Add reusePort argument to ServerSocket.

runtime/bin/socket_linux.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_LINUX)
 
 #include <errno.h>  // NOLINT
 #include <stdio.h>  // NOLINT
 #include <stdlib.h>  // NOLINT
@@ skipping 289 matching lines @@
     if (ShouldIncludeIfaAddrs(ifa, lookup_family)) {
       addresses->SetAt(i, new InterfaceSocketAddress(
           ifa->ifa_addr, strdup(ifa->ifa_name)));
       i++;
     }
   }
   freeifaddrs(ifaddr);
   return addresses;
 }
 
+#ifndef SO_REUSEPORT
+#define SO_REUSEPORT 15
+#endif  // SO_REUSEPORT
 
 intptr_t ServerSocket::CreateBindListen(RawAddr addr,
                                         intptr_t port,
                                         intptr_t backlog,
-                                        bool v6_only) {
+                                        bool v6_only,
+                                        bool reuse_port) {
   intptr_t fd;
 
   fd = TEMP_FAILURE_RETRY(socket(addr.ss.ss_family, SOCK_STREAM, 0));
   if (fd < 0) return -1;
 
   FDUtils::SetCloseOnExec(fd);
 
   int optval = 1;
+
+  if (reuse_port) {
+    if (TEMP_FAILURE_RETRY(setsockopt(fd,
+                                      SOL_SOCKET,
+                                      SO_REUSEPORT,
+                                      &optval,
+                                      sizeof(optval))) != 0) {
+      int e = errno;
+      VOID_TEMP_FAILURE_RETRY(close(fd));
+      errno = e;
+      return -1;
+    }
+  } else {
+    optval = 0;
+    VOID_TEMP_FAILURE_RETRY(setsockopt(fd,
+                                       SOL_SOCKET,
+                                       SO_REUSEPORT,
+                                       &optval,
+                                       sizeof(optval)));
+  }
+
+  optval = 1;
   TEMP_FAILURE_RETRY(
       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)));
 
   if (addr.ss.ss_family == AF_INET6) {
     optval = v6_only ? 1 : 0;
     TEMP_FAILURE_RETRY(
         setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &optval, sizeof(optval)));
   }
 
   SocketAddress::SetAddrPort(&addr, port);
@@ skipping 83 matching lines @@
                                        IPPROTO_TCP,
                                        TCP_NODELAY,
                                        reinterpret_cast<char *>(&on),
                                        sizeof(on))) == 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)