persistence + proper disconnect

src/bin/server/db.rs

@@ -0,0 +1,53 @@
+use std::path::Path;
+
+use bincode::{Decode, Encode};
+use openworm::net::BINCODE_CONFIG;
+use sled::{Db, Tree};
+
+pub const DB_VERSION: u64 = 0;
+
+pub fn open_db(path: impl AsRef<Path>) -> Db {
+    let db = sled::open(path).expect("failed to open database");
+    if !db.was_recovered() {
+        println!("no previous db found, creating new");
+        db.insert_("version", DB_VERSION);
+        db.flush().unwrap();
+    } else {
+        let version: u64 = db.get_("version").expect("failed to read db version");
+        println!("found existing db version {version}");
+        if version != DB_VERSION {
+            panic!("non matching db version! (auto update in the future)");
+        }
+    }
+    db
+}
+
+pub trait DbUtil {
+    fn insert_<K: AsRef<[u8]>, V: Encode>(&self, k: K, v: V);
+    fn get_<K: AsRef<[u8]>, V: Decode<()>>(&self, k: K) -> Option<V>;
+    fn iter_all<V: Decode<()>>(&self) -> impl Iterator<Item = V>;
+}
+
+impl DbUtil for Tree {
+    fn insert_<K: AsRef<[u8]>, V: Encode>(&self, k: K, v: V) {
+        let bytes = bincode::encode_to_vec(v, BINCODE_CONFIG).unwrap();
+        self.insert(k, bytes).unwrap();
+    }
+
+    fn get_<K: AsRef<[u8]>, V: Decode<()>>(&self, k: K) -> Option<V> {
+        let bytes = self.get(k).unwrap()?;
+        Some(
+            bincode::decode_from_slice(&bytes, BINCODE_CONFIG)
+                .unwrap()
+                .0,
+        )
+    }
+
+    fn iter_all<V: Decode<()>>(&self) -> impl Iterator<Item = V> {
+        self.iter().map(|r| {
+            bincode::decode_from_slice(&r.unwrap().1, BINCODE_CONFIG)
+                .unwrap()
+                .0
+        })
+    }
+}