1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003, 2006, 2008, 2009, 2010 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 #ifdef GUILE_DEBUG_MALLOC
61 #include "libguile/debug-malloc.h"
72 /* Lock this mutex before doing lazy sweeping.
74 scm_i_pthread_mutex_t scm_i_sweep_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
76 /* Set this to != 0 if every cell that is accessed shall be checked:
78 int scm_debug_cell_accesses_p
= 0;
79 int scm_expensive_debug_cell_accesses_p
= 0;
81 /* Set this to 0 if no additional gc's shall be performed, otherwise set it to
82 * the number of cell accesses after which a gc shall be called.
84 int scm_debug_cells_gc_interval
= 0;
87 Global variable, so you can switch it off at runtime by setting
88 scm_i_cell_validation_already_running.
90 int scm_i_cell_validation_already_running
;
92 /* Hash table that keeps a reference to objects the user wants to protect from
93 garbage collection. It could arguably be private but applications have come
94 to rely on it (e.g., Lilypond 2.13.9). */
98 #if (SCM_DEBUG_CELL_ACCESSES == 1)
103 Assert that the given object is a valid reference to a valid cell. This
104 test involves to determine whether the object is a cell pointer, whether
105 this pointer actually points into a heap segment and whether the cell
106 pointed to is not a free cell. Further, additional garbage collections may
107 get executed after a user defined number of cell accesses. This helps to
108 find places in the C code where references are dropped for extremely short
113 scm_i_expensive_validation_check (SCM cell
)
115 /* If desired, perform additional garbage collections after a user
116 * defined number of cell accesses.
118 if (scm_debug_cells_gc_interval
)
120 static unsigned int counter
= 0;
128 counter
= scm_debug_cells_gc_interval
;
135 scm_assert_cell_valid (SCM cell
)
137 if (!scm_i_cell_validation_already_running
&& scm_debug_cell_accesses_p
)
139 scm_i_cell_validation_already_running
= 1; /* set to avoid recursion */
142 During GC, no user-code should be run, and the guile core
143 should use non-protected accessors.
145 if (scm_gc_running_p
)
149 Only scm_in_heap_p and rescanning the heap is wildly
152 if (scm_expensive_debug_cell_accesses_p
)
153 scm_i_expensive_validation_check (cell
);
155 scm_i_cell_validation_already_running
= 0; /* re-enable */
161 SCM_DEFINE (scm_set_debug_cell_accesses_x
, "set-debug-cell-accesses!", 1, 0, 0,
163 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
164 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
165 "but no additional calls to garbage collection are issued.\n"
166 "If @var{flag} is a number, strict cell access checking is enabled,\n"
167 "with an additional garbage collection after the given\n"
168 "number of cell accesses.\n"
169 "This procedure only exists when the compile-time flag\n"
170 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
171 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
173 if (scm_is_false (flag
))
175 scm_debug_cell_accesses_p
= 0;
177 else if (scm_is_eq (flag
, SCM_BOOL_T
))
179 scm_debug_cells_gc_interval
= 0;
180 scm_debug_cell_accesses_p
= 1;
181 scm_expensive_debug_cell_accesses_p
= 0;
185 scm_debug_cells_gc_interval
= scm_to_signed_integer (flag
, 0, INT_MAX
);
186 scm_debug_cell_accesses_p
= 1;
187 scm_expensive_debug_cell_accesses_p
= 1;
189 return SCM_UNSPECIFIED
;
194 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
198 scm_t_c_hook scm_before_gc_c_hook
;
199 scm_t_c_hook scm_before_mark_c_hook
;
200 scm_t_c_hook scm_before_sweep_c_hook
;
201 scm_t_c_hook scm_after_sweep_c_hook
;
202 scm_t_c_hook scm_after_gc_c_hook
;
205 /* GC Statistics Keeping
207 unsigned long scm_gc_ports_collected
= 0;
209 static unsigned long protected_obj_count
= 0;
212 SCM_SYMBOL (sym_cells_allocated
, "cells-allocated");
213 SCM_SYMBOL (sym_heap_size
, "heap-size");
214 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
215 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
216 SCM_SYMBOL (sym_mallocated
, "bytes-malloced");
217 SCM_SYMBOL (sym_mtrigger
, "gc-malloc-threshold");
218 SCM_SYMBOL (sym_heap_segments
, "cell-heap-segments");
219 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
220 SCM_SYMBOL (sym_gc_mark_time_taken
, "gc-mark-time-taken");
221 SCM_SYMBOL (sym_times
, "gc-times");
222 SCM_SYMBOL (sym_cells_marked
, "cells-marked");
223 SCM_SYMBOL (sym_cells_marked_conservatively
, "cells-marked-conservatively");
224 SCM_SYMBOL (sym_cells_swept
, "cells-swept");
225 SCM_SYMBOL (sym_malloc_yield
, "malloc-yield");
226 SCM_SYMBOL (sym_cell_yield
, "cell-yield");
227 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
228 SCM_SYMBOL (sym_total_cells_allocated
, "total-cells-allocated");
231 /* Number of calls to SCM_NEWCELL since startup. */
232 unsigned scm_newcell_count
;
233 unsigned scm_newcell2_count
;
236 /* {Scheme Interface to GC}
