garage/src/rpc/layout/version.rs

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use std::collections::HashMap;
use std::collections::HashSet;
use std::convert::TryInto;
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use bytesize::ByteSize;
use itertools::Itertools;
use garage_util::crdt::{Crdt, LwwMap};
use garage_util::data::*;
First version of admin API (#298) **Spec:** - [x] Start writing - [x] Specify all layout endpoints - [x] Specify all endpoints for operations on keys - [x] Specify all endpoints for operations on key/bucket permissions - [x] Specify all endpoints for operations on buckets - [x] Specify all endpoints for operations on bucket aliases View rendered spec at <https://git.deuxfleurs.fr/Deuxfleurs/garage/src/branch/admin-api/doc/drafts/admin-api.md> **Code:** - [x] Refactor code for admin api to use common api code that was created for K2V **General endpoints:** - [x] Metrics - [x] GetClusterStatus - [x] ConnectClusterNodes - [x] GetClusterLayout - [x] UpdateClusterLayout - [x] ApplyClusterLayout - [x] RevertClusterLayout **Key-related endpoints:** - [x] ListKeys - [x] CreateKey - [x] ImportKey - [x] GetKeyInfo - [x] UpdateKey - [x] DeleteKey **Bucket-related endpoints:** - [x] ListBuckets - [x] CreateBucket - [x] GetBucketInfo - [x] DeleteBucket - [x] PutBucketWebsite - [x] DeleteBucketWebsite **Operations on key/bucket permissions:** - [x] BucketAllowKey - [x] BucketDenyKey **Operations on bucket aliases:** - [x] GlobalAliasBucket - [x] GlobalUnaliasBucket - [x] LocalAliasBucket - [x] LocalUnaliasBucket **And also:** - [x] Separate error type for the admin API (this PR includes a quite big refactoring of error handling) - [x] Add management of website access - [ ] Check that nothing is missing wrt what can be done using the CLI - [ ] Improve formatting of the spec - [x] Make sure everyone is cool with the API design Fix #231 Fix #295 Co-authored-by: Alex Auvolat <alex@adnab.me> Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/298 Co-authored-by: Alex <alex@adnab.me> Co-committed-by: Alex <alex@adnab.me>
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use garage_util::error::*;
use super::graph_algo::*;
use super::*;
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// The Message type will be used to collect information on the algorithm.
pub type Message = Vec<String>;
impl LayoutVersion {
pub fn new(replication_factor: usize) -> Self {
// We set the default zone redundancy to be Maximum, meaning that the maximum
// possible value will be used depending on the cluster topology
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let parameters = LayoutParameters {
zone_redundancy: ZoneRedundancy::Maximum,
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};
LayoutVersion {
version: 0,
replication_factor,
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partition_size: 0,
roles: LwwMap::new(),
node_id_vec: Vec::new(),
nongateway_node_count: 0,
ring_assignment_data: Vec::new(),
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parameters,
}
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}
// ===================== accessors ======================
First version of admin API (#298) **Spec:** - [x] Start writing - [x] Specify all layout endpoints - [x] Specify all endpoints for operations on keys - [x] Specify all endpoints for operations on key/bucket permissions - [x] Specify all endpoints for operations on buckets - [x] Specify all endpoints for operations on bucket aliases View rendered spec at <https://git.deuxfleurs.fr/Deuxfleurs/garage/src/branch/admin-api/doc/drafts/admin-api.md> **Code:** - [x] Refactor code for admin api to use common api code that was created for K2V **General endpoints:** - [x] Metrics - [x] GetClusterStatus - [x] ConnectClusterNodes - [x] GetClusterLayout - [x] UpdateClusterLayout - [x] ApplyClusterLayout - [x] RevertClusterLayout **Key-related endpoints:** - [x] ListKeys - [x] CreateKey - [x] ImportKey - [x] GetKeyInfo - [x] UpdateKey - [x] DeleteKey **Bucket-related endpoints:** - [x] ListBuckets - [x] CreateBucket - [x] GetBucketInfo - [x] DeleteBucket - [x] PutBucketWebsite - [x] DeleteBucketWebsite **Operations on key/bucket permissions:** - [x] BucketAllowKey - [x] BucketDenyKey **Operations on bucket aliases:** - [x] GlobalAliasBucket - [x] GlobalUnaliasBucket - [x] LocalAliasBucket - [x] LocalUnaliasBucket **And also:** - [x] Separate error type for the admin API (this PR includes a quite big refactoring of error handling) - [x] Add management of website access - [ ] Check that nothing is missing wrt what can be done using the CLI - [ ] Improve formatting of the spec - [x] Make sure everyone is cool with the API design Fix #231 Fix #295 Co-authored-by: Alex Auvolat <alex@adnab.me> Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/298 Co-authored-by: Alex <alex@adnab.me> Co-committed-by: Alex <alex@adnab.me>
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/// Returns a list of IDs of nodes that have a role in this
/// version of the cluster layout, including gateway nodes
pub fn all_nodes(&self) -> &[Uuid] {
&self.node_id_vec[..]
