1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003, 2006, 2008, 2009, 2010, 2011 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"
33 extern unsigned long * __libc_ia64_register_backing_store_base
;
36 #include "libguile/_scm.h"
37 #include "libguile/eval.h"
38 #include "libguile/stime.h"
39 #include "libguile/stackchk.h"
40 #include "libguile/struct.h"
41 #include "libguile/smob.h"
42 #include "libguile/arrays.h"
43 #include "libguile/async.h"
44 #include "libguile/ports.h"
45 #include "libguile/root.h"
46 #include "libguile/strings.h"
47 #include "libguile/vectors.h"
48 #include "libguile/weaks.h"
49 #include "libguile/hashtab.h"
50 #include "libguile/tags.h"
52 #include "libguile/private-gc.h"
53 #include "libguile/validate.h"
54 #include "libguile/deprecation.h"
55 #include "libguile/gc.h"
56 #include "libguile/dynwind.h"
58 #include "libguile/bdw-gc.h"
60 /* For GC_set_start_callback. */
61 #include <gc/gc_mark.h>
63 #ifdef GUILE_DEBUG_MALLOC
64 #include "libguile/debug-malloc.h"
75 /* Set this to != 0 if every cell that is accessed shall be checked:
77 int scm_debug_cell_accesses_p
= 0;
78 int scm_expensive_debug_cell_accesses_p
= 0;
80 /* Set this to 0 if no additional gc's shall be performed, otherwise set it to
81 * the number of cell accesses after which a gc shall be called.
83 int scm_debug_cells_gc_interval
= 0;
85 /* Hash table that keeps a reference to objects the user wants to protect from
86 garbage collection. It could arguably be private but applications have come
87 to rely on it (e.g., Lilypond 2.13.9). */
91 #if (SCM_DEBUG_CELL_ACCESSES == 1)
96 Assert that the given object is a valid reference to a valid cell. This
97 test involves to determine whether the object is a cell pointer, whether
98 this pointer actually points into a heap segment and whether the cell
99 pointed to is not a free cell. Further, additional garbage collections may
100 get executed after a user defined number of cell accesses. This helps to
101 find places in the C code where references are dropped for extremely short
106 scm_i_expensive_validation_check (SCM cell
)
108 /* If desired, perform additional garbage collections after a user
109 * defined number of cell accesses.
111 if (scm_debug_cells_gc_interval
)
113 static unsigned int counter
= 0;
121 counter
= scm_debug_cells_gc_interval
;
127 /* Whether cell validation is already running. */
128 static int scm_i_cell_validation_already_running
= 0;
131 scm_assert_cell_valid (SCM cell
)
133 if (!scm_i_cell_validation_already_running
&& scm_debug_cell_accesses_p
)
135 scm_i_cell_validation_already_running
= 1; /* set to avoid recursion */
138 During GC, no user-code should be run, and the guile core
139 should use non-protected accessors.
141 if (scm_gc_running_p
)
145 Only scm_in_heap_p and rescanning the heap is wildly
148 if (scm_expensive_debug_cell_accesses_p
)
149 scm_i_expensive_validation_check (cell
);
151 scm_i_cell_validation_already_running
= 0; /* re-enable */
157 SCM_DEFINE (scm_set_debug_cell_accesses_x
, "set-debug-cell-accesses!", 1, 0, 0,
159 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
160 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
161 "but no additional calls to garbage collection are issued.\n"
162 "If @var{flag} is a number, strict cell access checking is enabled,\n"
163 "with an additional garbage collection after the given\n"
164 "number of cell accesses.\n"
165 "This procedure only exists when the compile-time flag\n"
166 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
167 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
169 if (scm_is_false (flag
))
171 scm_debug_cell_accesses_p
= 0;
173 else if (scm_is_eq (flag
, SCM_BOOL_T
))
175 scm_debug_cells_gc_interval
= 0;
176 scm_debug_cell_accesses_p
= 1;
177 scm_expensive_debug_cell_accesses_p
= 0;
181 scm_debug_cells_gc_interval
= scm_to_signed_integer (flag
, 0, INT_MAX
);
182 scm_debug_cell_accesses_p
= 1;
183 scm_expensive_debug_cell_accesses_p
= 1;
185 return SCM_UNSPECIFIED
;
190 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
194 scm_t_c_hook scm_before_gc_c_hook
;
195 scm_t_c_hook scm_before_mark_c_hook
;
196 scm_t_c_hook scm_before_sweep_c_hook
;
197 scm_t_c_hook scm_after_sweep_c_hook
;
198 scm_t_c_hook scm_after_gc_c_hook
;
202 run_before_gc_c_hook (void)
204 scm_c_hook_run (&scm_before_gc_c_hook
, NULL
);
208 /* GC Statistics Keeping
210 unsigned long scm_gc_ports_collected
= 0;
211 static long gc_time_taken
= 0;
212 static long gc_start_time
= 0;
215 static unsigned long protected_obj_count
= 0;
218 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
