Up

Cargo.toml

@@ -44,6 +44,7 @@ serde = "1.0.137"
 serde_derive = "1.0.137"
 serde-big-array = "0.4.1"
 siphasher = "0.3.10"
+slabigator = "0.1.0"
 tokio = { version = "1.19.2", features = [
   "net",
   "io-std",

src/globals.rs

@@ -1,4 +1,3 @@
-use std::collections::vec_deque::VecDeque;
 use std::net::{IpAddr, SocketAddr};
 use std::path::PathBuf;
 use std::sync::atomic::AtomicU32;
@@ -7,6 +6,7 @@ use std::time::Duration;
 
 use parking_lot::{Mutex, RwLock};
 use siphasher::sip128::SipHasher13;
+use slabigator::Slab;
 use tokio::runtime::Handle;
 use tokio::sync::oneshot;
 
@@ -35,8 +35,8 @@ pub struct Globals {
     pub tcp_concurrent_connections: Arc<AtomicU32>,
     pub udp_max_active_connections: u32,
     pub tcp_max_active_connections: u32,
-    pub udp_active_connections: Arc<Mutex<VecDeque<oneshot::Sender<()>>>>,
-    pub tcp_active_connections: Arc<Mutex<VecDeque<oneshot::Sender<()>>>>,
+    pub udp_active_connections: Arc<Mutex<Slab<oneshot::Sender<()>>>>,
+    pub tcp_active_connections: Arc<Mutex<Slab<oneshot::Sender<()>>>>,
     pub key_cache_capacity: usize,
     pub hasher: SipHasher13,
     pub cache: Cache,

src/main.rs

@@ -35,7 +35,6 @@ mod resolver;
 #[cfg(feature = "metrics")]
 mod varz;
 
-use std::collections::vec_deque::VecDeque;
 use std::convert::TryFrom;
 use std::fs::File;
 use std::io::prelude::*;
@@ -67,6 +66,7 @@ use parking_lot::RwLock;
 use privdrop::PrivDrop;
 use rand::prelude::*;
 use siphasher::sip128::SipHasher13;
+use slabigator::Slab;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpSocket, TcpStream, UdpSocket};
 use tokio::runtime::Handle;
@@ -286,14 +286,14 @@ async fn tcp_acceptor(globals: Arc<Globals>, tcp_listener: TcpListener) -> Resul
     let active_connections = globals.tcp_active_connections.clone();
     while let Ok((mut client_connection, _client_addr)) = tcp_listener.accept().await {
         let (tx, rx) = oneshot::channel::<()>();
-        {
+        let tx_channel_index = {
             let mut active_connections = active_connections.lock();
-            if active_connections.len() >= globals.tcp_max_active_connections as _ {
+            if active_connections.is_full() {
                 let tx_oldest = active_connections.pop_back().unwrap();
                 let _ = tx_oldest.send(());
             }
-            active_connections.push_front(tx);
-        }
+            active_connections.push_front(tx)?
+        };
         let _count = concurrent_connections.fetch_add(1, Ordering::Relaxed);
         #[cfg(feature = "metrics")]
         let varz = globals.varz.clone();
@@ -304,6 +304,7 @@ async fn tcp_acceptor(globals: Arc<Globals>, tcp_listener: TcpListener) -> Resul
         }
         client_connection.set_nodelay(true)?;
         let globals = globals.clone();
+        let active_connections = active_connections.clone();
         let concurrent_connections = concurrent_connections.clone();
         let fut = async {
             let mut binlen = [0u8, 0];
@@ -328,6 +329,8 @@ async fn tcp_acceptor(globals: Arc<Globals>, tcp_listener: TcpListener) -> Resul
             let _count = concurrent_connections.fetch_sub(1, Ordering::Relaxed);
             #[cfg(feature = "metrics")]
             varz.inflight_tcp_queries.set(_count.saturating_sub(1) as _);
+            let mut active_connections = active_connections.lock();
+            _ = active_connections.remove(tx_channel_index);
         }));
     }
     Ok(())
@@ -356,14 +359,14 @@ async fn udp_acceptor(
             client_addr,
         });
         let (tx, rx) = oneshot::channel::<()>();
-        {
+        let tx_channel_index = {
             let mut active_connections = active_connections.lock();
-            if active_connections.len() >= globals.udp_max_active_connections as _ {
+            if active_connections.is_full() {
                 let tx_oldest = active_connections.pop_back().unwrap();
                 let _ = tx_oldest.send(());
             }
-            active_connections.push_front(tx);
-        }
+            active_connections.push_front(tx)?
+        };
         let _count = concurrent_connections.fetch_add(1, Ordering::Relaxed);
         #[cfg(feature = "metrics")]
         let varz = globals.varz.clone();
@@ -373,6 +376,7 @@ async fn udp_acceptor(
             varz.client_queries_udp.inc();
         }
         let globals = globals.clone();
+        let active_connections = active_connections.clone();
         let concurrent_connections = concurrent_connections.clone();
         let fut = handle_client_query(globals, client_ctx, packet);
         let fut_abort = rx;
@@ -381,6 +385,8 @@ async fn udp_acceptor(
             let _count = concurrent_connections.fetch_sub(1, Ordering::Relaxed);
             #[cfg(feature = "metrics")]
             varz.inflight_udp_queries.set(_count.saturating_sub(1) as _);
+            let mut active_connections = active_connections.lock();
+            _ = active_connections.remove(tx_channel_index);
         }));
     }
 }
@@ -717,12 +723,12 @@ fn main() -> Result<(), Error> {
         tcp_concurrent_connections: Arc::new(AtomicU32::new(0)),
         udp_max_active_connections: config.udp_max_active_connections,
         tcp_max_active_connections: config.tcp_max_active_connections,
-        udp_active_connections: Arc::new(Mutex::new(VecDeque::with_capacity(
+        udp_active_connections: Arc::new(Mutex::new(Slab::with_capacity(
             config.udp_max_active_connections as _,
-        ))),
-        tcp_active_connections: Arc::new(Mutex::new(VecDeque::with_capacity(
+        )?)),
+        tcp_active_connections: Arc::new(Mutex::new(Slab::with_capacity(
             config.tcp_max_active_connections as _,
-        ))),
+        )?)),
         key_cache_capacity,
         hasher,
         cache,