Program Listing for File realtime_box_best_effort.h
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// Copyright (c) 2024, Lennart Nachtigall
//
// 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 Willow Garage, 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.
// Author: Lennart Nachtigall
#ifndef REALTIME_TOOLS__REALTIME_BOX_BEST_EFFORT_H_
#define REALTIME_TOOLS__REALTIME_BOX_BEST_EFFORT_H_
#include <initializer_list>
#include <mutex>
#include <optional>
#include <utility>
#include <rcpputils/pointer_traits.hpp>
namespace realtime_tools
{
template <typename T>
constexpr auto is_ptr_or_smart_ptr = rcpputils::is_pointer<T>::value;
template <class T, typename mutex_type = std::mutex>
class RealtimeBoxBestEffort
{
static_assert(
std::is_same_v<mutex_type, std::mutex> || std::is_same_v<mutex_type, std::recursive_mutex>);
static_assert(std::is_copy_constructible_v<T>, "Passed type must be copy constructible");
public:
using mutex_t = mutex_type;
using type = T;
// Provide various constructors
constexpr explicit RealtimeBoxBestEffort(const T & init = T{}) : value_(init) {}
constexpr explicit RealtimeBoxBestEffort(const T && init) : value_(std::move(init)) {}
// Only enabled for types that can be constructed from an initializer list
template <typename U = T>
constexpr RealtimeBoxBestEffort(
const std::initializer_list<U> & init,
std::enable_if_t<std::is_constructible_v<U, std::initializer_list>>)
: value_(init)
{
}
template <typename U = T>
typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, bool> trySet(const T & value)
{
std::unique_lock<mutex_t> guard(lock_, std::defer_lock);
if (!guard.try_lock()) {
return false;
}
value_ = value;
return true;
}
bool trySet(const std::function<void(T &)> & func)
{
std::unique_lock<mutex_t> guard(lock_, std::defer_lock);
if (!guard.try_lock()) {
return false;
}
func(value_);
return true;
}
template <typename U = T>
[[nodiscard]] typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, std::optional<U>> tryGet() const
{
std::unique_lock<mutex_t> guard(lock_, std::defer_lock);
if (!guard.try_lock()) {
return std::nullopt;
}
return value_;
}
bool tryGet(const std::function<void(const T &)> & func)
{
std::unique_lock<mutex_t> guard(lock_, std::defer_lock);
if (!guard.try_lock()) {
return false;
}
func(value_);
return true;
}
template <typename U = T>
typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, void> set(const T & value)
{
std::lock_guard<mutex_t> guard(lock_);
// cppcheck-suppress missingReturn
value_ = value;
}
void set(const std::function<void(T &)> & func)
{
std::lock_guard<mutex_t> guard(lock_);
func(value_);
}
template <typename U = T>
[[nodiscard]] typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, U> get() const
{
std::lock_guard<mutex_t> guard(lock_);
return value_;
}
template <typename U = T>
typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, void> get(T & in) const
{
std::lock_guard<mutex_t> guard(lock_);
// cppcheck-suppress missingReturn
in = value_;
}
void get(const std::function<void(const T &)> & func)
{
std::lock_guard<mutex_t> guard(lock_);
func(value_);
}
template <typename U = T>
typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, void> operator=(const T & value)
{
set(value);
}
template <typename U = T, typename = typename std::enable_if_t<!is_ptr_or_smart_ptr<U>>>
[[nodiscard]] operator T() const
{
// Only makes sense with the getNonRT method otherwise we would return an std::optional
return get();
}
template <typename U = T, typename = typename std::enable_if_t<!is_ptr_or_smart_ptr<U>>>
[[nodiscard]] operator std::optional<T>() const
{
return tryGet();
}
// In case one wants to actually use a pointer
// in this implementation we allow accessing the lock directly.
// Note: Be careful with lock.unlock().
// It may only be called from the thread that locked the mutex!
[[nodiscard]] const mutex_t & getMutex() const { return lock_; }
[[nodiscard]] mutex_t & getMutex() { return lock_; }
private:
T value_;
mutable mutex_t lock_;
};
} // namespace realtime_tools
#endif // REALTIME_TOOLS__REALTIME_BOX_BEST_EFFORT_H_