[mqtt-client] boost-like project folder structure

Summary: resolves T12767

Reviewers: ivica

Reviewed By: ivica

Subscribers: miljen

Tags: #spacetime

Maniphest Tasks: T12767

Differential Revision: https://repo.mireo.local/D25970

include/async_mqtt5/impl/sentry_op.hpp

@@ -0,0 +1,91 @@
+#ifndef ASYNC_MQTT5_SENTRY_OP_HPP
+#define ASYNC_MQTT5_SENTRY_OP_HPP
+
+#include <boost/asio/error.hpp>
+#include <boost/asio/recycling_allocator.hpp>
+#include <boost/asio/prepend.hpp>
+#include <boost/asio/cancellation_state.hpp>
+#include <boost/asio/steady_timer.hpp>
+
+#include <async_mqtt5/types.hpp>
+
+namespace async_mqtt5::detail {
+
+namespace asio = boost::asio;
+
+template <typename ClientService>
+class sentry_op {
+	using client_service = ClientService;
+	struct on_timer {};
+	struct on_disconnect {};
+
+	static constexpr auto check_interval = std::chrono::seconds(3);
+
+	std::shared_ptr<client_service> _svc_ptr;
+	std::unique_ptr<asio::steady_timer> _sentry_timer;
+
+public:
+	sentry_op(
+		const std::shared_ptr<client_service>& svc_ptr
+	) :
+		_svc_ptr(svc_ptr),
+		_sentry_timer(new asio::steady_timer(svc_ptr->get_executor()))
+	{}
+
+	sentry_op(sentry_op&&) noexcept = default;
+	sentry_op(const sentry_op&) = delete;
+
+	using executor_type = typename client_service::executor_type;
+	executor_type get_executor() const noexcept {
+		return _svc_ptr->get_executor();
+	}
+
+	using allocator_type = asio::recycling_allocator<void>;
+	allocator_type get_allocator() const noexcept {
+		return allocator_type {};
+	}
+
+	using cancellation_slot_type = asio::cancellation_slot;
+	asio::cancellation_slot get_cancellation_slot() const noexcept {
+		return _svc_ptr->_cancel_sentry.slot();
+	}
+
+	void perform() {
+		_sentry_timer->expires_after(check_interval);
+		_sentry_timer->async_wait(
+			asio::prepend(std::move(*this), on_timer {})
+		);
+	}
+
+	void operator()(on_timer, error_code ec) {
+		get_cancellation_slot().clear();
+
+		if (ec == asio::error::operation_aborted || !_svc_ptr->is_open())
+			return;
+
+		if (_svc_ptr->_replies.any_expired()) {
+			auto props = disconnect_props{};
+			// TODO add what packet was expected?
+			props[prop::reason_string] = "No reply received within 20 seconds";
+			auto svc_ptr = _svc_ptr;
+			return async_disconnect(
+				disconnect_rc_e::unspecified_error, props, false, svc_ptr,
+				asio::prepend(std::move(*this), on_disconnect {})
+			);
+		}
+
+		perform();
+	}
+
+	void operator()(on_disconnect, error_code ec) {
+		get_cancellation_slot().clear();
+
+		if (!ec || ec == asio::error::try_again)
+			perform();
+	}
+};
+
+
+} // end namespace async_mqtt5::detail
+
+#endif // !ASYNC_MQTT5_SENTRY_OP_HPP