sd_event_loop.hpp

#pragma once

#include <systemd/sd-event.h>
#include <chrono>
#include <map>

namespace eventloop
{

/** @struct EventSourceDeleter
 *
 *  Custom deleter for the sd_event_source*.
 */
struct EventSourceDeleter
{
    void operator()(sd_event_source* event) const
    {
        event = sd_event_source_unref(event);
    }
};

using EventSource = std::unique_ptr<sd_event_source, EventSourceDeleter>;
using IntervalType = std::chrono::microseconds;

/** @enum Timers
 *
 *  For SOL functioning, there are two timers involved. The character accumulate
 *  interval timer is the amount of time that the BMC will wait before
 *  transmitting a partial SOL packet. The retry interval timer is the time that
 *  BMC will wait before the first retry and the time between retries when
 *  sending SOL packets to the remote console.
 */
enum class Timers
{
    ACCUMULATE,   /**< Character Accumulate Timer */
    RETRY,        /**< Retry Interval Timer */
};

class EventLoop
{
    public:

        EventLoop() = default;
        ~EventLoop() = default;
        EventLoop(const EventLoop&) = delete;
        EventLoop& operator=(const EventLoop&) = delete;
        EventLoop(EventLoop&&) = delete;
        EventLoop& operator=(EventLoop&&) = delete;

        /** @brief Timer Map
         *
         *  The key for the timer map is the timer type. There are two types of
         *  timers, character accumulate timer and retry interval timer. The
         *  entries in the values is the event source for the timer and the
         *  interval.
         */
        using TimerMap = std::map<Timers, std::tuple<EventSource,
                                                     IntervalType>>;

        /** @brief SOL Payload Map.
         *
         *  The key for the payload map is the payload instance, the entries in
         *  the value are a map of timers.
         */
        using PayloadMap = std::map<uint8_t, TimerMap>;

        /** @brief Initialise the event loop and add the handler for incoming
         *         IPMI packets.
         *
         *  @return EXIT_SUCCESS on success and EXIT_FAILURE on failure.
         */
        int startEventLoop();

        /** @brief Remove host console I/O event source. */
        void stopHostConsole();

        /** @brief Initialize the timers for the SOL payload instance
         *
         *  This API would add the Character accumulate interval timer event
         *  source and the retry interval timer event source for the SOL payload
         *  instance to the event loop.
         *
         *  @param[in] payloadInst - SOL payload instance.
         *  @param[in] accumulateInterval - Character accumulate interval.
         *  @param[in] retryInterval - Retry interval.
         */
        void startSOLPayloadInstance(uint8_t payloadInst,
                                     IntervalType accumulateInterval,
                                     IntervalType retryInterval);

        /** @brief Stop the timers for the SOL payload instance.
         *
         *  This would remove the character accumulate interval timer event
         *  source and the retry interval timer event source from the event
         *  loop.
         *
         *  @param[in] payloadInst - SOL payload instance
         */
        void stopSOLPayloadInstance(uint8_t payloadInst);

        /** @brief Modify the timer event source to enable/disable.
         *
         *  When the timer is enabled, the timer it set to fire again at
         *  timer's interval for the instance added to the event loop iteration
         *  timestamp. When the timer is disabled, the event source for the
         *  timer is disabled.
         *
         *  @param[in] payloadInst - SOL payload instance.
         *  @param[in] type -  Timer type.
         *  @param[in] status - on/off the event source.
         */
        void switchTimer(uint8_t payloadInst,
                         Timers type,
                         bool status);

        /** @brief Modify the retry interval timer event source to enable/
         *         disable
         *
         *  When the timer is enabled, the timer it set to fire again at
         *  retry interval for the instance added to the event loop iteration
         *  timestamp. When the timer is disabled the event source for the
         *  retry interval timer is disabled.
         *
         *  @param[in] payloadInst - SOL payload instance.
         *  @param[in] status - on/off the event source.
         */
        void switchRetryTimer(uint8_t payloadInst, bool status);

    private:
        /** @brief Event source object for host console. */
        EventSource hostConsole = nullptr;

        /** @brief Event source for the UDP socket listening on IPMI standard
         *         port.
         */
        EventSource udpIPMI = nullptr;

        /** @brief Map to keep information regarding IPMI payload instance and
         *         timers for character accumulate interval and retry interval.
         */
        PayloadMap payloadInfo;

        /** @brief Event loop object. */
        sd_event* event = nullptr;
};

} // namespace eventloop