From a9e95a33bc723dc42daea2fcde6dde1d4cc5efad Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Sat, 27 Dec 2014 18:02:53 +0100
Subject: [PATCH] unix: only set SO_REUSEADDR when bind() fails
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Only call setsockopt() when the initial bind() fails with EADDRINUSE,
then retry.  Saves a system call in what is normally the common case.

PR-URL: https://github.com/libuv/libuv/pull/88
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
---
 src/unix/tcp.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/unix/tcp.c b/src/unix/tcp.c
index 8c19c1ab..e1803236 100644
--- a/src/unix/tcp.c
+++ b/src/unix/tcp.c
@@ -62,6 +62,7 @@ int uv__tcp_bind(uv_tcp_t* tcp,
                  unsigned int flags) {
   int err;
   int on;
+  int fd;
 
   /* Cannot set IPv6-only mode on non-IPv6 socket. */
   if ((flags & UV_TCP_IPV6ONLY) && addr->sa_family != AF_INET6)
@@ -73,26 +74,29 @@ int uv__tcp_bind(uv_tcp_t* tcp,
   if (err)
     return err;
 
-  on = 1;
-  if (setsockopt(tcp->io_watcher.fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))
-    return -errno;
+  fd = tcp->io_watcher.fd;
 
 #ifdef IPV6_V6ONLY
   if (addr->sa_family == AF_INET6) {
     on = (flags & UV_TCP_IPV6ONLY) != 0;
-    if (setsockopt(tcp->io_watcher.fd,
-                   IPPROTO_IPV6,
-                   IPV6_V6ONLY,
-                   &on,
-                   sizeof on) == -1) {
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)))
       return -errno;
-    }
   }
 #endif
 
-  errno = 0;
-  if (bind(tcp->io_watcher.fd, addr, addrlen) && errno != EADDRINUSE)
-    return -errno;
+  if (bind(fd, addr, addrlen)) {
+    if (errno != EADDRINUSE)
+      return -errno;
+
+    on = 1;
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))
+      return -errno;
+
+    errno = 0;
+    if (bind(fd, addr, addrlen) && errno != EADDRINUSE)
+      return -errno;
+  }
+
   tcp->delayed_error = -errno;
 
   if (addr->sa_family == AF_INET6)