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 #if SCM_ENABLE_DEPRECATED == 1
86 /* Hash table that keeps a reference to objects the user wants to protect from
87 garbage collection. It could arguably be private but applications have come
88 to rely on it (e.g., Lilypond 2.13.9). */
91 static SCM scm_protects
;
94 #if (SCM_DEBUG_CELL_ACCESSES == 1)
99 Assert that the given object is a valid reference to a valid cell. This
100 test involves to determine whether the object is a cell pointer, whether
101 this pointer actually points into a heap segment and whether the cell
102 pointed to is not a free cell. Further, additional garbage collections may
103 get executed after a user defined number of cell accesses. This helps to
104 find places in the C code where references are dropped for extremely short
109 scm_i_expensive_validation_check (SCM cell
)
111 /* If desired, perform additional garbage collections after a user
112 * defined number of cell accesses.
114 if (scm_debug_cells_gc_interval
)
116 static unsigned int counter
= 0;
124 counter
= scm_debug_cells_gc_interval
;
130 /* Whether cell validation is already running. */
131 static int scm_i_cell_validation_already_running
= 0;
134 scm_assert_cell_valid (SCM cell
)
136 if (!scm_i_cell_validation_already_running
&& scm_debug_cell_accesses_p
)
138 scm_i_cell_validation_already_running
= 1; /* set to avoid recursion */
141 During GC, no user-code should be run, and the guile core
142 should use non-protected accessors.
144 if (scm_gc_running_p
)
148 Only scm_in_heap_p and rescanning the heap is wildly
151 if (scm_expensive_debug_cell_accesses_p
)
152 scm_i_expensive_validation_check (cell
);
154 scm_i_cell_validation_already_running
= 0; /* re-enable */
160 SCM_DEFINE (scm_set_debug_cell_accesses_x
, "set-debug-cell-accesses!", 1, 0, 0,
162 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
163 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
164 "but no additional calls to garbage collection are issued.\n"
165 "If @var{flag} is a number, strict cell access checking is enabled,\n"
166 "with an additional garbage collection after the given\n"
167 "number of cell accesses.\n"
168 "This procedure only exists when the compile-time flag\n"
169 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
170 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
172 if (scm_is_false (flag
))
174 scm_debug_cell_accesses_p
= 0;
176 else if (scm_is_eq (flag
, SCM_BOOL_T
))
178 scm_debug_cells_gc_interval
= 0;
179 scm_debug_cell_accesses_p
= 1;
180 scm_expensive_debug_cell_accesses_p
= 0;
184 scm_debug_cells_gc_interval
= scm_to_signed_integer (flag
, 0, INT_MAX
);
185 scm_debug_cell_accesses_p
= 1;
186 scm_expensive_debug_cell_accesses_p
= 1;
188 return SCM_UNSPECIFIED
;
193 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
197 scm_t_c_hook scm_before_gc_c_hook
;
198 scm_t_c_hook scm_before_mark_c_hook
;
199 scm_t_c_hook scm_before_sweep_c_hook
;
200 scm_t_c_hook scm_after_sweep_c_hook
;
201 scm_t_c_hook scm_after_gc_c_hook
;
205 run_before_gc_c_hook (void)
207 scm_c_hook_run (&scm_before_gc_c_hook
, NULL
);
211 /* GC Statistics Keeping
213 unsigned long scm_gc_ports_collected
= 0;
214 static long gc_time_taken
= 0;
215 static long gc_start_time
= 0;
218 static unsigned long protected_obj_count
= 0;
221 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
222 SCM_SYMBOL (sym_heap_size
, "heap-size");
223 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
224 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
225 SCM_SYMBOL (sym_heap_allocated_since_gc
, "heap-allocated-since-gc");
226 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
227 SCM_SYMBOL (sym_times
, "gc-times");
230 /* {Scheme Interface to GC}
233 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
235 if (scm_is_integer (key
))
237 int c_tag
= scm_to_int (key
);
239 char const * name
= scm_i_tag_name (c_tag
);
242 key
= scm_from_locale_string (name
);
247 sprintf (s
, "tag %d", c_tag
);
248 key
= scm_from_locale_string (s
);
252 return scm_cons (scm_cons (key
, val
), acc
);
255 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
257 "Return an alist of statistics of the current live objects. ")
258 #define FUNC_NAME s_scm_gc_live_object_stats
260 SCM tab
= scm_make_hash_table (scm_from_int (57));
264 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
270 extern int scm_gc_malloc_yield_percentage
;
271 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
