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author | Alex Auvolat <alex@adnab.me> | 2022-11-07 19:34:40 +0100 |
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committer | Alex Auvolat <alex@adnab.me> | 2022-11-07 20:11:30 +0100 |
commit | ea5afc251106b3f6e2d07f942ba1f88abeef8765 (patch) | |
tree | fe9679c408cbac8af18bb6400105ebc4a3bd1ad3 /src/rpc/layout.rs | |
parent | 28d7a49f6365fadaffaa903cc10434c1ed28d564 (diff) | |
download | garage-ea5afc251106b3f6e2d07f942ba1f88abeef8765.tar.gz garage-ea5afc251106b3f6e2d07f942ba1f88abeef8765.zip |
Style improvements
Diffstat (limited to 'src/rpc/layout.rs')
-rw-r--r-- | src/rpc/layout.rs | 247 |
1 files changed, 125 insertions, 122 deletions
diff --git a/src/rpc/layout.rs b/src/rpc/layout.rs index 38e56b88..95f69dc8 100644 --- a/src/rpc/layout.rs +++ b/src/rpc/layout.rs @@ -19,7 +19,7 @@ use std::convert::TryInto; const NB_PARTITIONS: usize = 1usize << PARTITION_BITS; -//The Message type will be used to collect information on the algorithm. +// The Message type will be used to collect information on the algorithm. type Message = Vec<String>; /// The layout of the cluster, i.e. the list of roles @@ -30,11 +30,11 @@ pub struct ClusterLayout { 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. + /// 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: u32, - ///Parameters used to compute the assignation currently given by - ///ring_assignation_data + /// Parameters used to compute the assignation currently given by + /// ring_assignation_data pub parameters: LayoutParameters, pub roles: LwwMap<Uuid, NodeRoleV>, @@ -53,14 +53,14 @@ pub struct ClusterLayout { pub ring_assignation_data: Vec<CompactNodeType>, /// Parameters to be used in the next partition assignation computation. - pub staged_parameters: Lww<LayoutParameters>, + pub staging_parameters: Lww<LayoutParameters>, /// Role changes which are staged for the next version of the layout - pub staging: LwwMap<Uuid, NodeRoleV>, + pub staging_roles: LwwMap<Uuid, NodeRoleV>, pub staging_hash: Hash, } -///This struct is used to set the parameters to be used in the assignation computation -///algorithm. It is stored as a Crdt. +/// This struct is used to set the parameters to be used in the assignation computation +/// algorithm. It is stored as a Crdt. #[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)] pub struct LayoutParameters { pub zone_redundancy: usize, @@ -114,20 +114,19 @@ impl NodeRole { } } -//Implementation of the ClusterLayout methods unrelated to the assignation algorithm. +// Implementation of the ClusterLayout methods unrelated to the assignation 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. + // 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 staged_parameters = Lww::<LayoutParameters>::new(parameters.clone()); + let staging_parameters = Lww::<LayoutParameters>::new(parameters.clone()); let empty_lwwmap = LwwMap::new(); - let empty_lwwmap_hash = blake2sum(&rmp_to_vec_all_named(&empty_lwwmap).unwrap()[..]); - ClusterLayout { + let mut ret = ClusterLayout { version: 0, replication_factor, partition_size: 0, @@ -135,10 +134,17 @@ impl ClusterLayout { node_id_vec: Vec::new(), ring_assignation_data: Vec::new(), parameters, - staged_parameters, - staging: empty_lwwmap, - staging_hash: empty_lwwmap_hash, - } + 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(&rmp_to_vec_all_named(&hashed_tuple).unwrap()[..]) } pub fn merge(&mut self, other: &ClusterLayout) -> bool { @@ -148,16 +154,15 @@ impl ClusterLayout { true } Ordering::Equal => { - let param_changed = self.staged_parameters.get() != other.staged_parameters.get(); - self.staged_parameters.merge(&other.staged_parameters); - self.staging.merge(&other.staging); + self.staging_parameters.merge(&other.staging_parameters); + self.staging_roles.merge(&other.staging_roles); - let new_staging_hash = blake2sum(&rmp_to_vec_all_named(&self.staging).unwrap()[..]); - let stage_changed = new_staging_hash != self.staging_hash; + let new_staging_hash = self.calculate_staging_hash(); + let changed = new_staging_hash != self.staging_hash; self.staging_hash = new_staging_hash; - stage_changed || param_changed + changed } Ordering::Less => false, } @@ -179,13 +184,14 @@ 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(); let msg = self.calculate_partition_assignation()?; - self.staging.clear(); - self.staging_hash = blake2sum(&rmp_to_vec_all_named(&self.staging).unwrap()[..]); + self.staging_roles.clear(); + self.staging_hash = self.calculate_staging_hash(); self.version += 1; @@ -208,9 +214,9 @@ To know the correct value of the new layout version, invoke `garage layout show` } } - self.staging.clear(); - self.staging_hash = blake2sum(&rmp_to_vec_all_named(&self.staging).unwrap()[..]); - self.staged_parameters.update(self.parameters.clone()); + self.staging_roles.clear(); + self.staging_hash = self.calculate_staging_hash(); + self.staging_parameters.update(self.parameters.clone()); self.version += 1; @@ -235,7 +241,7 @@ 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. + /// Returns the uuids of the non_gateway nodes in self.node_id_vec. pub fn nongateway_nodes(&self) -> Vec<Uuid> { let mut result = Vec::<Uuid>::new(); for uuid in self.node_id_vec.iter() { @@ -247,7 +253,7 @@ To know the correct value of the new layout version, invoke `garage layout show` result } - ///Given a node uuids, this function returns the label of its zone + /// Given a node uuids, this function returns the label of its zone pub fn get_node_zone(&self, uuid: &Uuid) -> Result<String, Error> { match self.node_role(uuid) { Some(role) => Ok(role.zone.clone()), @@ -257,7 +263,7 @@ To know the correct value of the new layout version, invoke `garage layout show` } } - ///Given a node uuids, this function returns its capacity or fails if it does not have any + /// 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<u32, Error> { match self.node_role(uuid) { Some(NodeRole { @@ -273,7 +279,7 @@ To know the correct value of the new layout version, invoke `garage layout show` } } - ///Returns the number of partitions associated to this node in the ring + /// 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 { @@ -293,7 +299,7 @@ To know the correct value of the new layout version, invoke `garage layout show` )) } - ///Returns the sum of capacities of non gateway nodes in the cluster + /// Returns the sum of capacities of non gateway nodes in the cluster pub fn get_total_capacity(&self) -> Result<u32, Error> { let mut total_capacity = 0; for uuid in self.nongateway_nodes().iter() { @@ -307,7 +313,7 @@ To know the correct value of the new layout version, invoke `garage layout show` /// returns true if consistent, false if error pub fn check(&self) -> bool { // Check that the hash of the staging data is correct - let staging_hash = blake2sum(&rmp_to_vec_all_named(&self.staging).unwrap()[..]); + let staging_hash = self.calculate_staging_hash(); if staging_hash != self.staging_hash { return false; } @@ -346,14 +352,14 @@ To know the correct value of the new layout version, invoke `garage layout show` } } - //Check that every partition is associated to distinct nodes + // 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_assignation_data[rf * p..rf * (p + 1)].to_vec(); if nodes_of_p.iter().unique().count() != rf { return false; } - //Check that every partition is spread over at least zone_redundancy zones. + // 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.") @@ -364,7 +370,7 @@ To know the correct value of the new layout version, invoke `garage layout show` } } - //Check that the nodes capacities is consistent with the stored partitions + // 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_assignation_data.iter() { node_usage[*n as usize] += 1; @@ -380,8 +386,8 @@ To know the correct value of the new layout version, invoke `garage layout show` } } - //Check that the partition size stored is the one computed by the asignation - //algorithm. + // 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().expect("Critical Error"); match cl2.compute_optimal_partition_size(&zone_to_id) { @@ -394,7 +400,7 @@ To know the correct value of the new layout version, invoke `garage layout show` } } -//Implementation of the ClusterLayout methods related to the assignation algorithm. +// Implementation of the ClusterLayout methods related to the assignation algorithm. impl ClusterLayout { /// This function calculates a new partition-to-node assignation. /// The computed assignation respects the node replication factor @@ -403,16 +409,13 @@ impl ClusterLayout { /// Among such optimal assignation, it minimizes the distance to /// the former assignation (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. + /// 