239 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
241 if (scm_is_integer (key
))
243 int c_tag
= scm_to_int (key
);
245 char const * name
= scm_i_tag_name (c_tag
);
248 key
= scm_from_locale_string (name
);
253 sprintf (s
, "tag %d", c_tag
);
254 key
= scm_from_locale_string (s
);
258 return scm_cons (scm_cons (key
, val
), acc
);
261 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
263 "Return an alist of statistics of the current live objects. ")
264 #define FUNC_NAME s_scm_gc_live_object_stats
266 SCM tab
= scm_make_hash_table (scm_from_int (57));
270 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
276 extern int scm_gc_malloc_yield_percentage
;
277 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
279 "Return an association list of statistics about Guile's current\n"
281 #define FUNC_NAME s_scm_gc_stats
284 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
287 heap_size
= GC_get_heap_size ();
288 free_bytes
= GC_get_free_bytes ();
289 bytes_since_gc
= GC_get_bytes_since_gc ();
290 total_bytes
= GC_get_total_bytes ();
293 /* njrev: can any of these scm_cons's or scm_list_n signal a memory
294 error? If so we need a frame here. */
296 scm_list_n (scm_cons (sym_gc_time_taken
, SCM_INUM0
),
298 scm_cons (sym_cells_allocated
,
299 scm_from_ulong (local_scm_cells_allocated
)),
300 scm_cons (sym_mallocated
,
301 scm_from_ulong (local_scm_mallocated
)),
302 scm_cons (sym_mtrigger
,
303 scm_from_ulong (local_scm_mtrigger
)),
304 scm_cons (sym_gc_mark_time_taken
,
305 scm_from_ulong (local_scm_gc_mark_time_taken
)),
306 scm_cons (sym_cells_marked
,
307 scm_from_double (local_scm_gc_cells_marked
)),
308 scm_cons (sym_cells_swept
,
309 scm_from_double (local_scm_gc_cells_swept
)),
310 scm_cons (sym_malloc_yield
,
311 scm_from_long (local_scm_gc_malloc_yield_percentage
)),
312 scm_cons (sym_cell_yield
,
313 scm_from_long (local_scm_gc_cell_yield_percentage
)),
314 scm_cons (sym_heap_segments
, heap_segs
),
316 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
317 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
318 scm_cons (sym_heap_total_allocated
,
319 scm_from_size_t (total_bytes
)),
320 scm_cons (sym_protected_objects
,
321 scm_from_ulong (protected_obj_count
)),
322 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
330 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
332 "Dump information about the garbage collector's internal data "
333 "structures and memory usage to the standard output.")
334 #define FUNC_NAME s_scm_gc_dump
338 return SCM_UNSPECIFIED
;
343 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
345 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
346 "returned by this function for @var{obj}")
347 #define FUNC_NAME s_scm_object_address
349 return scm_from_ulong (SCM_UNPACK (obj
));
354 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
356 "Disables the garbage collector. Nested calls are permitted. "
357 "GC is re-enabled once @code{gc-enable} has been called the "
358 "same number of times @code{gc-disable} was called.")
359 #define FUNC_NAME s_scm_gc_disable
362 return SCM_UNSPECIFIED
;
366 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
368 "Enables the garbage collector.")
369 #define FUNC_NAME s_scm_gc_enable
372 return SCM_UNSPECIFIED
;
377 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
379 "Scans all of SCM objects and reclaims for further use those that are\n"
380 "no longer accessible.")
381 #define FUNC_NAME s_scm_gc
383 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex
);
385 /* njrev: It looks as though other places, e.g. scm_realloc,
386 can call scm_i_gc without acquiring the sweep mutex. Does this
387 matter? Also scm_i_gc (or its descendants) touch the
388 scm_sys_protects, which are protected in some cases
389 (e.g. scm_permobjs above in scm_gc_stats) by a critical section,
390 not by the sweep mutex. Shouldn't all the GC-relevant objects be
391 protected in the same way? */
392 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex
);
393 scm_c_hook_run (&scm_after_gc_c_hook
, 0);
394 return SCM_UNSPECIFIED
;
399 scm_i_gc (const char *what
)
406 /* {GC Protection Helper Functions}
411 * If within a function you need to protect one or more scheme objects from
412 * garbage collection, pass them as parameters to one of the
413 * scm_remember_upto_here* functions below. These functions don't do
414 * anything, but since the compiler does not know that they are actually
415 * no-ops, it will generate code that calls these functions with the given
416 * parameters. Therefore, you can be sure that the compiler will keep those
417 * scheme values alive (on the stack or in a register) up to the point where
418 * scm_remember_upto_here* is called. In other words, place the call to
419 * scm_remember_upto_here* _behind_ the last code in your function, that
420 * depends on the scheme object to exist.