273 "Return an association list of statistics about Guile's current\n"
275 #define FUNC_NAME s_scm_gc_stats
278 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
281 heap_size
= GC_get_heap_size ();
282 free_bytes
= GC_get_free_bytes ();
283 bytes_since_gc
= GC_get_bytes_since_gc ();
284 total_bytes
= GC_get_total_bytes ();
288 scm_list_n (scm_cons (sym_gc_time_taken
, scm_from_long (gc_time_taken
)),
289 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
290 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
291 scm_cons (sym_heap_total_allocated
,
292 scm_from_size_t (total_bytes
)),
293 scm_cons (sym_heap_allocated_since_gc
,
294 scm_from_size_t (bytes_since_gc
)),
295 scm_cons (sym_protected_objects
,
296 scm_from_ulong (protected_obj_count
)),
297 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
305 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
307 "Dump information about the garbage collector's internal data "
308 "structures and memory usage to the standard output.")
309 #define FUNC_NAME s_scm_gc_dump
313 return SCM_UNSPECIFIED
;
318 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
320 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
321 "returned by this function for @var{obj}")
322 #define FUNC_NAME s_scm_object_address
324 return scm_from_ulong (SCM_UNPACK (obj
));
329 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
331 "Disables the garbage collector. Nested calls are permitted. "
332 "GC is re-enabled once @code{gc-enable} has been called the "
333 "same number of times @code{gc-disable} was called.")
334 #define FUNC_NAME s_scm_gc_disable
337 return SCM_UNSPECIFIED
;
341 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
343 "Enables the garbage collector.")
344 #define FUNC_NAME s_scm_gc_enable
347 return SCM_UNSPECIFIED
;
352 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
354 "Scans all of SCM objects and reclaims for further use those that are\n"
355 "no longer accessible.")
356 #define FUNC_NAME s_scm_gc
359 return SCM_UNSPECIFIED
;
364 scm_i_gc (const char *what
)
366 #ifndef HAVE_GC_SET_START_CALLBACK
367 run_before_gc_c_hook ();
374 /* {GC Protection Helper Functions}
379 * If within a function you need to protect one or more scheme objects from
380 * garbage collection, pass them as parameters to one of the
381 * scm_remember_upto_here* functions below. These functions don't do
382 * anything, but since the compiler does not know that they are actually
383 * no-ops, it will generate code that calls these functions with the given
384 * parameters. Therefore, you can be sure that the compiler will keep those
385 * scheme values alive (on the stack or in a register) up to the point where
386 * scm_remember_upto_here* is called. In other words, place the call to
387 * scm_remember_upto_here* _behind_ the last code in your function, that
388 * depends on the scheme object to exist.
390 * Example: We want to make sure that the string object str does not get
391 * garbage collected during the execution of 'some_function' in the code
392 * below, because otherwise the characters belonging to str would be freed and
393 * 'some_function' might access freed memory. To make sure that the compiler
394 * keeps str alive on the stack or in a register such that it is visible to
395 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
396 * call to 'some_function'. Note that this would not be necessary if str was
397 * used anyway after the call to 'some_function'.
398 * char *chars = scm_i_string_chars (str);
399 * some_function (chars);
400 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
403 /* Remove any macro versions of these while defining the functions.
404 Functions are always included in the library, for upward binary
405 compatibility and in case combinations of GCC and non-GCC are used. */
406 #undef scm_remember_upto_here_1
407 #undef scm_remember_upto_here_2
410 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
412 /* Empty. Protects a single object from garbage collection. */
416 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
418 /* Empty. Protects two objects from garbage collection. */
422 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
424 /* Empty. Protects any number of objects from garbage collection. */
428 These crazy functions prevent garbage collection
429 of arguments after the first argument by
430 ensuring they remain live throughout the
431 function because they are used in the last
432 line of the code block.
