ }
- // In various cases, not enough nodes will have been added for all partitions
- // in the step above (e.g. due to node removals, or new zones being added).
- // Here we add more nodes to make a complete (but 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 _ in 0..2 {
- for (id, info) in ipart.nodes.iter() {
- if part.nodes.len() < self.replication_factor {
- part.add(None, n_zones, id, info.unwrap());
- }
- }
- }
- assert!(part.nodes.len() == self.replication_factor);
- }
- }
- None => {
- // Not enough nodes in cluster to build a correct assignation.
- // Signal it by returning an error.
- return false;
- }
+ // We compute the optimal partition size
+ // Capacities should be given in a unit so that partition size is at least 100.
+ // In this case, integer rounding plays a marginal role in the percentages of
+ // optimality.
+ let partition_size = self.compute_optimal_partition_size(&zone_to_id)?;
+
+ if old_assignment_opt != None {
+ msg.push(format!(
+ "Optimal size of a partition: {} (was {} in the previous layout).",
+ ByteSize::b(partition_size).to_string_as(false),
+ ByteSize::b(self.partition_size).to_string_as(false)
+ ));
+ } else {
+ msg.push(format!(
+ "Given the replication and redundancy constraints, the \
+ optimal size of a partition is {}.",
+ ByteSize::b(partition_size).to_string_as(false)
+ ));
+ }
+ // We write the partition size.
+ self.partition_size = partition_size;
+
+ if partition_size < 100 {
+ msg.push(
+ "WARNING: The partition size is low (< 100), make sure the capacities of your nodes are correct and are of at least a few MB"
+ .into(),
+ );
}
- // 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 errratio = |node, parts| {
- let tgt = *target_partitions_per_node.get(node).unwrap() as f32;
- (parts - tgt) / tgt
- };
- let square = |x| x * x;
-
- let partsrm = partitions_per_node.get(*idrm).cloned().unwrap_or(0) as f32;
-
- 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;
- }
+ // We compute a first flow/assignment that is heuristically close to the previous
+ // assignment
+ let mut gflow = self.compute_candidate_assignment(&zone_to_id, &old_assignment_opt)?;
+ if let Some(assoc) = &old_assignment_opt {
+ // We minimize the distance to the previous assignment.
+ self.minimize_rebalance_load(&mut gflow, &zone_to_id, assoc)?;
+ }
- // We want to try replacing node idrm by node idadd
- // if that brings us close to our goal.
- let partsadd = partitions_per_node.get(*idadd).cloned().unwrap_or(0) as f32;
- let oldcost = square(errratio(*idrm, partsrm) - errratio(*idadd, partsadd));
- let newcost =
- square(errratio(*idrm, partsrm - 1.) - errratio(*idadd, partsadd + 1.));
- if newcost >= oldcost {
- // not closer to our goal
- continue;
- }
- let gain = oldcost - newcost;
+ // We display statistics of the computation
+ msg.extend(self.output_stat(&gflow, &old_assignment_opt, &zone_to_id, &id_to_zone)?);
+ msg.push("".to_string());
- let mut newpart = part.clone();
+ // We update the layout structure
+ self.update_ring_from_flow(id_to_zone.len(), &gflow)?;
- newpart.nodes.remove(irm);
- if !newpart.add(None, n_zones, idadd, infoadd) {
- continue;
- }
- assert!(newpart.nodes.len() == self.replication_factor);
+ if let Err(e) = self.check() {
+ return Err(Error::Message(
+ format!("Layout check returned an error: {}\nOriginal result of computation: <<<<\n{}\n>>>>", e, msg.join("\n"))
+ ));
+ }
- if !old_partitions[i]
- .is_valid_transition_to(&newpart, self.replication_factor)
- {
- continue;
- }
+ Ok(msg)
+ }
- 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;
- }
+ /// The LwwMap of node roles might have changed. This function updates the node_id_vec
+ /// and returns the assignment given by ring, with the new indices of the nodes, and
+ /// None if the node is not present anymore.
