mirror of
https://github.com/PX4/PX4-Autopilot.git
synced 2026-05-25 00:31:36 +08:00
uORB: introduce SubscriptionBlocking
- uORB::SubscriptionBlocking is a specialized uORB::Subscription that allows you to do a blocking read - this is intended to be an easy to use, hard to misuse replacement for the typical orb fd + poll pattern we've relied on historically
This commit is contained in:
Daniel Agar
GitHub
@@ -0,0 +1,152 @@
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/****************************************************************************
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*
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* Copyright (c) 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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#pragma once
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#include "SubscriptionCallback.hpp"
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#include <containers/LockGuard.hpp>
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#include <px4_time.h>
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namespace uORB
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{
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// Subscription with callback that schedules a WorkItem
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template<typename T>
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class SubscriptionBlocking : public SubscriptionCallback
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{
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public:
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/**
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* Constructor
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*
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* @param meta The uORB metadata (usually from the ORB_ID() macro) for the topic.
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* @param interval_us The requested maximum update interval in microseconds.
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* @param instance The instance for multi sub.
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*/
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SubscriptionBlocking(const orb_metadata *meta, uint32_t interval_us = 0, uint8_t instance = 0) :
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SubscriptionCallback(meta, interval_us, instance)
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{
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// pthread_mutexattr_init
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pthread_mutexattr_t attr;
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int ret_attr_init = pthread_mutexattr_init(&attr);
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if (ret_attr_init != 0) {
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PX4_ERR("pthread_mutexattr_init failed, status=%d", ret_attr_init);
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}
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// pthread_mutexattr_settype
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int ret_mutexattr_settype = pthread_mutexattr_settype(&attr, PTHREAD_PRIO_NONE);
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if (ret_mutexattr_settype != 0) {
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PX4_ERR("pthread_mutexattr_settype failed, status=%d", ret_mutexattr_settype);
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}
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// pthread_mutex_init
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int ret_mutex_init = pthread_mutex_init(&_mutex, &attr);
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if (ret_mutex_init != 0) {
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PX4_ERR("pthread_mutex_init failed, status=%d", ret_mutex_init);
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}
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}
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virtual ~SubscriptionBlocking()
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{
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pthread_mutex_destroy(&_mutex);
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pthread_cond_destroy(&_cv);
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}
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void call() override
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{
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// signal immediately if no interval, otherwise only if interval has elapsed
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if ((_interval_us == 0) || (hrt_elapsed_time(&_last_update) >= _interval_us)) {
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pthread_cond_signal(&_cv);
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}
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}
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/**
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* Copy the struct if updated.
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* @param data The data reference where the struct will be copied.
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* @param timeout_us The requested timeout in microseconds, or 0 to wait indefinitely.
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*
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* @return true only if topic was updated and copied successfully.
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*/
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bool updateBlocking(T &data, uint32_t timeout_us = 0)
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{
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if (!_registered) {
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registerCallback();
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}
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if (updated()) {
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// copy immediately if updated
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return copy(&data);
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} else {
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// otherwise wait
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LockGuard lg{_mutex};
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if (timeout_us == 0) {
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// wait with no timeout
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if (pthread_cond_wait(&_cv, &_mutex) == 0) {
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return update(&data);
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}
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} else {
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// otherwise wait with timeout based on interval
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// Calculate an absolute time in the future
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struct timespec ts;
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px4_clock_gettime(CLOCK_REALTIME, &ts);
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uint64_t nsecs = ts.tv_nsec + (timeout_us * 1000);
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static constexpr unsigned billion = (1000 * 1000 * 1000);
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ts.tv_sec += nsecs / billion;
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nsecs -= (nsecs / billion) * billion;
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ts.tv_nsec = nsecs;
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if (px4_pthread_cond_timedwait(&_cv, &_mutex, &ts) == 0) {
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return update(&data);
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}
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}
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}
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return false;
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}
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private:
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pthread_mutex_t _mutex = PTHREAD_MUTEX_INITIALIZER;
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pthread_cond_t _cv = PTHREAD_COND_INITIALIZER;
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};
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} // namespace uORB
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@@ -53,11 +53,11 @@ public:
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* Constructor
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*
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* @param meta The uORB metadata (usually from the ORB_ID() macro) for the topic.
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* @param interval_ms The requested maximum update interval in milliseconds.
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* @param interval_us The requested maximum update interval in microseconds.
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* @param instance The instance for multi sub.
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*/
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SubscriptionCallback(const orb_metadata *meta, uint8_t interval_ms = 0, uint8_t instance = 0) :
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SubscriptionInterval(meta, interval_ms, instance)
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SubscriptionCallback(const orb_metadata *meta, uint32_t interval_us = 0, uint8_t instance = 0) :
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SubscriptionInterval(meta, interval_us, instance)
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{
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}
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@@ -68,11 +68,9 @@ public:
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bool registerCallback()
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{
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bool ret = false;
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if (_subscription.get_node() && _subscription.get_node()->register_callback(this)) {
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// registered
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ret = true;
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_registered = true;
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} else {
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// force topic creation by subscribing with old API
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@@ -81,15 +79,14 @@ public:
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// try to register callback again
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if (_subscription.subscribe()) {
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if (_subscription.get_node() && _subscription.get_node()->register_callback(this)) {
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ret = true;
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_registered = true;
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}
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}
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orb_unsubscribe(fd);
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}
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return ret;
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return _registered;
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}
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void unregisterCallback()
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@@ -97,10 +94,16 @@ public:
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if (_subscription.get_node()) {
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_subscription.get_node()->unregister_callback(this);
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}
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_registered = false;
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}
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virtual void call() = 0;
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protected:
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bool _registered{false};
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};
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// Subscription with callback that schedules a WorkItem
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