Outstanding requests dropped when requester dies (issue 190)

So far the requests in req/rep pattern were delivered to and processed
by worker even though the original requester was dead. Thus,
the worker processing replies with noone to deliver results to.
This optimisation drops requests in two situations:

1. Queued inbound requests in XREP socket when peer disconnects.
2. Queued outbound requests in XREQ when socket is closed.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

2 files changed, 72 insertions, 4 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 9238850..8ec3b0c 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -6,7 +6,8 @@ noinst_PROGRAMS = test_pair_inproc \
                   test_reqrep_inproc \
                   test_reqrep_tcp \
                   test_hwm \
-                  test_reqrep_device
+                  test_reqrep_device \
+                  test_reqrep_drop
 
 if !ON_MINGW
 noinst_PROGRAMS += test_shutdown_stress \
@@ -17,13 +18,11 @@ endif
 
 test_pair_inproc_SOURCES = test_pair_inproc.cpp testutil.hpp
 test_pair_tcp_SOURCES = test_pair_tcp.cpp testutil.hpp
-
 test_reqrep_inproc_SOURCES = test_reqrep_inproc.cpp testutil.hpp
 test_reqrep_tcp_SOURCES = test_reqrep_tcp.cpp testutil.hpp
-
 test_hwm_SOURCES = test_hwm.cpp
-
 test_reqrep_device_SOURCES = test_reqrep_device.cpp
+test_reqrep_drop_SOURCES = test_reqrep_drop.cpp
 
 if !ON_MINGW
 test_shutdown_stress_SOURCES = test_shutdown_stress.cpp
diff --git a/tests/test_reqrep_drop.cpp b/tests/test_reqrep_drop.cpp
new file mode 100644
index 0000000..353aee7
--- /dev/null
+++ b/tests/test_reqrep_drop.cpp
@@ -0,0 +1,69 @@
+/*
+    Copyright (c) 2007-2011 iMatix Corporation
+    Copyright (c) 2007-2011 Other contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+
+#include "../include/zmq.h"
+#include "../include/zmq_utils.h"
+
+int main (int argc, char *argv [])
+{
+    void *ctx = zmq_init (1);
+    assert (ctx);
+
+    //  Create a server.
+    void *xrep = zmq_socket (ctx, ZMQ_XREP);
+    assert (xrep);
+    int rc = zmq_bind (xrep, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    //  Create a client.
+    void *xreq = zmq_socket (ctx, ZMQ_XREQ);
+    assert (xreq);
+    rc = zmq_connect (xreq, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    //  Send requests.
+    rc = zmq_send (xreq, "ABC", 3, 0);
+    assert (rc == 3);
+    rc = zmq_send (xreq, "DEF", 3, 0);
+    assert (rc == 3);
+
+    //  Disconnect client.
+    rc = zmq_close (xreq);
+    assert (rc == 0);
+
+    //  Wait a while for disconnect to happen.
+    zmq_sleep (1);
+
+    //  Try to receive a request -- it should have been discarded.
+    char buff [3];
+    rc = zmq_recv (xrep, buff, 3, ZMQ_DONTWAIT);
+    assert (rc < 0);
+    assert (errno == EAGAIN);
+
+    //  Clean up.
+    rc = zmq_close (xrep);
+    assert (rc == 0);
+    rc = zmq_term (ctx);
+    assert (rc == 0);
+
+    return 0 ;
+}