PX4-Autopilot/platforms/common/uORB/Subscription.cpp

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/**
 * @file Subscription.cpp
 *
 */

#include "Subscription.hpp"
#include <px4_platform_common/defines.h>

namespace uORB
{

bool Subscription::subscribe()
{
	// check if already subscribed
	if (_node != nullptr) {
		return true;
	}

	if (_orb_id != ORB_ID::INVALID && uORB::Manager::get_instance()) {
		unsigned initial_generation;
		void *node = uORB::Manager::orb_add_internal_subscriber(_orb_id, _instance, &initial_generation);

		if (node) {
			_node = node;
			_last_generation = initial_generation;
			return true;
		}
	}

	return false;
}

void Subscription::unsubscribe()
{
	if (_node != nullptr) {
		uORB::Manager::orb_remove_internal_subscriber(_node);
	}

	_node = nullptr;
	_last_generation = 0;
}

bool Subscription::update(void *dst)
{
	if (subscribe()) {
		return Manager::orb_data_copy(_node, dst, _last_generation, true);
	}

	return false;
}

bool Subscription::copy(void *dst)
{
	if (subscribe()) {
		return Manager::orb_data_copy(_node, dst, _last_generation, false);
	}

	return false;
}

bool Subscription::ChangeInstance(uint8_t instance)
{
	if (instance != _instance) {
		if (uORB::Manager::orb_device_node_exists(_orb_id, instance)) {
			// if desired new instance exists, unsubscribe from current
			unsubscribe();
			_instance = instance;
			subscribe();
			return true;
		}

	} else {
		// already on desired index
		return true;
	}

	return false;
}

Subscription::Subscription(ORB_ID id, uint8_t instance) :
	_orb_id(id),
	_instance(instance)
{
	subscribe();
}

Subscription::Subscription(const orb_metadata *meta, uint8_t instance) :
	_orb_id((meta == nullptr) ? ORB_ID::INVALID : static_cast<ORB_ID>(meta->o_id)),
	_instance(instance)
{
	subscribe();
}

Subscription::Subscription(const Subscription &other) : _orb_id(other._orb_id), _instance(other._instance) {}

Subscription::Subscription(const Subscription &&other) noexcept : _orb_id(other._orb_id), _instance(other._instance) {}

Subscription &Subscription::operator=(const Subscription &other)
{
	// Check for self-assignment
	if (this == &other) {
		return *this;
	}

	unsubscribe();
	_orb_id = other._orb_id;
	_instance = other._instance;
	return *this;
}

Subscription &Subscription::operator=(Subscription &&other) noexcept
{
	unsubscribe();
	_orb_id = other._orb_id;
	_instance = other._instance;
	return *this;
}

Subscription::~Subscription()
{
	unsubscribe();
}

bool Subscription::advertised()
{
	if (subscribe()) {
		return Manager::is_advertised(_node);
	}

	return false;
}

bool Subscription::updated()
{
	if (subscribe()) {
		return Manager::updates_available(_node, _last_generation);
	}

	return false;
}

} // namespace uORB