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;
212 static unsigned long protected_obj_count
= 0;
215 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
216 SCM_SYMBOL (sym_heap_size
, "heap-size");
217 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
218 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
219 SCM_SYMBOL (sym_heap_allocated_since_gc
, "heap-allocated-since-gc");
220 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
221 SCM_SYMBOL (sym_times
, "gc-times");
224 /* Number of calls to SCM_NEWCELL since startup. */
225 unsigned scm_newcell_count
;
226 unsigned scm_newcell2_count
;
229 /* {Scheme Interface to GC}
232 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
234 if (scm_is_integer (key
))
236 int c_tag
= scm_to_int (key
);
238 char const * name
= scm_i_tag_name (c_tag
);
241 key
= scm_from_locale_string (name
);
246 sprintf (s
, "tag %d", c_tag
);
247 key
= scm_from_locale_string (s
);
251 return scm_cons (scm_cons (key
, val
), acc
);
254 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
256 "Return an alist of statistics of the current live objects. ")
257 #define FUNC_NAME s_scm_gc_live_object_stats
259 SCM tab
= scm_make_hash_table (scm_from_int (57));
263 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
269 extern int scm_gc_malloc_yield_percentage
;
270 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
272 "Return an association list of statistics about Guile's current\n"
274 #define FUNC_NAME s_scm_gc_stats
277 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
280 heap_size
= GC_get_heap_size ();
281 free_bytes
= GC_get_free_bytes ();
282 bytes_since_gc
= GC_get_bytes_since_gc ();
283 total_bytes
= GC_get_total_bytes ();
287 scm_list_n (scm_cons (sym_gc_time_taken
, SCM_INUM0
),
288 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
289 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
290 scm_cons (sym_heap_total_allocated
,
291 scm_from_size_t (total_bytes
)),
292 scm_cons (sym_heap_allocated_since_gc
,
293 scm_from_size_t (bytes_since_gc
)),
294 scm_cons (sym_protected_objects
,
295 scm_from_ulong (protected_obj_count
)),
296 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
304 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
306 "Dump information about the garbage collector's internal data "
307 "structures and memory usage to the standard output.")
308 #define FUNC_NAME s_scm_gc_dump
312 return SCM_UNSPECIFIED
;
317 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
319 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
320 "returned by this function for @var{obj}")
321 #define FUNC_NAME s_scm_object_address
323 return scm_from_ulong (SCM_UNPACK (obj
));
328 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
330 "Disables the garbage collector. Nested calls are permitted. "
331 "GC is re-enabled once @code{gc-enable} has been called the "
332 "same number of times @code{gc-disable} was called.")
333 #define FUNC_NAME s_scm_gc_disable
336 return SCM_UNSPECIFIED
;
340 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
342 "Enables the garbage collector.")
343 #define FUNC_NAME s_scm_gc_enable
346 return SCM_UNSPECIFIED
;
351 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
353 "Scans all of SCM objects and reclaims for further use those that are\n"
354 "no longer accessible.")
355 #define FUNC_NAME s_scm_gc
358 return SCM_UNSPECIFIED
;
363 scm_i_gc (const char *what
)
365 #ifndef HAVE_GC_SET_START_CALLBACK
366 run_before_gc_c_hook ();
373 /* {GC Protection Helper Functions}
378 * If within a function you need to protect one or more scheme objects from
379 * garbage collection, pass them as parameters to one of the
380 * scm_remember_upto_here* functions below. These functions don't do
381 * anything, but since the compiler does not know that they are actually
382 * no-ops, it will generate code that calls these functions with the given
383 * parameters. Therefore, you can be sure that the compiler will keep those
384 * scheme values alive (on the stack or in a register) up to the point where
385 * scm_remember_upto_here* is called. In other words, place the call to
386 * scm_remember_upto_here* _behind_ the last code in your function, that
387 * depends on the scheme object to exist.
389 * Example: We want to make sure that the string object str does not get
390 * garbage collected during the execution of 'some_function' in the code
391 * below, because otherwise the characters belonging to str would be freed and
392 * 'some_function' might access freed memory. To make sure that the compiler
393 * keeps str alive on the stack or in a register such that it is visible to
394 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
395 * call to 'some_function'. Note that this would not be necessary if str was
396 * used anyway after the call to 'some_function'.