+ /// We work with the assumption that only this function and calculate_new_assignment
+ /// do modify assignment_ring and node_id_vec.
+ fn update_node_id_vec(&mut self) -> Result<Option<Vec<Vec<usize>>>, Error> {
+ // (1) We compute the new node list
+ // Non gateway nodes should be coded on 8bits, hence they must be first in the list
+ // We build the new node ids
+ let new_non_gateway_nodes: Vec<Uuid> = self
+ .roles
+ .items()
+ .iter()
+ .filter(|(_, _, v)| matches!(&v.0, Some(r) if r.capacity != None))
+ .map(|(k, _, _)| *k)
+ .collect();
+
+ if new_non_gateway_nodes.len() > MAX_NODE_NUMBER {
+ return Err(Error::Message(format!(
+ "There are more than {} non-gateway nodes in the new \
+ layout. This is not allowed.",
+ MAX_NODE_NUMBER
+ )));
}
- // 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
+ let new_gateway_nodes: Vec<Uuid> = self
+ .roles
+ .items()
.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() {
- let tgt = *target_partitions_per_node.get(node).unwrap();
- let pct = 100f32 * (*npart as f32) / (tgt as f32);
- println!("{:?}\t{}\t({}% of {})", node, npart, pct as i32, tgt);
- }
- 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;
- }
+ .filter(|(_, _, v)| matches!(v, NodeRoleV(Some(r)) if r.capacity == None))
+ .map(|(k, _, _)| *k)
+ .collect();
+
+ let mut new_node_id_vec = Vec::<Uuid>::new();
+ new_node_id_vec.extend(new_non_gateway_nodes);
+ new_node_id_vec.extend(new_gateway_nodes);
+
+ let old_node_id_vec = self.node_id_vec.clone();
+ self.node_id_vec = new_node_id_vec.clone();
+
+ // (2) We retrieve the old association
+ // We rewrite the old association with the new indices. We only consider partition
+ // to node assignments where the node is still in use.
+ if self.ring_assignment_data.is_empty() {
+ // This is a new association
+ return Ok(None);
}
- 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);
- }
+
+ if self.ring_assignment_data.len() != NB_PARTITIONS * self.replication_factor {
+ return Err(Error::Message(
+ "The old assignment does not have a size corresponding to \
+ the old replication factor or the number of partitions."
+ .into(),
+ ));
+ }
+
+ // We build a translation table between the uuid and new ids
+ let mut uuid_to_new_id = HashMap::<Uuid, usize>::new();
+
+ // We add the indices of only the new non-gateway nodes that can be used in the
+ // association ring
+ for (i, uuid) in new_node_id_vec.iter().enumerate() {
+ uuid_to_new_id.insert(*uuid, i);
}
- println!();
- // Calculate and save new assignation data
- let (nodes, assignation_data) =
- self.compute_assignation_data(&configured_nodes[..], &partitions[..]);
+ let mut old_assignment = vec![Vec::<usize>::new(); NB_PARTITIONS];
+ let rf = self.replication_factor;
- self.node_id_vec = nodes;
- self.ring_assignation_data = assignation_data;
+ for (p, old_assign_p) in old_assignment.iter_mut().enumerate() {
+ for old_id in &self.ring_assignment_data[p * rf..(p + 1) * rf] {
+ let uuid = old_node_id_vec[*old_id as usize];
+ if uuid_to_new_id.contains_key(&uuid) {
+ old_assign_p.push(uuid_to_new_id[&uuid]);
+ }
+ }
+ }
- true
+ // We write the ring
+ self.ring_assignment_data = Vec::<CompactNodeType>::new();
+
+ Ok(Some(old_assignment))
}
- fn initial_partition_assignation(&self) -> Option<Vec<PartitionAss<'_>>> {
- let (configured_nodes, zones) = self.configured_nodes_and_zones();
- let n_zones = zones.len();
+ /// This function generates ids for the zone of the nodes appearing in
+ /// self.node_id_vec.
