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rippled/include/xrpl/basics/LocalValue.h
2024-06-20 13:57:14 -05:00

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//------------------------------------------------------------------------------
/*
This file is part of rippled: https://github.com/ripple/rippled
Copyright (c) 2012, 2013 Ripple Labs Inc.
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
#ifndef RIPPLE_BASICS_LOCALVALUE_H_INCLUDED
#define RIPPLE_BASICS_LOCALVALUE_H_INCLUDED
#include <boost/thread/tss.hpp>
#include <memory>
#include <unordered_map>
namespace ripple {
namespace detail {
struct LocalValues
{
explicit LocalValues() = default;
bool onCoro = true;
struct BasicValue
{
virtual ~BasicValue() = default;
virtual void*
get() = 0;
};
template <class T>
struct Value : BasicValue
{
T t_;
Value() = default;
explicit Value(T const& t) : t_(t)
{
}
void*
get() override
{
return &t_;
}
};
// Keys are the address of a LocalValue.
std::unordered_map<void const*, std::unique_ptr<BasicValue>> values;
static inline void
cleanup(LocalValues* lvs)
{
if (lvs && !lvs->onCoro)
delete lvs;
}
};
template <class = void>
boost::thread_specific_ptr<detail::LocalValues>&
getLocalValues()
{
static boost::thread_specific_ptr<detail::LocalValues> tsp(
&detail::LocalValues::cleanup);
return tsp;
}
} // namespace detail
template <class T>
class LocalValue
{
public:
template <class... Args>
LocalValue(Args&&... args) : t_(std::forward<Args>(args)...)
{
}
/** Stores instance of T specific to the calling coroutine or thread. */
T&
operator*();
/** Stores instance of T specific to the calling coroutine or thread. */
T*
operator->()
{
return &**this;
}
private:
T t_;
};
template <class T>
T&
LocalValue<T>::operator*()
{
auto lvs = detail::getLocalValues().get();
if (!lvs)
{
lvs = new detail::LocalValues();
lvs->onCoro = false;
detail::getLocalValues().reset(lvs);
}
else
{
auto const iter = lvs->values.find(this);
if (iter != lvs->values.end())
return *reinterpret_cast<T*>(iter->second->get());
}
return *reinterpret_cast<T*>(
lvs->values
.emplace(this, std::make_unique<detail::LocalValues::Value<T>>(t_))
.first->second->get());
}
} // namespace ripple
#endif