listen: backlog improvements after review

- backlog size is now a constant, not a function
- improved formatting

Author: alexs-sh

src/net/tcp/listener.rs

@@ -13,11 +13,11 @@ use std::{fmt, io};
 
 use crate::io_source::IoSource;
 use crate::net::TcpStream;
-use crate::sys::get_listen_backlog_size;
 #[cfg(any(unix, target_os = "hermit"))]
 use crate::sys::tcp::set_reuseaddr;
 #[cfg(not(target_os = "wasi"))]
 use crate::sys::tcp::{bind, listen, new_for_addr};
+use crate::sys::LISTEN_BACKLOG_SIZE;
 use crate::{event, sys, Interest, Registry, Token};
 
 /// A structure representing a socket server
@@ -79,7 +79,7 @@ impl TcpListener {
         set_reuseaddr(&listener.inner, true)?;
 
         bind(&listener.inner, addr)?;
-        listen(&listener.inner, get_listen_backlog_size())?;
+        listen(&listener.inner, LISTEN_BACKLOG_SIZE)?;
         Ok(listener)
     }
 

src/sys/mod.rs

@@ -98,42 +98,40 @@ cfg_not_os_poll! {
 /// - Default values vary depending on the OS and its version. Common defaults
 ///   include: -1, 128, 1024, and 4096.
 ///
+// Here is the original code from the standard library
+// https://github.com/rust-lang/rust/blob/4f808ba6bf9f1c8dde30d009e73386d984491587/library/std/src/os/unix/net/listener.rs#L72
+//
 #[allow(dead_code)]
-pub(crate) const fn get_listen_backlog_size() -> i32 {
-    // Here is the original code from the standard library
-    // https://github.com/rust-lang/rust/blob/4f808ba6bf9f1c8dde30d009e73386d984491587/library/std/src/os/unix/net/listener.rs#L72
-    #[cfg(any(
-        target_os = "windows",
-        target_os = "redox",
-        target_os = "espidf",
-        target_os = "horizon"
-    ))]
-    const BACKLOG_SIZE: i32 = 128;
+#[cfg(any(
+    target_os = "windows",
+    target_os = "redox",
+    target_os = "espidf",
+    target_os = "horizon"
+))]
+pub(crate) const LISTEN_BACKLOG_SIZE: i32 = 128;
 
-    #[allow(dead_code)]
-    #[cfg(any(
-                // Silently capped to `/proc/sys/net/core/somaxconn`.
-                target_os = "linux",
-                // Silently capped to `kern.ipc.soacceptqueue`.
-                target_os = "freebsd",
-                // Silently capped to `kern.somaxconn sysctl`.
-                target_os = "openbsd",
-                // Silently capped to the default 128.
-                target_vendor = "apple",
-            ))]
-    const BACKLOG_SIZE: i32 = -1;
+#[allow(dead_code)]
+#[cfg(any(
+    // Silently capped to `/proc/sys/net/core/somaxconn`.
+    target_os = "linux",
+    // Silently capped to `kern.ipc.soacceptqueue`.
+    target_os = "freebsd",
+    // Silently capped to `kern.somaxconn sysctl`.
+    target_os = "openbsd",
+    // Silently capped to the default 128.
+    target_vendor = "apple",
+))]
+pub(crate) const LISTEN_BACKLOG_SIZE: i32 = -1;
 
-    #[allow(dead_code)]
-    #[cfg(not(any(
-        target_os = "windows",
-        target_os = "redox",
-        target_os = "espidf",
-        target_os = "horizon",
-        target_os = "linux",
-        target_os = "freebsd",
-        target_os = "openbsd",
-        target_vendor = "apple",
-    )))]
-    const BACKLOG_SIZE: i32 = libc::SOMAXCONN;
-    BACKLOG_SIZE
-}
+#[allow(dead_code)]
+#[cfg(not(any(
+    target_os = "windows",
+    target_os = "redox",
+    target_os = "espidf",
+    target_os = "horizon",
+    target_os = "linux",
+    target_os = "freebsd",
+    target_os = "openbsd",
+    target_vendor = "apple",
+)))]
+pub(crate) const LISTEN_BACKLOG_SIZE: i32 = libc::SOMAXCONN;

src/sys/unix/uds/listener.rs

@@ -6,9 +6,9 @@ use std::path::Path;
 use std::{io, mem};
 
 use crate::net::UnixStream;
-use crate::sys::get_listen_backlog_size;
 use crate::sys::unix::net::new_socket;
 use crate::sys::unix::uds::{path_offset, unix_addr};
+use crate::sys::LISTEN_BACKLOG_SIZE;
 
 pub(crate) fn bind_addr(address: &SocketAddr) -> io::Result<net::UnixListener> {
     let fd = new_socket(libc::AF_UNIX, libc::SOCK_STREAM)?;
@@ -17,7 +17,7 @@ pub(crate) fn bind_addr(address: &SocketAddr) -> io::Result<net::UnixListener> {
     let (unix_address, addrlen) = unix_addr(address);
     let sockaddr = &unix_address as *const libc::sockaddr_un as *const libc::sockaddr;
     syscall!(bind(fd, sockaddr, addrlen))?;
-    syscall!(listen(fd, get_listen_backlog_size()))?;
+    syscall!(listen(fd, LISTEN_BACKLOG_SIZE))?;
 
     Ok(socket)
 }