gecko/layout/base/nsPresArena.h

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 *   Håkan Waara <hwaara@chello.se>
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 *   Daniel Glazman <glazman@netscape.com>
 *   Mats Palmgren <mats.palmgren@bredband.net>
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#ifndef nsPresArena_h___
#define nsPresArena_h___

#include "nscore.h"
#include "nsQueryFrame.h"

// Uncomment this to disable arenas, instead forwarding to
// malloc for every allocation.
//#define DEBUG_TRACEMALLOC_PRESARENA 1

// The debugging version of nsPresArena does not free all the memory it
// allocated when the arena itself is destroyed.
#ifdef DEBUG_TRACEMALLOC_PRESARENA
#define PRESARENA_MUST_FREE_DURING_DESTROY PR_TRUE
#else
#define PRESARENA_MUST_FREE_DURING_DESTROY PR_FALSE
#endif

class nsPresArena {
public:
  nsPresArena();
  ~nsPresArena();

  // Pool allocation with recycler lists indexed by object size.
  NS_HIDDEN_(void*) AllocateBySize(size_t aSize);
  NS_HIDDEN_(void)  FreeBySize(size_t aSize, void* aPtr);

  // Pool allocation with recycler lists indexed by object-type code.
  // Every type code must always be used with the same object size.
  NS_HIDDEN_(void*) AllocateByCode(nsQueryFrame::FrameIID aCode, size_t aSize);
  NS_HIDDEN_(void)  FreeByCode(nsQueryFrame::FrameIID aCode, void* aPtr);

  PRUint32 Size();

  /**
   * Get the poison value that can be used to fill a memory space with
   * an address that leads to a safe crash when dereferenced.
   *
   * The caller is responsible for ensuring that a pres shell has been
   * initialized before calling this.
   */
  static PRUword GetPoisonValue();

private:
  struct State;
  State* mState;
};

#endif