Merge pull request #870 from redboltz/add_reconnect_example

Added general async_client reconnect example.

Author: redboltz

example/CMakeLists.txt

@@ -1,6 +1,7 @@
 LIST (APPEND exec_PROGRAMS
     no_tls_client.cpp
     no_tls_async_client.cpp
+    no_tls_async_client_reconnect.cpp
     no_tls_server.cpp
     no_tls_both.cpp
     v5_no_tls_client.cpp

example/no_tls_async_client_reconnect.cpp

@@ -0,0 +1,105 @@
+// Copyright Takatoshi Kondo 2020
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <iostream>
+#include <iomanip>
+#include <map>
+
+#include <mqtt_client_cpp.hpp>
+
+int main(int argc, char** argv) {
+    if (argc != 3) {
+        std::cout << argv[0] << " host port" << std::endl;
+        return -1;
+    }
+
+    MQTT_NS::setup_log();
+
+    boost::asio::io_context ioc;
+
+    // Create no TLS client
+    auto c = MQTT_NS::make_async_client(ioc, argv[1], argv[2]);
+
+    // Setup client
+    c->set_client_id("cid1");
+    c->set_clean_session(true);
+
+    boost::asio::steady_timer tim_connect_wait_limit(ioc);
+    boost::asio::steady_timer tim_reconnect_delay(ioc);
+
+    std::function<void()> connect;
+    std::function<void()> reconnect;
+
+    connect =
+        [&] {
+            std::cout << "async_connect" << std::endl;
+            c->async_connect(
+                [&]
+                (MQTT_NS::error_code ec){
+                    std::cout << "async_connect callback: " << ec.message() << std::endl;
+                    if (ec) reconnect();
+                }
+            );
+
+            std::cout << "tim_connect_wait_limit set" << std::endl;
+            tim_connect_wait_limit.expires_after(std::chrono::seconds(3));
+            tim_connect_wait_limit.async_wait(
+                [&](boost::system::error_code ec) {
+                    std::cout << "tim_connect_wait_limit callback: " << ec.message() << std::endl;
+                    if (!ec) {
+                        c->async_force_disconnect(
+                            [&](boost::system::error_code ec) {
+                                std::cout << "async_force_disconnect callback: " << ec.message() << std::endl;
+                            }
+                        );
+                    }
+                }
+            );
+        };
+    reconnect =
+        [&] {
+            std::cout << "tim_reconnect_delay set" << std::endl;
+            tim_reconnect_delay.expires_after(std::chrono::seconds(3));
+            tim_reconnect_delay.async_wait(
+                [&](boost::system::error_code ec) {
+                    std::cout << "tim_reconnect_delay callback: " << ec.message() << std::endl;
+                    if (!ec) connect();
+                }
+            );
+        };
+
+    // Setup handlers
+    c->set_connack_handler(
+        [&]
+        (bool sp, MQTT_NS::connect_return_code connack_return_code){
+            std::cout << "Connack handler called" << std::endl;
+            std::cout << "  Session Present: " << std::boolalpha << sp << std::endl;
+            std::cout << "  Connack Return Code: "
+                      << MQTT_NS::connect_return_code_to_str(connack_return_code) << std::endl;
+            if (connack_return_code == MQTT_NS::connect_return_code::accepted) {
+                tim_connect_wait_limit.cancel();
+            }
+            else {
+                reconnect();
+            }
+            return true;
+        });
+    c->set_close_handler(
+        [&]
+        (){
+            std::cout << "closed." << std::endl;
+            reconnect();
+        });
+    c->set_error_handler(
+        [&]
+        (MQTT_NS::error_code ec){
+            std::cout << "error: " << ec.message() << std::endl;
+            reconnect();
+        });
+
+    connect();
+    ioc.run();
+}