From cb3cc85e38178fcad059e1cb8068dd3c99743134 Mon Sep 17 00:00:00 2001
From: Dennis Schwerdel <schwerdel@informatik.uni-kl.de>
Date: Fri, 20 Nov 2015 09:49:41 +0100
Subject: [PATCH] Performance improvements

---
 src/ethcloud.rs   | 39 +++++++++++++++++++++++++++++++++++----
 src/udpmessage.rs | 27 +++++++++++++--------------
 2 files changed, 48 insertions(+), 18 deletions(-)

diff --git a/src/ethcloud.rs b/src/ethcloud.rs
index 4abdc08..5136d30 100644
--- a/src/ethcloud.rs
+++ b/src/ethcloud.rs
@@ -1,5 +1,5 @@
 use std::net::{SocketAddr, ToSocketAddrs};
-use std::collections::HashMap;
+use std::collections::{HashMap, VecDeque};
 use std::hash::Hasher;
 use std::net::UdpSocket;
 use std::io::Read;
@@ -141,6 +141,7 @@ pub struct EthCloud {
     token: Token,
     next_peerlist: SteadyTime,
     update_freq: Duration,
+    cache: VecDeque<(SocketAddr, Mac, u16)>,
     buffer_out: [u8; 64*1024]
 }
 
@@ -163,6 +164,7 @@ impl EthCloud {
             token: token,
             next_peerlist: SteadyTime::now(),
             update_freq: peer_timeout/2,
+            cache: VecDeque::new(),
             buffer_out: [0; 64*1024]
         }
     }
@@ -202,7 +204,23 @@ impl EthCloud {
 
     fn handle_ethernet_frame(&mut self, frame: ethernet::Frame) -> Result<(), Error> {
         debug!("Read ethernet frame from tap {:?}", frame);
-        match self.mactable.lookup(frame.dst, frame.vlan) {
+        let mut addr = None;
+        for &(ref peer, ref mac, vlan) in &self.cache {
+            if mac == frame.dst && vlan == frame.vlan {
+                addr = Some(*peer);
+                break;
+            }
+        }
+        if addr.is_none() {
+            addr = self.mactable.lookup(frame.dst, frame.vlan);
+            if let Some(addr) = addr {
+                self.cache.push_front((addr, *frame.dst, frame.vlan));
+                if self.cache.len() > 3 {
+                    self.cache.pop_back();
+                }
+            }
+        }
+        match addr {
             Some(addr) => {
                 debug!("Found destination for {:?} (vlan {}) => {}", frame.dst, frame.vlan, addr);
                 try!(self.send_msg(addr, &udpmessage::Message::Frame(frame)))
@@ -235,8 +253,21 @@ impl EthCloud {
                         return Err(Error::TapdevError("Failed to write to tap device"));
                     }
                 }
-                self.peers.add(&peer);
-                self.mactable.learn(frame.src, frame.vlan, &peer);
+                let mut in_cache = false;
+                for &(ref addr, ref mac, vlan) in &self.cache {
+                    if mac == frame.src && vlan == frame.vlan && addr == &peer {
+                        in_cache = true;
+                        break;
+                    }
+                }
+                if !in_cache {
+                    self.peers.add(&peer);
+                    self.mactable.learn(frame.src, frame.vlan, &peer);
+                    self.cache.push_front((peer, *frame.src, frame.vlan));
+                    if self.cache.len() > 3 {
+                        self.cache.pop_back();
+                    }
+                }
             },
             udpmessage::Message::Peers(peers) => {
                 self.peers.add(&peer);
diff --git a/src/udpmessage.rs b/src/udpmessage.rs
index 35b502d..4de7947 100644
--- a/src/udpmessage.rs
+++ b/src/udpmessage.rs
@@ -38,19 +38,19 @@ impl<'a> fmt::Debug for Message<'a> {
 }
 
 pub fn decode(data: &[u8]) -> Result<(Token, Message), Error> {
-    if data.len() < 1 + mem::size_of::<Token>() {
+    if data.len() < mem::size_of::<Token>() {
         return Err(Error::ParseError("Empty message"));
     }
     let mut pos = 0;
-    let token = Token::from_be(* unsafe { as_obj::<Token>(&data[pos..]) });
+    let mut token = Token::from_be(* unsafe { as_obj::<Token>(&data[pos..]) });
     pos += mem::size_of::<Token>();
-    match data[pos] {
+    let switch = token & 0xff;
+    token = token >> 8;
+    match switch {
         0 => {
-            pos += 1;
             Ok((token, Message::Frame(try!(ethernet::decode(&data[pos..])))))
         },
         1 => {
-            pos += 1;
             if data.len() < pos + 1 {
                 return Err(Error::ParseError("Empty peers"));
             }
@@ -82,20 +82,23 @@ pub fn decode(data: &[u8]) -> Result<(Token, Message), Error> {
 }
 
 pub fn encode(token: Token, msg: &Message, buf: &mut [u8]) -> usize {
-    assert!(buf.len() >= mem::size_of::<Token>() + 1);
+    assert!(buf.len() >= mem::size_of::<Token>());
     let mut pos = 0;
+    let switch = match msg {
+        &Message::Frame(_) => 0,
+        &Message::Peers(_) => 1,
+        &Message::GetPeers => 2,
+        &Message::Close => 3
+    };
+    let token = (token << 8) | switch;
     let token_dat = unsafe { mem::transmute::<Token, [u8; 8]>(token.to_be()) };
     unsafe { ptr::copy_nonoverlapping(token_dat.as_ptr(), buf[pos..].as_mut_ptr(), token_dat.len()) };
     pos += token_dat.len();
     match msg {
         &Message::Frame(ref frame) => {
-            buf[pos] = 0;
-            pos += 1;
             pos += ethernet::encode(&frame, &mut buf[pos..])
         },
         &Message::Peers(ref peers) => {
-            buf[pos] = 1;
-            pos += 1;
             let count_pos = pos;
             pos += 1;
             assert!(buf.len() >= 2 + peers.len() * mem::size_of::<SocketAddrV4>());
@@ -122,12 +125,8 @@ pub fn encode(token: Token, msg: &Message, buf: &mut [u8]) -> usize {
             pos += 1;
         },
         &Message::GetPeers => {
-            buf[pos] = 2;
-            pos += 1;
         },
         &Message::Close => {
-            buf[pos] = 3;
-            pos += 1;
         }
     }
     pos