.

Cargo.toml

@@ -8,3 +8,4 @@ edition = "2018"
 
 [dependencies]
 anyhow = "1.0.33"
+log = "0.4.11"

src/db_2.rs

@@ -1,5 +1,6 @@
 use std::sync::Arc;
 use anyhow::Result;
+use log::warn;
 
 #[path = "db_3.rs"]
 mod imp;
@@ -54,7 +55,8 @@ impl Db {
 impl Drop for WriteBatch {
     fn drop(&mut self) {
         if !self.destructed {
-            panic!("write batch not committed or aborted");
+            warn!("write batch dropped without committing or aborting. aborting now");
+            self.db.abort_batch(self.batch);
         }
     }
 }

src/db_3.rs

@@ -1,8 +1,13 @@
+use std::sync::Arc;
 use std::fs::File;
-use std::path::PathBuf;
+use std::path::{PathBuf, Path};
 use std::collections::BTreeMap;
 use anyhow::Result;
 
+mod fs_thread;
+
+use fs_thread::FsThread;
+
 pub struct DbConfig {
     pub path: PathBuf,
     pub trees: Vec<String>,
@@ -11,6 +16,7 @@ pub struct DbConfig {
 pub struct Db {
     config: DbConfig,
     stores: BTreeMap<String, Store>,
+    fs_thread: Arc<FsThread>,
 }
 
 struct Store {
@@ -20,15 +26,36 @@ struct Store {
 }
 
 struct Log {
-    file: File,
+    path: PathBuf,
+    fs_thread: Arc<FsThread>,
 }
 
 struct Index {
     location: BTreeMap<Vec<u8>, u64>,
 }
 
 impl Db {
-    pub async fn open(config: DbConfig) -> Result<Db> { panic!() }
+    pub async fn open(config: DbConfig) -> Result<Db> {
+        let fs_thread = FsThread::start()?;
+        let fs_thread = Arc::new(fs_thread);
+        let mut stores = BTreeMap::new();
+
+        for tree in &config.trees {
+            let path = tree_path(&config.path, tree)?;
+            let store = Store::new(path, fs_thread.clone()).await?;
+            stores.insert(tree.clone(), store);
+        }
+
+        return Ok(Db {
+            config,
+            stores,
+            fs_thread,
+        });
+
+        fn tree_path(dir: &Path, tree: &str) -> Result<PathBuf> {
+            panic!()
+        }
+    }
 }
 
 impl Db {
@@ -50,3 +77,9 @@ impl Db {
 
     pub fn close_view(&self, view: u64) { panic!() }
 }
+
+impl Store {
+    async fn new(path: PathBuf, fs_thread: Arc<FsThread>) -> Result<Store> {
+        panic!()
+    }
+}

src/fs_thread.rs

@@ -0,0 +1,30 @@
+use anyhow::Result;
+
+pub struct FsThread;
+
+pub struct FsThreadContext;
+
+impl Drop for FsThread {
+    fn drop(&mut self) {
+        self.shutdown();
+    }
+}
+
+impl FsThread {
+    pub fn start() -> Result<FsThread> {
+        panic!()
+    }
+
+    pub async fn run<F, R>(&self, f: F) -> Result<R>
+    where F: FnOnce(&mut FsThreadContext) -> Result<R> + Send,
+          R: Send,
+    {
+        panic!()
+    }
+}
+
+impl FsThread {
+    fn shutdown(&mut self) {
+        panic!()
+    }
+}