Problem: no test case using the proposed zmq_socket_get_peer_state function

Solution: added test case (with dummy implementation of zmq_socket_get_peer_state)

include/zmq.h

@@ -661,6 +661,10 @@ ZMQ_EXPORT int zmq_poller_modify_fd (void *poller, int fd, short events);
 ZMQ_EXPORT int zmq_poller_remove_fd (void *poller, int fd);
 #endif
 
+ZMQ_EXPORT int zmq_socket_get_peer_state (void *socket,
+                                          const void *identity,
+                                          size_t identity_size);
+
 /******************************************************************************/
 /*  Scheduling timers                                                         */
 /******************************************************************************/

src/zmq.cpp

@@ -1389,6 +1389,16 @@ int zmq_poller_wait_all (void *poller_, zmq_poller_event_t *events_, int n_event
     return rc;
 }
 
+//  Peer-specific state
+
+int zmq_socket_get_peer_state (void *socket,
+                               const void *identity,
+                               size_t identity_size)
+{
+    errno = ENOTSUP;
+    return -1;
+}
+
 //  Timers
 
 void *zmq_timers_new (void)

tests/test_router_mandatory.cpp

@@ -29,6 +29,107 @@
 
 #include "testutil.hpp"
 
+void test_get_peer_state ()
+{
+#ifdef ZMQ_BUILD_DRAFT_API
+    size_t len = MAX_SOCKET_STRING;
+    char my_endpoint[MAX_SOCKET_STRING];
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+    void *router = zmq_socket (ctx, ZMQ_ROUTER);
+    assert (router);
+
+    int rc = zmq_bind (router, "tcp://127.0.0.1:*");
+    assert (rc == 0);
+
+    rc = zmq_getsockopt (router, ZMQ_LAST_ENDPOINT, my_endpoint, &len);
+    assert (rc == 0);
+
+    int mandatory = 1;
+    rc = zmq_setsockopt (router, ZMQ_ROUTER_MANDATORY, &mandatory,
+                         sizeof (mandatory));
+
+    //  Create dealer called "X" and connect it to our router
+    void *dealer1 = zmq_socket (ctx, ZMQ_DEALER);
+    assert (dealer1);
+    rc = zmq_setsockopt (dealer1, ZMQ_IDENTITY, "X", 1);
+    assert (rc == 0);
+    rc = zmq_connect (dealer1, my_endpoint);
+    assert (rc == 0);
+
+    //  Create dealer called "Y" and connect it to our router
+    void *dealer2 = zmq_socket (ctx, ZMQ_DEALER);
+    assert (dealer2);
+    rc = zmq_setsockopt (dealer2, ZMQ_IDENTITY, "Y", 1);
+    assert (rc == 0);
+    rc = zmq_connect (dealer2, my_endpoint);
+    assert (rc == 0);
+
+    //  Get message from dealer to know when connection is ready
+    char buffer[255];
+    rc = zmq_send (dealer1, "Hello", 5, 0);
+    assert (rc == 5);
+    rc = zmq_recv (router, buffer, 255, 0);
+    assert (rc == 1);
+    assert (buffer[0] == 'X');
+
+    void *poller = zmq_poller_new ();
+    assert (poller);
+
+    //  Poll on router and dealer1, but not on dealer2
+    rc = zmq_poller_add (poller, router, NULL, ZMQ_POLLOUT);
+    assert (rc == 0);
+    rc = zmq_poller_add (poller, dealer1, NULL, ZMQ_POLLIN);
+    assert (rc == 0);
+
+    const size_t count = 10000;
+    const size_t event_size = 2;
+    zmq_poller_event_t events[event_size];
+    for (size_t iterations = 0;
+         iterations < count
+         && zmq_poller_wait_all (poller, events, event_size, -1) != -1;
+         ++iterations) {
+        for (size_t i = 0; i < event_size; ++i) {
+            if (events[i].socket == router) {
+                rc = zmq_socket_get_peer_state (router, "X", 1);
+                assert (rc != -1);
+                if (rc & ZMQ_POLLOUT) {
+                    rc = zmq_send (router, "X", 1, ZMQ_SNDMORE);
+                    assert (rc == 1);
+                    rc = zmq_send (router, "Hello", 5, 0);
+                    assert (rc == 5);
+                }
+                rc = zmq_socket_get_peer_state (router, "Y", 1);
+                assert (rc != -1);
+                if (rc & ZMQ_POLLOUT) {
+                    rc = zmq_send (router, "Y", 1, ZMQ_SNDMORE);
+                    assert (rc == 1);
+                    rc = zmq_send (router, "Hello", 5, 0);
+                    assert (rc == 5);
+                }
+            }
+            if (events[i].socket == dealer1) {
+                rc = zmq_recv (dealer1, buffer, 255, ZMQ_DONTWAIT);
+                assert (rc == 5);
+            }
+            // never read from dealer2, so its pipe becomes full eventually
+        }
+    }
+
+    rc = zmq_close (router);
+    assert (rc == 0);
+
+    rc = zmq_close (dealer1);
+    assert (rc == 0);
+
+    rc = zmq_close (dealer2);
+    assert (rc == 0);
+
+    rc = zmq_ctx_term (ctx);
+    assert (rc == 0);
+#endif
+}
+
 void test_basic ()
 {
     size_t len = MAX_SOCKET_STRING;
@@ -98,6 +199,7 @@ int main (void)
     setup_test_environment ();
 
     test_basic ();
+    test_get_peer_state ();
 
-    return 0;
+    return 0 ;
 }