1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003, 2006, 2008, 2009 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 License
5 * as published by the Free Software Foundation; either version 3 of
6 * the License, or (at your option) any later version.
8 * This library is distributed in the hope that it will be useful, but
9 * 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
19 /* #define DEBUGINFO */
25 #include "libguile/gen-scmconfig.h"
34 extern unsigned long * __libc_ia64_register_backing_store_base
;
37 #include "libguile/_scm.h"
38 #include "libguile/eval.h"
39 #include "libguile/stime.h"
40 #include "libguile/stackchk.h"
41 #include "libguile/struct.h"
42 #include "libguile/smob.h"
43 #include "libguile/arrays.h"
44 #include "libguile/async.h"
45 #include "libguile/ports.h"
46 #include "libguile/root.h"
47 #include "libguile/strings.h"
48 #include "libguile/vectors.h"
49 #include "libguile/weaks.h"
50 #include "libguile/hashtab.h"
51 #include "libguile/tags.h"
53 #include "libguile/private-gc.h"
54 #include "libguile/validate.h"
55 #include "libguile/deprecation.h"
56 #include "libguile/gc.h"
57 #include "libguile/dynwind.h"
59 #include "libguile/bdw-gc.h"
61 #ifdef GUILE_DEBUG_MALLOC
62 #include "libguile/debug-malloc.h"
73 /* Lock this mutex before doing lazy sweeping.
75 scm_i_pthread_mutex_t scm_i_sweep_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
77 /* Set this to != 0 if every cell that is accessed shall be checked:
79 int scm_debug_cell_accesses_p
= 0;
80 int scm_expensive_debug_cell_accesses_p
= 0;
82 /* Set this to 0 if no additional gc's shall be performed, otherwise set it to
83 * the number of cell accesses after which a gc shall be called.
85 int scm_debug_cells_gc_interval
= 0;
88 Global variable, so you can switch it off at runtime by setting
89 scm_i_cell_validation_already_running.
91 int scm_i_cell_validation_already_running
;
96 #if (SCM_DEBUG_CELL_ACCESSES == 1)
101 Assert that the given object is a valid reference to a valid cell. This
102 test involves to determine whether the object is a cell pointer, whether
103 this pointer actually points into a heap segment and whether the cell
104 pointed to is not a free cell. Further, additional garbage collections may
105 get executed after a user defined number of cell accesses. This helps to
106 find places in the C code where references are dropped for extremely short
111 scm_i_expensive_validation_check (SCM cell
)
113 /* If desired, perform additional garbage collections after a user
114 * defined number of cell accesses.
116 if (scm_debug_cells_gc_interval
)
118 static unsigned int counter
= 0;
126 counter
= scm_debug_cells_gc_interval
;
133 scm_assert_cell_valid (SCM cell
)
135 if (!scm_i_cell_validation_already_running
&& scm_debug_cell_accesses_p
)
137 scm_i_cell_validation_already_running
= 1; /* set to avoid recursion */
140 During GC, no user-code should be run, and the guile core
141 should use non-protected accessors.
143 if (scm_gc_running_p
)
147 Only scm_in_heap_p and rescanning the heap is wildly
150 if (scm_expensive_debug_cell_accesses_p
)
151 scm_i_expensive_validation_check (cell
);
153 scm_i_cell_validation_already_running
= 0; /* re-enable */
159 SCM_DEFINE (scm_set_debug_cell_accesses_x
, "set-debug-cell-accesses!", 1, 0, 0,
161 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
162 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
163 "but no additional calls to garbage collection are issued.\n"
164 "If @var{flag} is a number, strict cell access checking is enabled,\n"
165 "with an additional garbage collection after the given\n"
166 "number of cell accesses.\n"
167 "This procedure only exists when the compile-time flag\n"
168 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
169 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
171 if (scm_is_false (flag
))
173 scm_debug_cell_accesses_p
= 0;
175 else if (scm_is_eq (flag
, SCM_BOOL_T
))
177 scm_debug_cells_gc_interval
= 0;
178 scm_debug_cell_accesses_p
= 1;
179 scm_expensive_debug_cell_accesses_p
= 0;
183 scm_debug_cells_gc_interval
= scm_to_signed_integer (flag
, 0, INT_MAX
);
184 scm_debug_cell_accesses_p
= 1;
185 scm_expensive_debug_cell_accesses_p
= 1;
187 return SCM_UNSPECIFIED
;
192 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
196 scm_t_c_hook scm_before_gc_c_hook
;
197 scm_t_c_hook scm_before_mark_c_hook
;
198 scm_t_c_hook scm_before_sweep_c_hook
;
199 scm_t_c_hook scm_after_sweep_c_hook
;
