From 98e2a991953700bf2542d240153018a76e725f0f Mon Sep 17 00:00:00 2001
From: Ruihan Li <lrh2000@pku.edu.cn>
Date: Sat, 27 Jul 2024 09:27:56 +0800
Subject: [PATCH] Store `Arc<Backlog>` in UNIX listeners

---
 .../src/net/socket/unix/stream/listener.rs    | 55 ++++++++-----------
 1 file changed, 22 insertions(+), 33 deletions(-)

diff --git a/kernel/aster-nix/src/net/socket/unix/stream/listener.rs b/kernel/aster-nix/src/net/socket/unix/stream/listener.rs
index f2dca11b2..a6935ea7d 100644
--- a/kernel/aster-nix/src/net/socket/unix/stream/listener.rs
+++ b/kernel/aster-nix/src/net/socket/unix/stream/listener.rs
@@ -12,24 +12,22 @@ use crate::{
 };
 
 pub(super) struct Listener {
-    addr: UnixSocketAddrBound,
+    backlog: Arc<Backlog>,
 }
 
 impl Listener {
     pub(super) fn new(addr: UnixSocketAddrBound, backlog: usize) -> Result<Self> {
-        BACKLOG_TABLE.add_backlog(&addr, backlog)?;
-        Ok(Self { addr })
+        let backlog = BACKLOG_TABLE.add_backlog(addr, backlog)?;
+        Ok(Self { backlog })
     }
 
     pub(super) fn addr(&self) -> &UnixSocketAddrBound {
-        &self.addr
+        self.backlog.addr()
     }
 
     pub(super) fn try_accept(&self) -> Result<(Arc<dyn FileLike>, SocketAddr)> {
-        let addr = self.addr().clone();
-
         let connected = {
-            let local_endpoint = BACKLOG_TABLE.pop_incoming(&addr)?;
+            let local_endpoint = self.backlog.pop_incoming()?;
             Connected::new(local_endpoint)
         };
 
@@ -41,9 +39,7 @@ impl Listener {
     }
 
     pub(super) fn poll(&self, mask: IoEvents, poller: Option<&mut Poller>) -> IoEvents {
-        let addr = self.addr();
-        let backlog = BACKLOG_TABLE.get_backlog(addr).unwrap();
-        backlog.poll(mask, poller)
+        self.backlog.poll(mask, poller)
     }
 
     pub(super) fn register_observer(
@@ -51,18 +47,14 @@ impl Listener {
         observer: Weak<dyn Observer<IoEvents>>,
         mask: IoEvents,
     ) -> Result<()> {
-        let addr = self.addr();
-        let backlog = BACKLOG_TABLE.get_backlog(addr)?;
-        backlog.register_observer(observer, mask)
+        self.backlog.register_observer(observer, mask)
     }
 
     pub(super) fn unregister_observer(
         &self,
         observer: &Weak<dyn Observer<IoEvents>>,
     ) -> Option<Weak<dyn Observer<IoEvents>>> {
-        let addr = self.addr();
-        let backlog = BACKLOG_TABLE.get_backlog(addr).ok()?;
-        backlog.unregister_observer(observer)
+        self.backlog.unregister_observer(observer)
     }
 }
 
@@ -80,9 +72,9 @@ impl BacklogTable {
         }
     }
 
-    fn add_backlog(&self, addr: &UnixSocketAddrBound, backlog: usize) -> Result<()> {
+    fn add_backlog(&self, addr: UnixSocketAddrBound, backlog: usize) -> Result<Arc<Backlog>> {
         let inode = {
-            let UnixSocketAddrBound::Path(_, dentry) = addr else {
+            let UnixSocketAddrBound::Path(_, ref dentry) = addr else {
                 todo!()
             };
             create_keyable_inode(dentry)
@@ -92,9 +84,9 @@ impl BacklogTable {
         if backlog_sockets.contains_key(&inode) {
             return_errno_with_message!(Errno::EADDRINUSE, "the addr is already used");
         }
-        let new_backlog = Arc::new(Backlog::new(backlog));
-        backlog_sockets.insert(inode, new_backlog);
-        Ok(())
+        let new_backlog = Arc::new(Backlog::new(addr, backlog));
+        backlog_sockets.insert(inode, new_backlog.clone());
+        Ok(new_backlog)
     }
 
     fn get_backlog(&self, addr: &UnixSocketAddrBound) -> Result<Arc<Backlog>> {
@@ -112,16 +104,6 @@ impl BacklogTable {
             .ok_or_else(|| Error::with_message(Errno::EINVAL, "the socket is not listened"))
     }
 
-    fn pop_incoming(&self, addr: &UnixSocketAddrBound) -> Result<Endpoint> {
-        let backlog = self.get_backlog(addr)?;
-
-        if let Some(endpoint) = backlog.pop_incoming() {
-            Ok(endpoint)
-        } else {
-            return_errno_with_message!(Errno::EAGAIN, "no pending connection is available")
-        }
-    }
-
     fn push_incoming(&self, addr: &UnixSocketAddrBound, endpoint: Endpoint) -> Result<()> {
         let backlog = self.get_backlog(addr).map_err(|_| {
             Error::with_message(
@@ -144,20 +126,26 @@ impl BacklogTable {
 }
 
 struct Backlog {
+    addr: UnixSocketAddrBound,
     pollee: Pollee,
     backlog: usize,
     incoming_endpoints: Mutex<VecDeque<Endpoint>>,
 }
 
 impl Backlog {
-    fn new(backlog: usize) -> Self {
+    fn new(addr: UnixSocketAddrBound, backlog: usize) -> Self {
         Self {
+            addr,
             pollee: Pollee::new(IoEvents::empty()),
             backlog,
             incoming_endpoints: Mutex::new(VecDeque::with_capacity(backlog)),
         }
     }
 
+    fn addr(&self) -> &UnixSocketAddrBound {
+        &self.addr
+    }
+
     fn push_incoming(&self, endpoint: Endpoint) -> Result<()> {
         let mut endpoints = self.incoming_endpoints.lock();
         if endpoints.len() >= self.backlog {
@@ -168,13 +156,14 @@ impl Backlog {
         Ok(())
     }
 
-    fn pop_incoming(&self) -> Option<Endpoint> {
+    fn pop_incoming(&self) -> Result<Endpoint> {
         let mut incoming_endpoints = self.incoming_endpoints.lock();
         let endpoint = incoming_endpoints.pop_front();
         if incoming_endpoints.is_empty() {
             self.pollee.del_events(IoEvents::IN);
         }
         endpoint
+            .ok_or_else(|| Error::with_message(Errno::EAGAIN, "no pending connection is available"))
     }
 
     fn poll(&self, mask: IoEvents, poller: Option<&mut Poller>) -> IoEvents {