433 It'd be better to have a nice compiler hint to
434 aid the conservative stack-scanning GC. --03/09/00 gjb */
436 scm_return_first (SCM elt
, ...)
442 scm_return_first_int (int i
, ...)
449 scm_permanent_object (SCM obj
)
451 return (scm_gc_protect_object (obj
));
455 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
456 other references are dropped, until the object is unprotected by calling
457 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
458 i. e. it is possible to protect the same object several times, but it is
459 necessary to unprotect the object the same number of times to actually get
460 the object unprotected. It is an error to unprotect an object more often
461 than it has been protected before. The function scm_protect_object returns
465 /* Implementation note: For every object X, there is a counter which
466 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
472 scm_gc_protect_object (SCM obj
)
476 /* This critical section barrier will be replaced by a mutex. */
477 /* njrev: Indeed; if my comment above is correct, there is the same
478 critsec/mutex inconsistency here. */
479 SCM_CRITICAL_SECTION_START
;
481 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
482 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
484 protected_obj_count
++;
486 SCM_CRITICAL_SECTION_END
;
492 /* Remove any protection for OBJ established by a prior call to
493 scm_protect_object. This function returns OBJ.
495 See scm_protect_object for more information. */
497 scm_gc_unprotect_object (SCM obj
)
501 /* This critical section barrier will be replaced by a mutex. */
502 /* njrev: and again. */
503 SCM_CRITICAL_SECTION_START
;
505 if (scm_gc_running_p
)
507 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
511 handle
= scm_hashq_get_handle (scm_protects
, obj
);
513 if (scm_is_false (handle
))
515 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
520 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
521 if (scm_is_eq (count
, scm_from_int (0)))
522 scm_hashq_remove_x (scm_protects
, obj
);
524 SCM_SETCDR (handle
, count
);
526 protected_obj_count
--;
528 SCM_CRITICAL_SECTION_END
;
534 scm_gc_register_root (SCM
*p
)
540 scm_gc_unregister_root (SCM
*p
)
546 scm_gc_register_roots (SCM
*b
, unsigned long n
)
549 for (; p
< b
+ n
; ++p
)
550 scm_gc_register_root (p
);
554 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
557 for (; p
< b
+ n
; ++p
)
558 scm_gc_unregister_root (p
);
565 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
568 /* Get an integer from an environment variable. */
570 scm_getenv_int (const char *var
, int def
)
573 char *val
= getenv (var
);
577 res
= strtol (val
, &end
, 10);
584 scm_storage_prehistory ()
586 GC_all_interior_pointers
= 0;
587 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
591 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
592 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
593 /* When using GC 6.8, this call is required to initialize thread-local
594 freelists (shouldn't be necessary with GC 7.0). */
598 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
600 /* We only need to register a displacement for those types for which the
601 higher bits of the type tag are used to store a pointer (that is, a
602 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
603 handled in `scm_alloc_struct ()'. */
604 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
605 /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */
608 if (!GC_is_visible (&scm_protects
))
611 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
612 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
613 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
614 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
615 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
618 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
621 scm_init_gc_protect_object ()
623 scm_protects
= scm_c_make_hash_table (31);
626 /* We can't have a cleanup handler since we have no thread to run it
633 on_exit (cleanup
, 0);
642 SCM scm_after_gc_hook
;
644 static SCM after_gc_async_cell
;
646 /* The function after_gc_async_thunk causes the execution of the
647 * after-gc-hook. It is run after the gc, as soon as the asynchronous
648 * events are handled by the evaluator.
651 after_gc_async_thunk (void)
653 /* Fun, no? Hook-run *and* run-hook? */
654 scm_c_hook_run (&scm_after_gc_c_hook
, NULL
);
655 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
656 return SCM_UNSPECIFIED
;
660 /* The function queue_after_gc_hook is run by the scm_before_gc_c_hook
661 * at the end of the garbage collection. The only purpose of this
662 * function is to mark the after_gc_async (which will eventually lead to
663 * the execution of the after_gc_async_thunk).
