1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003, 2006, 2008 Free Software Foundation, Inc.
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 /* #define DEBUGINFO */
29 #include "libguile/_scm.h"
30 #include "libguile/eval.h"
31 #include "libguile/stime.h"
32 #include "libguile/stackchk.h"
33 #include "libguile/struct.h"
34 #include "libguile/smob.h"
35 #include "libguile/unif.h"
36 #include "libguile/async.h"
37 #include "libguile/ports.h"
38 #include "libguile/root.h"
39 #include "libguile/strings.h"
40 #include "libguile/vectors.h"
41 #include "libguile/weaks.h"
42 #include "libguile/hashtab.h"
43 #include "libguile/tags.h"
45 #include "libguile/private-gc.h"
46 #include "libguile/validate.h"
47 #include "libguile/deprecation.h"
48 #include "libguile/gc.h"
49 #include "libguile/dynwind.h"
51 #ifdef GUILE_DEBUG_MALLOC
52 #include "libguile/debug-malloc.h"
63 /* Lock this mutex before doing lazy sweeping.
65 scm_i_pthread_mutex_t scm_i_sweep_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
67 /* Set this to != 0 if every cell that is accessed shall be checked:
69 int scm_debug_cell_accesses_p
= 0;
70 int scm_expensive_debug_cell_accesses_p
= 0;
72 /* Set this to 0 if no additional gc's shall be performed, otherwise set it to
73 * the number of cell accesses after which a gc shall be called.
75 int scm_debug_cells_gc_interval
= 0;
78 Global variable, so you can switch it off at runtime by setting
79 scm_i_cell_validation_already_running.
81 int scm_i_cell_validation_already_running
;
83 #if (SCM_DEBUG_CELL_ACCESSES == 1)
88 Assert that the given object is a valid reference to a valid cell. This
89 test involves to determine whether the object is a cell pointer, whether
90 this pointer actually points into a heap segment and whether the cell
91 pointed to is not a free cell. Further, additional garbage collections may
92 get executed after a user defined number of cell accesses. This helps to
93 find places in the C code where references are dropped for extremely short
98 scm_i_expensive_validation_check (SCM cell
)
100 if (!scm_in_heap_p (cell
))
102 fprintf (stderr
, "scm_assert_cell_valid: this object does not live in the heap: %lux\n",
103 (unsigned long) SCM_UNPACK (cell
));
107 /* If desired, perform additional garbage collections after a user
108 * defined number of cell accesses.
110 if (scm_debug_cells_gc_interval
)
112 static unsigned int counter
= 0;
120 counter
= scm_debug_cells_gc_interval
;
127 scm_assert_cell_valid (SCM cell
)
129 if (!scm_i_cell_validation_already_running
&& scm_debug_cell_accesses_p
)
131 scm_i_cell_validation_already_running
= 1; /* set to avoid recursion */
134 During GC, no user-code should be run, and the guile core
135 should use non-protected accessors.
137 if (scm_gc_running_p
)
141 Only scm_in_heap_p and rescanning the heap is wildly
144 if (scm_expensive_debug_cell_accesses_p
)
145 scm_i_expensive_validation_check (cell
);
147 if (!SCM_GC_MARK_P (cell
))
150 "scm_assert_cell_valid: this object is unmarked. \n"
151 "It has been garbage-collected in the last GC run: "
153 (unsigned long) SCM_UNPACK (cell
));
157 scm_i_cell_validation_already_running
= 0; /* re-enable */
163 SCM_DEFINE (scm_set_debug_cell_accesses_x
, "set-debug-cell-accesses!", 1, 0, 0,
165 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
166 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
167 "but no additional calls to garbage collection are issued.\n"
168 "If @var{flag} is a number, strict cell access checking is enabled,\n"
169 "with an additional garbage collection after the given\n"
170 "number of cell accesses.\n"
171 "This procedure only exists when the compile-time flag\n"
172 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
173 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
175 if (scm_is_false (flag
))
177 scm_debug_cell_accesses_p
= 0;
179 else if (scm_is_eq (flag
, SCM_BOOL_T
))
181 scm_debug_cells_gc_interval
= 0;
182 scm_debug_cell_accesses_p
= 1;
183 scm_expensive_debug_cell_accesses_p
= 0;
187 scm_debug_cells_gc_interval
= scm_to_signed_integer (flag
, 0, INT_MAX
);
188 scm_debug_cell_accesses_p
= 1;
189 scm_expensive_debug_cell_accesses_p
= 1;
191 return SCM_UNSPECIFIED
;
196 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
202 * is the number of bytes of malloc allocation needed to trigger gc.