219 SCM_SYMBOL (sym_heap_size
, "heap-size");
220 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
221 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
222 SCM_SYMBOL (sym_heap_allocated_since_gc
, "heap-allocated-since-gc");
223 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
224 SCM_SYMBOL (sym_times
, "gc-times");
227 /* {Scheme Interface to GC}
230 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
232 if (scm_is_integer (key
))
234 int c_tag
= scm_to_int (key
);
236 char const * name
= scm_i_tag_name (c_tag
);
239 key
= scm_from_locale_string (name
);
244 sprintf (s
, "tag %d", c_tag
);
245 key
= scm_from_locale_string (s
);
249 return scm_cons (scm_cons (key
, val
), acc
);
252 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
254 "Return an alist of statistics of the current live objects. ")
255 #define FUNC_NAME s_scm_gc_live_object_stats
257 SCM tab
= scm_make_hash_table (scm_from_int (57));
261 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
267 extern int scm_gc_malloc_yield_percentage
;
268 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
270 "Return an association list of statistics about Guile's current\n"
272 #define FUNC_NAME s_scm_gc_stats
275 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
278 heap_size
= GC_get_heap_size ();
279 free_bytes
= GC_get_free_bytes ();
280 bytes_since_gc
= GC_get_bytes_since_gc ();
281 total_bytes
= GC_get_total_bytes ();
285 scm_list_n (scm_cons (sym_gc_time_taken
, scm_from_long (gc_time_taken
)),
286 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
287 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
288 scm_cons (sym_heap_total_allocated
,
289 scm_from_size_t (total_bytes
)),
290 scm_cons (sym_heap_allocated_since_gc
,
291 scm_from_size_t (bytes_since_gc
)),
292 scm_cons (sym_protected_objects
,
293 scm_from_ulong (protected_obj_count
)),
294 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
302 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
304 "Dump information about the garbage collector's internal data "
305 "structures and memory usage to the standard output.")
306 #define FUNC_NAME s_scm_gc_dump
310 return SCM_UNSPECIFIED
;
315 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
317 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
318 "returned by this function for @var{obj}")
319 #define FUNC_NAME s_scm_object_address
321 return scm_from_ulong (SCM_UNPACK (obj
));
326 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
328 "Disables the garbage collector. Nested calls are permitted. "
329 "GC is re-enabled once @code{gc-enable} has been called the "
330 "same number of times @code{gc-disable} was called.")
331 #define FUNC_NAME s_scm_gc_disable
334 return SCM_UNSPECIFIED
;
338 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
340 "Enables the garbage collector.")
341 #define FUNC_NAME s_scm_gc_enable
344 return SCM_UNSPECIFIED
;
349 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
351 "Scans all of SCM objects and reclaims for further use those that are\n"
352 "no longer accessible.")
353 #define FUNC_NAME s_scm_gc
356 return SCM_UNSPECIFIED
;
361 scm_i_gc (const char *what
)
363 #ifndef HAVE_GC_SET_START_CALLBACK
364 run_before_gc_c_hook ();
371 /* {GC Protection Helper Functions}
376 * If within a function you need to protect one or more scheme objects from
377 * garbage collection, pass them as parameters to one of the
378 * scm_remember_upto_here* functions below. These functions don't do
379 * anything, but since the compiler does not know that they are actually
380 * no-ops, it will generate code that calls these functions with the given
381 * parameters. Therefore, you can be sure that the compiler will keep those
382 * scheme values alive (on the stack or in a register) up to the point where
383 * scm_remember_upto_here* is called. In other words, place the call to
384 * scm_remember_upto_here* _behind_ the last code in your function, that
385 * depends on the scheme object to exist.
387 * Example: We want to make sure that the string object str does not get
388 * garbage collected during the execution of 'some_function' in the code
389 * below, because otherwise the characters belonging to str would be freed and
390 * 'some_function' might access freed memory. To make sure that the compiler
391 * keeps str alive on the stack or in a register such that it is visible to
392 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
393 * call to 'some_function'. Note that this would not be necessary if str was
394 * used anyway after the call to 'some_function'.
