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927c1c6e3a
Summary: related to T13767 T13767 Reviewers: ivica Reviewed By: ivica Subscribers: miljen, iljazovic Differential Revision: https://repo.mireo.local/D29686
108 lines
3.3 KiB
C++
108 lines
3.3 KiB
C++
//
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// Copyright (c) 2023-2024 Ivica Siladic, Bruno Iljazovic, Korina Simicevic
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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//[publisher
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#include <cstdlib>
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#include <iostream>
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#include <boost/asio/as_tuple.hpp>
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#include <boost/asio/co_spawn.hpp>
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#include <boost/asio/detached.hpp>
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#include <boost/asio/io_context.hpp>
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#include <boost/asio/signal_set.hpp>
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#include <boost/asio/steady_timer.hpp>
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#include <boost/asio/use_awaitable.hpp>
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#include <boost/asio/ip/tcp.hpp>
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#include <async_mqtt5.hpp>
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#ifdef BOOST_ASIO_HAS_CO_AWAIT
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// Modified completion token that will prevent co_await from throwing exceptions.
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constexpr auto use_nothrow_awaitable = boost::asio::as_tuple(boost::asio::use_awaitable);
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using client_type = async_mqtt5::mqtt_client<boost::asio::ip::tcp::socket>;
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int next_sensor_reading() {
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srand(static_cast<unsigned int>(std::time(0)));
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return rand() % 100;
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}
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boost::asio::awaitable<void> publish_sensor_readings(
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client_type& client, boost::asio::steady_timer& timer
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) {
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// Configure the Client.
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// It is mandatory to call brokers() and async_run() to configure the Brokers to connect to and start the Client.
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client.brokers("<your-mqtt-broker>", 1883) // Broker that we want to connect to. 1883 is the default TCP port.
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.async_run(boost::asio::detached); // Start the client.
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for (;;) {
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// Get the next sensor reading.
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auto reading = std::to_string(next_sensor_reading());
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// Publish the sensor reading with QoS 1.
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auto&& [ec, rc, props] = co_await client.async_publish<async_mqtt5::qos_e::at_least_once>(
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"<your-mqtt-topic>", reading,
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async_mqtt5::retain_e::no, async_mqtt5::publish_props {}, use_nothrow_awaitable
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);
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// An error can occur as a result of:
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// a) wrong publish parameters
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// b) mqtt_client::cancel is called while the Client is publishing the message
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// resulting in cancellation.
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if (ec) {
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std::cout << "Publish error occurred: " << ec.message() << std::endl;
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break;
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}
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// Reason code is the reply from the server presenting the result of the publish operation.
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std::cout << "Result of publish request: " << rc.message() << std::endl;
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if (!rc)
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std::cout << "Published sensor reading: " << reading << std::endl;
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// Wait 5 seconds before publishing the next reading.
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timer.expires_after(std::chrono::seconds(5));
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auto&& [tec] = co_await timer.async_wait(use_nothrow_awaitable);
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// An error occurred if we cancelled the timer.
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if (tec)
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break;
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}
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co_return;
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}
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int main() {
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// Initialise execution context.
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boost::asio::io_context ioc;
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// Initialise the Client to connect to the Broker over TCP.
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client_type client(ioc);
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// Initialise the timer.
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boost::asio::steady_timer timer(ioc);
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// Set up signals to stop the program on demand.
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boost::asio::signal_set signals(ioc, SIGINT, SIGTERM);
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signals.async_wait([&client, &timer](async_mqtt5::error_code /* ec */, int /* signal */) {
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// After we are done with publishing all the messages, cancel the timer and the Client.
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// Alternatively, use mqtt_client::async_disconnect.
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timer.cancel();
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client.cancel();
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});
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// Spawn the coroutine.
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co_spawn(ioc.get_executor(), publish_sensor_readings(client, timer), boost::asio::detached);
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// Start the execution.
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ioc.run();
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}
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#endif
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//]
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