From 7d067926dd20beb1f2df314d35e33274fbfc1e97 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Tue, 21 May 2019 16:29:34 +1000
Subject: [PATCH] Replace RocksDB with LevelDB

---
 beacon_node/db/Cargo.toml           |   6 +-
 beacon_node/db/src/leveldb_store.rs | 100 ++++++++++++++++++++++++++++
 beacon_node/db/src/lib.rs           |  20 ++++++
 3 files changed, 125 insertions(+), 1 deletion(-)
 create mode 100644 beacon_node/db/src/leveldb_store.rs

diff --git a/beacon_node/db/Cargo.toml b/beacon_node/db/Cargo.toml
index b6cdafe04..808d420a5 100644
--- a/beacon_node/db/Cargo.toml
+++ b/beacon_node/db/Cargo.toml
@@ -4,12 +4,16 @@ version = "0.1.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"
 
+[dev-dependencies]
+tempfile = "3"
+
 [dependencies]
 blake2-rfc = "0.2.18"
 bls = { path = "../../eth2/utils/bls" }
 bytes = "0.4.10"
+db-key = "0.0.5"
+leveldb = "0.8.4"
 parking_lot = "0.7"
-rocksdb = "0.10.1"
 ssz = { path = "../../eth2/utils/ssz" }
 ssz_derive = { path = "../../eth2/utils/ssz_derive" }
 tree_hash = { path = "../../eth2/utils/tree_hash" }
diff --git a/beacon_node/db/src/leveldb_store.rs b/beacon_node/db/src/leveldb_store.rs
new file mode 100644
index 000000000..c60e34283
--- /dev/null
+++ b/beacon_node/db/src/leveldb_store.rs
@@ -0,0 +1,100 @@
+use super::*;
+use db_key::Key;
+use leveldb::database::kv::KV;
+use leveldb::database::Database;
+use leveldb::error::Error as LevelDBError;
+use leveldb::options::{Options, ReadOptions, WriteOptions};
+use parking_lot::RwLock;
+use std::path::Path;
+
+pub struct LevelDB<K: Key> {
+    db: RwLock<Database<K>>,
+}
+
+impl<K: Key> LevelDB<K> {
+    pub fn open(path: &Path) -> Result<Self, Error> {
+        let mut options = Options::new();
+
+        options.create_if_missing = true;
+
+        let db = Database::open(path, options)?;
+
+        Ok(Self {
+            db: RwLock::new(db),
+        })
+    }
+
+    fn read_options(&self) -> ReadOptions<K> {
+        ReadOptions::new()
+    }
+
+    fn write_options(&self) -> WriteOptions {
+        WriteOptions::new()
+    }
+
+    fn get_key_for_col(col: &str, key: &[u8]) -> BytesKey {
+        let mut col = col.as_bytes().to_vec();
+        col.append(&mut key.to_vec());
+        BytesKey { key: col }
+    }
+}
+
+pub struct BytesKey {
+    key: Vec<u8>,
+}
+
+impl Key for BytesKey {
+    fn from_u8(key: &[u8]) -> Self {
+        Self { key: key.to_vec() }
+    }
+
+    fn as_slice<T, F: Fn(&[u8]) -> T>(&self, f: F) -> T {
+        f(self.key.as_slice())
+    }
+}
+
+impl Store for LevelDB<BytesKey> {
+    fn get_bytes(&self, col: &str, key: &[u8]) -> Result<Option<DBValue>, Error> {
+        let column_key = Self::get_key_for_col(col, key);
+
+        self.db
+            .read()
+            .get(self.read_options(), column_key)
+            .map_err(Into::into)
+    }
+
+    fn put_bytes(&self, col: &str, key: &[u8], val: &[u8]) -> Result<(), Error> {
+        let column_key = Self::get_key_for_col(col, key);
+
+        self.db
+            .write()
+            .put(self.write_options(), column_key, val)
+            .map_err(Into::into)
+    }
+
+    fn key_exists(&self, col: &str, key: &[u8]) -> Result<bool, Error> {
+        let column_key = Self::get_key_for_col(col, key);
+
+        self.db
+            .read()
+            .get(self.read_options(), column_key)
+            .map_err(Into::into)
+            .and_then(|val| Ok(val.is_some()))
+    }
+
+    fn key_delete(&self, col: &str, key: &[u8]) -> Result<(), Error> {
+        let column_key = Self::get_key_for_col(col, key);
+        self.db
+            .write()
+            .delete(self.write_options(), column_key)
+            .map_err(Into::into)
+    }
+}
+
+impl From<LevelDBError> for Error {
+    fn from(e: LevelDBError) -> Error {
+        Error::DBError {
+            message: format!("{:?}", e),
+        }
+    }
+}
diff --git a/beacon_node/db/src/lib.rs b/beacon_node/db/src/lib.rs
index 21b5b0a75..d31dc06b0 100644
--- a/beacon_node/db/src/lib.rs
+++ b/beacon_node/db/src/lib.rs
@@ -2,8 +2,10 @@
 mod block_at_slot;
 mod errors;
 mod impls;
+mod leveldb_store;
 mod memory_db;
 
+pub use self::leveldb_store::LevelDB;
 pub use self::memory_db::MemoryDB;
 pub use errors::Error;
 pub use types::*;
@@ -106,6 +108,7 @@ mod tests {
     use super::*;
     use ssz::{Decode, Encode};
     use ssz_derive::{Decode, Encode};
+    use tempfile::tempdir;
 
     #[derive(PartialEq, Debug, Encode, Decode)]
     struct StorableThing {
@@ -127,6 +130,23 @@ mod tests {
         }
     }
 
+    #[test]
+    fn leveldb_can_store_and_retrieve() {
+        let dir = tempdir().unwrap();
+        let path = dir.path();
+
+        let store = LevelDB::open(&path).unwrap();
+
+        let key = Hash256::random();
+        let item = StorableThing { a: 1, b: 42 };
+
+        store.put(&key, &item).unwrap();
+
+        let retrieved = store.get(&key).unwrap().unwrap();
+
+        assert_eq!(item, retrieved);
+    }
+
     #[test]
     fn memorydb_can_store_and_retrieve() {
         let store = MemoryDB::open();