Introduce IfaceExt

kernel/src/net/iface/ext.rs

@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use alloc::string::String;
+use core::sync::atomic::{AtomicU64, Ordering};
+
+use ostd::sync::WaitQueue;
+
+use super::Iface;
+
+/// The iface extension.
+pub struct IfaceExt {
+    /// The name of the iface.
+    name: String,
+    /// The time when we should do the next poll.
+    /// We store the total number of milliseconds since the system booted.
+    next_poll_at_ms: AtomicU64,
+    /// The wait queue that the background polling thread will sleep on.
+    polling_wait_queue: WaitQueue,
+}
+
+impl IfaceExt {
+    pub(super) fn new(name: String) -> Self {
+        Self {
+            name,
+            next_poll_at_ms: AtomicU64::new(0),
+            polling_wait_queue: WaitQueue::new(),
+        }
+    }
+
+    pub(super) fn next_poll_at_ms(&self) -> Option<u64> {
+        let millis = self.next_poll_at_ms.load(Ordering::Relaxed);
+        if millis == 0 {
+            None
+        } else {
+            Some(millis)
+        }
+    }
+
+    pub(super) fn polling_wait_queue(&self) -> &WaitQueue {
+        &self.polling_wait_queue
+    }
+
+    fn schedule_next_poll(&self, poll_at: Option<u64>) {
+        let Some(new_instant) = poll_at else {
+            self.next_poll_at_ms.store(0, Ordering::Relaxed);
+            return;
+        };
+
+        let old_instant = self.next_poll_at_ms.load(Ordering::Relaxed);
+        self.next_poll_at_ms.store(new_instant, Ordering::Relaxed);
+
+        if old_instant == 0 || new_instant < old_instant {
+            self.polling_wait_queue.wake_all();
+        }
+    }
+}
+
+pub trait IfaceEx {
+    /// Gets the name of the iface.
+    ///
+    /// In Linux, the name is usually the driver name followed by a unit number.
+    fn name(&self) -> &str;
+
+    /// Transmits or receives packets queued in the iface, and updates socket status accordingly.
+    ///
+    /// The background polling thread is woken up to perform the next poll if necessary.
+    fn poll(&self);
+}
+
+impl IfaceEx for dyn Iface<IfaceExt> {
+    fn name(&self) -> &str {
+        &self.ext().name
+    }
+
+    fn poll(&self) {
+        self.raw_poll(&|next_poll| self.ext().schedule_next_poll(next_poll));
+    }
+}