attempt at documenting table crate

src/table/replication/fullcopy.rs

@@ -6,19 +6,19 @@ 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 {
-	// 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) -> Vec<UUID> {
 		vec![self.system.id]
 	}

src/table/replication/mod.rs

@@ -1,6 +1,8 @@
 mod parameters;
 
-pub mod fullcopy;
-pub mod sharded;
+mod fullcopy;
+mod sharded;
 
+pub use fullcopy::TableFullReplication;
 pub use parameters::*;
+pub use sharded::TableShardedReplication;

src/table/replication/parameters.rs

@@ -2,20 +2,26 @@ use garage_rpc::ring::*;
 
 use garage_util::data::*;
 
+/// Trait to describe how a table shall be replicated
 pub trait TableReplication: Send + Sync {
 	// See examples in table_sharded.rs and table_fullcopy.rs
 	// To understand various replication methods
 
-	// Which nodes to send reads from
+	/// Which nodes to send read requests to
 	fn read_nodes(&self, hash: &Hash) -> Vec<UUID>;
+	/// Responses needed to consider a read succesfull
 	fn read_quorum(&self) -> usize;
 
-	// Which nodes to send writes to
+	/// Which nodes to send writes to
 	fn write_nodes(&self, hash: &Hash) -> Vec<UUID>;
+	/// Responses needed to consider a write succesfull
 	fn write_quorum(&self) -> usize;
+	// this feels like its write_nodes().len() - write_quorum()
 	fn max_write_errors(&self) -> usize;
 
 	// Accessing partitions, for Merkle tree & sync
+	/// Get partition for data with given hash
 	fn partition_of(&self, hash: &Hash) -> Partition;
+	/// List of existing partitions
 	fn partitions(&self) -> Vec<(Partition, Hash)>;
 }

src/table/replication/sharded.rs

@@ -6,22 +6,25 @@ use garage_util::data::*;
 
 use crate::replication::*;
 
+/// 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 {
+	/// The membership manager of this node
 	pub system: Arc<System>,
+	/// How many time each data should be replicated
 	pub replication_factor: usize,
+	/// How many nodes to contact for a read, should be at most `replication_factor`
 	pub read_quorum: usize,
+	/// How many nodes to contact for a write, should be at most `replication_factor`
 	pub write_quorum: usize,
 }
 
 impl TableReplication for TableShardedReplication {
-	// 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
-
 	fn read_nodes(&self, hash: &Hash) -> Vec<UUID> {
 		let ring = self.system.ring.borrow().clone();
 		ring.walk_ring(&hash, self.replication_factor)