+ fn generate_nongateway_zone_ids(&self) -> Result<(Vec<String>, HashMap<String, usize>), Error> {
+ let mut id_to_zone = Vec::<String>::new();
+ let mut zone_to_id = HashMap::<String, usize>::new();
+
+ for uuid in self.nongateway_nodes().iter() {
+ let r = self.node_role(uuid).unwrap();
+ if !zone_to_id.contains_key(&r.zone) && r.capacity != None {
+ zone_to_id.insert(r.zone.clone(), id_to_zone.len());
+ id_to_zone.push(r.zone.clone());
+ }
+ }
+ Ok((id_to_zone, zone_to_id))
+ }
- // Create a vector of partition indices (0 to 2**PARTITION_BITS-1)
- let partitions_idx = (0usize..(1usize << PARTITION_BITS)).collect::<Vec<_>>();
+ /// This function computes by dichotomy the largest realizable partition size, given
+ /// the layout roles and parameters.
+ fn compute_optimal_partition_size(
+ &self,
+ zone_to_id: &HashMap<String, usize>,
+ ) -> Result<u64, Error> {
+ let empty_set = HashSet::<(usize, usize)>::new();
+ let mut g = self.generate_flow_graph(1, zone_to_id, &empty_set)?;
+ g.compute_maximal_flow()?;
+ if g.get_flow_value()? < (NB_PARTITIONS * self.replication_factor) as i64 {
+ return Err(Error::Message(
+ "The storage capacity of he cluster is to small. It is \
+ impossible to store partitions of size 1."
+ .into(),
+ ));
+ }
- // Prepare ring
- let mut partitions: Vec<PartitionAss> = partitions_idx
- .iter()
- .map(|_i| PartitionAss::new())
- .collect::<Vec<_>>();
+ let mut s_down = 1;
+ let mut s_up = self.get_total_capacity()?;
+ while s_down + 1 < s_up {
+ g = self.generate_flow_graph((s_down + s_up) / 2, zone_to_id, &empty_set)?;
+ g.compute_maximal_flow()?;
+ if g.get_flow_value()? < (NB_PARTITIONS * self.replication_factor) as i64 {
+ s_up = (s_down + s_up) / 2;
+ } else {
+ s_down = (s_down + s_up) / 2;
+ }
+ }
- // 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<_>>();
+ Ok(s_down)
+ }
- 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;
+ fn generate_graph_vertices(nb_zones: usize, nb_nodes: usize) -> Vec<Vertex> {
+ let mut vertices = vec![Vertex::Source, Vertex::Sink];
+ for p in 0..NB_PARTITIONS {
+ vertices.push(Vertex::Pup(p));
+ vertices.push(Vertex::Pdown(p));
+ for z in 0..nb_zones {
+ vertices.push(Vertex::PZ(p, z));
}
+ }
+ for n in 0..nb_nodes {
+ vertices.push(Vertex::N(n));
+ }
+ vertices
+ }
- 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(Some(rep + 1), n_zones, node_id, node_info) {
- remaining -= 1;
- *pos = pos2 + 1;
- break;
- }
- }
- }
- }
- if remaining == remaining0 {
- // No progress made, exit
- return None;
+ /// Generates the graph to compute the maximal flow corresponding to the optimal
+ /// partition assignment.
+ /// exclude_assoc is the set of (partition, node) association that we are forbidden
+ /// to use (hence we do not add the corresponding edge to the graph). This parameter
+ /// is used to compute a first flow that uses only edges appearing in the previous
+ /// assignment. This produces a solution that heuristically should be close to the
+ /// previous one.