204 unsigned long scm_mtrigger
;
206 /* GC Statistics Keeping
208 unsigned long scm_cells_allocated
= 0;
209 unsigned long scm_last_cells_allocated
= 0;
210 unsigned long scm_mallocated
= 0;
211 long int scm_i_find_heap_calls
= 0;
212 /* Global GC sweep statistics since the last full GC. */
213 scm_t_sweep_statistics scm_i_gc_sweep_stats
= { 0, 0 };
215 /* Total count of cells marked/swept. */
216 static double scm_gc_cells_marked_acc
= 0.;
217 static double scm_gc_cells_marked_conservatively_acc
= 0.;
218 static double scm_gc_cells_swept_acc
= 0.;
219 static double scm_gc_cells_allocated_acc
= 0.;
221 static unsigned long scm_gc_time_taken
= 0;
222 static unsigned long scm_gc_mark_time_taken
= 0;
224 static unsigned long scm_gc_times
= 0;
226 static int scm_gc_cell_yield_percentage
= 0;
227 static unsigned long protected_obj_count
= 0;
229 /* The following are accessed from `gc-malloc.c' and `gc-card.c'. */
230 int scm_gc_malloc_yield_percentage
= 0;
231 unsigned long scm_gc_malloc_collected
= 0;
234 SCM_SYMBOL (sym_cells_allocated
, "cells-allocated");
235 SCM_SYMBOL (sym_heap_size
, "cell-heap-size");
236 SCM_SYMBOL (sym_mallocated
, "bytes-malloced");
237 SCM_SYMBOL (sym_mtrigger
, "gc-malloc-threshold");
238 SCM_SYMBOL (sym_heap_segments
, "cell-heap-segments");
239 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
240 SCM_SYMBOL (sym_gc_mark_time_taken
, "gc-mark-time-taken");
241 SCM_SYMBOL (sym_times
, "gc-times");
242 SCM_SYMBOL (sym_cells_marked
, "cells-marked");
243 SCM_SYMBOL (sym_cells_marked_conservatively
, "cells-marked-conservatively");
244 SCM_SYMBOL (sym_cells_swept
, "cells-swept");
245 SCM_SYMBOL (sym_malloc_yield
, "malloc-yield");
246 SCM_SYMBOL (sym_cell_yield
, "cell-yield");
247 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
248 SCM_SYMBOL (sym_total_cells_allocated
, "total-cells-allocated");
251 /* Number of calls to SCM_NEWCELL since startup. */
252 unsigned scm_newcell_count
;
253 unsigned scm_newcell2_count
;
256 /* {Scheme Interface to GC}
259 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
261 if (scm_is_integer (key
))
263 int c_tag
= scm_to_int (key
);
265 char const * name
= scm_i_tag_name (c_tag
);
268 key
= scm_from_locale_string (name
);
273 sprintf (s
, "tag %d", c_tag
);
274 key
= scm_from_locale_string (s
);
278 return scm_cons (scm_cons (key
, val
), acc
);
281 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
283 "Return an alist of statistics of the current live objects. ")
284 #define FUNC_NAME s_scm_gc_live_object_stats
286 SCM tab
= scm_make_hash_table (scm_from_int (57));
289 scm_i_all_segments_statistics (tab
);
292 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
298 extern int scm_gc_malloc_yield_percentage
;
299 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
301 "Return an association list of statistics about Guile's current\n"
303 #define FUNC_NAME s_scm_gc_stats
306 SCM heap_segs
= SCM_EOL
;
307 unsigned long int local_scm_mtrigger
;
308 unsigned long int local_scm_mallocated
;
309 unsigned long int local_scm_heap_size
;
310 int local_scm_gc_cell_yield_percentage
;
311 int local_scm_gc_malloc_yield_percentage
;
312 unsigned long int local_scm_cells_allocated
;
