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/*
+----------------------------------------------------------------------+
| Swoole |
+----------------------------------------------------------------------+
| This source file is subject to version 2.0 of the Apache license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| http://www.apache.org/licenses/LICENSE-2.0.html |
| If you did not receive a copy of the Apache2.0 license and are unable|
| to obtain it through the world-wide-web, please send a note to |
| license@swoole.com so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Author: Tianfeng Han <rango@swoole.com> |
+----------------------------------------------------------------------+
*/
#pragma once
#include <unordered_map>
#include <list>
#include <utility>
#include <memory>
#include <time.h>
namespace swoole {
/**
* This cache isn't thread safe
*/
class LRUCache {
private:
typedef std::pair<time_t, std::shared_ptr<void>> cache_node_t;
typedef std::list<std::pair<std::string, cache_node_t>> cache_list_t;
std::unordered_map<std::string, cache_list_t::iterator> cache_map;
cache_list_t cache_list;
size_t cache_capacity;
public:
explicit LRUCache(size_t capacity) {
cache_capacity = capacity;
}
std::shared_ptr<void> get(const std::string &key) {
auto iter = cache_map.find(key);
if (iter == cache_map.end()) {
return nullptr;
}
if (iter->second->second.first < ::time(nullptr) && iter->second->second.first > 0) {
return nullptr;
}
cache_list.splice(cache_list.begin(), cache_list, iter->second);
return iter->second->second.second; // iter -> list::iter -> cache_node_t -> value
}
void set(const std::string &key, const std::shared_ptr<void> &val, time_t expire = 0) {
time_t expire_time;
if (expire <= 0) {
expire_time = 0;
} else {
expire_time = ::time(nullptr) + expire;
}
auto iter = cache_map.find(key);
if (iter != cache_map.end()) {
iter->second->second.first = expire_time;
iter->second->second.second = val;
cache_list.splice(cache_list.begin(), cache_list, iter->second);
return;
}
size_t size = cache_list.size();
if (size == cache_capacity && size > 0) {
auto del = cache_list.back();
cache_map.erase(del.first);
cache_list.pop_back();
}
cache_list.emplace_front(key, cache_node_t{expire_time, val});
cache_map[key] = cache_list.begin();
}
void del(const std::string &key) {
auto iter = cache_map.find(key);
if (iter == cache_map.end()) {
return;
}
cache_list.erase(iter->second);
cache_map.erase(iter);
}
void clear() {
cache_list.clear();
cache_map.clear();
}
};
} // namespace swoole
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