sync starter code

Signed-off-by: Alex Chi <iskyzh@gmail.com>

mini-lsm-starter/src/wal.rs

@@ -0,0 +1,30 @@
+use std::fs::File;
+use std::path::Path;
+use std::sync::Arc;
+
+use anyhow::Result;
+use bytes::Bytes;
+use crossbeam_skiplist::SkipMap;
+use parking_lot::Mutex;
+
+pub struct Wal {
+    file: Arc<Mutex<File>>,
+}
+
+impl Wal {
+    pub fn create(path: impl AsRef<Path>) -> Result<Self> {
+        unimplemented!()
+    }
+
+    pub fn recover(path: impl AsRef<Path>, skiplist: &SkipMap<Bytes, Bytes>) -> Result<Self> {
+        unimplemented!()
+    }
+
+    pub fn put(&self, key: &[u8], value: &[u8]) -> Result<()> {
+        unimplemented!()
+    }
+
+    pub fn sync(&self) -> Result<()> {
+        unimplemented!()
+    }
+}