mirror of
https://gitee.com/mirrors_PX4/PX4-Autopilot.git
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8f5b7de498
* the forceInit() method was combined with the existing subscribe() * delete unused last_update()
133 lines
3.5 KiB
C++
133 lines
3.5 KiB
C++
/****************************************************************************
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*
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* Copyright (c) 2012-2019 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file Subscription.cpp
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*
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*/
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#include "Subscription.hpp"
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#include <px4_defines.h>
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namespace uORB
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{
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bool
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Subscription::subscribe()
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{
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// valid ORB_ID required
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if (_meta == nullptr) {
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return false;
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}
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// check if already subscribed
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if (_node != nullptr) {
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return true;
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}
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DeviceMaster *device_master = uORB::Manager::get_instance()->get_device_master();
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if (device_master != nullptr) {
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uORB::DeviceNode *node = device_master->getDeviceNode(_meta, _instance);
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if (node != nullptr) {
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_node = node;
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_node->add_internal_subscriber();
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// If there were any previous publications, allow the subscriber to read them
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const unsigned curr_gen = _node->published_message_count();
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const uint8_t q_size = _node->get_queue_size();
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if (q_size < curr_gen) {
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_last_generation = curr_gen - q_size;
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} else {
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_last_generation = 0;
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}
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return true;
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}
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}
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return false;
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}
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void
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Subscription::unsubscribe()
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{
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if (_node != nullptr) {
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_node->remove_internal_subscriber();
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}
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_node = nullptr;
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_last_generation = 0;
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}
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bool
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Subscription::init()
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{
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if (_meta != nullptr) {
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// this throttles the relatively expensive calls to getDeviceNode()
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if ((_last_generation == 0) || (_last_generation < 1000) || (_last_generation % 100 == 0)) {
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if (subscribe()) {
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return true;
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}
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}
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if (_node == nullptr) {
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// use generation to count attempts to subscribe
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_last_generation++;
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}
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}
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return false;
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}
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bool
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Subscription::update(uint64_t *time, void *dst)
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{
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if ((time != nullptr) && (dst != nullptr) && published()) {
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// always copy data to dst regardless of update
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const uint64_t t = _node->copy_and_get_timestamp(dst, _last_generation);
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if (*time == 0 || *time != t) {
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*time = t;
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return true;
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}
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}
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return false;
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}
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} // namespace uORB
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