Add support for pinging (#77)

* Add keepalive interval and the server timeout.

include/signalrclient/signalr_client_config.h

@@ -47,6 +47,10 @@ namespace signalr
         SIGNALRCLIENT_API const std::shared_ptr<scheduler>& __cdecl get_scheduler() const noexcept;
         SIGNALRCLIENT_API void set_handshake_timeout(std::chrono::milliseconds);
         SIGNALRCLIENT_API std::chrono::milliseconds get_handshake_timeout() const noexcept;
+        SIGNALRCLIENT_API void set_server_timeout(std::chrono::milliseconds);
+        SIGNALRCLIENT_API std::chrono::milliseconds get_server_timeout() const noexcept;
+        SIGNALRCLIENT_API void set_keepalive_interval(std::chrono::milliseconds);
+        SIGNALRCLIENT_API std::chrono::milliseconds get_keepalive_interval() const noexcept;
 
     private:
 #ifdef USE_CPPRESTSDK
@@ -56,5 +60,7 @@ namespace signalr
         std::map<std::string, std::string> m_http_headers;
         std::shared_ptr<scheduler> m_scheduler;
         std::chrono::milliseconds m_handshake_timeout;
+        std::chrono::milliseconds m_server_timeout;
+        std::chrono::milliseconds m_keepalive_interval;
     };
 }

src/signalrclient/hub_connection_impl.cpp

@@ -185,6 +185,10 @@ namespace signalr
                                 callback(exception);
                             }, exception);
                     }
+                    else
+                    {
+                        connection->start_keepalive();
+                    }
                 };
 
                 auto handshake_request = handshake::write_handshake(connection->m_protocol);
@@ -348,6 +352,7 @@ namespace signalr
                 }
             }
 
+            reset_server_timeout();
             auto messages = m_protocol->parse_messages(response);
 
             for (const auto& val : messages)
@@ -385,7 +390,10 @@ namespace signalr
                     // Sent to server only, should not be received by client
                     throw std::runtime_error("Received unexpected message type 'CancelInvocation'.");
                 case message_type::ping:
-                    // TODO
+                    if (m_logger.is_enabled(trace_level::debug))
+                    {
+                        m_logger.log(trace_level::debug, "ping message received.");
+                    }
                     break;
                 case message_type::close:
                     // TODO
@@ -477,6 +485,8 @@ namespace signalr
                         }
                     }
                 });
+
+            reset_send_ping();
         }
         catch (const std::exception& e)
         {
@@ -510,6 +520,126 @@ namespace signalr
         m_disconnected = disconnected;
     }
 
+    void hub_connection_impl::reset_send_ping()
+    {
+        auto timeMs = (std::chrono::steady_clock::now() + m_signalr_client_config.get_keepalive_interval()).time_since_epoch();
+        m_nextActivationSendPing.store(std::chrono::duration_cast<std::chrono::milliseconds>(timeMs).count());
+    }
+
+    void hub_connection_impl::reset_server_timeout()
+    {
+        auto timeMs = (std::chrono::steady_clock::now() + m_signalr_client_config.get_server_timeout()).time_since_epoch();
+        m_nextActivationServerTimeout.store(std::chrono::duration_cast<std::chrono::milliseconds>(timeMs).count());
+    }
+
+    void hub_connection_impl::start_keepalive()
+    {
+        if (m_logger.is_enabled(trace_level::debug))
+        {
+            m_logger.log(trace_level::debug, "starting keep alive timer.");
+        }
+
+        auto send_ping = [](std::shared_ptr<hub_connection_impl> connection)
+        {
+            if (!connection)
+            {
+                return;
+            }
+
+            if (connection->get_connection_state() != connection_state::connected)
+            {
+                return;
+            }
+
+            try
+            {
+                hub_message ping_msg(signalr::message_type::ping);
+                auto message = connection->m_protocol->write_message(&ping_msg);
+
+                std::weak_ptr<hub_connection_impl> weak_connection = connection;
+                connection->m_connection->send(
+                    message,
+                    connection->m_protocol->transfer_format(), [weak_connection](std::exception_ptr exception)
+                    {
+                        auto connection = weak_connection.lock();
+                        if (connection)
+                        {
+                            if (exception)
+                            {
+                                if (connection->m_logger.is_enabled(trace_level::warning))
+                                {
+                                    connection->m_logger.log(trace_level::warning, "failed to send ping!");
+                                }
+                            }
+                            else
+                            {
+                                connection->reset_send_ping();
+                            }
+                        }
+                    });
+            }
+            catch (const std::exception& e)
+            {
+                if (connection->m_logger.is_enabled(trace_level::warning))
+                {
+                    connection->m_logger.log(trace_level::warning, std::string("failed to send ping: ").append(e.what()));
+                }
+            }
+        };
+
+        send_ping(shared_from_this());
+        reset_server_timeout();
+
+        std::weak_ptr<hub_connection_impl> weak_connection = shared_from_this();
+        timer(m_signalr_client_config.get_scheduler(),
+            [send_ping, weak_connection](std::chrono::milliseconds)
+            {
+                auto connection = weak_connection.lock();
+
+                if (!connection)
+                {
+                    return true;
+                }
+
+                if (connection->get_connection_state() != connection_state::connected)
+                {
+                    return true;
+                }
+
+                auto timeNowmSeconds =
+                    std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now().time_since_epoch()).count();
+
+                if (timeNowmSeconds > connection->m_nextActivationServerTimeout.load())
+                {
+                    if (connection->get_connection_state() == connection_state::connected)
+                    {
+                        auto error_msg = std::string("server timeout (")
+                            .append(std::to_string(connection->m_signalr_client_config.get_server_timeout().count()))
+                            .append(" ms) elapsed without receiving a message from the server.");
+                        if (connection->m_logger.is_enabled(trace_level::warning))
+                        {
+                            connection->m_logger.log(trace_level::warning, error_msg);
+                        }
+
+                        connection->m_connection->stop([](std::exception_ptr)
+                            {
+                            }, std::make_exception_ptr(signalr_exception(error_msg)));
+                    }
+                }
+
+                if (timeNowmSeconds > connection->m_nextActivationSendPing.load())
+                {
+                    if (connection->m_logger.is_enabled(trace_level::debug))
+                    {
+                        connection->m_logger.log(trace_level::debug, "sending ping to server.");
+                    }
+                    send_ping(connection);
+                }
+
+                return false;
+            });
+    }
+
     // unnamed namespace makes it invisble outside this translation unit
     namespace
     {