313 unsigned long int local_scm_gc_time_taken
;
314 unsigned long int local_scm_gc_times
;
315 unsigned long int local_scm_gc_mark_time_taken
;
316 unsigned long int local_protected_obj_count
;
317 double local_scm_gc_cells_swept
;
318 double local_scm_gc_cells_marked
;
319 double local_scm_gc_cells_marked_conservatively
;
320 double local_scm_total_cells_allocated
;
322 unsigned long *bounds
= 0;
324 SCM_CRITICAL_SECTION_START
;
326 bounds
= scm_i_segment_table_info (&table_size
);
328 /* Below, we cons to produce the resulting list. We want a snapshot of
329 * the heap situation before consing.
331 local_scm_mtrigger
= scm_mtrigger
;
332 local_scm_mallocated
= scm_mallocated
;
333 local_scm_heap_size
=
334 (scm_i_master_freelist
.heap_total_cells
+ scm_i_master_freelist2
.heap_total_cells
);
336 local_scm_cells_allocated
=
337 scm_cells_allocated
+ scm_i_gc_sweep_stats
.collected
;
339 local_scm_gc_time_taken
= scm_gc_time_taken
;
340 local_scm_gc_mark_time_taken
= scm_gc_mark_time_taken
;
341 local_scm_gc_times
= scm_gc_times
;
342 local_scm_gc_malloc_yield_percentage
= scm_gc_malloc_yield_percentage
;
343 local_scm_gc_cell_yield_percentage
= scm_gc_cell_yield_percentage
;
344 local_protected_obj_count
= protected_obj_count
;
345 local_scm_gc_cells_swept
=
346 (double) scm_gc_cells_swept_acc
347 + (double) scm_i_gc_sweep_stats
.swept
;
348 local_scm_gc_cells_marked
= scm_gc_cells_marked_acc
349 + (double) scm_i_gc_sweep_stats
.swept
350 - (double) scm_i_gc_sweep_stats
.collected
;
351 local_scm_gc_cells_marked_conservatively
352 = scm_gc_cells_marked_conservatively_acc
;
354 local_scm_total_cells_allocated
= scm_gc_cells_allocated_acc
355 + (double) scm_i_gc_sweep_stats
.collected
;
357 for (i
= table_size
; i
--;)
359 heap_segs
= scm_cons (scm_cons (scm_from_ulong (bounds
[2*i
]),
360 scm_from_ulong (bounds
[2*i
+1])),
364 /* njrev: can any of these scm_cons's or scm_list_n signal a memory
365 error? If so we need a frame here. */
367 scm_list_n (scm_cons (sym_gc_time_taken
,
368 scm_from_ulong (local_scm_gc_time_taken
)),
369 scm_cons (sym_cells_allocated
,
370 scm_from_ulong (local_scm_cells_allocated
)),
371 scm_cons (sym_total_cells_allocated
,
372 scm_from_double (local_scm_total_cells_allocated
)),
373 scm_cons (sym_heap_size
,
374 scm_from_ulong (local_scm_heap_size
)),
375 scm_cons (sym_cells_marked_conservatively
,
376 scm_from_ulong (local_scm_gc_cells_marked_conservatively
)),
377 scm_cons (sym_mallocated
,
378 scm_from_ulong (local_scm_mallocated
)),
379 scm_cons (sym_mtrigger
,
380 scm_from_ulong (local_scm_mtrigger
)),
382 scm_from_ulong (local_scm_gc_times
)),
383 scm_cons (sym_gc_mark_time_taken
,
384 scm_from_ulong (local_scm_gc_mark_time_taken
)),
385 scm_cons (sym_cells_marked
,
386 scm_from_double (local_scm_gc_cells_marked
)),
387 scm_cons (sym_cells_swept
,
388 scm_from_double (local_scm_gc_cells_swept
)),
389 scm_cons (sym_malloc_yield
,
390 scm_from_long(local_scm_gc_malloc_yield_percentage
)),
391 scm_cons (sym_cell_yield
,
392 scm_from_long (local_scm_gc_cell_yield_percentage
)),
393 scm_cons (sym_protected_objects
,
394 scm_from_ulong (local_protected_obj_count
)),
395 scm_cons (sym_heap_segments
, heap_segs
),
397 SCM_CRITICAL_SECTION_END
;
