libs-base/Source/AutoreleaseStack.m

#include <assert.h>

/* The initial size of the released_objects array */
#define DEFAULT_SIZE 64

/* Array of objects to be released later */
static unsigned released_capacity = 0;
static unsigned released_index = 0;
static id *released_objects = NULL;
static void **released_frame_pointers = NULL;

static inline void
grow_released_arrays()
{
  assert(released_objects);
  if (released_index == released_capacity)
    {
      released_capacity *= 2;
      OBJC_REALLOC(released_objects, id, released_capacity);
      OBJC_REALLOC(released_frame_pointers, void*, released_capacity);
    }
}

void
objc_release_stack_objects_to_frame_address(void *frame_address)
{
  assert(released_objects);
  /* xxx This assumes stack grows up */
  while ((released_frame_pointers[released_index] 
	  > frame_address)
	 && released_index)
    {
      [released_objects[released_index] release];
      released_index--;
    }
}

void
objc_release_stack_objects()
{
  assert(released_objects);
  objc_release_stack_objects_to_frame_address(__builtin_frame_address(1));
}

void
objc_stack_release_object_with_address (id o, void *a)
{
  released_index++;
  grow_released_arrays();
  released_objects[released_index] = o;
  released_frame_pointers[released_index] = a;
}

/* The object will not be released until after the function that is 3
   stack frames up exits.  One frame for this function, one frame for
   the "stackRelease" method that calls this, and one for the method
   that called "stackRelease". 
   Careful, if you try to call this too few stack frames away from main,
   you get a seg fault
*/
void
objc_stack_release_object(id anObj)
{
  void *s;

  /* assert(__builtin_frame_address(2)); */
  s = __builtin_frame_address(3);

  /* Do the pending releases of other objects */
  objc_release_stack_objects_to_frame_address(s);

  /* Queue this object for later release */
  objc_stack_release_object_with_address(anObj, s);
}

unsigned
objc_stack_release_count()
{
  return released_index;
}

@implementation AutoreleaseStack

+ initialize
{
  static init_done = 0;

  /* Initialize if we haven't done it yet */
  if (!init_done)
    {
      init_done = 1;
      
      released_capacity = DEFAULT_SIZE;
      OBJC_MALLOC(released_objects, id, released_capacity);
      OBJC_MALLOC(released_frame_pointers, void*, released_capacity);
    }
  return self;
}

- init
{
  objc_stack_release_object(self, 0);
  return self;
}

- (void) dealloc
{
  while (released_objects[release_index] != self)
    {
      [released_objects[released_index] release];
      released_index--;
    }
  released_index--;
  [super dealloc];
}

- addObject: anObject
{
  objc_stack_release_object(anObject);
  return self;
}

@end