Pass options as immutable borrow

src/db_options.rs

@@ -995,9 +995,9 @@ impl Options {
     ///   index_sparseness: 16,
     /// };
     ///
-    /// opts.set_plain_table_factory(factory_opts);
+    /// opts.set_plain_table_factory(&factory_opts);
     /// ```
-    pub fn set_plain_table_factory(&mut self, options: PlainTableFactoryOptions) {
+    pub fn set_plain_table_factory(&mut self, options: &PlainTableFactoryOptions) {
         unsafe {
             ffi::rocksdb_options_set_plain_table_factory(
                 self.inner,