Add configuration for socket listen queue size (#26)

.github/workflows/clippy.yml

@@ -1,6 +1,6 @@
 name: Clippy
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build:

.github/workflows/rustfmt.yml

@@ -1,6 +1,6 @@
 name: Rustfmt
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build:

.github/workflows/tests.yml

@@ -1,6 +1,6 @@
 name: Tests
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   test-latest:

src/cli.rs

@@ -49,6 +49,19 @@ fn make_app() -> Command {
                      different help output.",
                 ),
         )
+        .arg(
+            Arg::new("backlog")
+                .short('b')
+                .long("backlog")
+                .default_value("1")
+                .value_parser(value_parser!(i32).range(1..))
+                .value_name("LISTEN-QUEUE")
+                .help(
+                    "The length of the socket backlog queue in any listen call which \
+                     must be a positive integer greater than or equal to 1.  The OS may \
+                     silently cap this value to a lower setting.",
+                ),
+        )
         .arg(
             Arg::new("no_pid")
                 .long("no-pid")
@@ -57,7 +70,7 @@ fn make_app() -> Command {
                     "When this is set the LISTEN_PID environment variable is not \
              emitted.  This is supported by some systems such as the listenfd \
              crate to skip the pid check.  This is necessary for proxying \
-             through to other processe like cargo-watch which would break \
+             through to other processes like cargo-watch which would break \
              the pid check.  This has no effect on windows.",
                 ),
         )
@@ -120,7 +133,7 @@ pub fn execute() -> Result<(), Error> {
         log!("warning: no sockets created");
     } else {
         for fd in fds {
-            let raw_fd = fd.create_raw_fd()?;
+            let raw_fd = fd.create_raw_fd(*matches.get_one("backlog").expect("default value"))?;
             raw_fds.push((fd, raw_fd));
         }
     }

src/fd.rs

@@ -96,8 +96,8 @@ impl Fd {
     }
 
     /// Creates a raw fd from the fd spec.
-    pub fn create_raw_fd(&self) -> Result<RawFd, anyhow::Error> {
-        create_raw_fd(self)
+    pub fn create_raw_fd(&self, listen_backlog: i32) -> Result<RawFd, anyhow::Error> {
+        create_raw_fd(self, listen_backlog)
     }
 
     pub fn describe_raw_fd(&self, raw_fd: RawFd) -> Result<String, anyhow::Error> {
@@ -148,7 +148,7 @@ mod imp {
     use nix::sys::socket::sockopt::ReuseAddr;
     use nix::sys::socket::sockopt::ReusePort;
 
-    pub fn create_raw_fd(fd: &Fd) -> Result<RawFd, Error> {
+    pub fn create_raw_fd(fd: &Fd, listen_backlog: i32) -> Result<RawFd, Error> {
         let (addr, fam, ty) = sock_info(fd)?;
         let sock = socket::socket(fam, ty, socket::SockFlag::empty(), None)?;
         setsockopt(sock, ReuseAddr, &true)?;
@@ -163,7 +163,7 @@ mod imp {
             .map_err(From::from)
             .and_then(|_| {
                 if fd.should_listen() {
-                    socket::listen(sock, 1)?;
+                    socket::listen(sock, listen_backlog as usize)?;
                 }
                 Ok(())
             });
@@ -234,13 +234,13 @@ mod imp {
 
     use anyhow::{bail, Error};
 
-    pub fn create_raw_fd(fd: &Fd) -> Result<RawFd, Error> {
+    pub fn create_raw_fd(fd: &Fd, listen_backlog: i32) -> Result<RawFd, Error> {
         let (addr, dom, ty) = sock_info(fd)?;
         let sock = socket2::Socket::new(dom, ty, None)?;
 
         sock.bind(&addr)?;
         if fd.should_listen() {
-            sock.listen(1)?;
+            sock.listen(listen_backlog as _)?;
         }
 
         Ok(sock.into_raw_socket())