405 Update nice-to-know-statistics.
410 /* CELLS SWEPT is another word for the number of cells that were examined
411 during GC. YIELD is the number that we cleaned out. MARKED is the number
412 that weren't cleaned. */
413 scm_gc_cell_yield_percentage
= (scm_i_gc_sweep_stats
.collected
* 100) /
414 (scm_i_master_freelist
.heap_total_cells
+ scm_i_master_freelist2
.heap_total_cells
);
416 scm_gc_cells_allocated_acc
+=
417 (double) scm_i_gc_sweep_stats
.collected
;
418 scm_gc_cells_marked_acc
+= (double) scm_cells_allocated
;
419 scm_gc_cells_marked_conservatively_acc
+= (double) scm_i_find_heap_calls
;
420 scm_gc_cells_swept_acc
+= (double) scm_i_gc_sweep_stats
.swept
;
425 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
427 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
428 "returned by this function for @var{obj}")
429 #define FUNC_NAME s_scm_object_address
431 return scm_from_ulong (SCM_UNPACK (obj
));
436 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
438 "Scans all of SCM objects and reclaims for further use those that are\n"
439 "no longer accessible.")
440 #define FUNC_NAME s_scm_gc
442 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex
);
443 scm_gc_running_p
= 1;
445 /* njrev: It looks as though other places, e.g. scm_realloc,
446 can call scm_i_gc without acquiring the sweep mutex. Does this
447 matter? Also scm_i_gc (or its descendants) touch the
448 scm_sys_protects, which are protected in some cases
449 (e.g. scm_permobjs above in scm_gc_stats) by a critical section,
450 not by the sweep mutex. Shouldn't all the GC-relevant objects be
451 protected in the same way? */
452 scm_gc_running_p
= 0;
453 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex
);
454 scm_c_hook_run (&scm_after_gc_c_hook
, 0);
455 return SCM_UNSPECIFIED
;
462 /* The master is global and common while the freelist will be
463 * individual for each thread.
467 scm_gc_for_newcell (scm_t_cell_type_statistics
*freelist
, SCM
*free_cells
)
472 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex
);
473 scm_gc_running_p
= 1;
475 *free_cells
= scm_i_sweep_for_freelist (freelist
);
476 if (*free_cells
== SCM_EOL
)
478 float delta
= scm_i_gc_heap_size_delta (freelist
);
481 size_t bytes
= ((unsigned long) delta
) * sizeof (scm_t_cell
);
482 freelist
->heap_segment_idx
=
483 scm_i_get_new_heap_segment (freelist
, bytes
, abort_on_error
);
485 *free_cells
= scm_i_sweep_for_freelist (freelist
);
489 if (*free_cells
== SCM_EOL
)
492 out of fresh cells. Try to get some new ones.
494 char reason
[] = "0-cells";
495 reason
[0] += freelist
->span
;
500 *free_cells
= scm_i_sweep_for_freelist (freelist
);
503 if (*free_cells
== SCM_EOL
)
506 failed getting new cells. Get new juice or die.
