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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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.
*
* 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.
*/
#pragma once
#include <AK/HashMap.h>
#include <AK/InlineLinkedList.h>
namespace AK {
template<typename K, typename V>
class InlineLRUCache {
public:
~InlineLRUCache()
{
while (size())
remove_last();
}
size_t size() const { return m_map.size(); }
size_t capacity() const { return m_capacity; }
void set_capacity(size_t capacity)
{
if (capacity == m_capacity)
return;
m_capacity = capacity;
while (size() >= capacity)
remove_last();
}
V* get(const K& key)
{
auto it = m_map.find(key);
if (it == m_map.end())
return nullptr;
V* entry = (*it).value;
m_entries.remove(entry);
m_entries.prepend(entry);
return entry;
}
void put(K&& key, V&& value)
{
auto it = m_map.find(key);
if (it != m_map.end())
return;
V* new_entry = new V(move(value));
m_entries.prepend(new_entry);
m_map.set(key, new_entry);
while (size() > capacity())
remove_last();
}
private:
void remove_last()
{
V* entry = m_entries.tail();
ASSERT(entry);
m_entries.remove(entry);
m_map.remove(entry->m_key);
delete entry;
}
InlineLinkedList<V> m_entries;
HashMap<K, V*> m_map;
size_t m_capacity { 16 };
};
}
using AK::InlineLRUCache;
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