}
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/// Returns a list of IDs of nodes that have a storage capacity
/// assigned in this version of the cluster layout
pub fn nongateway_nodes(&self) -> &[Uuid] {
&self.node_id_vec[..self.nongateway_node_count]
}
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/// Returns the role of a node in the layout, if it has one
pub fn node_role(&self, node: &Uuid) -> Option<&NodeRole> {
match self.roles.get(node) {
Some(NodeRoleV(Some(v))) => Some(v),
_ => None,
}
}
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/// Returns the capacity of a node in the layout, if it has one
pub fn get_node_capacity(&self, uuid: &Uuid) -> Option<u64> {
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match self.node_role(uuid) {
Some(NodeRole {
capacity: Some(cap),
zone: _,
tags: _,
}) => Some(*cap),
_ => None,
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}
}
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/// Given a node uuids, this function returns the label of its zone if it has one
pub fn get_node_zone(&self, uuid: &Uuid) -> Option<&str> {
match self.node_role(uuid) {
Some(role) => Some(&role.zone),
_ => None,
}
}
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/// 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(),
))
}
/// 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) -> impl Iterator<Item = (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))
})
}
/// Return the n servers in which data for this hash should be replicated
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pub fn nodes_of(&self, position: &Hash, n: usize) -> impl Iterator<Item = Uuid> + '_ {
assert_eq!(n, self.replication_factor);
let data = &self.ring_assignment_data;
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let partition_nodes = if data.len() == self.replication_factor * (1 << PARTITION_BITS) {
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;
&data[partition_start..partition_end]
} else {
warn!("Ring not yet ready, read/writes will be lost!");
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&[]
};
partition_nodes
.iter()
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.map(move |i| self.node_id_vec[*i as usize])
}
// ===================== internal information extractors ======================
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pub(crate) fn expect_get_node_capacity(&self, uuid: &Uuid) -> u64 {
self.get_node_capacity(&uuid)
.expect("non-gateway node with zero capacity")
}
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pub(crate) fn expect_get_node_zone(&self, uuid: &Uuid) -> &str {
self.get_node_zone(&uuid).expect("node without a zone")
}
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/// Returns the sum of capacities of non gateway nodes in the cluster
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fn get_total_capacity(&self) -> u64 {
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let mut total_capacity = 0;
for uuid in self.nongateway_nodes() {
total_capacity += self.expect_get_node_capacity(&uuid);
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}
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total_capacity
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}
/// Returns the effective value of the zone_redundancy parameter
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pub(crate) fn effective_zone_redundancy(&self) -> usize {
match self.parameters.zone_redundancy {
ZoneRedundancy::AtLeast(v) => v,
ZoneRedundancy::Maximum => {
let n_zones = self
.roles
.items()
.iter()
.filter_map(|(_, _, role)| role.0.as_ref().map(|x| x.zone.as_str()))
.collect::<HashSet<&str>>()
.len();
std::cmp::min(n_zones, self.replication_factor)
}
}
}
/// Check a cluster layout for internal consistency
/// (assignment, roles, parameters, partition size)
/// returns true if consistent, false if error
pub fn check(&self) -> Result<(), String> {
// 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 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 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 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_assignment_data.iter() {
if *x as usize >= self.node_id_vec.len() {
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 Err("ring_assignment_data contains id of a gateway node".into()),
}
}
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// Check that every partition is associated to distinct nodes
let zone_redundancy = self.effective_zone_redundancy();
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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();
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if nodes_of_p.iter().unique().count() != rf {
return Err(format!("partition does not contain {} unique node ids", rf));
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}
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// Check that every partition is spread over at least zone_redundancy zones.