508 float delta
= scm_i_gc_heap_size_delta (freelist
);
509 assert (delta
> 0.0);
510 size_t bytes
= ((unsigned long) delta
) * sizeof (scm_t_cell
);
511 freelist
->heap_segment_idx
=
512 scm_i_get_new_heap_segment (freelist
, bytes
, abort_on_error
);
514 *free_cells
= scm_i_sweep_for_freelist (freelist
);
517 if (*free_cells
== SCM_EOL
)
522 *free_cells
= SCM_FREE_CELL_CDR (cell
);
524 scm_gc_running_p
= 0;
525 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex
);
528 scm_c_hook_run (&scm_after_gc_c_hook
, 0);
534 scm_t_c_hook scm_before_gc_c_hook
;
535 scm_t_c_hook scm_before_mark_c_hook
;
536 scm_t_c_hook scm_before_sweep_c_hook
;
537 scm_t_c_hook scm_after_sweep_c_hook
;
538 scm_t_c_hook scm_after_gc_c_hook
;
541 scm_check_deprecated_memory_return()
543 if (scm_mallocated
< scm_i_deprecated_memory_return
)
545 /* The byte count of allocated objects has underflowed. This is
546 probably because you forgot to report the sizes of objects you
547 have allocated, by calling scm_done_malloc or some such. When
548 the GC freed them, it subtracted their size from
549 scm_mallocated, which underflowed. */
551 "scm_gc_sweep: Byte count of allocated objects has underflowed.\n"
552 "This is probably because the GC hasn't been correctly informed\n"
553 "about object sizes\n");
556 scm_mallocated
-= scm_i_deprecated_memory_return
;
557 scm_i_deprecated_memory_return
= 0;
560 /* Must be called while holding scm_i_sweep_mutex.
562 This function is fairly long, but it touches various global
563 variables. To not obscure the side effects on global variables,
564 this function has not been split up.
567 scm_i_gc (const char *what
)
569 unsigned long t_before_gc
= 0;
571 scm_i_thread_put_to_sleep ();
573 scm_c_hook_run (&scm_before_gc_c_hook
, 0);
576 fprintf (stderr
,"gc reason %s\n", what
);
578 scm_is_null (*SCM_FREELIST_LOC (scm_i_freelist
))
580 : (scm_is_null (*SCM_FREELIST_LOC (scm_i_freelist2
)) ? "o" : "m"));
583 t_before_gc
= scm_c_get_internal_run_time ();
584 scm_gc_malloc_collected
= 0;
587 Set freelists to NULL so scm_cons() always triggers gc, causing
588 the assertion above to fail.
590 *SCM_FREELIST_LOC (scm_i_freelist
) = SCM_EOL
;
591 *SCM_FREELIST_LOC (scm_i_freelist2
) = SCM_EOL
;
594 Let's finish the sweep. The conservative GC might point into the
595 garbage, and marking that would create a mess.
597 scm_i_sweep_all_segments ("GC", &scm_i_gc_sweep_stats
);
598 scm_check_deprecated_memory_return();
600 /* Sanity check our numbers. */
602 /* If this was not true, someone touched mark bits outside of the
604 assert (scm_cells_allocated
== scm_i_marked_count ());
605 assert (scm_i_gc_sweep_stats
.swept
606 == (scm_i_master_freelist
.heap_total_cells
607 + scm_i_master_freelist2
.heap_total_cells
));
608 assert (scm_i_gc_sweep_stats
.collected
+ scm_cells_allocated
609 == scm_i_gc_sweep_stats
.swept
);
612 scm_c_hook_run (&scm_before_mark_c_hook
, 0);
615 scm_gc_mark_time_taken
+= (scm_c_get_internal_run_time () - t_before_gc
);
617 scm_cells_allocated
= scm_i_marked_count ();
621 TODO: the after_sweep hook should probably be moved to just before
622 the mark, since that's where the sweep is finished in lazy
625 MDJ 030219 <djurfeldt@nada.kth.se>: No, probably not. The
626 original meaning implied at least two things: that it would be
629 1. the freelist is re-initialized (no evaluation possible, though)
633 2. the heap is "fresh"
634 (it is well-defined what data is used and what is not)
