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lrucache.h
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lrucache.h
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#ifndef _XSCRIPT_INTERNAL_LRUCACHE_H_
#define _XSCRIPT_INTERNAL_LRUCACHE_H_
#include <list>
#include <map>
#include <stdexcept>
#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/thread/mutex.hpp>
#include "xscript/cache_counter.h"
#include "xscript/profiler.h"
#include "xscript/tag.h"
namespace xscript {
template<typename Data>
struct TagExpiredFunc {
bool operator() (const Data &element, const Tag &tag) const {
(void)element;
return tag.expired();
}
};
template<typename Key, typename Data, typename ExpireFunc = TagExpiredFunc<Data> >
class LRUCache {
struct ListElement;
typedef std::list<ListElement> List;
#ifndef HAVE_HASHMAP
typedef std::map<Key, typename List::iterator> Map;
#else
typedef details::hash_map<Key, typename List::iterator> Map;
#endif
public:
typedef typename Map::iterator iterator;
typedef typename Map::const_iterator const_iterator;
private:
class ListElement {
public:
ListElement(const Data &data, const Tag &tag, const iterator &iter) :
data_(data), tag_(tag), map_iterator_(iter),
stored_time_(time(NULL)), prefetch_marked_(false) {}
Data data_;
Tag tag_;
iterator map_iterator_;
time_t stored_time_;
bool prefetch_marked_;
};
Map key2data_;
List data_;
unsigned int max_size_;
bool check_expire_;
boost::mutex mutex_;
ExpireFunc expired_;
CacheCounter& counter_;
public:
typedef boost::function<void (const Data &data)> CleanupFunc;
explicit LRUCache(unsigned int size, bool check_expire, CacheCounter &counter);
~LRUCache();
void clear();
bool load(const Key &key, Data &data, Tag &tag);
bool load(const Key &key, Data &data, Tag &tag, const CleanupFunc &cleanFunc);
void save(const Key &key, const Data &data, const Tag &tag);
void save(const Key &key, const Data &data, const Tag &tag, const CleanupFunc &cleanFunc);
private:
void push_front(const Key &key, const Data &data, const Tag &tag);
typename List::iterator getShrinked();
};
template<typename Key, typename Data, typename ExpireFunc>
LRUCache<Key, Data, ExpireFunc>::LRUCache(unsigned int size, bool check_expire, CacheCounter &counter) :
max_size_(size), check_expire_(check_expire), counter_(counter)
{}
template<typename Key, typename Data, typename ExpireFunc>
LRUCache<Key, Data, ExpireFunc>::~LRUCache() {
}
template<typename Key, typename Data, typename ExpireFunc>
void
LRUCache<Key, Data, ExpireFunc>::save(const Key &key, const Data &data, const Tag &tag) {
CleanupFunc cleanFunc;
save(key, data, tag, cleanFunc);
}
template<typename Key, typename Data, typename ExpireFunc>
void
LRUCache<Key, Data, ExpireFunc>::save(
const Key &key, const Data &data, const Tag &tag, const CleanupFunc &cleanFunc) {
boost::mutex::scoped_lock lock(mutex_);
if (key2data_.empty()) {
push_front(key, data, tag);
lock.unlock();
counter_.incInserted();
return;
}
iterator it = key2data_.find(key);
if (key2data_.end() != it) {
Data data_tmp = it->second->data_;
data_.erase(it->second);
data_.push_front(ListElement(data, tag, it));
it->second = data_.begin();
lock.unlock();
counter_.incUpdated();
if (!cleanFunc.empty()) {
cleanFunc(data_tmp);
}
return;
}
if (key2data_.size() < max_size_) {
push_front(key, data, tag);
lock.unlock();
counter_.incInserted();
return;
}
typename List::iterator erase_it = getShrinked();
Data data_tmp = erase_it->data_;
key2data_.erase(erase_it->map_iterator_);
data_.erase(erase_it);
push_front(key, data, tag);
lock.unlock();
counter_.incInserted();
if (!cleanFunc.empty()) {
cleanFunc(data_tmp);
}
}
template<typename Key, typename Data, typename ExpireFunc>
typename LRUCache<Key, Data, ExpireFunc>::List::iterator
LRUCache<Key, Data, ExpireFunc>::getShrinked() {
typename List::reverse_iterator delete_it = data_.rbegin();
bool expired_found = false;
if (check_expire_) {
for(typename List::reverse_iterator it = data_.rbegin();
it != data_.rend();
++it) {
if (expired_(it->data_, it->tag_)) {
expired_found = true;
delete_it = it;
break;
}
}
}
if (expired_found) {
counter_.incExpired();
}
else {
counter_.incExcluded();
}
return (++delete_it).base();
}
template<typename Key, typename Data, typename ExpireFunc>
void
LRUCache<Key, Data, ExpireFunc>::push_front(const Key &key, const Data &data, const Tag &tag) {
data_.push_front(ListElement(data, tag, key2data_.end()));
std::pair<iterator, bool> res = key2data_.insert(std::make_pair(key, data_.begin()));
data_.begin()->map_iterator_ = res.first;
}
template<typename Key, typename Data, typename ExpireFunc>
bool
LRUCache<Key, Data, ExpireFunc>::load(const Key &key, Data &data, Tag &tag) {
CleanupFunc cleanFunc;
return load(key, data, tag, cleanFunc);
}
template<typename Key, typename Data, typename ExpireFunc>
bool
LRUCache<Key, Data, ExpireFunc>::load(
const Key &key, Data &data, Tag &tag, const CleanupFunc &cleanFunc) {
boost::mutex::scoped_lock lock(mutex_);
iterator it = key2data_.find(key);
if (key2data_.end() == it) {
return false;
}
ListElement& element = *(it->second);
if (expired_(element.data_, element.tag_)) {
Data data_tmp = element.data_;
data_.erase(it->second);
key2data_.erase(it);
lock.unlock();
counter_.incExpired();
if (!cleanFunc.empty()) {
cleanFunc(data_tmp);
}
return false;
}
if (!element.prefetch_marked_ && element.tag_.needPrefetch(element.stored_time_)) {
element.prefetch_marked_ = true;
return false;
}
data = element.data_;
tag = element.tag_;
typename List::iterator list_it = it->second;
if (data_.begin() != list_it && data_.end() != list_it) {
data_.splice(data_.begin(), data_, list_it);
it->second = data_.begin();
}
lock.unlock();
counter_.incLoaded();
return true;
}
template<typename Key, typename Data, typename ExpireFunc>
void
LRUCache<Key, Data, ExpireFunc>::clear() {
Map key2data_tmp;
List data_tmp;
boost::mutex::scoped_lock lock(mutex_);
key2data_.swap(key2data_tmp);
data_.swap(data_tmp);
}
} // namespace xscript
#endif // _XSCRIPT_INTERNAL_LRUCACHE_H_