+ fn generate_flow_graph(
+ &self,
+ partition_size: u64,
+ zone_to_id: &HashMap<String, usize>,
+ exclude_assoc: &HashSet<(usize, usize)>,
+ ) -> Result<Graph<FlowEdge>, Error> {
+ let vertices =
+ ClusterLayout::generate_graph_vertices(zone_to_id.len(), self.nongateway_nodes().len());
+ let mut g = Graph::<FlowEdge>::new(&vertices);
+ let nb_zones = zone_to_id.len();
+ let redundancy = self.parameters.zone_redundancy;
+ for p in 0..NB_PARTITIONS {
+ g.add_edge(Vertex::Source, Vertex::Pup(p), redundancy as u64)?;
+ g.add_edge(
+ Vertex::Source,
+ Vertex::Pdown(p),
+ (self.replication_factor - redundancy) as u64,
+ )?;
+ for z in 0..nb_zones {
+ g.add_edge(Vertex::Pup(p), Vertex::PZ(p, z), 1)?;
+ g.add_edge(
+ Vertex::Pdown(p),
+ Vertex::PZ(p, z),
+ self.replication_factor as u64,
+ )?;
+ }
+ }
+ for n in 0..self.nongateway_nodes().len() {
+ let node_capacity = self.get_node_capacity(&self.node_id_vec[n])?;
+ let node_zone = zone_to_id[&self.get_node_zone(&self.node_id_vec[n])?];
+ g.add_edge(Vertex::N(n), Vertex::Sink, node_capacity / partition_size)?;
+ for p in 0..NB_PARTITIONS {
+ if !exclude_assoc.contains(&(p, n)) {
+ g.add_edge(Vertex::PZ(p, node_zone), Vertex::N(n), 1)?;
}
}
}
-
- Some(partitions)
+ Ok(g)
}
- 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)>>();
+ /// This function computes a first optimal assignment (in the form of a flow graph).
+ fn compute_candidate_assignment(
+ &self,
+ zone_to_id: &HashMap<String, usize>,
+ prev_assign_opt: &Option<Vec<Vec<usize>>>,
+ ) -> Result<Graph<FlowEdge>, Error> {
+ // We list the (partition,node) associations that are not used in the
+ // previous assignment
+ let mut exclude_edge = HashSet::<(usize, usize)>::new();
+ if let Some(prev_assign) = prev_assign_opt {
+ let nb_nodes = self.nongateway_nodes().len();
+ for (p, prev_assign_p) in prev_assign.iter().enumerate() {
+ for n in 0..nb_nodes {
+ exclude_edge.insert((p, n));
+ }
+ for n in prev_assign_p.iter() {
+ exclude_edge.remove(&(p, *n));
+ }
+ }
+ }
- let zones = configured_nodes
- .iter()
- .filter(|(_id, info)| info.capacity.is_some())
- .map(|(_id, info)| info.zone.as_str())
- .collect::<HashSet<&str>>();
+ // We compute the best flow using only the edges used in the previous assignment
+ let mut g = self.generate_flow_graph(self.partition_size, zone_to_id, &exclude_edge)?;
+ g.compute_maximal_flow()?;
- (configured_nodes, zones)
+ // We add the excluded edges and compute the maximal flow with the full graph.
+ // The algorithm is such that it will start with the flow that we just computed
+ // and find ameliorating paths from that.
+ for (p, n) in exclude_edge.iter() {
+ let node_zone = zone_to_id[&self.get_node_zone(&self.node_id_vec[*n])?];
+ g.add_edge(Vertex::PZ(*p, node_zone), Vertex::N(*n), 1)?;
+ }
+ g.compute_maximal_flow()?;
+ Ok(g)
}
- fn compute_assignation_data<'a>(
+ /// This function updates the flow graph gflow to minimize the distance between
+ /// its corresponding assignment and the previous one
+ fn minimize_rebalance_load(
&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());
+ gflow: &mut Graph<FlowEdge>,
+ zone_to_id: &HashMap<String, usize>,
+ prev_assign: &[Vec<usize>],
+ ) -> Result<(), Error> {
+ // We define a cost function on the edges (pairs of vertices) corresponding
+ // to the distance between the two assignments.
+ let mut cost = CostFunction::new();
+ for (p, assoc_p) in prev_assign.iter().enumerate() {
+ for n in assoc_p.iter() {
+ let node_zone = zone_to_id[&self.get_node_zone(&self.node_id_vec[*n])?];
+ cost.insert((Vertex::PZ(p, node_zone), Vertex::N(*n)), -1);
}
}
- nodes.extend(
- configured_nodes
- .iter()
- .filter(|(_id, info)| info.capacity.is_none())
- .map(|(id, _)| **id),
- );
+ // We compute the maximal length of a simple path in gflow. It is used in the
+ // Bellman-Ford algorithm in optimize_flow_with_cost to set the number
+ // of iterations.