636 Neither of these conditions would hold just before the mark phase.
638 Of course, the lazy sweeping has muddled the distinction between
639 scm_before_sweep_c_hook and scm_after_sweep_c_hook, but even if
640 there were no difference, it would still be useful to have two
641 distinct classes of hook functions since this can prevent some
642 bad interference when several modules adds gc hooks.
644 scm_c_hook_run (&scm_before_sweep_c_hook
, 0);
647 Nothing here: lazy sweeping.
649 scm_i_reset_segments ();
651 *SCM_FREELIST_LOC (scm_i_freelist
) = SCM_EOL
;
652 *SCM_FREELIST_LOC (scm_i_freelist2
) = SCM_EOL
;
654 /* Invalidate the freelists of other threads. */
655 scm_i_thread_invalidate_freelists ();
657 scm_c_hook_run (&scm_after_sweep_c_hook
, 0);
661 scm_i_gc_sweep_stats
.collected
= scm_i_gc_sweep_stats
.swept
= 0;
662 scm_i_gc_sweep_freelist_reset (&scm_i_master_freelist
);
663 scm_i_gc_sweep_freelist_reset (&scm_i_master_freelist2
);
665 /* Arguably, this statistic is fairly useless: marking will dominate
668 scm_gc_time_taken
+= (scm_c_get_internal_run_time () - t_before_gc
);
670 scm_i_thread_wake_up ();
672 For debugging purposes, you could do
673 scm_i_sweep_all_segments("debug"), but then the remains of the
674 cell aren't left to analyse.
680 /* {GC Protection Helper Functions}
685 * If within a function you need to protect one or more scheme objects from
686 * garbage collection, pass them as parameters to one of the
687 * scm_remember_upto_here* functions below. These functions don't do
688 * anything, but since the compiler does not know that they are actually
689 * no-ops, it will generate code that calls these functions with the given
690 * parameters. Therefore, you can be sure that the compiler will keep those
691 * scheme values alive (on the stack or in a register) up to the point where
692 * scm_remember_upto_here* is called. In other words, place the call to
693 * scm_remember_upto_here* _behind_ the last code in your function, that
694 * depends on the scheme object to exist.
696 * Example: We want to make sure that the string object str does not get
697 * garbage collected during the execution of 'some_function' in the code
698 * below, because otherwise the characters belonging to str would be freed and
699 * 'some_function' might access freed memory. To make sure that the compiler
700 * keeps str alive on the stack or in a register such that it is visible to
701 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
702 * call to 'some_function'. Note that this would not be necessary if str was
703 * used anyway after the call to 'some_function'.
704 * char *chars = scm_i_string_chars (str);
705 * some_function (chars);
706 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
709 /* Remove any macro versions of these while defining the functions.
710 Functions are always included in the library, for upward binary
711 compatibility and in case combinations of GCC and non-GCC are used. */
712 #undef scm_remember_upto_here_1
713 #undef scm_remember_upto_here_2
716 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
718 /* Empty. Protects a single object from garbage collection. */
722 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
724 /* Empty. Protects two objects from garbage collection. */
728 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
730 /* Empty. Protects any number of objects from garbage collection. */
734 These crazy functions prevent garbage collection
735 of arguments after the first argument by
736 ensuring they remain live throughout the
737 function because they are used in the last
738 line of the code block.
739 It'd be better to have a nice compiler hint to
740 aid the conservative stack-scanning GC. --03/09/00 gjb */
742 scm_return_first (SCM elt
, ...)
748 scm_return_first_int (int i
, ...)