666 queue_after_gc_hook (void * hook_data SCM_UNUSED
,
667 void *fn_data SCM_UNUSED
,
668 void *data SCM_UNUSED
)
670 /* If cell access debugging is enabled, the user may choose to perform
671 * additional garbage collections after an arbitrary number of cell
672 * accesses. We don't want the scheme level after-gc-hook to be performed
673 * for each of these garbage collections for the following reason: The
674 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
675 * after-gc-hook was performed with every gc, and if the gc was performed
676 * after a very small number of cell accesses, then the number of cell
677 * accesses during the execution of the after-gc-hook will suffice to cause
678 * the execution of the next gc. Then, guile would keep executing the
679 * after-gc-hook over and over again, and would never come to do other
682 * To overcome this problem, if cell access debugging with additional
683 * garbage collections is enabled, the after-gc-hook is never run by the
684 * garbage collecter. When running guile with cell access debugging and the
685 * execution of the after-gc-hook is desired, then it is necessary to run
686 * the hook explicitly from the user code. This has the effect, that from
687 * the scheme level point of view it seems that garbage collection is
688 * performed with a much lower frequency than it actually is. Obviously,
689 * this will not work for code that depends on a fixed one to one
690 * relationship between the execution counts of the C level garbage
691 * collection hooks and the execution count of the scheme level
695 #if (SCM_DEBUG_CELL_ACCESSES == 1)
696 if (scm_debug_cells_gc_interval
== 0)
699 scm_i_thread
*t
= SCM_I_CURRENT_THREAD
;
701 if (scm_is_false (SCM_CDR (after_gc_async_cell
)))
703 SCM_SETCDR (after_gc_async_cell
, t
->active_asyncs
);
704 t
->active_asyncs
= after_gc_async_cell
;
705 t
->pending_asyncs
= 1;
715 start_gc_timer (void * hook_data SCM_UNUSED
,
716 void *fn_data SCM_UNUSED
,
717 void *data SCM_UNUSED
)
720 gc_start_time
= scm_c_get_internal_run_time ();
726 accumulate_gc_timer (void * hook_data SCM_UNUSED
,
727 void *fn_data SCM_UNUSED
,
728 void *data SCM_UNUSED
)
731 { long now
= scm_c_get_internal_run_time ();
732 gc_time_taken
+= now
- gc_start_time
;
743 scm_i_tag_name (scm_t_bits tag
)
745 switch (tag
& 0x7f) /* 7 bits */
749 case scm_tcs_cons_imcar
:
750 return "cons (immediate car)";
751 case scm_tcs_cons_nimcar
:
752 return "cons (non-immediate car)";
753 case scm_tc7_pointer
:
755 case scm_tc7_hashtable
:
759 case scm_tc7_dynamic_state
:
760 return "dynamic state";
763 case scm_tc7_objcode
:
767 case scm_tc7_vm_cont
:
768 return "vm continuation";
770 return "weak vector";
782 case scm_tc16_complex
:
783 return "complex number";
785 case scm_tc16_fraction
:
793 case scm_tc7_stringbuf
:
794 return "string buffer";
799 case scm_tc7_variable
:
807 int k
= 0xff & (tag
>> 8);
808 return (scm_smobs
[k
].name
);
822 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
824 scm_after_gc_hook
= scm_make_hook (SCM_INUM0
);
825 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
827 /* When the async is to run, the cdr of the gc_async pair gets set to
828 the asyncs queue of the current thread. */
829 after_gc_async_cell
= scm_cons (scm_c_make_gsubr ("%after-gc-thunk", 0, 0, 0,
830 after_gc_async_thunk
),
833 scm_c_hook_add (&scm_before_gc_c_hook
, queue_after_gc_hook
, NULL
, 0);
834 scm_c_hook_add (&scm_before_gc_c_hook
, start_gc_timer
, NULL
, 0);
835 scm_c_hook_add (&scm_after_gc_c_hook
, accumulate_gc_timer
, NULL
, 0);
837 #ifdef HAVE_GC_SET_START_CALLBACK
838 GC_set_start_callback (run_before_gc_c_hook
);
841 #include "libguile/gc.x"
847 #define FUNC_NAME "scm_gc_sweep"
850 fprintf (stderr
, "%s: doing nothing\n", FUNC_NAME
);