src/signalrclient/hub_connection_impl.h

@@ -65,6 +65,9 @@ namespace signalr
         signalr_client_config m_signalr_client_config;
         std::unique_ptr<hub_protocol> m_protocol;
 
+        std::atomic<int64_t> m_nextActivationServerTimeout;
+        std::atomic<int64_t> m_nextActivationSendPing;
+
         std::mutex m_stop_callback_lock;
         std::vector<std::function<void(std::exception_ptr)>> m_stop_callbacks;
 
@@ -75,5 +78,10 @@ namespace signalr
         void invoke_hub_method(const std::string& method_name, const std::vector<signalr::value>& arguments, const std::string& callback_id,
             std::function<void()> set_completion, std::function<void(const std::exception_ptr)> set_exception) noexcept;
         bool invoke_callback(completion_message* completion);
+
+        void reset_send_ping();
+        void reset_server_timeout();
+
+        void start_keepalive();
     };
 }

src/signalrclient/signalr_client_config.cpp

@@ -44,6 +44,8 @@ namespace signalr
 
     signalr_client_config::signalr_client_config()
         : m_handshake_timeout(std::chrono::seconds(15))
+        , m_server_timeout(std::chrono::seconds(30))
+        , m_keepalive_interval(std::chrono::seconds(15))
     {
         m_scheduler = std::make_shared<signalr_default_scheduler>();
     }
@@ -92,4 +94,34 @@ namespace signalr
     {
         return m_handshake_timeout;
     }
+
+    void signalr_client_config::set_server_timeout(std::chrono::milliseconds timeout)
+    {
+        if (timeout <= std::chrono::seconds(0))
+        {
+            throw std::runtime_error("timeout must be greater than 0.");
+        }
+
+        m_server_timeout = timeout;
+    }
+
+    std::chrono::milliseconds signalr_client_config::get_server_timeout() const noexcept
+    {
+        return m_server_timeout;
+    }
+
+    void signalr_client_config::set_keepalive_interval(std::chrono::milliseconds interval)
+    {
+        if (interval <= std::chrono::seconds(0))
+        {
+            throw std::runtime_error("interval must be greater than 0.");
+        }
+
+        m_keepalive_interval = interval;
+    }
+
+    std::chrono::milliseconds signalr_client_config::get_keepalive_interval() const noexcept
+    {
+        return m_keepalive_interval;
+    }
 }

test/signalrclienttests/hub_connection_tests.cpp

@@ -1738,9 +1738,9 @@ TEST(config, can_replace_scheduler)
 
     mre.get();
 