755 scm_permanent_object (SCM obj
)
757 SCM cell
= scm_cons (obj
, SCM_EOL
);
758 SCM_CRITICAL_SECTION_START
;
759 SCM_SETCDR (cell
, scm_permobjs
);
761 SCM_CRITICAL_SECTION_END
;
766 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
767 other references are dropped, until the object is unprotected by calling
768 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
769 i. e. it is possible to protect the same object several times, but it is
770 necessary to unprotect the object the same number of times to actually get
771 the object unprotected. It is an error to unprotect an object more often
772 than it has been protected before. The function scm_protect_object returns
776 /* Implementation note: For every object X, there is a counter which
777 scm_gc_protect_object(X) increments and scm_gc_unprotect_object(X) decrements.
783 scm_gc_protect_object (SCM obj
)
787 /* This critical section barrier will be replaced by a mutex. */
788 /* njrev: Indeed; if my comment above is correct, there is the same
789 critsec/mutex inconsistency here. */
790 SCM_CRITICAL_SECTION_START
;
792 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
793 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
795 protected_obj_count
++;
797 SCM_CRITICAL_SECTION_END
;
803 /* Remove any protection for OBJ established by a prior call to
804 scm_protect_object. This function returns OBJ.
806 See scm_protect_object for more information. */
808 scm_gc_unprotect_object (SCM obj
)
812 /* This critical section barrier will be replaced by a mutex. */
813 /* njrev: and again. */
814 SCM_CRITICAL_SECTION_START
;
816 if (scm_gc_running_p
)
818 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
822 handle
= scm_hashq_get_handle (scm_protects
, obj
);
824 if (scm_is_false (handle
))
826 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
831 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
832 if (scm_is_eq (count
, scm_from_int (0)))
833 scm_hashq_remove_x (scm_protects
, obj
);
835 SCM_SETCDR (handle
, count
);
837 protected_obj_count
--;
839 SCM_CRITICAL_SECTION_END
;
845 scm_gc_register_root (SCM
*p
)
848 SCM key
= scm_from_ulong ((unsigned long) p
);
850 /* This critical section barrier will be replaced by a mutex. */
851 /* njrev: and again. */
852 SCM_CRITICAL_SECTION_START
;
854 handle
= scm_hashv_create_handle_x (scm_gc_registered_roots
, key
,
856 /* njrev: note also that the above can probably signal an error */
857 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
859 SCM_CRITICAL_SECTION_END
;
863 scm_gc_unregister_root (SCM
*p
)
866 SCM key
= scm_from_ulong ((unsigned long) p
);
868 /* This critical section barrier will be replaced by a mutex. */
869 /* njrev: and again. */
870 SCM_CRITICAL_SECTION_START
;
872 handle
= scm_hashv_get_handle (scm_gc_registered_roots
, key
);
874 if (scm_is_false (handle
))
876 fprintf (stderr
, "scm_gc_unregister_root called on unregistered root\n");
881 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
882 if (scm_is_eq (count
, scm_from_int (0)))
883 scm_hashv_remove_x (scm_gc_registered_roots
, key
);
885 SCM_SETCDR (handle
, count
);
888 SCM_CRITICAL_SECTION_END
;
892 scm_gc_register_roots (SCM
*b
, unsigned long n
)
895 for (; p
< b
+ n
; ++p
)
896 scm_gc_register_root (p
);
900 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
903 for (; p
< b
+ n
; ++p
)
904 scm_gc_unregister_root (p
);
907 int scm_i_terminating
;
913 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
916 /* Get an integer from an environment variable. */
918 scm_getenv_int (const char *var
, int def
)
921 char *val
= getenv (var
);
925 res
= strtol (val
, &end
, 10);
932 scm_storage_prehistory ()
934 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
935 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
936 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
937 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
938 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