let zones_of_p = nodes_of_p
.iter()
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.map(|n| self.expect_get_node_zone(&self.node_id_vec[*n as usize]))
.collect::<Vec<_>>();
if zones_of_p.iter().unique().count() < zone_redundancy {
return Err(format!(
"nodes of partition are in less than {} distinct zones",
zone_redundancy
));
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}
}
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// Check that the nodes capacities is consistent with the stored partitions
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let mut node_usage = vec![0; MAX_NODE_NUMBER];
for n in self.ring_assignment_data.iter() {
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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.expect_get_node_capacity(&uuid);
if partusage > nodecap {
return Err(format!(
"node usage ({}) is bigger than node capacity ({})",
usage * self.partition_size,
nodecap
));
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}
}
}
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// Check that the partition size stored is the one computed by the asignation
// algorithm.
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let cl2 = self.clone();
let (_, zone_to_id) = cl2.generate_nongateway_zone_ids().unwrap();
match cl2.compute_optimal_partition_size(&zone_to_id, zone_redundancy) {
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)),
_ => (),
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}
Ok(())
}
// ================== updates to layout, internals ===================
pub(crate) fn calculate_next_version(
mut self,
staging: &LayoutStaging,
) -> Result<(Self, Message), Error> {
self.version += 1;
self.roles.merge(&staging.roles);
self.roles.retain(|(_, _, v)| v.0.is_some());
self.parameters = *staging.parameters.get();
let msg = self.calculate_partition_assignment()?;
Ok((self, msg))
}
/// This function calculates a new partition-to-node assignment.
/// The computed assignment respects the node replication factor
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/// and the zone redundancy parameter It maximizes the capacity of a
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/// 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.
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/// 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> {
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// 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()?;
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let zone_redundancy = self.effective_zone_redundancy();
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let mut msg = Message::new();
msg.push("==== COMPUTATION OF A NEW PARTITION ASSIGNATION ====".into());
msg.push("".into());
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msg.push(format!(
"Partitions are \
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replicated {} times on at least {} distinct zones.",
self.replication_factor, zone_redundancy
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));
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// We generate for once numerical ids for the zones of non gateway nodes,
// to use them as indices in the flow graphs.
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let (id_to_zone, zone_to_id) = self.generate_nongateway_zone_ids()?;
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if self.nongateway_nodes().len() < self.replication_factor {
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return Err(Error::Message(format!(
"The number of nodes with positive \
capacity ({}) is smaller than the replication factor ({}).",
self.nongateway_nodes().len(),
self.replication_factor
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)));
}
if id_to_zone.len() < zone_redundancy {
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return Err(Error::Message(format!(
"The number of zones with non-gateway \
nodes ({}) is smaller than the redundancy parameter ({})",
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id_to_zone.len(),
zone_redundancy
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)));
}
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// 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, zone_redundancy)?;
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msg.push("".into());
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if old_assignment_opt.is_some() {
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msg.push(format!(
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"Optimal partition size: {} ({} in previous layout)",
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ByteSize::b(partition_size).to_string_as(false),
ByteSize::b(self.partition_size).to_string_as(false)
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));
} else {
msg.push(format!(
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"Optimal partition size: {}",
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ByteSize::b(partition_size).to_string_as(false)
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));
}
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// We write the partition size.
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self.partition_size = partition_size;
if partition_size < 100 {
msg.push(
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"WARNING: The partition size is low (< 100), make sure the capacities of your nodes are correct and are of at least a few MB"
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.into(),
);
}
// 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, zone_redundancy)?;
if let Some(assoc) = &old_assignment_opt {
// We minimize the distance to the previous assignment.
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self.minimize_rebalance_load(&mut gflow, &zone_to_id, assoc)?;
}
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// We display statistics of the computation
msg.extend(self.output_stat(&gflow, &old_assignment_opt, &zone_to_id, &id_to_zone)?);
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// We update the layout structure
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self.update_ring_from_flow(id_to_zone.len(), &gflow)?;
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"))
));
}
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Ok(msg)
}
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/// 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.
