Add support for fully replicated tables with epidemic dissemination of updates

1 files changed, 100 insertions, 0 deletions

diff --git a/src/table_fullcopy.rs b/src/table_fullcopy.rs
new file mode 100644
index 00000000..d5194d55
--- /dev/null
+++ b/src/table_fullcopy.rs
@@ -0,0 +1,100 @@
+use arc_swap::ArcSwapOption;
+use std::sync::Arc;
+
+use crate::data::*;
+use crate::membership::{Ring, System};
+use crate::table::*;
+
+#[derive(Clone)]
+pub struct TableFullReplication {
+	pub write_factor: usize,
+	pub write_quorum: usize,
+
+	neighbors: ArcSwapOption<Neighbors>,
+}
+
+#[derive(Clone)]
+struct Neighbors {
+	ring: Arc<Ring>,
+	neighbors: Vec<UUID>,
+}
+
+impl TableFullReplication {
+	pub fn new(write_factor: usize, write_quorum: usize) -> Self {
+		TableFullReplication {
+			write_factor,
+			write_quorum,
+			neighbors: ArcSwapOption::from(None),
+		}
+	}
+
+	fn get_neighbors(&self, system: &System) -> Vec<UUID> {
+		let neighbors = self.neighbors.load_full();
+		if let Some(n) = neighbors {
+			if Arc::ptr_eq(&n.ring, &system.ring.borrow()) {
+				return n.neighbors.clone();
+			}
+		}
+
+		// Recalculate neighbors
+		let ring = system.ring.borrow().clone();
+		let my_id = system.id.clone();
+
+		let mut nodes = vec![];
+		for (node, _) in ring.config.members.iter() {
+			let node_ranking = hash(&[node.as_slice(), my_id.as_slice()].concat());
+			nodes.push((node.clone(), node_ranking));
+		}
+		nodes.sort_by(|(_, rank1), (_, rank2)| rank1.cmp(rank2));
+		let mut neighbors = nodes
+			.drain(..)
+			.map(|(node, _)| node)
+			.filter(|node| *node != my_id)
+			.take(self.write_factor)
+			.collect::<Vec<_>>();
+		neighbors.push(my_id);
+		self.neighbors.swap(Some(Arc::new(Neighbors {
+			ring,
+			neighbors: neighbors.clone(),
+		})));
+		neighbors
+	}
+}
+
+impl TableReplication for TableFullReplication {
+	// 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
+
+	fn read_nodes(&self, _hash: &Hash, system: &System) -> Vec<UUID> {
+		vec![system.id.clone()]
+	}
+	fn read_quorum(&self) -> usize {
+		1
+	}
+
+	fn write_nodes(&self, _hash: &Hash, system: &System) -> Vec<UUID> {
+		self.get_neighbors(system)
+	}
+	fn write_quorum(&self) -> usize {
+		self.write_quorum
+	}
+	fn max_write_errors(&self) -> usize {
+		self.write_factor - self.write_quorum
+	}
+	fn epidemic_writes(&self) -> bool {
+		true
+	}
+
+	fn replication_nodes(&self, _hash: &Hash, ring: &Ring) -> Vec<UUID> {
+		ring.config.members.keys().cloned().collect::<Vec<_>>()
+	}
+	fn split_points(&self, _ring: &Ring) -> Vec<Hash> {
+		let mut ret = vec![];
+		ret.push([0u8; 32].into());
+		ret.push([0xFFu8; 32].into());
+		ret
+	}
+}