Reorganize table API

src/table.rs

@@ -52,10 +52,10 @@ impl<F: TableFormat + 'static> TableRpcHandler for TableRpcHandlerAdapter<F> {
 pub enum TableRPC<F: TableFormat> {
 	Ok,
 
-	ReadEntry(F::K, Vec<u8>),
-	ReadEntryResponse(Option<F::V>),
+	ReadEntry(F::P, F::S),
+	ReadEntryResponse(Option<F::E>),
 
-	Update(Vec<(F::K, F::V)>),
+	Update(Vec<F::E>),
 }
 
 pub struct Partition {
@@ -64,21 +64,59 @@ pub struct Partition {
 	pub other_nodes: Vec<UUID>,
 }
 
-pub trait TableKey {
+pub trait PartitionKey: Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + Send + Sync {
 	fn hash(&self) -> Hash;
 }
 
-pub trait TableValue {
-	fn sort_key(&self) -> Vec<u8>;
+pub trait SortKey: Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync {
+	fn sort_key(&self) -> &[u8];
+}
+
+pub trait Entry<P: PartitionKey, S: SortKey>: Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync {
+	fn partition_key(&self) -> &P;
+	fn sort_key(&self) -> &S;
+
 	fn merge(&mut self, other: &Self);
 }
 
+#[derive(Clone, Serialize, Deserialize)]
+pub struct EmptySortKey;
+impl SortKey for EmptySortKey {
+	fn sort_key(&self) -> &[u8] {
+		&[]
+	}
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct StringKey(String);
+impl PartitionKey for StringKey {
+	fn hash(&self) -> Hash {
+		hash(self.0.as_bytes())
+	}
+}
+impl SortKey for StringKey {
+	fn sort_key(&self) -> &[u8] {
+		self.0.as_bytes()
+	}
+}
+impl AsRef<str> for StringKey {
+	fn as_ref(&self) -> &str {
+		&self.0
+	}
+}
+impl From<&str> for StringKey {
+	fn from(s: &str) -> StringKey {
+		StringKey(s.to_string())
+	}
+}
+
 #[async_trait]
 pub trait TableFormat: Send + Sync {
-	type K: Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + TableKey + Send + Sync;
-	type V: Clone + Serialize + for<'de> Deserialize<'de> + TableValue + Send + Sync;
+	type P: PartitionKey;
+	type S: SortKey;
+	type E: Entry<Self::P, Self::S>;
 
-	async fn updated(&self, key: &Self::K, old: Option<&Self::V>, new: &Self::V);
+	async fn updated(&self, old: Option<&Self::E>, new: &Self::E);
 }
 
 impl<F: TableFormat + 'static> Table<F> {
@@ -99,12 +137,12 @@ impl<F: TableFormat + 'static> Table<F> {
 		Box::new(TableRpcHandlerAdapter::<F>{ table: self })
 	}
 
-	pub async fn insert(&self, k: &F::K, v: &F::V) -> Result<(), Error> {
-		let hash = k.hash();
+	pub async fn insert(&self, e: &F::E) -> Result<(), Error> {
+		let hash = e.partition_key().hash();
 		let who = self.system.members.read().await
 			.walk_ring(&hash, self.param.replication_factor);
 
-		let rpc = &TableRPC::<F>::Update(vec![(k.clone(), v.clone())]);
+		let rpc = &TableRPC::<F>::Update(vec![e.clone()]);
 		
 		self.rpc_try_call_many(&who[..],
 							   &rpc,
@@ -112,12 +150,12 @@ impl<F: TableFormat + 'static> Table<F> {
 		Ok(())
 	}
 
-	pub async fn get(&self, k: &F::K, sort_key: &[u8]) -> Result<Option<F::V>, Error> {
-		let hash = k.hash();
+	pub async fn get(&self, partition_key: &F::P, sort_key: &F::S) -> Result<Option<F::E>, Error> {
+		let hash = partition_key.hash();
 		let who = self.system.members.read().await
 			.walk_ring(&hash, self.param.replication_factor);
 
-		let rpc = &TableRPC::<F>::ReadEntry(k.clone(), sort_key.to_vec());
+		let rpc = &TableRPC::<F>::ReadEntry(partition_key.clone(), sort_key.clone());
 		let resps = self.rpc_try_call_many(&who[..],
 										   &rpc,
 										   self.param.read_quorum)
@@ -179,36 +217,40 @@ impl<F: TableFormat + 'static> Table<F> {
 		}
 	}
 
-	fn handle_read_entry(&self, key: &F::K, sort_key: &[u8]) -> Result<Option<F::V>, Error> {
-		let mut tree_key = key.hash().to_vec();
-		tree_key.extend(sort_key);
+	fn handle_read_entry(&self, p: &F::P, s: &F::S) -> Result<Option<F::E>, Error> {
+		let tree_key = self.tree_key(p, s);
 		if let Some(bytes) = self.store.get(&tree_key)? {
-			let (_, v) = rmp_serde::decode::from_read_ref::<_, (F::K, F::V)>(&bytes)?;
-			Ok(Some(v))
+			let e = rmp_serde::decode::from_read_ref::<_, F::E>(&bytes)?;
+			Ok(Some(e))
 		} else {
 			Ok(None)
 		}
 	}
 
-	async fn handle_update(&self, mut pairs: Vec<(F::K, F::V)>) -> Result<(), Error> {
-		for mut pair in pairs.drain(..) {
-			let mut tree_key = pair.0.hash().to_vec();
-			tree_key.extend(pair.1.sort_key());
+	async fn handle_update(&self, mut entries: Vec<F::E>) -> Result<(), Error> {
+		for mut entry in entries.drain(..) {
+			let tree_key = self.tree_key(entry.partition_key(), entry.sort_key());
 
 			let old_val = match self.store.get(&tree_key)? {
 				Some(prev_bytes) => {
-					let (_, old_val) = rmp_serde::decode::from_read_ref::<_, (F::K, F::V)>(&prev_bytes)?;
-					pair.1.merge(&old_val);
-					Some(old_val)
+					let old_entry = rmp_serde::decode::from_read_ref::<_, F::E>(&prev_bytes)?;
+					entry.merge(&old_entry);
+					Some(old_entry)
 				}
 				None => None
 			};
 
-			let new_bytes = rmp_serde::encode::to_vec_named(&pair)?;
+			let new_bytes = rmp_serde::encode::to_vec_named(&entry)?;
 			self.store.insert(&tree_key, new_bytes)?;
 
-			self.instance.updated(&pair.0, old_val.as_ref(), &pair.1).await;
+			self.instance.updated(old_val.as_ref(), &entry).await;
 		}
 		Ok(())
 	}
+
+	fn tree_key(&self, p: &F::P, s: &F::S) -> Vec<u8> {
+		let mut ret = p.hash().to_vec();
+		ret.extend(s.sort_key());
+		ret
+	}
 }