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fn update_node_id_vec(&mut self) -> Result<Option<Vec<Vec<usize>>>, Error> {
// (1) We compute the new node list
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// Non gateway nodes should be coded on 8bits, hence they must be first in the list
// We build the new node ids
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let new_non_gateway_nodes: Vec<Uuid> = self
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.roles
.items()
.iter()
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.filter(|(_, _, v)| matches!(&v.0, Some(r) if r.capacity.is_some()))
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.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
)));
}
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let new_gateway_nodes: Vec<Uuid> = self
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.roles
.items()
.iter()
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.filter(|(_, _, v)| matches!(v, NodeRoleV(Some(r)) if r.capacity.is_none()))
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.map(|(k, _, _)| *k)
.collect();
let old_node_id_vec = std::mem::take(&mut self.node_id_vec);
self.nongateway_node_count = new_non_gateway_nodes.len();
self.node_id_vec.clear();
self.node_id_vec.extend(new_non_gateway_nodes);
self.node_id_vec.extend(new_gateway_nodes);
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let new_node_id_vec = &self.node_id_vec;
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// (2) We retrieve the old association
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// 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() {
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// This is a new association
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return Ok(None);
}
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if self.ring_assignment_data.len() != NB_PARTITIONS * self.replication_factor {
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return Err(Error::Message(
"The old assignment does not have a size corresponding to \
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the old replication factor or the number of partitions."
.into(),
));
}
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// We build a translation table between the uuid and new ids
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let mut uuid_to_new_id = HashMap::<Uuid, usize>::new();
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// We add the indices of only the new non-gateway nodes that can be used in the
// association ring
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for (i, uuid) in new_node_id_vec.iter().enumerate() {
uuid_to_new_id.insert(*uuid, i);
}
let mut old_assignment = vec![Vec::<usize>::new(); NB_PARTITIONS];
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let rf = self.replication_factor;
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for (p, old_assign_p) in old_assignment.iter_mut().enumerate() {
for old_id in &self.ring_assignment_data[p * rf..(p + 1) * rf] {
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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]);
}
}
}
// We clear the ring assignemnt data
self.ring_assignment_data = Vec::<CompactNodeType>::new();
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Ok(Some(old_assignment))
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}
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/// This function generates ids for the zone of the nodes appearing in
/// self.node_id_vec.
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pub(crate) fn generate_nongateway_zone_ids(
&self,
) -> Result<(Vec<String>, HashMap<String, usize>), Error> {
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let mut id_to_zone = Vec::<String>::new();
let mut zone_to_id = HashMap::<String, usize>::new();
for uuid in self.nongateway_nodes().iter() {
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let r = self.node_role(uuid).unwrap();
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if !zone_to_id.contains_key(&r.zone) && r.capacity.is_some() {
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zone_to_id.insert(r.zone.clone(), id_to_zone.len());
id_to_zone.push(r.zone.clone());
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}
}
Ok((id_to_zone, zone_to_id))
}
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/// This function computes by dichotomy the largest realizable partition size, given
/// the layout roles and parameters.
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fn compute_optimal_partition_size(
&self,
zone_to_id: &HashMap<String, usize>,
zone_redundancy: usize,
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) -> Result<u64, Error> {
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let empty_set = HashSet::<(usize, usize)>::new();
let mut g = self.generate_flow_graph(1, zone_to_id, &empty_set, zone_redundancy)?;
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g.compute_maximal_flow()?;
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if g.get_flow_value()? < (NB_PARTITIONS * self.replication_factor) as i64 {
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return Err(Error::Message(
"The storage capacity of he cluster is to small. It is \
impossible to store partitions of size 1."
.into(),
));
}
let mut s_down = 1;
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let mut s_up = self.get_total_capacity();
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while s_down + 1 < s_up {
g = self.generate_flow_graph(
(s_down + s_up) / 2,
zone_to_id,
&empty_set,
zone_redundancy,
)?;
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g.compute_maximal_flow()?;
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if g.get_flow_value()? < (NB_PARTITIONS * self.replication_factor) as i64 {
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s_up = (s_down + s_up) / 2;
} else {
s_down = (s_down + s_up) / 2;
}
}
Ok(s_down)
}
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
}
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/// Generates the graph to compute the maximal flow corresponding to the optimal
/// partition assignment.
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/// 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
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/// previous one.
