garage/src/table/replication/fullcopy.rs
Alex Auvolat c94406f428
Improve how node roles are assigned in Garage
- change the terminology: the network configuration becomes the role
  table, the configuration of a nodes becomes a node's role
- the modification of the role table takes place in two steps: first,
  changes are staged in a CRDT data structure. Then, once the user is
  happy with the changes, they can commit them all at once (or revert
  them).
- update documentation
- fix tests
- implement smarter partition assignation algorithm

This patch breaks the format of the network configuration: when
migrating, the cluster will be in a state where no roles are assigned.
All roles must be re-assigned and commited at once. This migration
should not pose an issue.
2021-11-16 16:05:53 +01:00

51 lines
1.2 KiB
Rust

use std::sync::Arc;
use garage_rpc::ring::*;
use garage_rpc::system::System;
use garage_util::data::*;
use crate::replication::*;
/// Full replication schema: all nodes store everything
/// Writes are disseminated in an epidemic manner in the network
/// Advantage: do all reads locally, extremely fast
/// Inconvenient: only suitable to reasonably small tables
#[derive(Clone)]
pub struct TableFullReplication {
/// The membership manager of this node
pub system: Arc<System>,
/// Max number of faults allowed while replicating a record
pub max_faults: usize,
}
impl TableReplication for TableFullReplication {
fn read_nodes(&self, _hash: &Hash) -> Vec<Uuid> {
vec![self.system.id]
}
fn read_quorum(&self) -> usize {
1
}
fn write_nodes(&self, _hash: &Hash) -> Vec<Uuid> {
let ring = self.system.ring.borrow();
ring.layout.node_ids().to_vec()
}
fn write_quorum(&self) -> usize {
let nmembers = self.system.ring.borrow().layout.node_ids().len();
if nmembers > self.max_faults {
nmembers - self.max_faults
} else {
1
}
}
fn max_write_errors(&self) -> usize {
self.max_faults
}
fn partition_of(&self, _hash: &Hash) -> Partition {
0u16
}
fn partitions(&self) -> Vec<(Partition, Hash)> {
vec![(0u16, [0u8; 32].into())]
}
}