alloc.c

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    GC_clear_marks();
#   ifdef SAVE_CALL_CHAIN
        GC_save_callers(GC_last_stack);
#   endif
    GC_is_full_gc = TRUE;
    if (!GC_stopped_mark(stop_func)) {
      if (!GC_incremental) {
    	/* We're partially done and have no way to complete or use 	*/
    	/* current work.  Reestablish invariants as cheaply as		*/
    	/* possible.							*/
    	GC_invalidate_mark_state();
	GC_unpromote_black_lists();
      } /* else we claim the world is already still consistent.  We'll 	*/
        /* finish incrementally.					*/
      return(FALSE);
    }
    GC_finish_collection();
    if (GC_print_stats) {
        GET_TIME(current_time);
        GC_log_printf("Complete collection took %lu msecs\n",
                  MS_TIME_DIFF(current_time,start_time));
    }
    return(TRUE);
}



/*
 * Perform n units of garbage collection work.  A unit is intended to touch
 * roughly GC_RATE pages.  Every once in a while, we do more than that.
 * This needs to be a fairly large number with our current incremental
 * GC strategy, since otherwise we allocate too much during GC, and the
 * cleanup gets expensive.
 */
# define GC_RATE 10 
# define MAX_PRIOR_ATTEMPTS 1
 	/* Maximum number of prior attempts at world stop marking	*/
 	/* A value of 1 means that we finish the second time, no matter */
 	/* how long it takes.  Doesn't count the initial root scan	*/
 	/* for a full GC.						*/

int GC_deficit = 0;	/* The number of extra calls to GC_mark_some	*/
			/* that we have made.				*/

void GC_collect_a_little_inner(int n)
{
    int i;
    
    if (GC_dont_gc) return;
    if (GC_incremental && GC_collection_in_progress()) {
    	for (i = GC_deficit; i < GC_RATE*n; i++) {
    	    if (GC_mark_some((ptr_t)0)) {
    	        /* Need to finish a collection */
#     		ifdef SAVE_CALL_CHAIN
        	    GC_save_callers(GC_last_stack);
#     		endif
#		ifdef PARALLEL_MARK
		    GC_wait_for_reclaim();
#		endif
		if (GC_n_attempts < MAX_PRIOR_ATTEMPTS
		    && GC_time_limit != GC_TIME_UNLIMITED) {
		  GET_TIME(GC_start_time);
		  if (!GC_stopped_mark(GC_timeout_stop_func)) {
		    GC_n_attempts++;
		    break;
		  }
		} else {
		  (void)GC_stopped_mark(GC_never_stop_func);
		}
    	        GC_finish_collection();
    	        break;
    	    }
    	}
    	if (GC_deficit > 0) GC_deficit -= GC_RATE*n;
	if (GC_deficit < 0) GC_deficit = 0;
    } else {
        GC_maybe_gc();
    }
}

int GC_collect_a_little(void)
{
    int result;
    DCL_LOCK_STATE;

    LOCK();
    GC_collect_a_little_inner(1);
    result = (int)GC_collection_in_progress();
    UNLOCK();
    if (!result && GC_debugging_started) GC_print_all_smashed();
    return(result);
}

/*
 * Assumes lock is held, signals are disabled.
 * We stop the world.
 * If stop_func() ever returns TRUE, we may fail and return FALSE.
 * Increment GC_gc_no if we succeed.
 */
GC_bool GC_stopped_mark(GC_stop_func stop_func)
{
    unsigned i;
    int dummy;
    CLOCK_TYPE start_time, current_time;
	
    if (GC_print_stats)
	GET_TIME(start_time);

#   if defined(REGISTER_LIBRARIES_EARLY)
        GC_cond_register_dynamic_libraries();
#   endif
    STOP_WORLD();
    IF_THREADS(GC_world_stopped = TRUE);
    if (GC_print_stats) {
	GC_log_printf("--> Marking for collection %lu ",
		  (unsigned long)GC_gc_no + 1);
	GC_log_printf("after %lu allocd bytes\n",
	   	   (unsigned long) GC_bytes_allocd);
    }
#   ifdef MAKE_BACK_GRAPH
      if (GC_print_back_height) {
        GC_build_back_graph();
      }
#   endif