+ let nb_nodes = self.nongateway_nodes().len();
+ let path_length = 4 * nb_nodes;
+ gflow.optimize_flow_with_cost(&cost, path_length)?;
- (nodes, assignation_data)
+ Ok(())
}
- 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));
+ /// This function updates the assignment ring from the flow graph.
+ fn update_ring_from_flow(
+ &mut self,
+ nb_zones: usize,
+ gflow: &Graph<FlowEdge>,
+ ) -> Result<(), Error> {
+ self.ring_assignment_data = Vec::<CompactNodeType>::new();
+ for p in 0..NB_PARTITIONS {
+ for z in 0..nb_zones {
+ let assoc_vertex = gflow.get_positive_flow_from(Vertex::PZ(p, z))?;
+ for vertex in assoc_vertex.iter() {
+ if let Vertex::N(n) = vertex {
+ self.ring_assignment_data.push((*n).try_into().unwrap());
}
}
- partitions.push(part);
}
- partitions
- } else {
- // Otherwise start fresh
- (0..(1 << PARTITION_BITS))
- .map(|_| PartitionAss::new())
- .collect()
}
+
+ if self.ring_assignment_data.len() != NB_PARTITIONS * self.replication_factor {
+ return Err(Error::Message(
+ "Critical Error : the association ring we produced does not \
+ have the right size."
+ .into(),
+ ));
+ }
+ Ok(())
}
- 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;
+ /// This function returns a message summing up the partition repartition of the new
+ /// layout, and other statistics of the partition assignment computation.
+ fn output_stat(
+ &self,
+ gflow: &Graph<FlowEdge>,
+ prev_assign_opt: &Option<Vec<Vec<usize>>>,
+ zone_to_id: &HashMap<String, usize>,
+ id_to_zone: &[String],
+ ) -> Result<Message, Error> {
+ let mut msg = Message::new();
+
+ let used_cap = self.partition_size * NB_PARTITIONS as u64 * self.replication_factor as u64;
+ let total_cap = self.get_total_capacity()?;
+ let percent_cap = 100.0 * (used_cap as f32) / (total_cap as f32);
+ msg.push("".into());
+ msg.push(format!(
+ "Usable capacity / Total cluster capacity: {} / {} ({:.1} %)",
+ ByteSize::b(used_cap).to_string_as(false),
+ ByteSize::b(total_cap).to_string_as(false),
+ percent_cap
+ ));
+ msg.push("".into());
+ msg.push(
+ "If the percentage is too low, it might be that the \
+ replication/redundancy constraints force the use of nodes/zones with small \
+ storage capacities. \
+ You might want to rebalance the storage capacities or relax the constraints. \
+ See the detailed statistics below and look for saturated nodes/zones."
