Program Listing for File realtime_buffer.h
↰ Return to documentation for file (/tmp/ws/src/realtime_tools/include/realtime_tools/realtime_buffer.h
)
// Copyright (c) 2013, hiDOF, Inc.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// * Neither the name of the hiDOF, Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
/*
* Publishing ROS messages is difficult, as the publish function is
* not realtime safe. This class provides the proper locking so that
* you can call publish in realtime and a separate (non-realtime)
* thread will ensure that the message gets published over ROS.
*
* Author: Wim Meeussen
*/
#ifndef REALTIME_TOOLS__REALTIME_BUFFER_H_
#define REALTIME_TOOLS__REALTIME_BUFFER_H_
#include <chrono>
#include <mutex>
#include <thread>
namespace realtime_tools
{
template <class T>
class RealtimeBuffer
{
public:
RealtimeBuffer() : new_data_available_(false)
{
// allocate memory
non_realtime_data_ = new T();
realtime_data_ = new T();
}
explicit RealtimeBuffer(const T & data) : new_data_available_(false)
{
// allocate memory
non_realtime_data_ = new T(data);
realtime_data_ = new T(data);
}
~RealtimeBuffer()
{
if (non_realtime_data_) {
delete non_realtime_data_;
}
if (realtime_data_) {
delete realtime_data_;
}
}
RealtimeBuffer(const RealtimeBuffer & source)
{
// allocate memory
non_realtime_data_ = new T();
realtime_data_ = new T();
// Copy the data from old RTB to new RTB
writeFromNonRT(*source.readFromNonRT());
}
RealtimeBuffer & operator=(const RealtimeBuffer & source)
{
if (this == &source) {
return *this;
}
// Copy the data from old RTB to new RTB
writeFromNonRT(*source.readFromNonRT());
return *this;
}
T * readFromRT()
{
// Check if the data is currently being written to (is locked)
std::unique_lock<std::mutex> guard(mutex_, std::try_to_lock);
if (guard.owns_lock()) {
// swap pointers
if (new_data_available_) {
T * tmp = realtime_data_;
realtime_data_ = non_realtime_data_;
non_realtime_data_ = tmp;
new_data_available_ = false;
}
}
return realtime_data_;
}
T * readFromNonRT() const
{
std::lock_guard<std::mutex> guard(mutex_);
if (new_data_available_) {
return non_realtime_data_;
} else {
return realtime_data_;
}
}
void writeFromNonRT(const T & data)
{
#ifdef NON_POLLING
std::lock_guard<std::mutex> guard(mutex_);
#else
std::unique_lock<std::mutex> guard(mutex_, std::defer_lock);
while (!guard.try_lock()) {
std::this_thread::sleep_for(std::chrono::microseconds(500));
}
#endif
// copy data into non-realtime buffer
*non_realtime_data_ = data;
new_data_available_ = true;
}
void initRT(const T & data)
{
*non_realtime_data_ = data;
*realtime_data_ = data;
}
void reset()
{
// delete the old memory
if (non_realtime_data_) {
delete non_realtime_data_;
}
if (realtime_data_) {
delete realtime_data_;
}
// allocate memory
non_realtime_data_ = new T();
realtime_data_ = new T();
}
private:
T * realtime_data_;
T * non_realtime_data_;
bool new_data_available_;
// Set as mutable so that readFromNonRT() can be performed on a const buffer
mutable std::mutex mutex_;
}; // class
} // namespace realtime_tools
#endif // REALTIME_TOOLS__REALTIME_BUFFER_H_