-    // http_client->send (negotiate), websocket_client->start, handshake timeout timer, websocket_client->send, websocket_client->send, websocket_client->stop
+    // http_client->send (negotiate), websocket_client->start, handshake timeout timer, websocket_client->send, websocket_client->send, keep alive timer, websocket_client->send ping, websocket_client->stop
     // handshake timeout timer can trigger more than once if test takes more than 1 second
-    ASSERT_GE(6, scheduler->schedule_count);
+    ASSERT_GE(scheduler->schedule_count, 8);
 }
 
 class throw_hub_protocol : public hub_protocol
@@ -1814,3 +1814,135 @@ TEST(send, throws_if_protocol_fails)
 
     ASSERT_EQ(connection_state::connected, hub_connection->get_connection_state());
 }
+
+TEST(keepalive, sends_ping_messages)
+{
+    signalr_client_config config;
+    config.set_keepalive_interval(std::chrono::seconds(1));
+    config.set_server_timeout(std::chrono::seconds(3));
+    auto ping_mre = manual_reset_event<void>();
+    auto messages = std::make_shared<std::deque<std::string>>();
+    auto websocket_client = create_test_websocket_client(
+        /* send function */ [messages, &ping_mre](const std::string& msg, std::function<void(std::exception_ptr)> callback)
+        {
+            if (messages->size() < 3)
+            {
+                messages->push_back(msg);
+            }
+            if (messages->size() == 3)
+            {
+                ping_mre.set();
+            }
+            callback(nullptr);
+        },
+        [](const std::string&, std::function<void(std::exception_ptr)> callback) { callback(nullptr); },
+        [](std::function<void(std::exception_ptr)> callback) { callback(nullptr); },
+        false);
+    auto hub_connection = create_hub_connection(websocket_client);
+    hub_connection.set_client_config(config);
+
+    auto mre = manual_reset_event<void>();
+    hub_connection.start([&mre](std::exception_ptr exception)
+        {
+            mre.set(exception);
+        });
+
+    ASSERT_FALSE(websocket_client->receive_loop_started.wait(5000));
+    ASSERT_FALSE(websocket_client->handshake_sent.wait(5000));
+    websocket_client->receive_message("{}\x1e");
+
+    mre.get();
+
+    ping_mre.get();
+
+    ASSERT_EQ(3, messages->size());
+    ASSERT_EQ("{\"protocol\":\"json\",\"version\":1}\x1e", (*messages)[0]);
+    ASSERT_EQ("{\"type\":6}\x1e", (*messages)[1]);
+    ASSERT_EQ("{\"type\":6}\x1e",  (*messages)[2]);
+    ASSERT_EQ(connection_state::connected, hub_connection.get_connection_state());
+}
+
+TEST(keepalive, server_timeout_on_no_ping_from_server)
+{
+    signalr_client_config config;
+    config.set_keepalive_interval(std::chrono::seconds(1));
+    config.set_server_timeout(std::chrono::seconds(1));
+    auto websocket_client = create_test_websocket_client();
+    auto hub_connection = create_hub_connection(websocket_client);
+    hub_connection.set_client_config(config);
+
+    auto disconnected_called = false;
+
+    auto disconnect_mre = manual_reset_event<void>();
+    hub_connection.set_disconnected([&disconnected_called, &disconnect_mre](std::exception_ptr ex)
+        {
+            disconnect_mre.set(ex);
+        });
+
+    auto mre = manual_reset_event<void>();
+    hub_connection.start([&mre](std::exception_ptr exception)
+        {
+            mre.set(exception);
+        });
+
+    ASSERT_FALSE(websocket_client->receive_loop_started.wait(5000));
+    ASSERT_FALSE(websocket_client->handshake_sent.wait(5000));
+    websocket_client->receive_message("{}\x1e");
+
+    mre.get();
+
+    try
+    {
+        disconnect_mre.get();
+        ASSERT_TRUE(false);
+    }
+    catch (const std::exception& ex)
+    {
+        ASSERT_STREQ("server timeout (1000 ms) elapsed without receiving a message from the server.", ex.what());
+    }
+    ASSERT_EQ(connection_state::disconnected, hub_connection.get_connection_state());
+}
+
+TEST(keepalive, resets_server_timeout_timer_on_any_message_from_server)
+{
+    signalr_client_config config;
+    config.set_keepalive_interval(std::chrono::seconds(1));
+    config.set_server_timeout(std::chrono::seconds(1));
+    auto websocket_client = create_test_websocket_client();
+    auto hub_connection = create_hub_connection(websocket_client);
+    hub_connection.set_client_config(config);
+
+    auto disconnect_mre = manual_reset_event<void>();
+    hub_connection.set_disconnected([&disconnect_mre](std::exception_ptr ex)
+        {
+            disconnect_mre.set(ex);
+        });
+
+    auto mre = manual_reset_event<void>();
+    hub_connection.start([&mre](std::exception_ptr exception)
+        {
+            mre.set(exception);
+        });
+
+    ASSERT_FALSE(websocket_client->receive_loop_started.wait(5000));
+    ASSERT_FALSE(websocket_client->handshake_sent.wait(5000));
+    websocket_client->receive_message("{}\x1e");
+
+    mre.get();
+
+    std::this_thread::sleep_for(config.get_server_timeout() - std::chrono::milliseconds(500));
+    websocket_client->receive_message("{\"type\":6}\x1e");
+    std::this_thread::sleep_for(std::chrono::seconds(1));
+    ASSERT_EQ(connection_state::connected, hub_connection.get_connection_state());
+
+    try
+    {
+        disconnect_mre.get();
+        ASSERT_TRUE(false);
+    }
+    catch (const std::exception& ex)
+    {
+        ASSERT_STREQ("server timeout (1000 ms) elapsed without receiving a message from the server.", ex.what());
+    }
+    ASSERT_EQ(connection_state::disconnected, hub_connection.get_connection_state());
+}