941 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
948 j
= SCM_NUM_PROTECTS
;
950 scm_sys_protects
[--j
] = SCM_BOOL_F
;
952 scm_gc_init_freelist();
953 scm_gc_init_malloc ();
956 /* We can't have a cleanup handler since we have no thread to run it
963 on_exit (cleanup
, 0);
969 scm_stand_in_procs
= scm_make_weak_key_hash_table (scm_from_int (257));
970 scm_permobjs
= SCM_EOL
;
971 scm_protects
= scm_c_make_hash_table (31);
972 scm_gc_registered_roots
= scm_c_make_hash_table (31);
979 SCM scm_after_gc_hook
;
983 /* The function gc_async_thunk causes the execution of the after-gc-hook. It
984 * is run after the gc, as soon as the asynchronous events are handled by the
988 gc_async_thunk (void)
990 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
991 return SCM_UNSPECIFIED
;
995 /* The function mark_gc_async is run by the scm_after_gc_c_hook at the end of
996 * the garbage collection. The only purpose of this function is to mark the
997 * gc_async (which will eventually lead to the execution of the
1001 mark_gc_async (void * hook_data SCM_UNUSED
,
1002 void *fn_data SCM_UNUSED
,
1003 void *data SCM_UNUSED
)
1005 /* If cell access debugging is enabled, the user may choose to perform
1006 * additional garbage collections after an arbitrary number of cell
1007 * accesses. We don't want the scheme level after-gc-hook to be performed
1008 * for each of these garbage collections for the following reason: The
1009 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
1010 * after-gc-hook was performed with every gc, and if the gc was performed
1011 * after a very small number of cell accesses, then the number of cell
1012 * accesses during the execution of the after-gc-hook will suffice to cause
1013 * the execution of the next gc. Then, guile would keep executing the
1014 * after-gc-hook over and over again, and would never come to do other
1017 * To overcome this problem, if cell access debugging with additional
1018 * garbage collections is enabled, the after-gc-hook is never run by the
1019 * garbage collecter. When running guile with cell access debugging and the
1020 * execution of the after-gc-hook is desired, then it is necessary to run
1021 * the hook explicitly from the user code. This has the effect, that from
1022 * the scheme level point of view it seems that garbage collection is
1023 * performed with a much lower frequency than it actually is. Obviously,
1024 * this will not work for code that depends on a fixed one to one
1025 * relationship between the execution counts of the C level garbage
1026 * collection hooks and the execution count of the scheme level
1030 #if (SCM_DEBUG_CELL_ACCESSES == 1)
1031 if (scm_debug_cells_gc_interval
== 0)
1032 scm_system_async_mark (gc_async
);
1034 scm_system_async_mark (gc_async
);
1043 scm_gc_init_mark ();
1045 scm_after_gc_hook
= scm_permanent_object (scm_make_hook (SCM_INUM0
));
1046 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
1048 gc_async
= scm_c_make_subr ("%gc-thunk", scm_tc7_subr_0
,
1051 scm_c_hook_add (&scm_after_gc_c_hook
, mark_gc_async
, NULL
, 0);
1053 #include "libguile/gc.x"
1058 # include <sys/param.h>
1059 # include <sys/pstat.h>
1061 scm_ia64_register_backing_store_base (void)
1063 struct pst_vm_status vm_status
;
1065 while (pstat_getprocvm (&vm_status
, sizeof (vm_status
), 0, i
++) == 1)
1066 if (vm_status
.pst_type
== PS_RSESTACK
)
1067 return (void *) vm_status
.pst_vaddr
;
1071 scm_ia64_ar_bsp (const void *ctx
)
1074 __uc_get_ar_bsp(ctx
, &bsp
);
1075 return (void *) bsp
;
1079 # include <ucontext.h>
1081 scm_ia64_register_backing_store_base (void)
1083 extern void *__libc_ia64_register_backing_store_base
;
1084 return __libc_ia64_register_backing_store_base
;
1087 scm_ia64_ar_bsp (const void *opaque
)
1089 const ucontext_t
*ctx
= opaque
;
1090 return (void *) ctx
->uc_mcontext
.sc_ar_bsp
;
1093 #endif /* __ia64__ */
1097 #define FUNC_NAME "scm_gc_sweep"