+ .into(),
+ );
+ msg.push(format!(
+ "Recall that because of the replication factor, the actual available \
+ storage capacity is {} / {} = {}.",
+ ByteSize::b(used_cap).to_string_as(false),
+ self.replication_factor,
+ ByteSize::b(used_cap / self.replication_factor as u64).to_string_as(false)
+ ));
+
+ // We define and fill in the following tables
+ let storing_nodes = self.nongateway_nodes();
+ let mut new_partitions = vec![0; storing_nodes.len()];
+ let mut stored_partitions = vec![0; storing_nodes.len()];
+
+ let mut new_partitions_zone = vec![0; id_to_zone.len()];
+ let mut stored_partitions_zone = vec![0; id_to_zone.len()];
+
+ for p in 0..NB_PARTITIONS {
+ for z in 0..id_to_zone.len() {
+ let pz_nodes = gflow.get_positive_flow_from(Vertex::PZ(p, z))?;
+ if !pz_nodes.is_empty() {
+ stored_partitions_zone[z] += 1;
+ if let Some(prev_assign) = prev_assign_opt {
+ let mut old_zones_of_p = Vec::<usize>::new();
+ for n in prev_assign[p].iter() {
+ old_zones_of_p
+ .push(zone_to_id[&self.get_node_zone(&self.node_id_vec[*n])?]);
+ }
+ if !old_zones_of_p.contains(&z) {
+ new_partitions_zone[z] += 1;
+ }
+ }
+ }
+ for vert in pz_nodes.iter() {
+ if let Vertex::N(n) = *vert {
+ stored_partitions[n] += 1;
+ if let Some(prev_assign) = prev_assign_opt {
+ if !prev_assign[p].contains(&n) {
+ new_partitions[n] += 1;
+ }
+ }
+ }
+ }
+ }
+ }
+
+ if *prev_assign_opt == None {
+ new_partitions = stored_partitions.clone();
+ new_partitions_zone = stored_partitions_zone.clone();
+ }
+
+ // We display the statistics
+
+ msg.push("".into());
+ if *prev_assign_opt != None {
+ let total_new_partitions: usize = new_partitions.iter().sum();
+ msg.push(format!(
+ "A total of {} new copies of partitions need to be \
+ transferred.",
+ total_new_partitions
+ ));
+ }
+ msg.push("".into());
+ msg.push("==== DETAILED STATISTICS BY ZONES AND NODES ====".into());
+
+ for z in 0..id_to_zone.len() {
+ let mut nodes_of_z = Vec::<usize>::new();
+ for n in 0..storing_nodes.len() {
+ if self.get_node_zone(&self.node_id_vec[n])? == id_to_zone[z] {
+ nodes_of_z.push(n);
+ }
+ }
+ let replicated_partitions: usize =
+ nodes_of_z.iter().map(|n| stored_partitions[*n]).sum();
+ msg.push("".into());
+
+ msg.push(format!(
+ "Zone {}: {} distinct partitions stored ({} new, \
+ {} partition copies) ",
+ id_to_zone[z],
+ stored_partitions_zone[z],
+ new_partitions_zone[z],
+ replicated_partitions
+ ));
+
+ let available_cap_z: u64 = self.partition_size * replicated_partitions as u64;
+ let mut total_cap_z = 0;
+ for n in nodes_of_z.iter() {
+ total_cap_z += self.get_node_capacity(&self.node_id_vec[*n])?;
+ }
+ let percent_cap_z = 100.0 * (available_cap_z as f32) / (total_cap_z as f32);
+ msg.push(format!(
+ " Usable capacity / Total capacity: {} / {} ({:.1}%).",
+ ByteSize::b(available_cap_z).to_string_as(false),
+ ByteSize::b(total_cap_z).to_string_as(false),
+ percent_cap_z
+ ));
+
+ for n in nodes_of_z.iter() {
+ let available_cap_n = stored_partitions[*n] as u64 * self.partition_size;
+ let total_cap_n = self.get_node_capacity(&self.node_id_vec[*n])?;
+ let tags_n = (self
+ .node_role(&self.node_id_vec[*n])
+ .ok_or("Node not found."))?
+ .tags_string();
+ msg.push(format!(
+ " Node {:?}: {} partitions ({} new) ; \
+ usable/total capacity: {} / {} ({:.1}%) ; tags:{}",
+ self.node_id_vec[*n],
+ stored_partitions[*n],
+ new_partitions[*n],
+ ByteSize::b(available_cap_n).to_string_as(false),
+ ByteSize::b(total_cap_n).to_string_as(false),
+ (available_cap_n as f32) / (total_cap_n as f32) * 100.0,
+ tags_n
+ ));
}
}
- partitions_per_node
+
+ Ok(msg)
}
}
-// ---- Internal structs for partition assignation in layout ----
+// ====================================================================================
+
+#[cfg(test)]
+mod tests {
+ use super::{Error, *};
+ use std::cmp::min;
+
+ // This function checks that the partition size S computed is at least better than the
+ // one given by a very naive algorithm. To do so, we try to run the naive algorithm
+ // assuming a partion size of S+1. If we succed, it means that the optimal assignment
+ // was not optimal. The naive algorithm is the following :
+ // - we compute the max number of partitions associated to every node, capped at the
+ // partition number. It gives the number of tokens of every node.
