Allow reuse address when firing up the ros2cli daemon.

Especially in tests where the daemon is being repeatedly
created and destroyed, it can take some time for the kernel
to actually allow the address to be rebinded (even after the
old process has exited).  This can lead to some situations
where we fail to spawn the daemon.

To fix this, set "allow_reuse_address" inside the LocalXMLRPCServer,
which will set SO_REUSADDR on the socket.

Signed-off-by: Chris Lalancette <[email protected]>

ros2cli/ros2cli/xmlrpc/local_server.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 import socket
 import struct
 # Import SimpleXMLRPCRequestHandler to re-export it.
@@ -32,7 +33,15 @@ def get_local_ipaddrs():
 
 class LocalXMLRPCServer(SimpleXMLRPCServer):
 
-    allow_reuse_address = False
+    # Allow re-binding even if another server instance was recently bound (i.e. we are still in
+    # TCP TIME_WAIT). This is already the default behavior on Windows, and further SO_REUSEADDR can
+    # lead to undefined behavior on Windows; see
+    # https://learn.microsoft.com/en-us/windows/win32/winsock/using-so-reuseaddr-and-so-exclusiveaddruse.  # noqa
+    # So we don't set the option for Windows.
+    if os.name == 'nt':
+        allow_reuse_address = False
+    else:
+        allow_reuse_address = True
 
     def server_bind(self):
         # Prevent listening socket from lingering in TIME_WAIT state after close()