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_assignation(&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_assignation reframed with new ids + // We update the node ids, since the node role list might have changed with the + // changes in the layout. We retrieve the old_assignation reframed with new ids let old_assignation_opt = self.update_node_id_vec()?; - //We update the parameters - self.parameters = self.staged_parameters.get().clone(); - let mut msg = Message::new(); msg.push("==== COMPUTATION OF A NEW PARTITION ASSIGNATION ====".into()); msg.push("".into()); @@ -422,8 +425,8 @@ impl ClusterLayout { 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. + // 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(); @@ -443,10 +446,10 @@ impl ClusterLayout { ))); } - //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. + // 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_assignation_opt != None { @@ -461,7 +464,7 @@ impl ClusterLayout { partition_size )); } - //We write the partition size. + // We write the partition size. self.partition_size = partition_size; if partition_size < 100 { @@ -472,15 +475,15 @@ impl ClusterLayout { ); } - //We compute a first flow/assignation that is heuristically close to the previous - //assignation + // We compute a first flow/assignation that is heuristically close to the previous + // assignation let mut gflow = self.compute_candidate_assignation(&zone_to_id, &old_assignation_opt)?; if let Some(assoc) = &old_assignation_opt { - //We minimize the distance to the previous assignation. + // We minimize the distance to the previous assignation. self.minimize_rebalance_load(&mut gflow, &zone_to_id, assoc)?; } - //We display statistics of the computation + // We display statistics of the computation msg.append(&mut self.output_stat( &gflow, &old_assignation_opt, @@ -489,7 +492,7 @@ impl ClusterLayout { )?); msg.push("".to_string()); - //We update the layout structure + // We update the layout structure self.update_ring_from_flow(id_to_zone.len(), &gflow)?; if !self.check() { @@ -508,8 +511,8 @@ impl ClusterLayout { /// do modify assignation_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 + // Non gateway nodes should be coded on 8bits, hence they must be first in the list + // We build the new node ids let mut new_non_gateway_nodes: Vec<Uuid> = self .roles .items() @@ -542,12 +545,12 @@ impl ClusterLayout { 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 assignations where the node is still in use. + // We rewrite the old association with the new indices. We only consider partition + // to node assignations where the node is still in use. let mut old_assignation = vec![Vec::<usize>::new(); NB_PARTITIONS]; if self.ring_assignation_data.is_empty() { - //This is a new association + // This is a new association return Ok(None); } if self.ring_assignation_data.len() != NB_PARTITIONS * self.replication_factor { @@ -558,11 +561,11 @@ impl ClusterLayout { )); } - //We build a translation table between the uuid and new ids + // 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 + // 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); } @@ -577,14 +580,14 @@ impl ClusterLayout { } } - //We write the ring + // We write the ring self.ring_assignation_data = Vec::<CompactNodeType>::new(); Ok(Some(old_assignation)) } - ///This function generates ids for the zone of the nodes appearing in - ///self.node_id_vec. + /// 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(); @@ -607,8 +610,8 @@ impl ClusterLayout { Ok((id_to_zone, zone_to_id)) } - ///This function computes by dichotomy the largest realizable partition size, given - ///the layout roles and parameters. + /// 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>, @@ -662,13 +665,13 @@ impl ClusterLayout { vertices } - ///Generates the graph to compute the maximal flow corresponding to the optimal - ///partition assignation. - ///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 - ///assignation. This produces a solution that heuristically should be close to the - ///previous one. + /// Generates the graph to compute the maximal flow corresponding to the optimal + /// partition assignation. + /// 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 + /// assignation. This produces a solution that heuristically should be close to the + /// previous one. fn generate_flow_graph( &self, partition_size: u32, @@ -709,14 +712,14 @@ impl ClusterLayout { Ok(g) } - ///This function computes a first optimal assignation (in the form of a flow graph). + /// This function computes a first optimal assignation (in the form of a flow graph). fn compute_candidate_assignation( &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 assignation + // We list the (partition,node) associations that are not used in the + // previous assignation let mut exclude_edge = HashSet::<(usize, usize)>::new(); if let Some(prev_assign) = prev_assign_opt { let nb_nodes = self.nongateway_nodes().len(); @@ -730,13 +733,13 @@ impl ClusterLayout { } } - //We compute the best flow using only the edges used in the previous assignation + // We compute the best flow using only the edges used in the previous assignation let mut g = self.generate_flow_graph(self.partition_size, zone_to_id, &exclude_edge)?; g.compute_maximal_flow()?; - //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. + // 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)?; @@ -745,16 +748,16 @@ impl ClusterLayout { Ok(g) } - ///This function updates the flow graph gflow to minimize the distance between - ///its corresponding assignation and the previous one + /// This function updates the flow graph gflow to minimize the distance between + /// its corresponding assignation and the previous one fn minimize_rebalance_load( &self, 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 assignations. + // We define a cost function on the edges (pairs of vertices) corresponding + // to the distance between the two assignations. let mut cost = CostFunction::new(); for (p, assoc_p) in prev_assign.iter().enumerate() { for n in assoc_p.iter() { @@ -763,9 +766,9 @@ impl ClusterLayout { } } - //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. + // 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)?; @@ -773,7 +776,7 @@ impl ClusterLayout { Ok(()) } - ///This function updates the assignation ring from the flow graph. + /// This function updates the assignation ring from the flow graph. fn update_ring_from_flow( &mut self, nb_zones: usize, @@ -801,8 +804,8 @@ impl ClusterLayout { Ok(()) } - ///This function returns a message summing up the partition repartition of the new - ///layout, and other statistics of the partition assignation computation. + /// This function returns a message summing up the partition repartition of the new + /// layout, and other statistics of the partition assignation computation. fn output_stat( &self, gflow: &Graph<FlowEdge>, @@ -837,7 +840,7 @@ impl ClusterLayout { used_cap / self.replication_factor as u32 )); - //We define and fill in the following tables + // 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()]; @@ -879,7 +882,7 @@ impl ClusterLayout { new_partitions_zone = stored_partitions_zone.clone(); } - //We display the statistics + // We display the statistics msg.push("".into()); if *prev_assign_opt != None { @@ -951,27 +954,27 @@ impl ClusterLayout { } } -//==================================================================================== +// ==================================================================================== #[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 assignation - //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) + // 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 assignation + // 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(); @@ -994,8 +997,8 @@ mod tests { ); } - //For every partition, we count the number of zone already associated and - //the name of the last zone associated + // For every partition, we count the number of zone already associated and + // the name of the last zone associated let mut id_zone_token = vec![0; zones.len()]; for (z, t) in zone_token.iter() { @@ -1049,7 +1052,7 @@ mod tests { cl.node_id_vec.push(x); } - let update = cl.staging.update_mutator( + let update = cl.staging_roles.update_mutator( cl.node_id_vec[i], NodeRoleV(Some(NodeRole { zone: (node_zone_vec[i].to_string()), @@ -1057,10 +1060,10 @@ mod tests { tags: (vec![]), })), ); - cl.staging.merge(&update); + cl.staging_roles.merge(&update); } - cl.staging_hash = blake2sum(&rmp_to_vec_all_named(&cl.staging).unwrap()[..]); - cl.staged_parameters + cl.staging_hash = cl.calculate_staging_hash(); + cl.staging_parameters .update(LayoutParameters { zone_redundancy }); } |