    /* Mark from all roots.  */
        /* Minimize junk left in my registers and on the stack */
            GC_clear_a_few_frames();
            GC_noop(0,0,0,0,0,0);
	GC_initiate_gc();
	for(i = 0;;i++) {
	    if ((*stop_func)()) {
		    if (GC_print_stats) {
		    	GC_log_printf("Abandoned stopped marking after ");
			GC_log_printf("%u iterations\n", i);
		    }
		    GC_deficit = i; /* Give the mutator a chance. */
                    IF_THREADS(GC_world_stopped = FALSE);
	            START_WORLD();
	            return(FALSE);
	    }
	    if (GC_mark_some((ptr_t)(&dummy))) break;
	}
	
    GC_gc_no++;
    if (GC_print_stats) {
      GC_log_printf("Collection %lu reclaimed %ld bytes",
		    (unsigned long)GC_gc_no - 1,
	   	    (long)GC_bytes_found);
      GC_log_printf(" ---> heapsize = %lu bytes\n",
      	        (unsigned long) GC_heapsize);
        /* Printf arguments may be pushed in funny places.  Clear the	*/
        /* space.							*/
      GC_log_printf("");
    }

    /* Check all debugged objects for consistency */
        if (GC_debugging_started) {
            (*GC_check_heap)();
        }
    
    IF_THREADS(GC_world_stopped = FALSE);
    START_WORLD();
    if (GC_print_stats) {
      GET_TIME(current_time);
      GC_log_printf("World-stopped marking took %lu msecs\n",
	            MS_TIME_DIFF(current_time,start_time));
    }
    return(TRUE);
}

/* Set all mark bits for the free list whose first entry is q	*/
void GC_set_fl_marks(ptr_t q)
{
   ptr_t p;
   struct hblk * h, * last_h = 0;
   hdr *hhdr;  /* gcc "might be uninitialized" warning is bogus. */
   IF_PER_OBJ(size_t sz;)
   unsigned bit_no;

   for (p = q; p != 0; p = obj_link(p)){
	h = HBLKPTR(p);
	if (h != last_h) {
	  last_h = h; 
	  hhdr = HDR(h);
	  IF_PER_OBJ(sz = hhdr->hb_sz;)
	}
	bit_no = MARK_BIT_NO((ptr_t)p - (ptr_t)h, sz);
	if (!mark_bit_from_hdr(hhdr, bit_no)) {
      	  set_mark_bit_from_hdr(hhdr, bit_no);
          ++hhdr -> hb_n_marks;
        }
   }
}

#ifdef GC_ASSERTIONS
/* Check that all mark bits for the free list whose first entry is q	*/
/* are set.								*/
void GC_check_fl_marks(ptr_t q)
{
   ptr_t p;

   for (p = q; p != 0; p = obj_link(p)){
	if (!GC_is_marked(p)) {
	    GC_err_printf("Unmarked object %p on list %p\n", p, q);
	    ABORT("Unmarked local free list entry.");
	}
   }
}
#endif

/* Clear all mark bits for the free list whose first entry is q	*/
/* Decrement GC_bytes_found by number of bytes on free list.	*/
void GC_clear_fl_marks(ptr_t q)
{
   ptr_t p;
   struct hblk * h, * last_h = 0;
   hdr *hhdr;
   size_t sz;
   unsigned bit_no;

   for (p = q; p != 0; p = obj_link(p)){
	h = HBLKPTR(p);
	if (h != last_h) {
	  last_h = h; 
	  hhdr = HDR(h);
	  sz = hhdr->hb_sz;  /* Normally set only once. */
	}
	bit_no = MARK_BIT_NO((ptr_t)p - (ptr_t)h, sz);
	if (mark_bit_from_hdr(hhdr, bit_no)) {
	  size_t n_marks = hhdr -> hb_n_marks - 1;
      	  clear_mark_bit_from_hdr(hhdr, bit_no);
#	  ifdef PARALLEL_MARK
	    /* Appr. count, don't decrement to zero! */
	    if (0 != n_marks) {
              hhdr -> hb_n_marks = n_marks;
	    }
#	  else
            hhdr -> hb_n_marks = n_marks;
#	  endif
        }
	GC_bytes_found -= sz;
   }
}