200 scm_t_c_hook scm_after_gc_c_hook
;
203 /* GC Statistics Keeping
205 unsigned long scm_gc_ports_collected
= 0;
207 static unsigned long protected_obj_count
= 0;
210 SCM_SYMBOL (sym_cells_allocated
, "cells-allocated");
211 SCM_SYMBOL (sym_heap_size
, "heap-size");
212 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
213 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
214 SCM_SYMBOL (sym_mallocated
, "bytes-malloced");
215 SCM_SYMBOL (sym_mtrigger
, "gc-malloc-threshold");
216 SCM_SYMBOL (sym_heap_segments
, "cell-heap-segments");
217 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
218 SCM_SYMBOL (sym_gc_mark_time_taken
, "gc-mark-time-taken");
219 SCM_SYMBOL (sym_times
, "gc-times");
220 SCM_SYMBOL (sym_cells_marked
, "cells-marked");
221 SCM_SYMBOL (sym_cells_marked_conservatively
, "cells-marked-conservatively");
222 SCM_SYMBOL (sym_cells_swept
, "cells-swept");
223 SCM_SYMBOL (sym_malloc_yield
, "malloc-yield");
224 SCM_SYMBOL (sym_cell_yield
, "cell-yield");
225 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
226 SCM_SYMBOL (sym_total_cells_allocated
, "total-cells-allocated");
229 /* Number of calls to SCM_NEWCELL since startup. */
230 unsigned scm_newcell_count
;
231 unsigned scm_newcell2_count
;
234 /* {Scheme Interface to GC}
237 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
239 if (scm_is_integer (key
))
241 int c_tag
= scm_to_int (key
);
243 char const * name
= scm_i_tag_name (c_tag
);
246 key
= scm_from_locale_string (name
);
251 sprintf (s
, "tag %d", c_tag
);
252 key
= scm_from_locale_string (s
);
256 return scm_cons (scm_cons (key
, val
), acc
);
259 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
261 "Return an alist of statistics of the current live objects. ")
262 #define FUNC_NAME s_scm_gc_live_object_stats
264 SCM tab
= scm_make_hash_table (scm_from_int (57));
268 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
274 extern int scm_gc_malloc_yield_percentage
;
275 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
277 "Return an association list of statistics about Guile's current\n"
279 #define FUNC_NAME s_scm_gc_stats
282 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
285 heap_size
= GC_get_heap_size ();
286 free_bytes
= GC_get_free_bytes ();
287 bytes_since_gc
= GC_get_bytes_since_gc ();
288 total_bytes
= GC_get_total_bytes ();
291 /* njrev: can any of these scm_cons's or scm_list_n signal a memory
292 error? If so we need a frame here. */
294 scm_list_n (scm_cons (sym_gc_time_taken
, SCM_INUM0
),
296 scm_cons (sym_cells_allocated
,
297 scm_from_ulong (local_scm_cells_allocated
)),
298 scm_cons (sym_mallocated
,
299 scm_from_ulong (local_scm_mallocated
)),
300 scm_cons (sym_mtrigger
,
301 scm_from_ulong (local_scm_mtrigger
)),
302 scm_cons (sym_gc_mark_time_taken
,
303 scm_from_ulong (local_scm_gc_mark_time_taken
)),
304 scm_cons (sym_cells_marked
,
305 scm_from_double (local_scm_gc_cells_marked
)),
306 scm_cons (sym_cells_swept
,
307 scm_from_double (local_scm_gc_cells_swept
)),
308 scm_cons (sym_malloc_yield
,
309 scm_from_long (local_scm_gc_malloc_yield_percentage
)),
310 scm_cons (sym_cell_yield
,
311 scm_from_long (local_scm_gc_cell_yield_percentage
)),
312 scm_cons (sym_heap_segments
, heap_segs
),
314 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
315 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
316 scm_cons (sym_heap_total_allocated
,
317 scm_from_size_t (total_bytes
)),
318 scm_cons (sym_protected_objects
,
319 scm_from_ulong (protected_obj_count
)),
320 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
328 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
330 "Dump information about the garbage collector's internal data "
331 "structures and memory usage to the standard output.")
332 #define FUNC_NAME s_scm_gc_dump
336 return SCM_UNSPECIFIED
;
341 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
343 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
344 "returned by this function for @var{obj}")
345 #define FUNC_NAME s_scm_object_address
347 return scm_from_ulong (SCM_UNPACK (obj
));
352 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
354 "Disables the garbage collector. Nested calls are permitted. "
355 "GC is re-enabled once @code{gc-enable} has been called the "
356 "same number of times @code{gc-disable} was called.")
357 #define FUNC_NAME s_scm_gc_disable
360 return SCM_UNSPECIFIED
;
364 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
366 "Enables the garbage collector.")
