px4-firmware/platforms/common/events.cpp

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#include <pthread.h>

#include <drivers/drv_hrt.h>
#include <px4_platform_common/posix.h>
#include <px4_platform_common/events.h>
#include <uORB/uORB.h>

static orb_advert_t orb_event_pub = nullptr;
static pthread_mutex_t publish_event_mutex = PTHREAD_MUTEX_INITIALIZER;
static uint16_t event_sequence{events::initial_event_sequence};

namespace events
{

void send(EventType &event)
{
	event.timestamp = hrt_absolute_time();

	// We need some synchronization here because:
	// - modifying orb_event_pub
	// - the update of event_sequence needs to be atomic
	// - we need to ensure ordering of the sequence numbers: the sequence we set here
	//   has to be the one published next.
	pthread_mutex_lock(&publish_event_mutex);
	event.event_sequence = ++event_sequence; // Set the sequence here so we're able to detect uORB queue overflows

	if (orb_event_pub != nullptr) {
		orb_publish(ORB_ID(event), orb_event_pub, &event);

	} else {
		orb_event_pub = orb_advertise_queue(ORB_ID(event), &event, event_s::ORB_QUEUE_LENGTH);
	}

	pthread_mutex_unlock(&publish_event_mutex);
}

} /* namespace events */