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fn generate_flow_graph(
&self,
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partition_size: u64,
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zone_to_id: &HashMap<String, usize>,
exclude_assoc: &HashSet<(usize, usize)>,
zone_redundancy: usize,
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) -> Result<Graph<FlowEdge>, Error> {
let vertices =
LayoutVersion::generate_graph_vertices(zone_to_id.len(), self.nongateway_nodes().len());
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let mut g = Graph::<FlowEdge>::new(&vertices);
let nb_zones = zone_to_id.len();
for p in 0..NB_PARTITIONS {
g.add_edge(Vertex::Source, Vertex::Pup(p), zone_redundancy as u64)?;
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g.add_edge(
Vertex::Source,
Vertex::Pdown(p),
(self.replication_factor - zone_redundancy) as u64,
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)?;
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),
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self.replication_factor as u64,
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)?;
}
}
for n in 0..self.nongateway_nodes().len() {
let node_capacity = self.expect_get_node_capacity(&self.node_id_vec[n]);
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let node_zone = zone_to_id[self.expect_get_node_zone(&self.node_id_vec[n])];
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g.add_edge(Vertex::N(n), Vertex::Sink, node_capacity / partition_size)?;
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for p in 0..NB_PARTITIONS {
if !exclude_assoc.contains(&(p, n)) {
g.add_edge(Vertex::PZ(p, node_zone), Vertex::N(n), 1)?;
}
}
}
Ok(g)
}
/// This function computes a first optimal assignment (in the form of a flow graph).
fn compute_candidate_assignment(
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&self,
zone_to_id: &HashMap<String, usize>,
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prev_assign_opt: &Option<Vec<Vec<usize>>>,
zone_redundancy: usize,
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) -> Result<Graph<FlowEdge>, Error> {
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// We list the (partition,node) associations that are not used in the
// previous assignment
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let mut exclude_edge = HashSet::<(usize, usize)>::new();
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if let Some(prev_assign) = prev_assign_opt {
let nb_nodes = self.nongateway_nodes().len();
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for (p, prev_assign_p) in prev_assign.iter().enumerate() {
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for n in 0..nb_nodes {
exclude_edge.insert((p, n));
}
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for n in prev_assign_p.iter() {
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exclude_edge.remove(&(p, *n));
}
}
}
// 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,
zone_redundancy,
)?;
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g.compute_maximal_flow()?;
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// 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.
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for (p, n) in exclude_edge.iter() {
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let node_zone = zone_to_id[self.expect_get_node_zone(&self.node_id_vec[*n])];
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g.add_edge(Vertex::PZ(*p, node_zone), Vertex::N(*n), 1)?;
}
g.compute_maximal_flow()?;
Ok(g)
}
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/// This function updates the flow graph gflow to minimize the distance between
/// its corresponding assignment and the previous one
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fn minimize_rebalance_load(
&self,
gflow: &mut Graph<FlowEdge>,
zone_to_id: &HashMap<String, usize>,
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prev_assign: &[Vec<usize>],
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) -> Result<(), Error> {
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// We define a cost function on the edges (pairs of vertices) corresponding
// to the distance between the two assignments.
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let mut cost = CostFunction::new();
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for (p, assoc_p) in prev_assign.iter().enumerate() {
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for n in assoc_p.iter() {
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let node_zone = zone_to_id[self.expect_get_node_zone(&self.node_id_vec[*n])];
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cost.insert((Vertex::PZ(p, node_zone), Vertex::N(*n)), -1);
}
}
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// 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();
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let path_length = 4 * nb_nodes;
gflow.optimize_flow_with_cost(&cost, path_length)?;
Ok(())
}
/// This function updates the assignment ring from the flow graph.
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fn update_ring_from_flow(
&mut self,
nb_zones: usize,
gflow: &Graph<FlowEdge>,
) -> Result<(), Error> {
self.ring_assignment_data = Vec::<CompactNodeType>::new();
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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());
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}
}
}
}
if self.ring_assignment_data.len() != NB_PARTITIONS * self.replication_factor {
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return Err(Error::Message(
"Critical Error : the association ring we produced does not \
have the right size."
.into(),
));
}
Ok(())
}
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/// This function returns a message summing up the partition repartition of the new
/// layout, and other statistics of the partition assignment computation.
