SubscriptionCallback.hpp

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/**
 * @file SubscriptionCallback.hpp
 *
 */

#pragma once

#include <uORB/SubscriptionInterval.hpp>
#include <containers/List.hpp>
#include <px4_platform_common/px4_work_queue/WorkItem.hpp>

namespace uORB
{

// Subscription wrapper class with callbacks on new publications
class SubscriptionCallback : public SubscriptionInterval, public ListNode<SubscriptionCallback *>
{
public:
    /**
     * Constructor
     *
     * @param meta The uORB metadata (usually from the ORB_ID() macro) for the topic.
     * @param interval_ms The requested maximum update interval in milliseconds.
     * @param instance The instance for multi sub.
     */
    SubscriptionCallback(const orb_metadata *meta, uint8_t interval_ms = 0, uint8_t instance = 0) :
        SubscriptionInterval(meta, interval_ms, instance)
    {
    }

    virtual ~SubscriptionCallback()
    {
        unregisterCallback();
    };

    bool registerCallback()
    {
        bool ret = false;

        if (_subscription.get_node() && _subscription.get_node()->register_callback(this)) {
            // registered
            ret = true;

        } else {
            // force topic creation by subscribing with old API
            int fd = orb_subscribe_multi(_subscription.get_topic(), _subscription.get_instance());

            // try to register callback again
            if (_subscription.subscribe()) {
                if (_subscription.get_node() && _subscription.get_node()->register_callback(this)) {
                    ret = true;
                }
            }

            orb_unsubscribe(fd);
        }


        return ret;
    }

    void unregisterCallback()
    {
        if (_subscription.get_node()) {
            _subscription.get_node()->unregister_callback(this);
        }
    }

    virtual void call() = 0;

};

// Subscription with callback that schedules a WorkItem
class SubscriptionCallbackWorkItem : public SubscriptionCallback
{
public:
    /**
     * Constructor
     *
     * @param work_item The WorkItem that will be scheduled immediately on new publications.
     * @param meta The uORB metadata (usually from the ORB_ID() macro) for the topic.
     * @param instance The instance for multi sub.
     */
    SubscriptionCallbackWorkItem(px4::WorkItem *work_item, const orb_metadata *meta, uint8_t instance = 0) :
        SubscriptionCallback(meta, 0, instance),    // interval 0
        _work_item(work_item)
    {
    }

    virtual ~SubscriptionCallbackWorkItem() = default;

    void call() override
    {
        // schedule immediately if no interval, otherwise check time elapsed
        if ((_interval_us == 0) || (hrt_elapsed_time_atomic(&_last_update) >= _interval_us)) {
            _work_item->ScheduleNow();
        }
    }

private:
    px4::WorkItem *_work_item;
};

} // namespace uORB