#if defined(GC_ASSERTIONS) && defined(THREADS) && defined(THREAD_LOCAL_ALLOC)
extern void GC_check_tls(void);
#endif

/* Finish up a collection.  Assumes lock is held, signals are disabled,	*/
/* but the world is otherwise running.					*/
void GC_finish_collection()
{
    CLOCK_TYPE start_time;
    CLOCK_TYPE finalize_time;
    CLOCK_TYPE done_time;
	
#   if defined(GC_ASSERTIONS) && defined(THREADS) \
       && defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
	/* Check that we marked some of our own data.  		*/
        /* FIXME: Add more checks.				*/
        GC_check_tls();
#   endif

    if (GC_print_stats)
      GET_TIME(start_time);

    GC_bytes_found = 0;
#   if defined(LINUX) && defined(__ELF__) && !defined(SMALL_CONFIG)
	if (getenv("GC_PRINT_ADDRESS_MAP") != 0) {
	  GC_print_address_map();
	}
#   endif
    COND_DUMP;
    if (GC_find_leak) {
      /* Mark all objects on the free list.  All objects should be */
      /* marked when we're done.				   */
	{
	  word size;		/* current object size		*/
	  unsigned kind;
	  ptr_t q;

	  for (kind = 0; kind < GC_n_kinds; kind++) {
	    for (size = 1; size <= MAXOBJGRANULES; size++) {
	      q = GC_obj_kinds[kind].ok_freelist[size];
	      if (q != 0) GC_set_fl_marks(q);
	    }
	  }
	}
	GC_start_reclaim(TRUE);
	  /* The above just checks; it doesn't really reclaim anything. */
    }

    GC_finalize();
#   ifdef STUBBORN_ALLOC
      GC_clean_changing_list();
#   endif

    if (GC_print_stats)
      GET_TIME(finalize_time);

    if (GC_print_back_height) {
#     ifdef MAKE_BACK_GRAPH
	GC_traverse_back_graph();
#     else
#	ifndef SMALL_CONFIG
	  GC_err_printf("Back height not available: "
		        "Rebuild collector with -DMAKE_BACK_GRAPH\n");
#  	endif
#     endif
    }

    /* Clear free list mark bits, in case they got accidentally marked   */
    /* (or GC_find_leak is set and they were intentionally marked).	 */
    /* Also subtract memory remaining from GC_bytes_found count.         */
    /* Note that composite objects on free list are cleared.             */
    /* Thus accidentally marking a free list is not a problem;  only     */
    /* objects on the list itself will be marked, and that's fixed here. */
      {
	word size;		/* current object size		*/
	ptr_t q;	/* pointer to current object	*/
	unsigned kind;

	for (kind = 0; kind < GC_n_kinds; kind++) {
	  for (size = 1; size <= MAXOBJGRANULES; size++) {
	    q = GC_obj_kinds[kind].ok_freelist[size];
	    if (q != 0) GC_clear_fl_marks(q);
	  }
	}
      }


    if (GC_print_stats == VERBOSE)
	GC_log_printf("Bytes recovered before sweep - f.l. count = %ld\n",
	          (long)GC_bytes_found);
    
    /* Reconstruct free lists to contain everything not marked */
        GC_start_reclaim(FALSE);
	if (GC_print_stats) {
	  GC_log_printf("Heap contains %lu pointer-containing "
		        "+ %lu pointer-free reachable bytes\n",
		        (unsigned long)GC_composite_in_use,