garage/src/table/replication/sharded.rs

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use std::sync::Arc;
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use garage_rpc::membership::System;
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use garage_rpc::ring::*;
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use garage_util::data::*;
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use crate::replication::*;
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/// Sharded replication schema:
/// - based on the ring of nodes, a certain set of neighbors
/// store entries, given as a function of the position of the
/// entry's hash in the ring
/// - reads are done on all of the nodes that replicate the data
/// - writes as well
#[derive(Clone)]
pub struct TableShardedReplication {
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/// The membership manager of this node
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pub system: Arc<System>,
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/// How many time each data should be replicated
pub replication_factor: usize,
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/// How many nodes to contact for a read, should be at most `replication_factor`
pub read_quorum: usize,
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/// How many nodes to contact for a write, should be at most `replication_factor`
pub write_quorum: usize,
}
impl TableReplication for TableShardedReplication {
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fn read_nodes(&self, hash: &Hash) -> Vec<Uuid> {
let ring = self.system.ring.borrow();
ring.get_nodes(&hash, self.replication_factor)
}
fn read_quorum(&self) -> usize {
self.read_quorum
}
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fn write_nodes(&self, hash: &Hash) -> Vec<Uuid> {
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let ring = self.system.ring.borrow();
ring.get_nodes(&hash, self.replication_factor)
}
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fn write_quorum(&self) -> usize {
self.write_quorum
}
fn max_write_errors(&self) -> usize {
self.replication_factor - self.write_quorum
}
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fn partition_of(&self, hash: &Hash) -> Partition {
self.system.ring.borrow().partition_of(hash)
}
fn partitions(&self) -> Vec<(Partition, Hash)> {
self.system.ring.borrow().partitions()
}
}