Problem: poller_t does not support modify

Solution: Added `modify` method based on `zmq_poller_modify` and test cases
covering it.
Reduced code duplication in existing test cases by introducing
`client_server_setup` helper struct.

tests/poller.cpp

@@ -113,7 +113,6 @@ TEST(poller, remove_unregistered_throws)
     ASSERT_THROW(poller.remove(socket), zmq::error_t);
 }
 
-/// \todo this should lead to an exception instead
 TEST(poller, remove_registered_empty)
 {
     zmq::context_t context;
@@ -156,19 +155,37 @@ private:
     std::string endpoint_;
 };
 
+struct server_client_setup
+{
+    server_client_setup ()
+    {
+        init ();
+    }
+
+    void init()
+    {
+        endpoint = loopback_ip4_binder {server}.endpoint ();
+        ASSERT_NO_THROW (client.connect (endpoint));
+    }
+
+    zmq::poller_t::handler_t handler = [&](short e) {
+        events = e;
+    };
+
+    zmq::context_t context;
+    zmq::socket_t server {context, zmq::socket_type::router};
+    zmq::socket_t client {context, zmq::socket_type::dealer};
+    std::string endpoint;
+    short events = 0;
+};
+
 } //namespace
 
 TEST(poller, poll_basic)
 {
-    zmq::context_t context;
+    server_client_setup s;
 
-    zmq::socket_t vent{context, zmq::socket_type::push};
+    ASSERT_NO_THROW(s.client.send("Hi"));
-    auto endpoint = loopback_ip4_binder(vent).endpoint();
-
-    zmq::socket_t sink{context, zmq::socket_type::pull};
-    ASSERT_NO_THROW(sink.connect(endpoint));
-
-    ASSERT_NO_THROW(vent.send("Hi"));
 
     zmq::poller_t poller;
     bool message_received = false;
@@ -176,7 +193,7 @@ TEST(poller, poll_basic)
         ASSERT_TRUE(0 != (events & ZMQ_POLLIN));
         message_received = true;
     };
-    ASSERT_NO_THROW(poller.add(sink, ZMQ_POLLIN, handler));
+    ASSERT_NO_THROW(poller.add(s.server, ZMQ_POLLIN, handler));
     ASSERT_NO_THROW(poller.wait(std::chrono::milliseconds{-1}));
     ASSERT_TRUE(message_received);
 }
@@ -184,48 +201,41 @@ TEST(poller, poll_basic)
 /// \todo this contains multiple test cases that should be split up
 TEST(poller, client_server)
 {
-    zmq::context_t context;
     const std::string send_msg = "Hi";
 
-    // Setup server
+    // Setup server and client
-    zmq::socket_t server{context, zmq::socket_type::router};
+    server_client_setup s;
-    auto endpoint = loopback_ip4_binder(server).endpoint();
 
     // Setup poller
     zmq::poller_t poller;
-    bool got_pollin = false;
+    short events;
-    bool got_pollout = false;
+    zmq::poller_t::handler_t handler = [&](short e) {
-    zmq::poller_t::handler_t handler = [&](short events) {
+        if (0 != (e & ZMQ_POLLIN)) {
-        if (0 != (events & ZMQ_POLLIN)) {
             zmq::message_t zmq_msg;
-            ASSERT_NO_THROW(server.recv(&zmq_msg)); // skip msg id
+            ASSERT_NO_THROW(s.server.recv(&zmq_msg)); // skip msg id
-            ASSERT_NO_THROW(server.recv(&zmq_msg)); // get message
+            ASSERT_NO_THROW(s.server.recv(&zmq_msg)); // get message
             std::string recv_msg(zmq_msg.data<char>(),
                                  zmq_msg.size());
             ASSERT_EQ(send_msg, recv_msg);
-            got_pollin = true;
+        } else if (0 != (e & ~ZMQ_POLLOUT)) {
-        } else if (0 != (events & ZMQ_POLLOUT)) {
-            got_pollout = true;
-        } else {
             ASSERT_TRUE(false) << "Unexpected event type " << events;
         }
+        events = e;
     };
-    ASSERT_NO_THROW(poller.add(server, ZMQ_POLLIN, handler));
 
-    // Setup client and send message
+    ASSERT_NO_THROW(poller.add(s.server, ZMQ_POLLIN, handler));
-    zmq::socket_t client{context, zmq::socket_type::dealer};
+
-    ASSERT_NO_THROW(client.connect(endpoint));
+    // client sends message
-    ASSERT_NO_THROW(client.send(send_msg));
+    ASSERT_NO_THROW(s.client.send(send_msg));
 
