Split out storage engine module.

src/sql/engine/kv.rs

@@ -9,22 +9,22 @@ use std::borrow::Cow;
 use std::clone::Clone;
 use std::collections::HashSet;
 
-/// A SQL engine based on an underlying MVCC key/value store
-pub struct KV<S: kv::Store> {
-    /// The underlying key/value store
-    pub(super) kv: kv::MVCC<S>,
+/// A SQL engine based on an underlying MVCC key/value store.
+pub struct KV<E: kv::Engine> {
+    /// The underlying key/value store.
+    pub(super) kv: kv::MVCC<E>,
 }
 
 // FIXME Implement Clone manually due to https://github.com/rust-lang/rust/issues/26925
-impl<S: kv::Store> Clone for KV<S> {
+impl<E: kv::Engine> Clone for KV<E> {
     fn clone(&self) -> Self {
         KV::new(self.kv.clone())
     }
 }
 
-impl<S: kv::Store> KV<S> {
+impl<E: kv::Engine> KV<E> {
     /// Creates a new key/value-based SQL engine
-    pub fn new(kv: kv::MVCC<S>) -> Self {
+    pub fn new(kv: kv::MVCC<E>) -> Self {
         Self { kv }
     }
 
@@ -39,8 +39,8 @@ impl<S: kv::Store> KV<S> {
     }
 }
 
-impl<S: kv::Store> super::Engine for KV<S> {
-    type Transaction = Transaction<S>;
+impl<E: kv::Engine> super::Engine for KV<E> {
+    type Transaction = Transaction<E>;
 
     fn begin(&self, mode: super::Mode) -> Result<Self::Transaction> {
         Ok(Self::Transaction::new(self.kv.begin_with_mode(mode)?))
@@ -62,13 +62,13 @@ fn deserialize<'a, V: Deserialize<'a>>(bytes: &'a [u8]) -> Result<V> {
 }
 
 /// An SQL transaction based on an MVCC key/value transaction
-pub struct Transaction<S: kv::Store> {
-    txn: kv::mvcc::Transaction<S>,
+pub struct Transaction<E: kv::Engine> {
+    txn: kv::mvcc::Transaction<E>,
 }
 
-impl<S: kv::Store> Transaction<S> {
+impl<E: kv::Engine> Transaction<E> {
     /// Creates a new SQL transaction from an MVCC transaction
-    fn new(txn: kv::mvcc::Transaction<S>) -> Self {
+    fn new(txn: kv::mvcc::Transaction<E>) -> Self {
         Self { txn }
     }
 
@@ -99,7 +99,7 @@ impl<S: kv::Store> Transaction<S> {
     }
 }
 
-impl<S: kv::Store> super::Transaction for Transaction<S> {
+impl<E: kv::Engine> super::Transaction for Transaction<E> {
     fn id(&self) -> u64 {
         self.txn.id()
     }
@@ -270,7 +270,7 @@ impl<S: kv::Store> super::Transaction for Transaction<S> {
     }
 }
 
-impl<S: kv::Store> Catalog for Transaction<S> {
+impl<E: kv::Engine> Catalog for Transaction<E> {
     fn create_table(&mut self, table: Table) -> Result<()> {
         if self.read_table(&table.name)?.is_some() {
             return Err(Error::Value(format!("Table {} already exists", table.name)));

src/sql/engine/raft.rs

@@ -74,7 +74,7 @@ impl Raft {
     }
 
     /// Creates an underlying state machine for a Raft engine.
-    pub fn new_state<S: kv::Store>(kv: kv::MVCC<S>) -> Result<State<S>> {
+    pub fn new_state<E: kv::Engine>(kv: kv::MVCC<E>) -> Result<State<E>> {
         State::new(kv)
     }
 
@@ -260,17 +260,17 @@ impl Catalog for Transaction {
 }
 
 /// The Raft state machine for the Raft-based SQL engine, using a KV SQL engine
-pub struct State<S: kv::Store> {
+pub struct State<E: kv::Engine> {
     /// The underlying KV SQL engine
-    engine: super::KV<S>,
+    engine: super::KV<E>,
     /// The last applied index
     applied_index: u64,
 }
 
-impl<S: kv::Store> State<S> {
+impl<E: kv::Engine> State<E> {
     /// Creates a new Raft state maching using the given MVCC key/value store
-    pub fn new(store: kv::MVCC<S>) -> Result<Self> {
-        let engine = super::KV::new(store);
+    pub fn new(engine: kv::MVCC<E>) -> Result<Self> {
+        let engine = super::KV::new(engine);
         let applied_index = engine
             .get_metadata(b"applied_index")?
             .map(|b| Raft::deserialize(&b))
@@ -305,7 +305,7 @@ impl<S: kv::Store> State<S> {
     }
 }
 
-impl<S: kv::Store> raft::State for State<S> {
+impl<E: kv::Engine> raft::State for State<E> {
     fn applied_index(&self) -> u64 {
         self.applied_index
     }

src/storage/kv/bitcask.rs → src/storage/engine/bitcask.rs

@@ -1,12 +1,12 @@
-use super::Store;
+use super::Engine;
 use crate::error::Result;
 
 use fs4::FileExt;
 use std::io::{BufReader, BufWriter, Read, Seek, SeekFrom, Write};
 use std::path::PathBuf;
 
 /// A very simple variant of BitCask, itself a very simple log-structured
-/// key-value store used e.g. by the Riak database. It is not compatible with
+/// key-value engine used e.g. by the Riak database. It is not compatible with
 /// BitCask databases generated by other implementations. See:
 /// https://riak.com/assets/bitcask-intro.pdf
 ///
@@ -93,7 +93,7 @@ impl std::fmt::Display for BitCask {
     }
 }
 
-impl Store for BitCask {
+impl Engine for BitCask {
     type ScanIterator<'a> = ScanIterator<'a>;
 
     fn delete(&mut self, key: &[u8]) -> Result<()> {
@@ -380,14 +380,14 @@ impl Log {
 mod tests {
     use super::*;
 
-    const GOLDEN_DIR: &str = "src/storage/kv/golden/bitcask";
+    const GOLDEN_DIR: &str = "src/storage/engine/golden/bitcask";
 
-    super::super::tests::test_store!({
+    super::super::tests::test_engine!({
         let path = tempdir::TempDir::new("toydb")?.path().join("toydb");
         BitCask::new(path)?
     });
 
-    /// Creates a new BitCask store for testing.
+    /// Creates a new BitCask engine for testing.
     fn setup() -> Result<BitCask> {
         BitCask::new(tempdir::TempDir::new("toydb")?.path().join("toydb"))
     }

src/storage/kv/memory.rs → src/storage/engine/memory.rs

@@ -1,7 +1,7 @@
-use super::Store;
+use super::Engine;
 use crate::error::Result;
 
-/// An in-memory key/value store using the Rust standard library B-tree
+/// An in-memory key/value storage engine using the Rust standard library B-tree
 /// implementation. Data is not persisted.
 pub struct Memory {
     data: std::collections::BTreeMap<Vec<u8>, Vec<u8>>,
@@ -20,7 +20,7 @@ impl std::fmt::Display for Memory {
     }
 }
 
-impl Store for Memory {
+impl Engine for Memory {
     type ScanIterator<'a> = ScanIterator<'a>;
 
     fn flush(&mut self) -> Result<()> {
@@ -75,5 +75,5 @@ impl<'a> DoubleEndedIterator for ScanIterator<'a> {
 mod tests {
     use super::*;
 
-    super::super::tests::test_store!(Memory::new());
+    super::super::tests::test_engine!(Memory::new());
 }