Update to Rust programming language.

src-tauri/src/tauri_commands/db.rs

@@ -0,0 +1,19 @@
+use crate::DB;
+
+#[tauri::command]
+pub fn db_read(key: &str) -> String {
+    if let Some(value) = DB.lock().unwrap().get(key) {
+        value
+    } else {
+        String::from("")
+    }
+}
+
+#[tauri::command]
+pub fn db_write(key: &str, val: &str) -> bool {
+    if let Ok(_) = DB.lock().unwrap().set(key, &val) {
+        true
+    } else {
+        false
+    }
+}