In a future, don't remove cancelled entries

They have already been removed by the pop_back() call.

Cancellation in Rust is such a clusterfuck...

Cargo.lock

@@ -16,9 +16,9 @@ checksum = "aae1277d39aeec15cb388266ecc24b11c80469deae6067e17a1a7aa9e5c1f234"
 
 [[package]]
 name = "anyhow"
-version = "1.0.60"
+version = "1.0.61"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c794e162a5eff65c72ef524dfe393eb923c354e350bb78b9c7383df13f3bc142"
+checksum = "508b352bb5c066aac251f6daf6b36eccd03e8a88e8081cd44959ea277a3af9a8"
 
 [[package]]
 name = "autocfg"
@@ -177,7 +177,7 @@ dependencies = [
 
 [[package]]
 name = "encrypted-dns"
-version = "0.9.7"
+version = "0.9.8"
 dependencies = [
  "anyhow",
  "byteorder",

Cargo.toml

@@ -12,7 +12,7 @@ categories = ["asynchronous", "network-programming", "command-line-utilities"]
 readme = "README.md"
 
 [dependencies]
-anyhow = "1.0.60"
+anyhow = "1.0.61"
 byteorder = "1.4.3"
 clap = { version = "3.2.16", default-features = false, features = [
   "std",

src/main.rs

@@ -57,6 +57,7 @@ use dnscrypt::*;
 use dnscrypt_certs::*;
 use dnsstamps::{InformalProperty, WithInformalProperty};
 use errors::*;
+use future::Either;
 use futures::join;
 use futures::prelude::*;
 use globals::*;
@@ -339,12 +340,18 @@ async fn tcp_acceptor(globals: Arc<Globals>, tcp_listener: TcpListener) -> Resul
         };
         let fut_abort = rx;
         let fut_all = tokio::time::timeout(timeout, future::select(fut.boxed(), fut_abort));
-        runtime_handle.spawn(fut_all.map(move |_| {
+        runtime_handle.spawn(fut_all.map(move |either| {
             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);
+
+            if let Ok(Either::Right(_)) = either {
+                // Removing the active connection was already done during
+                // cancellation.
+            } else {
+                let mut active_connections = active_connections.lock();
+                _ = active_connections.remove(tx_channel_index);
+            }
         }));
     }
 }
@@ -394,12 +401,18 @@ async fn udp_acceptor(
         let fut = handle_client_query(globals, client_ctx, packet);
         let fut_abort = rx;
         let fut_all = tokio::time::timeout(timeout, future::select(fut.boxed(), fut_abort));
-        runtime_handle.spawn(fut_all.map(move |_| {
+        runtime_handle.spawn(fut_all.map(move |either| {
             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);
+
+            if let Ok(Either::Right(_)) = either {
+                // Removing the active connection was already done during
+                // cancellation.
+            } else {
+                let mut active_connections = active_connections.lock();
+                _ = active_connections.remove(tx_channel_index);
+            }
         }));
     }
 }