yapf_costcache.hpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef YAPF_COSTCACHE_HPP
#define YAPF_COSTCACHE_HPP
 
#include "../../misc/hashtable.hpp"
#include "../../tile_type.h"
#include "../../track_type.h"
 
template <class Types>
class CYapfSegmentCostCacheNoneT
{
public:
  typedef typename Types::Tpf Tpf; 
  typedef typename Types::NodeList::Item Node; 
 
  inline bool PfNodeCacheFetch(Node &)
  {
    return false;
  }
};
 
struct CSegmentCostCacheBase
{
  static int   s_rail_change_counter;
 
  static void NotifyTrackLayoutChange(TileIndex, Track)
  {
    s_rail_change_counter++;
  }
};
 
 
template <class Tsegment>
struct CSegmentCostCacheT : public CSegmentCostCacheBase {
  static constexpr int HASH_BITS = 14;
 
  using Key = typename Tsegment::Key; 
 
  HashTable<Tsegment, HASH_BITS> map;
  std::deque<Tsegment> heap;
 
  inline CSegmentCostCacheT() {}
 
  inline void Flush()
  {
    this->map.Clear();
    this->heap.clear();
  }
 
  inline Tsegment &Get(Key &key, bool *found)
  {
    Tsegment *item = this->map.Find(key);
    if (item == nullptr) {
      *found = false;
      item = &this->heap.emplace_back(key);
      this->map.Push(*item);
    } else {
      *found = true;
    }
    return *item;
  }
};
 
template <class Types>
class CYapfSegmentCostCacheGlobalT {
public:
  typedef typename Types::Tpf Tpf; 
  typedef typename Types::NodeList::Item Node; 
  typedef typename Node::Key Key; 
  typedef typename Node::CachedData CachedData;
  typedef typename CachedData::Key CacheKey;
  typedef CSegmentCostCacheT<CachedData> Cache;
  using LocalCache = std::deque<CachedData>;
 
protected:
  Cache &global_cache;
  LocalCache local_cache;
 
  inline CYapfSegmentCostCacheGlobalT() : global_cache(stGetGlobalCache()) {};
 
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf *>(this);
  }
 
  inline static Cache &stGetGlobalCache()
  {
    static int last_rail_change_counter = 0;
    static Cache C;
 
    /* delete the cache sometimes... */
    if (last_rail_change_counter != Cache::s_rail_change_counter) {
      last_rail_change_counter = Cache::s_rail_change_counter;
      C.Flush();
    }
    return C;
  }
 
public:
  inline bool PfNodeCacheFetch(Node &n)
  {
    CacheKey key(n.GetKey());
 
    if (!Yapf().CanUseGlobalCache(n)) {
      Yapf().ConnectNodeToCachedData(n, this->local_cache.emplace_back(key));
      return false;
    }
 
    bool found;
    CachedData &item = this->global_cache.Get(key, &found);
    Yapf().ConnectNodeToCachedData(n, item);
    return found;
  }
};
 
#endif /* YAPF_COSTCACHE_HPP */