+ // - every zone has a number of tokens equal to the sum of the tokens of its nodes.
+ // - we cycle over the partitions and associate zone tokens while respecting the
+ // zone redundancy constraint.
+ // NOTE: the naive algorithm is not optimal. Counter example:
+ // take nb_partition = 3 ; replication_factor = 5; redundancy = 4;
+ // number of tokens by zone : (A, 4), (B,1), (C,4), (D, 4), (E, 2)
+ // With these parameters, the naive algo fails, whereas there is a solution:
+ // (A,A,C,D,E) , (A,B,C,D,D) (A,C,C,D,E)
+ fn check_against_naive(cl: &ClusterLayout) -> Result<bool, Error> {
+ let over_size = cl.partition_size + 1;
+ let mut zone_token = HashMap::<String, usize>::new();
+
+ let (zones, zone_to_id) = cl.generate_nongateway_zone_ids()?;
+
+ if zones.is_empty() {
+ return Ok(false);
+ }
-#[derive(Clone)]
-struct PartitionAss<'a> {
- nodes: Vec<(&'a Uuid, Option<&'a NodeRole>)>,
-}
+ for z in zones.iter() {
+ zone_token.insert(z.clone(), 0);
+ }
+ for uuid in cl.nongateway_nodes().iter() {
+ let z = cl.get_node_zone(uuid)?;
+ let c = cl.get_node_capacity(uuid)?;
+ zone_token.insert(
+ z.clone(),
+ zone_token[&z] + min(NB_PARTITIONS, (c / over_size) as usize),
+ );
+ }
-impl<'a> PartitionAss<'a> {
- fn new() -> Self {
- Self { nodes: Vec::new() }
- }
+ // For every partition, we count the number of zone already associated and
+ // the name of the last zone associated
- fn nplus(&self, other: &PartitionAss<'a>) -> usize {
- self.nodes
- .iter()
- .filter(|x| !other.nodes.contains(x))
- .count()
- }
+ let mut id_zone_token = vec![0; zones.len()];
+ for (z, t) in zone_token.iter() {
+ id_zone_token[zone_to_id[z]] = *t;
+ }
- 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());
+ let mut nb_token = vec![0; NB_PARTITIONS];
+ let mut last_zone = vec![zones.len(); NB_PARTITIONS];
+
+ let mut curr_zone = 0;
+
+ let redundancy = cl.parameters.zone_redundancy;
+
+ for replic in 0..cl.replication_factor {
+ for p in 0..NB_PARTITIONS {
+ while id_zone_token[curr_zone] == 0
+ || (last_zone[p] == curr_zone
+ && redundancy - nb_token[p] <= cl.replication_factor - replic)
+ {
+ curr_zone += 1;
+ if curr_zone >= zones.len() {
+ return Ok(true);
+ }
+ }
+ id_zone_token[curr_zone] -= 1;
+ if last_zone[p] != curr_zone {
+ nb_token[p] += 1;
+ last_zone[p] = curr_zone;
+ }
+ }
}
- 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);
+ return Ok(false);
+ }
- if self.nodes.len() <= min_keep_nodes_per_part {
- n_removed == 0
- } else {
- n_removed <= self.nodes.len() - min_keep_nodes_per_part
+ fn show_msg(msg: &Message) {
+ for s in msg.iter() {
+ println!("{}", s);
}
}
- // add is a key function in creating a PartitionAss, i.e. the list of nodes
- // to which a partition is assigned. It tries to add a certain node id to the
- // assignation, but checks that doing so is compatible with the NECESSARY
- // condition that the partition assignation must be dispersed over different
- // zones (datacenters) if enough zones exist. This is why it takes a n_zones
- // parameter, which is the total number of zones that have existing nodes:
- // if nodes in the assignation already cover all n_zones zones, then any node
- // that is not yet in the assignation can be added. Otherwise, only nodes
- // that are in a new zone can be added.
