Problem: Poller size function missing

Solution: Add it to poller_t

Author: gummif

tests/poller.cpp

@@ -133,6 +133,20 @@ TEST_CASE("poller wait with no handlers throws", "[poller]")
                     const zmq::error_t&);
 }
 
+#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 3, 3)
+TEST_CASE("poller add/remove size checks", "[poller]")
+{
+    zmq::context_t context;
+    zmq::socket_t socket{context, zmq::socket_type::router};
+    zmq::poller_t<> poller;
+    CHECK(poller.size() == 0);
+    poller.add(socket, zmq::event_flags::pollin);
+    CHECK(poller.size() == 1);
+    CHECK_NOTHROW(poller.remove(socket));
+    CHECK(poller.size() == 0);
+}
+#endif
+
 TEST_CASE("poller remove unregistered throws", "[poller]")
 {
     zmq::context_t context;

zmq.hpp

@@ -2653,6 +2653,15 @@ template<typename T = no_user_data> class poller_t
         throw error_t();
     }
 
+#if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 3, 3)
+    size_t size() const noexcept
+    {
+        int rc = zmq_poller_size(const_cast<void *>(poller_ptr.get()));
+        ZMQ_ASSERT(rc >= 0);
+        return static_cast<size_t>(std::max(rc, 0));
+    }
+#endif
+
   private:
     struct destroy_poller_t
     {