/*
   AngelCode Scripting Library
   Copyright (c) 2003-2009 Andreas Jonsson

   This software is provided 'as-is', without any express or implied
   warranty. In no event will the authors be held liable for any
   damages arising from the use of this software.

   Permission is granted to anyone to use this software for any
   purpose, including commercial applications, and to alter it and
   redistribute it freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you
      must not claim that you wrote the original software. If you use
      this software in a product, an acknowledgment in the product
      documentation would be appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and
      must not be misrepresented as being the original software.

   3. This notice may not be removed or altered from any source
      distribution.

   The original version of this library can be located at:
   http://www.angelcode.com/angelscript/

   Andreas Jonsson
   andreas@angelcode.com
*/

//
// as_gc.h
//
// The garbage collector is used to resolve cyclic references
//

#ifndef AS_GC_H
#define AS_GC_H

#include "as_config.h"
#include "as_array.h"
#include "as_map.h"
#include "as_thread.h"

BEGIN_AS_NAMESPACE

class asCScriptEngine;
class asCObjectType;

class asCGarbageCollector {
public:
  asCGarbageCollector();

  int GarbageCollect(asDWORD flags);
  void GetStatistics(asUINT *currentSize, asUINT *totalDestroyed, asUINT *totalDetected);
  void GCEnumCallback(void *reference);
  void AddScriptObjectToGC(void *obj, asCObjectType *objType);

  asCScriptEngine *engine;

protected:
  struct asSObjTypePair {
    void *obj;
    asCObjectType *type;
  };
  struct asSIntTypePair {
    int i;
    asCObjectType *type;
  };

  enum egcDestroyState { destroyGarbage_init = 0, destroyGarbage_loop, destroyGarbage_haveMore };

  enum egcDetectState {
    clearCounters_init = 0,
    clearCounters_loop,
    countReferences_init,
    countReferences_loop,
    detectGarbage_init,
    detectGarbage_loop1,
    detectGarbage_loop2,
    verifyUnmarked,
    breakCircles_init,
    breakCircles_loop,
    breakCircles_haveGarbage
  };

  int DestroyGarbage();
  int IdentifyGarbageWithCyclicRefs();
  void ClearMap();
  asSObjTypePair GetObjectAtIdx(int idx);
  void RemoveObjectAtIdx(int idx);

  // Holds all the objects known by the garbage collector
  asCArray<asSObjTypePair> gcObjects;

  // This array temporarily holds references to objects known to be live objects
  asCArray<void *> liveObjects;

  // This map holds objects currently being searched for cyclic references, it also holds a
  // counter that gives the number of references to the object that the GC can't reach
  asCMap<void *, asSIntTypePair> gcMap;

  // State variables
  egcDestroyState destroyState;
  asUINT destroyIdx;
  asUINT numDestroyed;
  egcDetectState detectState;
  asUINT detectIdx;
  asUINT numDetected;
  asSMapNode<void *, asSIntTypePair> *gcMapCursor;

  // Critical section for multithreaded access
  DECLARECRITICALSECTION(gcCritical);
};

END_AS_NAMESPACE

#endif