- fn add(
- &mut self,
- target_len: Option<usize>,
- n_zones: usize,
- node: &'a Uuid,
- role: &'a NodeRole,
- ) -> bool {
- if let Some(tl) = target_len {
- if self.nodes.len() != tl - 1 {
- return false;
+ fn update_layout(
+ cl: &mut ClusterLayout,
+ node_id_vec: &Vec<u8>,
+ node_capacity_vec: &Vec<u64>,
+ node_zone_vec: &Vec<String>,
+ zone_redundancy: usize,
+ ) {
+ for i in 0..node_id_vec.len() {
+ if let Some(x) = FixedBytes32::try_from(&[i as u8; 32]) {
+ cl.node_id_vec.push(x);
}
- }
- 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
+ let update = cl.staging_roles.update_mutator(
+ cl.node_id_vec[i],
+ NodeRoleV(Some(NodeRole {
+ zone: (node_zone_vec[i].to_string()),
+ capacity: (Some(node_capacity_vec[i])),
+ tags: (vec![]),
+ })),
+ );
+ cl.staging_roles.merge(&update);
}
+ cl.staging_parameters
+ .update(LayoutParameters { zone_redundancy });
+ cl.staging_hash = cl.calculate_staging_hash();
+ }
+
+ #[test]
+ fn test_assignment() {
+ let mut node_id_vec = vec![1, 2, 3];
+ let mut node_capacity_vec = vec![4000, 1000, 2000];
+ let mut node_zone_vec = vec!["A", "B", "C"]
+ .into_iter()
+ .map(|x| x.to_string())
+ .collect();
+
+ let mut cl = ClusterLayout::new(3);
+ update_layout(&mut cl, &node_id_vec, &node_capacity_vec, &node_zone_vec, 3);
+ let v = cl.version;
+ let (mut cl, msg) = cl.apply_staged_changes(Some(v + 1)).unwrap();
+ show_msg(&msg);
+ assert_eq!(cl.check(), Ok(()));
+ assert!(matches!(check_against_naive(&cl), Ok(true)));
+
+ node_id_vec = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
+ node_capacity_vec = vec![4000, 1000, 1000, 3000, 1000, 1000, 2000, 10000, 2000];
+ node_zone_vec = vec!["A", "B", "C", "C", "C", "B", "G", "H", "I"]
+ .into_iter()
+ .map(|x| x.to_string())
+ .collect();
+ update_layout(&mut cl, &node_id_vec, &node_capacity_vec, &node_zone_vec, 2);
+ let v = cl.version;
+ let (mut cl, msg) = cl.apply_staged_changes(Some(v + 1)).unwrap();
+ show_msg(&msg);
+ assert_eq!(cl.check(), Ok(()));
+ assert!(matches!(check_against_naive(&cl), Ok(true)));
+
+ node_capacity_vec = vec![4000, 1000, 2000, 7000, 1000, 1000, 2000, 10000, 2000];
+ update_layout(&mut cl, &node_id_vec, &node_capacity_vec, &node_zone_vec, 3);
+ let v = cl.version;
+ let (mut cl, msg) = cl.apply_staged_changes(Some(v + 1)).unwrap();
+ show_msg(&msg);
+ assert_eq!(cl.check(), Ok(()));
+ assert!(matches!(check_against_naive(&cl), Ok(true)));
+
+ node_capacity_vec = vec![
+ 4000000, 4000000, 2000000, 7000000, 1000000, 9000000, 2000000, 10000, 2000000,
+ ];
+ update_layout(&mut cl, &node_id_vec, &node_capacity_vec, &node_zone_vec, 1);
+ let v = cl.version;
+ let (cl, msg) = cl.apply_staged_changes(Some(v + 1)).unwrap();
+ show_msg(&msg);
+ assert_eq!(cl.check(), Ok(()));
+ assert!(matches!(check_against_naive(&cl), Ok(true)));
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 05:42:45 +0000