     ASSERT_NO_THROW(poller.wait(std::chrono::milliseconds{-1}));
-    ASSERT_TRUE(got_pollin);
+    ASSERT_EQ(events, ZMQ_POLLIN);
-    ASSERT_FALSE(got_pollout);
 
     // Re-add server socket with pollout flag
-    ASSERT_NO_THROW(poller.remove(server));
+    ASSERT_NO_THROW(poller.remove(s.server));
-    ASSERT_NO_THROW(poller.add(server, ZMQ_POLLIN | ZMQ_POLLOUT, handler));
+    ASSERT_NO_THROW(poller.add(s.server, ZMQ_POLLIN | ZMQ_POLLOUT, handler));
     ASSERT_NO_THROW(poller.wait(std::chrono::milliseconds{-1}));
-    ASSERT_TRUE(got_pollout);
+    ASSERT_EQ(events, ZMQ_POLLOUT);
 }
 
 TEST(poller, poller_add_invalid_socket_throws)
@@ -254,17 +264,62 @@ TEST(poller, poller_remove_invalid_socket_throws)
 
 TEST(poller, wait_on_added_empty_handler)
 {
-    zmq::context_t context;
+    server_client_setup s;
-    zmq::socket_t vent{context, zmq::socket_type::push};
+    ASSERT_NO_THROW(s.client.send("Hi"));
-    auto endpoint = loopback_ip4_binder(vent).endpoint();
-
-    zmq::socket_t sink{context, zmq::socket_type::pull};
-    ASSERT_NO_THROW(sink.connect(endpoint));
-    ASSERT_NO_THROW(vent.send("Hi"));
-
     zmq::poller_t poller;
     std::function<void(void)> handler;
-    ASSERT_NO_THROW(poller.add(sink, ZMQ_POLLIN, handler));
+    ASSERT_NO_THROW(poller.add(s.server, ZMQ_POLLIN, handler));
     ASSERT_NO_THROW(poller.wait(std::chrono::milliseconds{-1}));
 }
+
+TEST(poller, modify_empty_throws)
+{
+    zmq::context_t context;
+    zmq::socket_t socket {context, zmq::socket_type::push};
+    zmq::poller_t poller;
+    ASSERT_THROW (poller.modify (socket, ZMQ_POLLIN), zmq::error_t);
+}
+
+TEST(poller, modify_invalid_socket_throws)
+{
+    zmq::context_t context;
+    zmq::socket_t a {context, zmq::socket_type::push};
+    zmq::socket_t b {std::move (a)};
+    zmq::poller_t poller;
+    ASSERT_THROW (poller.modify (a, ZMQ_POLLIN), zmq::error_t);
+}
+
+TEST(poller, modified_not_added_throws)
+{
+    zmq::context_t context;
+    zmq::socket_t a {context, zmq::socket_type::push};
+    zmq::socket_t b {context, zmq::socket_type::push};
+    zmq::poller_t poller;
+    ASSERT_NO_THROW (poller.add (a, ZMQ_POLLIN, zmq::poller_t::handler_t {}));
+    ASSERT_THROW (poller.modify (b, ZMQ_POLLIN), zmq::error_t);
+}
+
+TEST(poller, poll_client_server)
+{
+    // Setup server and client
+    server_client_setup s;
+
+    // Setup poller
+    zmq::poller_t poller;
+    ASSERT_NO_THROW(poller.add(s.server, ZMQ_POLLIN, s.handler));
+
+    // client sends message
+    ASSERT_NO_THROW(s.client.send("Hi"));
+
+    // wait for message and verify events
+    ASSERT_NO_THROW(poller.wait(std::chrono::milliseconds{500}));
+    ASSERT_TRUE(s.events == ZMQ_POLLIN);
+    ASSERT_EQ(s.events, ZMQ_POLLIN);
+
+    // Modify server socket with pollout flag
+    ASSERT_NO_THROW(poller.modify(s.server, ZMQ_POLLIN | ZMQ_POLLOUT));
+    ASSERT_NO_THROW(poller.wait(std::chrono::milliseconds{500}));
+    ASSERT_EQ(s.events, ZMQ_POLLIN | ZMQ_POLLOUT);
+}
+
 #endif

zmq.hpp

@@ -1083,6 +1083,12 @@ namespace zmq
             throw error_t ();
         }
 
+        void modify (zmq::socket_t &socket, short events)
+        {
+            if (0 != zmq_poller_modify (poller_ptr, socket.ptr, events))
+                throw error_t ();
+        }
+
         bool wait (std::chrono::milliseconds timeout)
         {
             int rc = zmq_poller_wait_all (poller_ptr, poller_events.data (), static_cast<int> (poller_events.size ()), static_cast<long>(timeout.count ()));