397 * char *chars = scm_i_string_chars (str);
398 * some_function (chars);
399 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
402 /* Remove any macro versions of these while defining the functions.
403 Functions are always included in the library, for upward binary
404 compatibility and in case combinations of GCC and non-GCC are used. */
405 #undef scm_remember_upto_here_1
406 #undef scm_remember_upto_here_2
409 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
411 /* Empty. Protects a single object from garbage collection. */
415 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
417 /* Empty. Protects two objects from garbage collection. */
421 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
423 /* Empty. Protects any number of objects from garbage collection. */
427 These crazy functions prevent garbage collection
428 of arguments after the first argument by
429 ensuring they remain live throughout the
430 function because they are used in the last
431 line of the code block.
432 It'd be better to have a nice compiler hint to
433 aid the conservative stack-scanning GC. --03/09/00 gjb */
435 scm_return_first (SCM elt
, ...)
441 scm_return_first_int (int i
, ...)
448 scm_permanent_object (SCM obj
)
450 return (scm_gc_protect_object (obj
));
454 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
455 other references are dropped, until the object is unprotected by calling
456 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
457 i. e. it is possible to protect the same object several times, but it is
458 necessary to unprotect the object the same number of times to actually get
459 the object unprotected. It is an error to unprotect an object more often
460 than it has been protected before. The function scm_protect_object returns
464 /* Implementation note: For every object X, there is a counter which
465 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
471 scm_gc_protect_object (SCM obj
)
475 /* This critical section barrier will be replaced by a mutex. */
476 /* njrev: Indeed; if my comment above is correct, there is the same
477 critsec/mutex inconsistency here. */
478 SCM_CRITICAL_SECTION_START
;
480 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
481 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
483 protected_obj_count
++;
485 SCM_CRITICAL_SECTION_END
;
491 /* Remove any protection for OBJ established by a prior call to
492 scm_protect_object. This function returns OBJ.
494 See scm_protect_object for more information. */
496 scm_gc_unprotect_object (SCM obj
)
500 /* This critical section barrier will be replaced by a mutex. */
501 /* njrev: and again. */
502 SCM_CRITICAL_SECTION_START
;
504 if (scm_gc_running_p
)
506 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
510 handle
= scm_hashq_get_handle (scm_protects
, obj
);
512 if (scm_is_false (handle
))
514 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
519 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
520 if (scm_is_eq (count
, scm_from_int (0)))
521 scm_hashq_remove_x (scm_protects
, obj
);
523 SCM_SETCDR (handle
, count
);
525 protected_obj_count
--;
527 SCM_CRITICAL_SECTION_END
;
533 scm_gc_register_root (SCM
*p
)
539 scm_gc_unregister_root (SCM
*p
)
545 scm_gc_register_roots (SCM
*b
, unsigned long n
)
548 for (; p
< b
+ n
; ++p
)
549 scm_gc_register_root (p
);
553 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
556 for (; p
< b
+ n
; ++p
)
557 scm_gc_unregister_root (p
);
564 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
567 /* Get an integer from an environment variable. */
569 scm_getenv_int (const char *var
, int def
)
572 char *val
= getenv (var
);
576 res
= strtol (val
, &end
, 10);
583 scm_storage_prehistory ()
585 GC_all_interior_pointers
= 0;
586 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
590 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
591 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
592 /* When using GC 6.8, this call is required to initialize thread-local
593 freelists (shouldn't be necessary with GC 7.0). */
597 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
599 /* We only need to register a displacement for those types for which the
600 higher bits of the type tag are used to store a pointer (that is, a
601 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
602 handled in `scm_alloc_struct ()'. */
603 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
604 /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */
607 if (!GC_is_visible (&scm_protects
))
610 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
611 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
612 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
613 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
614 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
617 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
620 scm_init_gc_protect_object ()
622 scm_protects
= scm_c_make_hash_table (31);
625 /* We can't have a cleanup handler since we have no thread to run it
632 on_exit (cleanup
, 0);
641 SCM scm_after_gc_hook
;
643 static SCM after_gc_async_cell
;
645 /* The function after_gc_async_thunk causes the execution of the
646 * after-gc-hook. It is run after the gc, as soon as the asynchronous
647 * events are handled by the evaluator.
