resourcedistributor.hpp

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#include <memory>
#include <unordered_map>
static constexpr size_t CLEAR_THRESHOLD = 100;
 
namespace xcal::render::opengl::utils {
template <typename T, typename Catgory = void, size_t Id = 0>
struct ResourceAllocator {
    static std::shared_ptr<T> allocate();
};
template <typename T, typename Catgory, size_t Id>
std::shared_ptr<T> ResourceAllocator<T, Catgory, Id>::allocate() {
    return std::make_shared<T>();
}
template <typename T, typename Catgory = void, size_t Id = 0>
class StaticResourceDistributor {
    static std::weak_ptr<T> resource_;
 
   public:
    static std::shared_ptr<T> instance() {
        auto resource = resource_.lock();
        if (!resource) {
            resource = ResourceAllocator<T, Catgory, Id>::allocate();
            resource_ = resource;
        }
        return resource;
    }
};
template <typename T, typename Catgory, size_t Id>
std::weak_ptr<T> StaticResourceDistributor<T, Catgory, Id>::resource_;
 
template <typename T, typename Catgory = void, size_t Id = 0>
class DynamicResourceDistributor {
    static std::unordered_map<size_t, std::weak_ptr<T>> resources_;
    static size_t last_size_;
 
   public:
    static std::shared_ptr<T> instance(size_t id = 0) {
        auto resource = resources_[id].lock();
        if (!resource) {
            resource = ResourceAllocator<T, Catgory, Id>::allocate();
            resources_[id] = resource;
        }
        if (resources_.size() > last_size_ + CLEAR_THRESHOLD) {
            std::vector<size_t> to_erase;
            for (auto& pair : resources_) {
                if (pair.second.expired()) {
                    to_erase.push_back(pair.first);
                }
            }
            for (auto id : to_erase) {
                resources_.erase(id);
            }
            
            last_size_ = resources_.size();
        }
        return resource;
    }
};
template <typename T, typename Catgory, size_t Id>
std::unordered_map<size_t, std::weak_ptr<T>>
    DynamicResourceDistributor<T, Catgory, Id>::resources_;
template <typename T, typename Catgory, size_t Id>
size_t DynamicResourceDistributor<T, Catgory, Id>::last_size_ = 0;
}  // namespace xcal::render::opengl::utils