test/signalrclienttests/test_websocket_client.cpp

@@ -10,12 +10,14 @@
 std::shared_ptr<test_websocket_client> create_test_websocket_client(
     std::function<void(const std::string & msg, std::function<void(std::exception_ptr)>)> send_function,
     std::function<void(const std::string&, std::function<void(std::exception_ptr)>)> connect_function,
-    std::function<void(std::function<void(std::exception_ptr)>)> close_function)
+    std::function<void(std::function<void(std::exception_ptr)>)> close_function,
+    bool ignore_pings)
 {
     auto websocket_client = std::make_shared<test_websocket_client>();
     websocket_client->set_send_function(send_function);
     websocket_client->set_connect_function(connect_function);
     websocket_client->set_close_function(close_function);
+    websocket_client->ignore_pings = ignore_pings;
 
     return websocket_client;
 }
@@ -24,7 +26,7 @@ test_websocket_client::test_websocket_client()
     : m_connect_function(std::make_shared<std::function<void(const std::string&, std::function<void(std::exception_ptr)>)>>([](const std::string&, std::function<void(std::exception_ptr)> callback) { callback(nullptr); })),
     m_send_function(std::make_shared<std::function<void(const std::string& msg, std::function<void(std::exception_ptr)>)>>([](const std::string msg, std::function<void(std::exception_ptr)> callback) { callback(nullptr); })),
     m_close_function(std::make_shared<std::function<void(std::function<void(std::exception_ptr)>)>>([](std::function<void(std::exception_ptr)> callback) { callback(nullptr); })),
-    m_receive_message_event(), m_receive_message(), m_stopped(true), receive_count(0)
+    m_receive_message_event(), m_receive_message(), m_stopped(true), receive_count(0), ignore_pings(true)
 {
     m_receive_loop_not_running.cancel();
 }
@@ -107,8 +109,14 @@ void test_websocket_client::send(const std::string& payload, signalr::transfer_f
 {
     handshake_sent.cancel();
     auto local_copy = m_send_function;
-    m_scheduler->schedule([payload, callback, local_copy]()
+    auto l_ignore_pings = ignore_pings;
+    m_scheduler->schedule([payload, callback, local_copy, l_ignore_pings]()
         {
+            if (l_ignore_pings && payload.find("\"type\":6") != -1)
+            {
+                callback(nullptr);
+                return;
+            }
             (*local_copy)(payload, callback);
         });
 }

test/signalrclienttests/test_websocket_client.h

@@ -41,6 +41,7 @@ public:
     cancellation_token_source receive_loop_started;
     cancellation_token_source handshake_sent;
     int receive_count;
+    bool ignore_pings;
 
 private:
     std::shared_ptr<std::function<void(const std::string&, std::function<void(std::exception_ptr)>)>> m_connect_function;
@@ -63,4 +64,4 @@ private:
 std::shared_ptr<test_websocket_client> create_test_websocket_client(
     std::function<void(const std::string & msg, std::function<void(std::exception_ptr)>)> send_function = [](const std::string&, std::function<void(std::exception_ptr)> callback) { callback(nullptr); },
     std::function<void(const std::string&, std::function<void(std::exception_ptr)>)> connect_function = [](const std::string&, std::function<void(std::exception_ptr)> callback) { callback(nullptr); },
-    std::function<void(std::function<void(std::exception_ptr)>)> close_function = [](std::function<void(std::exception_ptr)> callback) { callback(nullptr); });
+    std::function<void(std::function<void(std::exception_ptr)>)> close_function = [](std::function<void(std::exception_ptr)> callback) { callback(nullptr); }, bool ignore_pings = true);