395 * char *chars = scm_i_string_chars (str);
396 * some_function (chars);
397 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
400 /* Remove any macro versions of these while defining the functions.
401 Functions are always included in the library, for upward binary
402 compatibility and in case combinations of GCC and non-GCC are used. */
403 #undef scm_remember_upto_here_1
404 #undef scm_remember_upto_here_2
407 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
409 /* Empty. Protects a single object from garbage collection. */
413 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
415 /* Empty. Protects two objects from garbage collection. */
419 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
421 /* Empty. Protects any number of objects from garbage collection. */
425 These crazy functions prevent garbage collection
426 of arguments after the first argument by
427 ensuring they remain live throughout the
428 function because they are used in the last
429 line of the code block.
430 It'd be better to have a nice compiler hint to
431 aid the conservative stack-scanning GC. --03/09/00 gjb */
433 scm_return_first (SCM elt
, ...)
439 scm_return_first_int (int i
, ...)
446 scm_permanent_object (SCM obj
)
448 return (scm_gc_protect_object (obj
));
452 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
453 other references are dropped, until the object is unprotected by calling
454 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
455 i. e. it is possible to protect the same object several times, but it is
456 necessary to unprotect the object the same number of times to actually get
457 the object unprotected. It is an error to unprotect an object more often
458 than it has been protected before. The function scm_protect_object returns
462 /* Implementation note: For every object X, there is a counter which
463 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
469 scm_gc_protect_object (SCM obj
)
473 /* This critical section barrier will be replaced by a mutex. */
474 /* njrev: Indeed; if my comment above is correct, there is the same
475 critsec/mutex inconsistency here. */
476 SCM_CRITICAL_SECTION_START
;
478 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
479 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
481 protected_obj_count
++;
483 SCM_CRITICAL_SECTION_END
;
489 /* Remove any protection for OBJ established by a prior call to
490 scm_protect_object. This function returns OBJ.
492 See scm_protect_object for more information. */
494 scm_gc_unprotect_object (SCM obj
)
498 /* This critical section barrier will be replaced by a mutex. */
499 /* njrev: and again. */
500 SCM_CRITICAL_SECTION_START
;
502 if (scm_gc_running_p
)
504 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
508 handle
= scm_hashq_get_handle (scm_protects
, obj
);
510 if (scm_is_false (handle
))
512 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
517 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
518 if (scm_is_eq (count
, scm_from_int (0)))
519 scm_hashq_remove_x (scm_protects
, obj
);
521 SCM_SETCDR (handle
, count
);
523 protected_obj_count
--;
525 SCM_CRITICAL_SECTION_END
;
531 scm_gc_register_root (SCM
*p
)
537 scm_gc_unregister_root (SCM
*p
)
543 scm_gc_register_roots (SCM
*b
, unsigned long n
)
546 for (; p
< b
+ n
; ++p
)
547 scm_gc_register_root (p
);
551 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
554 for (; p
< b
+ n
; ++p
)
555 scm_gc_unregister_root (p
);
562 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
565 /* Get an integer from an environment variable. */
567 scm_getenv_int (const char *var
, int def
)
570 char *val
= getenv (var
);
574 res
= strtol (val
, &end
, 10);
581 scm_storage_prehistory ()
583 GC_all_interior_pointers
= 0;
584 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
588 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
589 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
590 /* When using GC 6.8, this call is required to initialize thread-local
591 freelists (shouldn't be necessary with GC 7.0). */
595 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
597 /* We only need to register a displacement for those types for which the
598 higher bits of the type tag are used to store a pointer (that is, a
599 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
600 handled in `scm_alloc_struct ()'. */
601 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
602 /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */
605 if (!GC_is_visible (&scm_protects
))
608 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
609 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
610 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
611 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
612 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
615 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
618 scm_init_gc_protect_object ()
620 scm_protects
= scm_c_make_hash_table (31);
623 /* We can't have a cleanup handler since we have no thread to run it
630 on_exit (cleanup
, 0);
639 SCM scm_after_gc_hook
;
641 static SCM after_gc_async_cell
;
643 /* The function after_gc_async_thunk causes the execution of the
644 * after-gc-hook. It is run after the gc, as soon as the asynchronous
645 * events are handled by the evaluator.
648 after_gc_async_thunk (void)
650 /* Fun, no? Hook-run *and* run-hook? */
651 scm_c_hook_run (&scm_after_gc_c_hook
, NULL
);
652 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
653 return SCM_UNSPECIFIED
;
657 /* The function queue_after_gc_hook is run by the scm_before_gc_c_hook
658 * at the end of the garbage collection. The only purpose of this
659 * function is to mark the after_gc_async (which will eventually lead to
660 * the execution of the after_gc_async_thunk).
