benchmars. optimised inserting empty list

benches/rlp.rs

@@ -0,0 +1,46 @@
+//! benchmarking for rlp
+//! should be started with:
+//! ```bash
+//! multirust run nightly cargo bench 
+//! ```
+
+#![feature(test)]
+
+extern crate test;
+extern crate ethcore_util;
+
+use test::Bencher;
+use ethcore_util::rlp::{RlpStream};
+
+#[bench]
+fn bench_stream_value(b: &mut Bencher) {
+    b.iter( || {
+        //1029
+        let mut stream = RlpStream::new();
+        stream.append(&1029u32);
+        let _ = stream.out().unwrap();
+    });
+}
+
+#[bench]
+fn bench_stream_nested_empty_lists(b: &mut Bencher) {
+    b.iter( || {
+        // [ [], [[]], [ [], [[]] ] ]
+        let mut stream = RlpStream::new_list(3);
+        stream.append_list(0);
+        stream.append_list(1).append_list(0);
+        stream.append_list(2).append_list(0).append_list(1).append_list(0);
+        let _ = stream.out().unwrap();
+    });
+}
+
+#[bench]
+fn bench_stream_1000_empty_lists(b: &mut Bencher) {
+    b.iter( || {
+        let mut stream = RlpStream::new();
+        for _ in 0..1000 {
+            stream.append_list(0);
+        }
+        let _ = stream.out().unwrap();
+    });
+}

src/rlp.rs

@@ -286,14 +286,13 @@ impl RlpStream {
     }
 
     /// declare appending the list of given size
-    /// TODO: optimise insertion of empty list
     pub fn append_list<'a>(&'a mut self, len: usize) -> &'a mut RlpStream {
         // push new list
         let position = self.encoder.bytes.len();
         match len {
             0 => {
                 // we may finish, if the appended list len is equal 0
-                self.encoder.insert_list_len_at_pos(0, position);
+                self.encoder.bytes.push(0xc0u8);
                 self.try_to_finish();
             },
             _ => self.unfinished_lists.push_back(ListInfo::new(position, len))