650 after_gc_async_thunk (void)
652 /* Fun, no? Hook-run *and* run-hook? */
653 scm_c_hook_run (&scm_after_gc_c_hook
, NULL
);
654 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
655 return SCM_UNSPECIFIED
;
659 /* The function queue_after_gc_hook is run by the scm_before_gc_c_hook
660 * at the end of the garbage collection. The only purpose of this
661 * function is to mark the after_gc_async (which will eventually lead to
662 * the execution of the after_gc_async_thunk).
665 queue_after_gc_hook (void * hook_data SCM_UNUSED
,
666 void *fn_data SCM_UNUSED
,
667 void *data SCM_UNUSED
)
669 /* If cell access debugging is enabled, the user may choose to perform
670 * additional garbage collections after an arbitrary number of cell
671 * accesses. We don't want the scheme level after-gc-hook to be performed
672 * for each of these garbage collections for the following reason: The
673 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
674 * after-gc-hook was performed with every gc, and if the gc was performed
675 * after a very small number of cell accesses, then the number of cell
676 * accesses during the execution of the after-gc-hook will suffice to cause
677 * the execution of the next gc. Then, guile would keep executing the
678 * after-gc-hook over and over again, and would never come to do other
681 * To overcome this problem, if cell access debugging with additional
682 * garbage collections is enabled, the after-gc-hook is never run by the
683 * garbage collecter. When running guile with cell access debugging and the
684 * execution of the after-gc-hook is desired, then it is necessary to run
685 * the hook explicitly from the user code. This has the effect, that from
686 * the scheme level point of view it seems that garbage collection is
687 * performed with a much lower frequency than it actually is. Obviously,
688 * this will not work for code that depends on a fixed one to one
689 * relationship between the execution counts of the C level garbage
690 * collection hooks and the execution count of the scheme level
694 #if (SCM_DEBUG_CELL_ACCESSES == 1)
695 if (scm_debug_cells_gc_interval
== 0)
698 scm_i_thread
*t
= SCM_I_CURRENT_THREAD
;
700 if (scm_is_false (SCM_CDR (after_gc_async_cell
)))
702 SCM_SETCDR (after_gc_async_cell
, t
->active_asyncs
);
703 t
->active_asyncs
= after_gc_async_cell
;
704 t
->pending_asyncs
= 1;
712 scm_i_tag_name (scm_t_bits tag
)
716 int k
= 0xff & (tag
>> 8);
717 return (scm_smobs
[k
].name
);
720 switch (tag
) /* 7 bits */
724 case scm_tcs_cons_imcar
:
725 return "cons (immediate car)";
726 case scm_tcs_cons_nimcar
:
727 return "cons (non-immediate car)";
728 case scm_tc7_pointer
:
730 case scm_tc7_hashtable
:
734 case scm_tc7_dynamic_state
:
735 return "dynamic state";
738 case scm_tc7_objcode
:
742 case scm_tc7_vm_cont
:
743 return "vm continuation";
745 return "weak vector";
757 case scm_tc16_complex
:
758 return "complex number";
760 case scm_tc16_fraction
:
768 case scm_tc7_stringbuf
:
769 return "string buffer";
774 case scm_tc7_variable
:
781 return "smob"; /* should not occur. */
794 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
796 scm_after_gc_hook
= scm_make_hook (SCM_INUM0
);
797 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
799 /* When the async is to run, the cdr of the gc_async pair gets set to
800 the asyncs queue of the current thread. */
801 after_gc_async_cell
= scm_cons (scm_c_make_gsubr ("%after-gc-thunk", 0, 0, 0,
802 after_gc_async_thunk
),
805 scm_c_hook_add (&scm_before_gc_c_hook
, queue_after_gc_hook
, NULL
, 0);
807 #ifdef HAVE_GC_SET_START_CALLBACK
808 GC_set_start_callback (run_before_gc_c_hook
);
811 #include "libguile/gc.x"
817 #define FUNC_NAME "scm_gc_sweep"
820 fprintf (stderr
, "%s: doing nothing\n", FUNC_NAME
);