663 queue_after_gc_hook (void * hook_data SCM_UNUSED
,
664 void *fn_data SCM_UNUSED
,
665 void *data SCM_UNUSED
)
667 /* If cell access debugging is enabled, the user may choose to perform
668 * additional garbage collections after an arbitrary number of cell
669 * accesses. We don't want the scheme level after-gc-hook to be performed
670 * for each of these garbage collections for the following reason: The
671 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
672 * after-gc-hook was performed with every gc, and if the gc was performed
673 * after a very small number of cell accesses, then the number of cell
674 * accesses during the execution of the after-gc-hook will suffice to cause
675 * the execution of the next gc. Then, guile would keep executing the
676 * after-gc-hook over and over again, and would never come to do other
679 * To overcome this problem, if cell access debugging with additional
680 * garbage collections is enabled, the after-gc-hook is never run by the
681 * garbage collecter. When running guile with cell access debugging and the
682 * execution of the after-gc-hook is desired, then it is necessary to run
683 * the hook explicitly from the user code. This has the effect, that from
684 * the scheme level point of view it seems that garbage collection is
685 * performed with a much lower frequency than it actually is. Obviously,
686 * this will not work for code that depends on a fixed one to one
687 * relationship between the execution counts of the C level garbage
688 * collection hooks and the execution count of the scheme level
692 #if (SCM_DEBUG_CELL_ACCESSES == 1)
693 if (scm_debug_cells_gc_interval
== 0)
696 scm_i_thread
*t
= SCM_I_CURRENT_THREAD
;
698 if (scm_is_false (SCM_CDR (after_gc_async_cell
)))
700 SCM_SETCDR (after_gc_async_cell
, t
->active_asyncs
);
701 t
->active_asyncs
= after_gc_async_cell
;
702 t
->pending_asyncs
= 1;
712 start_gc_timer (void * hook_data SCM_UNUSED
,
713 void *fn_data SCM_UNUSED
,
714 void *data SCM_UNUSED
)
717 gc_start_time
= scm_c_get_internal_run_time ();
723 accumulate_gc_timer (void * hook_data SCM_UNUSED
,
724 void *fn_data SCM_UNUSED
,
725 void *data SCM_UNUSED
)
728 { long now
= scm_c_get_internal_run_time ();
729 gc_time_taken
+= now
- gc_start_time
;
740 scm_i_tag_name (scm_t_bits tag
)
742 switch (tag
& 0x7f) /* 7 bits */
746 case scm_tcs_cons_imcar
:
747 return "cons (immediate car)";
748 case scm_tcs_cons_nimcar
:
749 return "cons (non-immediate car)";
750 case scm_tc7_pointer
:
752 case scm_tc7_hashtable
:
756 case scm_tc7_dynamic_state
:
757 return "dynamic state";
760 case scm_tc7_objcode
:
764 case scm_tc7_vm_cont
:
765 return "vm continuation";
767 return "weak vector";
779 case scm_tc16_complex
:
780 return "complex number";
782 case scm_tc16_fraction
:
790 case scm_tc7_stringbuf
:
791 return "string buffer";
796 case scm_tc7_variable
:
804 int k
= 0xff & (tag
>> 8);
805 return (scm_smobs
[k
].name
);
819 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
821 scm_after_gc_hook
= scm_make_hook (SCM_INUM0
);
822 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
824 /* When the async is to run, the cdr of the gc_async pair gets set to
825 the asyncs queue of the current thread. */
826 after_gc_async_cell
= scm_cons (scm_c_make_gsubr ("%after-gc-thunk", 0, 0, 0,
827 after_gc_async_thunk
),
830 scm_c_hook_add (&scm_before_gc_c_hook
, queue_after_gc_hook
, NULL
, 0);
831 scm_c_hook_add (&scm_before_gc_c_hook
, start_gc_timer
, NULL
, 0);
832 scm_c_hook_add (&scm_after_gc_c_hook
, accumulate_gc_timer
, NULL
, 0);
834 #ifdef HAVE_GC_SET_START_CALLBACK
835 GC_set_start_callback (run_before_gc_c_hook
);
838 #include "libguile/gc.x"
844 #define FUNC_NAME "scm_gc_sweep"
847 fprintf (stderr
, "%s: doing nothing\n", FUNC_NAME
);