ladybird/AK/InlineLRUCache.h
Andreas Kling 7014daa235 Kernel: Add an LRU block cache.
This papers over some of the incredibly inefficient access patterns in the
Ext2FS implementation for a while longer. :^)
2019-02-10 20:07:14 +01:00

71 lines
1.4 KiB
C++

#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;