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/*
* Copyright © 2012 Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Authored by: Thomas Voß <thomas.voss@canonical.com>
*/
#ifndef CORE_DBUS_LIFETIME_CONSTRAINED_CACHE_H_
#define CORE_DBUS_LIFETIME_CONSTRAINED_CACHE_H_
#include <core/signal.h>
#include <memory>
#include <tuple>
#include <map>
namespace core
{
namespace dbus
{
template<typename T>
struct LifetimeConstraintTraits
{
static inline const core::Signal<void>& access_signal_object_about_to_be_destroyed(const T& t)
{
return t.about_to_be_destroyed();
}
};
template<typename Key, typename Value>
class ThreadSafeLifetimeConstrainedCache
{
public:
ThreadSafeLifetimeConstrainedCache() = default;
~ThreadSafeLifetimeConstrainedCache()
{
std::lock_guard<std::mutex> lg(guard);
for (auto& element : cache)
{
std::get<1>(element.second).disconnect();
}
}
ThreadSafeLifetimeConstrainedCache(const ThreadSafeLifetimeConstrainedCache&) = delete;
ThreadSafeLifetimeConstrainedCache& operator=(const ThreadSafeLifetimeConstrainedCache&) = delete;
inline std::shared_ptr<Value> retrieve_value_for_key(const Key& key)
{
std::lock_guard<std::mutex> lg(guard);
auto it = cache.find(key);
if (it == cache.end())
return std::shared_ptr<Value>{};
return std::get<0>(it->second).lock();
}
inline bool insert_value_for_key(const Key& key, const std::shared_ptr<Value>& value)
{
std::lock_guard<std::mutex> lg(guard);
auto it = cache.find(key);
if (it != cache.end())
return false;
auto connection = LifetimeConstraintTraits<Value>::access_signal_object_about_to_be_destroyed(*value).connect([this, key]()
{
remove_value_for_key(key);
});
bool inserted{false};
std::tie(std::ignore, inserted) = cache.insert(
std::make_pair(
key,
std::make_tuple(std::weak_ptr<Value>(value), connection)));
return inserted;
}
inline void remove_value_for_key(const Key& key)
{
std::lock_guard<std::mutex> lg(guard);
auto it = cache.find(key);
if (it == cache.end())
return;
cache.erase(it);
}
inline bool has_value_for_key(const Key& key) const
{
std::lock_guard<std::mutex> lg(guard);
return cache.find(key) != cache.end();
}
private:
mutable std::mutex guard;
std::map<Key, std::tuple<std::weak_ptr<Value>, core::Connection>> cache;
};
}
}
#endif // CORE_DBUS_LIFETIME_CONSTRAINED_CACHE_H_
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