[ZEO4] Enable TCP_NODELAY for inet(6) sockets

See commit 3d886d42.

----

Originally included in slapos: nexedi/slapos@5cf4cf1f

src/ZEO/zrpc/client.py

@@ -568,6 +568,8 @@ class ConnectWrapper:
             self.close()
             return
         self.sock.setblocking(0)
+        if domain in (socket.AF_INET, socket.AF_INET6):
+            self.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
         self.state = "opened"
 
     def connect_procedure(self):

src/ZEO/zrpc/server.py

@@ -66,6 +66,7 @@ class Dispatcher(asyncore.dispatcher):
                         socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, True)
             else:
                 self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
         else:
             self.create_socket(socket.AF_UNIX, socket.SOCK_STREAM)
         self.set_reuse_addr()