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Remove broken LRU in image cache.

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It was broken 2 years ago by a bad revert(2008-12-06T22:41:32Z!loonycyborg@gmail.com) and always
caused some overhead (few fps)

It was also impossible to get an perfect LRU cache size (too many
different cases).  We need a cache strategy more adapted to a level
and turn based game (I have some plans because it's needed for local
ToD changes)
This commit is contained in:
Ali El Gariani 2010-09-14 20:28:32 +00:00
parent 4d0018a396
commit 949ccd0edb
1 changed files with 13 additions and 62 deletions
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75
src/image.cpp
View file

@ -44,29 +44,17 @@ static lg::log_domain log_display("display");
#define ERR_DP LOG_STREAM(err, log_display)
#define LOG_DP LOG_STREAM(info, log_display)
/**
* Iterators from this dummy list are needed to ensure that iterator member
* of cache_item is always non-singular iterator thus avoiding
* "Copy-contruct from singular iterator" error when libstdc++ debug mode
* is enabled. Note copying a singular iterator is undefined behaviour by
* the C++ standard.
*/
static std::list<int> dummy_list;
template<typename T>
struct cache_item
{
cache_item(): loaded(false), item(), position(dummy_list.end())
{
}
cache_item(): item(), loaded(false)
{}
cache_item(const T &item): loaded(true), item(item), position(dummy_list.end())
{
}
cache_item(const T &item): item(item), loaded(true)
{}
bool loaded;
T item;
std::list<int>::iterator position;
bool loaded;
};
namespace image {
@ -75,24 +63,18 @@ template<typename T>
class cache_type
{
public:
cache_type(): cache_size_(0), cache_max_size_(2000), lru_list_(), content_()
{
cache_type(): content_()
{}
cache_item<T> &get_element(int index) {
if (static_cast<unsigned>(index) >= content_.size())
content_.resize(index + 1);
return content_[index];
}
cache_item<T> &get_element(int index);
void on_load(int index);
void flush()
{
content_.clear();
lru_list_.clear();
cache_size_ = 0;
}
void flush() { content_.clear(); }
private:
int cache_size_;
int cache_max_size_;
std::list<int> lru_list_;
std::vector<cache_item<T> > content_;
};
@ -113,7 +95,6 @@ template <typename T>
void locator::add_to_cache(cache_type<T> &cache, const T &data) const
{
if (index_ != -1 ) cache.get_element(index_) = cache_item<T>(data);
cache.on_load(index_);
}
}
@ -1216,35 +1197,5 @@ bool precached_file_exists(const std::string& file)
return false;
}
template<typename T>
cache_item<T>& cache_type<T>::get_element(int index)
{
assert (index != -1);
if (unsigned(index) >= content_.size()) content_.resize(index + 1);
cache_item<T>& elt = content_[index];
if(elt.loaded) {
assert(*elt.position == index);
lru_list_.erase(elt.position);
lru_list_.push_front(index);
elt.position = lru_list_.begin();
}
return elt;
}
template<typename T>
void cache_type<T>::on_load(int index){
if(index == -1) return ;
cache_item<T>& elt = content_[index];
if(!elt.loaded) return ;
lru_list_.push_front(index);
elt.position = lru_list_.begin();
while(cache_size_ > cache_max_size_-100) {
cache_item<T>& elt = content_[lru_list_.back()];
elt.loaded=false;
elt.item = T();
lru_list_.pop_back();
cache_size_--;
}
}
} // end namespace image