fix: replace deprecated atomic fetch_update calls (#2665)

* fix: replace deprecated atomic fetch_update calls

Use try_update, available since the workspace's Rust 1.95 minimum, for all standard-library atomic update calls. Preserve closure behavior and memory ordering, and leave arc-swap's unrelated API unchanged.

Cover smoltcp port allocation's previous-value return and wrap boundary.

Fixes #2614

* Add unused_async allowance for tokio test

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

easytier-core/src/gateway/dataplane/flow.rs

@@ -252,7 +252,7 @@ impl<V> FlowTable<V> {
     fn increment_count(&self) -> FlowCountChange {
         let previous = self
             .count
-            .fetch_update(Ordering::AcqRel, Ordering::Acquire, |count| {
+            .try_update(Ordering::AcqRel, Ordering::Acquire, |count| {
                 count.checked_add(1)
             })
             .expect("flow count overflow");
@@ -294,7 +294,7 @@ impl<V> FlowTable<V> {
 
         let previous = self
             .count
-            .fetch_update(Ordering::AcqRel, Ordering::Acquire, |count| {
+            .try_update(Ordering::AcqRel, Ordering::Acquire, |count| {
                 count.checked_sub(delta)
             })
             .expect("flow count underflow");

easytier-core/src/gateway/proxy/tcp_proxy_engine.rs

@@ -186,7 +186,7 @@ impl TcpProxyEngine {
         for _ in 0..u16::MAX {
             let translated_port = self
                 .next_translated_port
-                .fetch_update(Ordering::Relaxed, Ordering::Relaxed, |port| {
+                .try_update(Ordering::Relaxed, Ordering::Relaxed, |port| {
                     Some(if port == u16::MAX { 1 } else { port + 1 })
                 })
                 .expect("translated port counter update cannot fail");

easytier-core/src/gateway/smoltcp/tokio_smoltcp/mod.rs

@@ -126,7 +126,7 @@ impl Net {
     }
     pub fn get_port(&self) -> u16 {
         self.from_port
-            .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| {
+            .try_update(Ordering::SeqCst, Ordering::SeqCst, |x| {
                 Some(if x > 60000 { 10000 } else { x + 1 })
             })
             .unwrap()
@@ -188,3 +188,36 @@ impl Drop for Net {
         self.stopper.notify_waiters()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use smoltcp::{phy::Medium, wire::HardwareAddress};
+
+    #[allow(clippy::unused_async)]
+    #[tokio::test]
+    async fn port_allocation_returns_previous_value_and_wraps() {
+        let mut capabilities = device::DeviceCapabilities::default();
+        capabilities.medium = Medium::Ip;
+        capabilities.max_transmission_unit = 1280;
+        let (device, _ingress, _egress) = channel_device::ChannelDevice::new(capabilities);
+        let net = Net::new(
+            device,
+            NetConfig::new(
+                Config::new(HardwareAddress::Ip),
+                "10.126.126.1/24".parse().unwrap(),
+                Vec::new(),
+                None,
+            ),
+        );
+
+        assert_eq!(net.get_port(), 10001);
+        assert_eq!(net.get_port(), 10002);
+
+        net.from_port.store(60000, Ordering::SeqCst);
+        assert_eq!(net.get_port(), 60000);
+        assert_eq!(net.get_port(), 60001);
+        assert_eq!(net.get_port(), 10000);
+        assert_eq!(net.get_port(), 10001);
+    }
+}

easytier/src/common/log/tracing_backend.rs

@@ -70,7 +70,7 @@ impl tracing::Subscriber for EventSubscriber {
     fn new_span(&self, _attributes: &Attributes<'_>) -> Id {
         let id = self
             .next_span_id
-            .fetch_update(Ordering::Relaxed, Ordering::Relaxed, |id| {
+            .try_update(Ordering::Relaxed, Ordering::Relaxed, |id| {
                 Some(if id == usize::MAX { 1 } else { id + 1 })
             })
             .expect("span id update always succeeds");