libsql-bindings: auto-finalize dangling statements (#523)

Right before closing a db connection, we go over active
prepared statements, if any, and finalize them forcefully
to free their memory. Normally we don't leave any prepared
statements dangling, but extensions can do so.

Author: psarna

sqld-libsql-bindings/src/lib.rs

@@ -35,6 +35,25 @@ impl Deref for Connection<'_> {
     }
 }
 
+impl Drop for Connection<'_> {
+    fn drop(&mut self) {
+        unsafe {
+            let db = self.conn.handle();
+            if db.is_null() {
+                return;
+            }
+            let mut stmt = ffi::sqlite3_next_stmt(db, std::ptr::null_mut());
+            while !stmt.is_null() {
+                let rc = ffi::sqlite3_finalize(stmt);
+                if rc != ffi::SQLITE_OK {
+                    tracing::error!("Failed to finalize a dangling statement: {rc}")
+                }
+                stmt = ffi::sqlite3_next_stmt(db, stmt);
+            }
+        }
+    }
+}
+
 impl<'a> Connection<'a> {
     /// returns a dummy, in-memory connection. For testing purposes only
     pub fn test(_: &mut ()) -> Self {