Add LevelDB-backed implementation of MetadataStore

Author: ekkolon

Cargo.lock

@@ -21,3 +21,6 @@ base64 = "0.22"
 blake3 = "1.8"
 dashmap = "6.1"
 tokio = { version = "1.49", default-features = false }
+
+# Chosen over `leveldb` crate which requires C++ LevelDB via FFI.
+rusty-leveldb = "1"

Cargo.toml

@@ -16,6 +16,7 @@ tracing.workspace = true
 base64 = { workspace = true }
 blake3 = { workspace = true }
 dashmap = { workspace = true }
+rusty-leveldb = { workspace = true }
 
 [dev-dependencies]
 tokio = { workspace = true, features = ["full"] }

minikv-core/Cargo.toml

@@ -1,5 +1,13 @@
-use thiserror::Error;
-
 /// Unified error type for minikv.
-#[derive(Debug, Error)]
-pub enum Error {}
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    /// Errors from the rusty-leveldb storage engine.
+    #[error("LevelDB error: {0}")]
+    LevelDb(String),
+}
+
+impl From<rusty_leveldb::Status> for Error {
+    fn from(s: rusty_leveldb::Status) -> Self {
+        Error::LevelDb(s.to_string())
+    }
+}