/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file geomCacheManager.h
 * @author drose
 * @date 2005-03-11
 */

#ifndef GEOMCACHEMANAGER_H
#define GEOMCACHEMANAGER_H

#include "pandabase.h"
#include "config_gobj.h"
#include "lightMutex.h"
#include "pStatCollector.h"

class GeomCacheEntry;

/**
 * This is used to keep track of, and limit the size of, the cache of munged
 * vertices, which would otherwise be distributed through all of the
 * GeomVertexData objects in the system.
 *
 * The actual data in the cache is not stored here, but rather it is
 * distributed among the various GeomVertexData source objects.  This allows
 * the cache data to propagate through the multiprocess pipeline.
 *
 * This structure actually caches any of a number of different types of
 * pointers, and mixes them all up in the same LRU cache list.  Some of them
 * (such as GeomMunger) are reference-counted here in the cache; most are not.
 */
class EXPCL_PANDA_GOBJ GeomCacheManager {
protected:
  GeomCacheManager();
  ~GeomCacheManager();

PUBLISHED:
  INLINE void set_max_size(int max_size) const;
  INLINE int get_max_size() const;

  INLINE int get_total_size() const;

  void flush();

  static GeomCacheManager *get_global_ptr();

public:
  INLINE void evict_old_entries();
  void evict_old_entries(int max_size, bool keep_current);
  INLINE static void flush_level();

private:
  // This mutex protects all operations on this object, especially the linked-
  // list operations.
  LightMutex _lock;

  int _total_size;

  // We maintain a doubly-linked list to keep the cache entries in least-
  // recently-used order: the items at the head of the list are ready to be
  // flushed.  We use our own doubly-linked list instead of an STL list, just
  // so we can avoid a tiny bit of overhead, especially in keeping the pointer
  // directly into the list from the calling objects.

  // The tail and the head of the list are both kept by the _prev and _next
  // pointers, respectively, within the following object, which always exists
  // solely to keep a handle to the list.  Keeping a token of the list this
  // way avoids special cases for an empty list.
  GeomCacheEntry *_list;

  static GeomCacheManager *_global_ptr;

public:
  static PStatCollector _geom_cache_size_pcollector;
  static PStatCollector _geom_cache_active_pcollector;
  static PStatCollector _geom_cache_record_pcollector;
  static PStatCollector _geom_cache_erase_pcollector;
  static PStatCollector _geom_cache_evict_pcollector;

  friend class GeomCacheEntry;
};

#include "geomCacheManager.I"

#endif