367 #define FUNC_NAME s_scm_gc_enable
370 return SCM_UNSPECIFIED
;
375 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
377 "Scans all of SCM objects and reclaims for further use those that are\n"
378 "no longer accessible.")
379 #define FUNC_NAME s_scm_gc
381 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex
);
383 /* njrev: It looks as though other places, e.g. scm_realloc,
384 can call scm_i_gc without acquiring the sweep mutex. Does this
385 matter? Also scm_i_gc (or its descendants) touch the
386 scm_sys_protects, which are protected in some cases
387 (e.g. scm_permobjs above in scm_gc_stats) by a critical section,
388 not by the sweep mutex. Shouldn't all the GC-relevant objects be
389 protected in the same way? */
390 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex
);
391 scm_c_hook_run (&scm_after_gc_c_hook
, 0);
392 return SCM_UNSPECIFIED
;
397 scm_i_gc (const char *what
)
404 /* {GC Protection Helper Functions}
409 * If within a function you need to protect one or more scheme objects from
410 * garbage collection, pass them as parameters to one of the
411 * scm_remember_upto_here* functions below. These functions don't do
412 * anything, but since the compiler does not know that they are actually
413 * no-ops, it will generate code that calls these functions with the given
414 * parameters. Therefore, you can be sure that the compiler will keep those
415 * scheme values alive (on the stack or in a register) up to the point where
416 * scm_remember_upto_here* is called. In other words, place the call to
417 * scm_remember_upto_here* _behind_ the last code in your function, that
418 * depends on the scheme object to exist.
420 * Example: We want to make sure that the string object str does not get
421 * garbage collected during the execution of 'some_function' in the code
422 * below, because otherwise the characters belonging to str would be freed and
423 * 'some_function' might access freed memory. To make sure that the compiler
424 * keeps str alive on the stack or in a register such that it is visible to
425 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
426 * call to 'some_function'. Note that this would not be necessary if str was
427 * used anyway after the call to 'some_function'.
428 * char *chars = scm_i_string_chars (str);
429 * some_function (chars);
430 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
433 /* Remove any macro versions of these while defining the functions.
434 Functions are always included in the library, for upward binary
435 compatibility and in case combinations of GCC and non-GCC are used. */
436 #undef scm_remember_upto_here_1
437 #undef scm_remember_upto_here_2
440 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
442 /* Empty. Protects a single object from garbage collection. */
446 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
448 /* Empty. Protects two objects from garbage collection. */
452 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
454 /* Empty. Protects any number of objects from garbage collection. */
458 These crazy functions prevent garbage collection
459 of arguments after the first argument by
460 ensuring they remain live throughout the
461 function because they are used in the last
462 line of the code block.
463 It'd be better to have a nice compiler hint to
464 aid the conservative stack-scanning GC. --03/09/00 gjb */
466 scm_return_first (SCM elt
, ...)
472 scm_return_first_int (int i
, ...)
479 scm_permanent_object (SCM obj
)
481 return (scm_gc_protect_object (obj
));
485 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
486 other references are dropped, until the object is unprotected by calling
487 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
488 i. e. it is possible to protect the same object several times, but it is
489 necessary to unprotect the object the same number of times to actually get
490 the object unprotected. It is an error to unprotect an object more often
491 than it has been protected before. The function scm_protect_object returns
495 /* Implementation note: For every object X, there is a counter which
496 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
502 scm_gc_protect_object (SCM obj
)
506 /* This critical section barrier will be replaced by a mutex. */
507 /* njrev: Indeed; if my comment above is correct, there is the same
508 critsec/mutex inconsistency here. */
509 SCM_CRITICAL_SECTION_START
;
511 handle
= scm_hashq_create_handle_x (protects
, obj
, scm_from_int (0));
512 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
514 protected_obj_count
++;
516 SCM_CRITICAL_SECTION_END
;
522 /* Remove any protection for OBJ established by a prior call to
523 scm_protect_object. This function returns OBJ.
