Problem: parts of in_event duplicated across subclasses of stream_listener_base_t

Solution: extract function create_engine into base class

src/ipc_listener.cpp

@@ -37,10 +37,8 @@
 
 #include <string.h>
 
-#include "stream_engine.hpp"
 #include "ipc_address.hpp"
 #include "io_thread.hpp"
-#include "session_base.hpp"
 #include "config.hpp"
 #include "err.hpp"
 #include "ip.hpp"
@@ -149,23 +147,7 @@ void zmq::ipc_listener_t::in_event ()
     }
 
     //  Create the engine object for this connection.
-    stream_engine_t *engine =
-      new (std::nothrow) stream_engine_t (fd, options, _endpoint);
-    alloc_assert (engine);
-
-    //  Choose I/O thread to run connecter in. Given that we are already
-    //  running in an I/O thread, there must be at least one available.
-    io_thread_t *io_thread = choose_io_thread (options.affinity);
-    zmq_assert (io_thread);
-
-    //  Create and launch a session object.
-    session_base_t *session =
-      session_base_t::create (io_thread, false, _socket, options, NULL);
-    errno_assert (session);
-    session->inc_seqnum ();
-    launch_child (session);
-    send_attach (session, engine, false);
-    _socket->event_accepted (_endpoint, fd);
+    create_engine (fd);
 }
 
 int zmq::ipc_listener_t::get_address (std::string &addr_)

src/stream_listener_base.cpp

@@ -29,7 +29,9 @@
 
 #include "precompiled.hpp"
 #include "stream_listener_base.hpp"
+#include "session_base.hpp"
 #include "socket_base.hpp"
+#include "stream_engine.hpp"
 
 zmq::stream_listener_base_t::stream_listener_base_t (
   zmq::io_thread_t *io_thread_,
@@ -92,3 +94,24 @@ int zmq::stream_listener_base_t::close ()
 
     return 0;
 }
+
+void zmq::stream_listener_base_t::create_engine (fd_t fd)
+{
+    stream_engine_t *engine =
+      new (std::nothrow) stream_engine_t (fd, options, _endpoint);
+    alloc_assert (engine);
+
+    //  Choose I/O thread to run connecter in. Given that we are already
+    //  running in an I/O thread, there must be at least one available.
+    io_thread_t *io_thread = choose_io_thread (options.affinity);
+    zmq_assert (io_thread);
+
+    //  Create and launch a session object.
+    session_base_t *session =
+      session_base_t::create (io_thread, false, _socket, options, NULL);
+    errno_assert (session);
+    session->inc_seqnum ();
+    launch_child (session);
+    send_attach (session, engine, false);
+    _socket->event_accepted (_endpoint, fd);
+}

src/stream_listener_base.hpp

@@ -69,6 +69,8 @@ class stream_listener_base_t : public own_t, public io_object_t
     //  Close the listening socket.
     virtual int close ();
 
+    void create_engine (fd_t fd);
+
     //  Underlying socket.
     fd_t _s;
 

src/tcp_listener.cpp

@@ -34,9 +34,7 @@
 #include <stdio.h>
 
 #include "tcp_listener.hpp"
-#include "stream_engine.hpp"
 #include "io_thread.hpp"
-#include "session_base.hpp"
 #include "config.hpp"
 #include "err.hpp"
 #include "ip.hpp"
@@ -90,23 +88,7 @@ void zmq::tcp_listener_t::in_event ()
     }
 
     //  Create the engine object for this connection.
-    stream_engine_t *engine =
-      new (std::nothrow) stream_engine_t (fd, options, _endpoint);
-    alloc_assert (engine);
-
-    //  Choose I/O thread to run connecter in. Given that we are already
-    //  running in an I/O thread, there must be at least one available.
-    io_thread_t *io_thread = choose_io_thread (options.affinity);
-    zmq_assert (io_thread);
-
-    //  Create and launch a session object.
-    session_base_t *session =
-      session_base_t::create (io_thread, false, _socket, options, NULL);
-    errno_assert (session);
-    session->inc_seqnum ();
-    launch_child (session);
-    send_attach (session, engine, false);
-    _socket->event_accepted (_endpoint, fd);
+    create_engine (fd);
 }
 
 int zmq::tcp_listener_t::get_address (std::string &addr_)

src/tipc_listener.cpp

@@ -37,10 +37,8 @@
 
 #include <string.h>
 
-#include "stream_engine.hpp"
 #include "tipc_address.hpp"
 #include "io_thread.hpp"
-#include "session_base.hpp"
 #include "config.hpp"
 #include "err.hpp"
 #include "ip.hpp"
@@ -75,23 +73,7 @@ void zmq::tipc_listener_t::in_event ()
     }
 
     //  Create the engine object for this connection.
-    stream_engine_t *engine =
-      new (std::nothrow) stream_engine_t (fd, options, _endpoint);
-    alloc_assert (engine);
-
-    //  Choose I/O thread to run connecter in. Given that we are already
-    //  running in an I/O thread, there must be at least one available.
-    io_thread_t *io_thread = choose_io_thread (options.affinity);
-    zmq_assert (io_thread);
-
-    //  Create and launch a session object.
-    session_base_t *session =
-      session_base_t::create (io_thread, false, _socket, options, NULL);
-    errno_assert (session);
-    session->inc_seqnum ();
-    launch_child (session);
-    send_attach (session, engine, false);
-    _socket->event_accepted (_endpoint, fd);
+    create_engine (fd);
 }
 
 int zmq::tipc_listener_t::get_address (std::string &addr_)