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fn output_stat(
&self,
gflow: &Graph<FlowEdge>,
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prev_assign_opt: &Option<Vec<Vec<usize>>>,
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zone_to_id: &HashMap<String, usize>,
id_to_zone: &[String],
) -> Result<Message, Error> {
let mut msg = Message::new();
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let used_cap = self.partition_size * NB_PARTITIONS as u64 * self.replication_factor as u64;
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let total_cap = self.get_total_capacity();
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let percent_cap = 100.0 * (used_cap as f32) / (total_cap as f32);
msg.push(format!(
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"Usable capacity / total cluster capacity: {} / {} ({:.1} %)",
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ByteSize::b(used_cap).to_string_as(false),
ByteSize::b(total_cap).to_string_as(false),
percent_cap
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));
msg.push(format!(
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"Effective capacity (replication factor {}): {}",
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self.replication_factor,
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ByteSize::b(used_cap / self.replication_factor as u64).to_string_as(false)
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));
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if percent_cap < 80. {
msg.push("".into());
msg.push(
"If the percentage is too low, it might be that the \
cluster topology and redundancy constraints are forcing the use of nodes/zones with small \
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storage capacities."
.into(),
);
msg.push(
"You might want to move storage capacity between zones or relax the redundancy constraint."
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.into(),
);
msg.push(
"See the detailed statistics below and look for saturated nodes/zones.".into(),
);
}
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// We define and fill in the following tables
let storing_nodes = self.nongateway_nodes();
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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()];
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for p in 0..NB_PARTITIONS {
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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;
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if let Some(prev_assign) = prev_assign_opt {
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let mut old_zones_of_p = Vec::<usize>::new();
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for n in prev_assign[p].iter() {
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old_zones_of_p
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.push(zone_to_id[self.expect_get_node_zone(&self.node_id_vec[*n])]);
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}
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;
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if let Some(prev_assign) = prev_assign_opt {
if !prev_assign[p].contains(&n) {
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new_partitions[n] += 1;
}
}
}
}
}
}
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if prev_assign_opt.is_none() {
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new_partitions = stored_partitions.clone();
//new_partitions_zone = stored_partitions_zone.clone();
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}
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// We display the statistics
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msg.push("".into());
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if prev_assign_opt.is_some() {
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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
));
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msg.push("".into());
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}
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let mut table = vec![];
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for z in 0..id_to_zone.len() {
let mut nodes_of_z = Vec::<usize>::new();
for n in 0..storing_nodes.len() {
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if self.expect_get_node_zone(&self.node_id_vec[n]) == id_to_zone[z] {
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nodes_of_z.push(n);
}
}
let replicated_partitions: usize =
nodes_of_z.iter().map(|n| stored_partitions[*n]).sum();
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table.push(format!(
"{}\tTags\tPartitions\tCapacity\tUsable capacity",
id_to_zone[z]
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));
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let available_cap_z: u64 = self.partition_size * replicated_partitions as u64;
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let mut total_cap_z = 0;
for n in nodes_of_z.iter() {
total_cap_z += self.expect_get_node_capacity(&self.node_id_vec[*n]);
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}
let percent_cap_z = 100.0 * (available_cap_z as f32) / (total_cap_z as f32);
for n in nodes_of_z.iter() {
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let available_cap_n = stored_partitions[*n] as u64 * self.partition_size;
let total_cap_n = self.expect_get_node_capacity(&self.node_id_vec[*n]);
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let tags_n = (self.node_role(&self.node_id_vec[*n]).ok_or("<??>"))?.tags_string();
table.push(format!(
" {:?}\t{}\t{} ({} new)\t{}\t{} ({:.1}%)",
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self.node_id_vec[*n],
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tags_n,
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stored_partitions[*n],
new_partitions[*n],
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ByteSize::b(total_cap_n).to_string_as(false),
ByteSize::b(available_cap_n).to_string_as(false),
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(available_cap_n as f32) / (total_cap_n as f32) * 100.0,
));
}
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table.push(format!(
" TOTAL\t\t{} ({} unique)\t{}\t{} ({:.1}%)",
replicated_partitions,
stored_partitions_zone[z],
//new_partitions_zone[z],
ByteSize::b(total_cap_z).to_string_as(false),
ByteSize::b(available_cap_z).to_string_as(false),
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percent_cap_z
));
table.push("".into());
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}
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msg.push(format_table::format_table_to_string(table));
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Ok(msg)
}
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}