From 6e828b7ae8726657ad05c06cfa0908484849e313 Mon Sep 17 00:00:00 2001
From: Dennis Schwerdel <schwerdel@informatik.uni-kl.de>
Date: Tue, 30 Aug 2016 08:52:22 +0200
Subject: [PATCH] Not overriding recently learned addresses in switch mode

---
 CHANGELOG.md    |  2 ++
 src/cloud.rs    | 10 +++++++---
 src/ethernet.rs | 19 ++++++++++++++++---
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b9c409..d1f546d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ This project follows [semantic versioning](http://semver.org).
 - [added] Support for automatic port forwarding via UPnP
 - [added] Added `-s` shorthand for `--subnet`
 - [added] Support for YAML config file via `--config`
+- [changed] Not overriding recently learnt addresses in switch mode
+- [changed] Caching resolved addresses to increase performance
 - [changed] Configurable magic header is now used instead of Network-ID (**incompatible**)
 - [changed] Clarified documentation on TUN netmasks
 - [changed] Added timestamps to output
diff --git a/src/cloud.rs b/src/cloud.rs
index 585d60b..e8af439 100644
--- a/src/cloud.rs
+++ b/src/cloud.rs
@@ -29,6 +29,10 @@ use super::poll::{self, Poll};
 
 type Hash = BuildHasherDefault<FnvHasher>;
 
+const MAX_RECONNECT_INTERVAL: u16 = 3600;
+const RESOLVE_INTERVAL: Time = 300;
+
+
 struct PeerList {
     timeout: Duration,
     peers: HashMap<SocketAddr, (Time, NodeId, Vec<SocketAddr>), Hash>,
@@ -404,7 +408,7 @@ impl<P: Protocol> GenericCloud<P> {
                 if let Ok(addrs) = resolve(&entry.address as &str) {
                     entry.resolved = addrs;
                 }
-                entry.next_resolve = now + 60;
+                entry.next_resolve = now + RESOLVE_INTERVAL;
             }
             // Ignore if next attempt is already in the future
             if entry.next > now {
@@ -417,8 +421,8 @@ impl<P: Protocol> GenericCloud<P> {
                 entry.timeout *= 2;
             }
             // Maximum interval is one hour
-            if entry.timeout > 3600 {
-                entry.timeout = 3600;
+            if entry.timeout > MAX_RECONNECT_INTERVAL {
+                entry.timeout = MAX_RECONNECT_INTERVAL;
             }
             // Schedule next connection attempt
             entry.next = now + entry.timeout as Time;
diff --git a/src/ethernet.rs b/src/ethernet.rs
index 0271dee..de8b8e8 100644
--- a/src/ethernet.rs
+++ b/src/ethernet.rs
@@ -4,6 +4,7 @@
 
 use std::net::SocketAddr;
 use std::collections::HashMap;
+use std::collections::hash_map::Entry;
 use std::hash::BuildHasherDefault;
 
 use fnv::FnvHasher;
@@ -99,9 +100,21 @@ impl Table for SwitchTable {
     /// Learns the given address, inserting it in the hash map
     #[inline]
     fn learn(&mut self, key: Address, _prefix_len: Option<u8>, addr: SocketAddr) {
-        let value = SwitchTableValue{address: addr, timeout: now()+self.timeout as Time};
-        if self.table.insert(key, value).is_none() {
-            info!("Learned address {} => {}", key, addr);
+        let deadline = now() + self.timeout as Time;
+        match self.table.entry(key) {
+            Entry::Vacant(entry) => {
+                entry.insert(SwitchTableValue{address: addr, timeout: deadline});
+                info!("Learned address {} => {}", key, addr);
+            },
+            Entry::Occupied(mut entry) => {
+                let mut entry = entry.get_mut();
+                if entry.timeout + 10 >= deadline {
+                    // Do not override recently learnt entries
+                    return
+                }
+                entry.timeout = deadline;
+                entry.address = addr;
+            }
         }
     }