525 See scm_protect_object for more information. */
527 scm_gc_unprotect_object (SCM obj
)
531 /* This critical section barrier will be replaced by a mutex. */
532 /* njrev: and again. */
533 SCM_CRITICAL_SECTION_START
;
535 if (scm_gc_running_p
)
537 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
541 handle
= scm_hashq_get_handle (protects
, obj
);
543 if (scm_is_false (handle
))
545 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
550 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
551 if (scm_is_eq (count
, scm_from_int (0)))
552 scm_hashq_remove_x (protects
, obj
);
554 SCM_SETCDR (handle
, count
);
556 protected_obj_count
--;
558 SCM_CRITICAL_SECTION_END
;
564 scm_gc_register_root (SCM
*p
)
570 scm_gc_unregister_root (SCM
*p
)
576 scm_gc_register_roots (SCM
*b
, unsigned long n
)
579 for (; p
< b
+ n
; ++p
)
580 scm_gc_register_root (p
);
584 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
587 for (; p
< b
+ n
; ++p
)
588 scm_gc_unregister_root (p
);
591 int scm_i_terminating
;
597 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
600 /* Get an integer from an environment variable. */
602 scm_getenv_int (const char *var
, int def
)
605 char *val
= getenv (var
);
609 res
= strtol (val
, &end
, 10);
616 scm_storage_prehistory ()
618 GC_all_interior_pointers
= 0;
619 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
623 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
624 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
625 /* When using GC 6.8, this call is required to initialize thread-local
626 freelists (shouldn't be necessary with GC 7.0). */
630 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
632 /* We only need to register a displacement for those types for which the
633 higher bits of the type tag are used to store a pointer (that is, a
634 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
635 handled in `scm_alloc_struct ()'. */
636 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
637 /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */
640 if (!GC_is_visible (&protects
))
643 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
644 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
645 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
646 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
647 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
650 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
653 scm_init_gc_protect_object ()
655 protects
= scm_c_make_hash_table (31);
658 /* We can't have a cleanup handler since we have no thread to run it
665 on_exit (cleanup
, 0);
674 SCM scm_after_gc_hook
;
678 /* The function gc_async_thunk causes the execution of the after-gc-hook. It
679 * is run after the gc, as soon as the asynchronous events are handled by the
683 gc_async_thunk (void)
685 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
686 return SCM_UNSPECIFIED
;
690 /* The function mark_gc_async is run by the scm_after_gc_c_hook at the end of
691 * the garbage collection. The only purpose of this function is to mark the
692 * gc_async (which will eventually lead to the execution of the
696 mark_gc_async (void * hook_data SCM_UNUSED
,
697 void *fn_data SCM_UNUSED
,
698 void *data SCM_UNUSED
)
700 /* If cell access debugging is enabled, the user may choose to perform
701 * additional garbage collections after an arbitrary number of cell
702 * accesses. We don't want the scheme level after-gc-hook to be performed
703 * for each of these garbage collections for the following reason: The
704 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
705 * after-gc-hook was performed with every gc, and if the gc was performed
706 * after a very small number of cell accesses, then the number of cell
707 * accesses during the execution of the after-gc-hook will suffice to cause
708 * the execution of the next gc. Then, guile would keep executing the
709 * after-gc-hook over and over again, and would never come to do other
712 * To overcome this problem, if cell access debugging with additional
713 * garbage collections is enabled, the after-gc-hook is never run by the
714 * garbage collecter. When running guile with cell access debugging and the
715 * execution of the after-gc-hook is desired, then it is necessary to run
716 * the hook explicitly from the user code. This has the effect, that from
717 * the scheme level point of view it seems that garbage collection is
718 * performed with a much lower frequency than it actually is. Obviously,
719 * this will not work for code that depends on a fixed one to one
720 * relationship between the execution counts of the C level garbage
721 * collection hooks and the execution count of the scheme level
725 #if (SCM_DEBUG_CELL_ACCESSES == 1)
726 if (scm_debug_cells_gc_interval
== 0)
727 scm_system_async_mark (gc_async
);
729 scm_system_async_mark (gc_async
);
736 scm_i_tag_name (scm_t_bits tag
)
740 int k
= 0xff & (tag
>> 8);
741 return (scm_smobs
[k
].name
);
744 switch (tag
) /* 7 bits */
748 case scm_tcs_cons_imcar
:
749 return "cons (immediate car)";
750 case scm_tcs_cons_nimcar
:
751 return "cons (non-immediate car)";
754 case scm_tc7_hashtable
:
758 case scm_tc7_dynamic_state
:
759 return "dynamic state";
761 return "weak vector";
773 case scm_tc16_complex
:
774 return "complex number";
776 case scm_tc16_fraction
:
784 case scm_tc7_stringbuf
:
785 return "string buffer";
790 case scm_tc7_variable
:
800 return "smob"; /* should not occur. */
813 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
815 scm_after_gc_hook
= scm_make_hook (SCM_INUM0
);
816 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
818 gc_async
= scm_c_make_gsubr ("%gc-thunk", 0, 0, 0, gc_async_thunk
);
820 scm_c_hook_add (&scm_after_gc_c_hook
, mark_gc_async
, NULL
, 0);
822 #include "libguile/gc.x"
828 #define FUNC_NAME "scm_gc_sweep"
831 fprintf (stderr
, "%s: doing nothing\n", __FUNCTION__
);