perf(locks) use RwLocks in place of Mutex when possible

src/bin/client.rs

@@ -7,7 +7,7 @@ use std::net::{SocketAddr, SocketAddrV4};
 use std::sync::Arc;
 use std::time::Duration;
 use tokio::net::UdpSocket;
-use tokio::sync::Mutex;
+use tokio::sync::RwLock;
 use tokio::time;
 use tokio_tun::TunBuilder;
 
@@ -64,7 +64,7 @@ async fn main() {
     info!("Created TUN device {}", tun.name());
 
     let udp_sock = Arc::new(UdpSocket::bind(local_addr).await.unwrap());
-    let connections = Arc::new(Mutex::new(
+    let connections = Arc::new(RwLock::new(
         LruCache::<SocketAddrV4, Arc<Socket>>::with_expiry_duration(UDP_TTL),
     ));
 
@@ -77,7 +77,7 @@ async fn main() {
         loop {
             tokio::select! {
                 Ok((size, SocketAddr::V4(addr))) = udp_sock.recv_from(&mut buf_r) => {
-                    if let Some(sock) = connections.lock().await.get_mut(&addr) {
+                    if let Some(sock) = connections.read().await.peek(&addr) {
                         sock.send(&buf_r[..size]).await;
                         continue;
                     }
@@ -95,7 +95,7 @@ async fn main() {
                         continue;
                     }
 
-                    assert!(connections.lock().await.insert(addr, sock.clone()).is_none());
+                    assert!(connections.write().await.insert(addr, sock.clone()).is_none());
                     debug!("inserted fake TCP socket into LruCache");
                     let udp_sock = udp_sock.clone();
 
@@ -108,7 +108,7 @@ async fn main() {
                                     udp_sock.send_to(&buf_r[..size], addr).await.unwrap();
                                 },
                                 None => {
-                                    connections.lock().await.remove(&addr);
+                                    connections.write().await.remove(&addr);
                                     debug!("removed fake TCP socket from LruCache");
                                     return;
                                 },
@@ -119,7 +119,7 @@ async fn main() {
                 _ = cleanup_timer.tick() => {
                     let mut total = 0;
 
-                    for c in connections.lock().await.notify_iter() {
+                    for c in connections.write().await.notify_iter() {
                         if let TimedEntry::Expired(_addr, sock) = c {
                             sock.close();
                             total += 1;

src/fake_tcp/mod.rs

@@ -9,7 +9,7 @@ use std::collections::{HashMap, HashSet};
 use std::fmt;
 use std::net::{Ipv4Addr, SocketAddrV4};
 use std::sync::atomic::{AtomicU32, Ordering};
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc, RwLock};
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::sync::mpsc::{self, Receiver, Sender};
 use tokio::sync::watch;
@@ -38,8 +38,8 @@ impl AddrTuple {
 
 #[derive(Debug)]
 struct Shared {
-    tuples: Mutex<HashMap<AddrTuple, Arc<Sender<Bytes>>>>,
-    listening: Mutex<HashSet<u16>>,
+    tuples: RwLock<HashMap<AddrTuple, Arc<Sender<Bytes>>>>,
+    listening: RwLock<HashSet<u16>>,
     outgoing: Sender<Bytes>,
     ready: Sender<Socket>,
 }
@@ -279,7 +279,7 @@ impl Drop for Socket {
         assert!(self
             .shared
             .tuples
-            .lock()
+            .write()
             .unwrap()
             .remove(&AddrTuple::new(self.local_addr, self.remote_addr))
             .is_some());
@@ -306,9 +306,9 @@ impl Stack {
         let (outgoing_tx, outgoing_rx) = mpsc::channel(MPSC_BUFFER_LEN);
         let (ready_tx, ready_rx) = mpsc::channel(MPSC_BUFFER_LEN);
         let shared = Arc::new(Shared {
-            tuples: Mutex::new(HashMap::new()),
+            tuples: RwLock::new(HashMap::new()),
             outgoing: outgoing_tx,
-            listening: Mutex::new(HashSet::new()),
+            listening: RwLock::new(HashSet::new()),
             ready: ready_tx,
         });
         let local_ip = tun.destination().unwrap();
@@ -322,7 +322,7 @@ impl Stack {
     }
 
     pub fn listen(&mut self, port: u16) {
-        assert!(self.shared.listening.lock().unwrap().insert(port));
+        assert!(self.shared.listening.write().unwrap().insert(port));
     }
 
     pub async fn accept(&mut self) -> Socket {
@@ -344,7 +344,7 @@ impl Stack {
         );
 
         {
-            let mut tuples = self.shared.tuples.lock().unwrap();
+            let mut tuples = self.shared.tuples.write().unwrap();
             assert!(tuples.insert(tuple, Arc::new(incoming.clone())).is_none());
         }
 
@@ -378,7 +378,7 @@ impl Stack {
 
                     let sender;
                     {
-                        let tuples = shared.tuples.lock().unwrap();
+                        let tuples = shared.tuples.read().unwrap();
                         sender = tuples.get(&tuple).cloned();
                     }
 
@@ -387,11 +387,11 @@ impl Stack {
                         continue;
                     }
 
-                    if tcp_packet.get_flags() == tcp::TcpFlags::SYN && shared.listening.lock().unwrap().contains(&tcp_packet.get_destination()) {
+                    if tcp_packet.get_flags() == tcp::TcpFlags::SYN && shared.listening.read().unwrap().contains(&tcp_packet.get_destination()) {
                         // SYN seen on listening socket
                         if tcp_packet.get_sequence() == 0 {
                             let (sock, incoming) = Socket::new(Mode::Server, shared.clone(), local_addr, remote_addr, Some(tcp_packet.get_sequence() + 1), State::Idle);
-                            assert!(shared.tuples.lock().unwrap().insert(tuple, Arc::new(incoming)).is_none());
+                            assert!(shared.tuples.write().unwrap().insert(tuple, Arc::new(incoming)).is_none());
                             tokio::spawn(sock.accept());
                         } else {
                             trace!("Bad TCP SYN packet from {}, sending RST", remote_addr);