422 * Example: We want to make sure that the string object str does not get
423 * garbage collected during the execution of 'some_function' in the code
424 * below, because otherwise the characters belonging to str would be freed and
425 * 'some_function' might access freed memory. To make sure that the compiler
426 * keeps str alive on the stack or in a register such that it is visible to
427 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
428 * call to 'some_function'. Note that this would not be necessary if str was
429 * used anyway after the call to 'some_function'.
430 * char *chars = scm_i_string_chars (str);
431 * some_function (chars);
432 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
435 /* Remove any macro versions of these while defining the functions.
436 Functions are always included in the library, for upward binary
437 compatibility and in case combinations of GCC and non-GCC are used. */
438 #undef scm_remember_upto_here_1
439 #undef scm_remember_upto_here_2
442 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
444 /* Empty. Protects a single object from garbage collection. */
448 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
450 /* Empty. Protects two objects from garbage collection. */
454 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
456 /* Empty. Protects any number of objects from garbage collection. */
460 These crazy functions prevent garbage collection
461 of arguments after the first argument by
462 ensuring they remain live throughout the
463 function because they are used in the last
464 line of the code block.
465 It'd be better to have a nice compiler hint to
466 aid the conservative stack-scanning GC. --03/09/00 gjb */
468 scm_return_first (SCM elt
, ...)
474 scm_return_first_int (int i
, ...)
481 scm_permanent_object (SCM obj
)
483 return (scm_gc_protect_object (obj
));
487 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
488 other references are dropped, until the object is unprotected by calling
489 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
490 i. e. it is possible to protect the same object several times, but it is
491 necessary to unprotect the object the same number of times to actually get
492 the object unprotected. It is an error to unprotect an object more often
493 than it has been protected before. The function scm_protect_object returns
497 /* Implementation note: For every object X, there is a counter which
498 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
504 scm_gc_protect_object (SCM obj
)
508 /* This critical section barrier will be replaced by a mutex. */
509 /* njrev: Indeed; if my comment above is correct, there is the same
510 critsec/mutex inconsistency here. */
511 SCM_CRITICAL_SECTION_START
;
513 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
514 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
516 protected_obj_count
++;
518 SCM_CRITICAL_SECTION_END
;
524 /* Remove any protection for OBJ established by a prior call to
525 scm_protect_object. This function returns OBJ.
527 See scm_protect_object for more information. */
529 scm_gc_unprotect_object (SCM obj
)
533 /* This critical section barrier will be replaced by a mutex. */
534 /* njrev: and again. */
535 SCM_CRITICAL_SECTION_START
;
537 if (scm_gc_running_p
)
539 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
543 handle
= scm_hashq_get_handle (scm_protects
, obj
);
545 if (scm_is_false (handle
))
547 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
552 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
553 if (scm_is_eq (count
, scm_from_int (0)))
554 scm_hashq_remove_x (scm_protects
, obj
);
556 SCM_SETCDR (handle
, count
);
558 protected_obj_count
--;
560 SCM_CRITICAL_SECTION_END
;
566 scm_gc_register_root (SCM
*p
)
572 scm_gc_unregister_root (SCM
*p
)
578 scm_gc_register_roots (SCM
*b
, unsigned long n
)
581 for (; p
< b
+ n
; ++p
)
582 scm_gc_register_root (p
);
586 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
589 for (; p
< b
+ n
; ++p
)
590 scm_gc_unregister_root (p
);
593 int scm_i_terminating
;
599 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
602 /* Get an integer from an environment variable. */
604 scm_getenv_int (const char *var
, int def
)
607 char *val
= getenv (var
);
611 res
= strtol (val
, &end
, 10);
618 scm_storage_prehistory ()
620 GC_all_interior_pointers
= 0;
621 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
625 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
626 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
627 /* When using GC 6.8, this call is required to initialize thread-local
628 freelists (shouldn't be necessary with GC 7.0). */
632 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
634 /* We only need to register a displacement for those types for which the
635 higher bits of the type tag are used to store a pointer (that is, a
636 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
637 handled in `scm_alloc_struct ()'. */
638 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
639 /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */
642 if (!GC_is_visible (&scm_protects
))
645 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
646 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
647 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
648 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
649 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
652 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
655 scm_init_gc_protect_object ()
657 scm_protects
= scm_c_make_hash_table (31);
660 /* We can't have a cleanup handler since we have no thread to run it
667 on_exit (cleanup
, 0);
676 SCM scm_after_gc_hook
;
680 /* The function gc_async_thunk causes the execution of the after-gc-hook. It
681 * is run after the gc, as soon as the asynchronous events are handled by the
685 gc_async_thunk (void)
687 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
688 return SCM_UNSPECIFIED
;
692 /* The function mark_gc_async is run by the scm_after_gc_c_hook at the end of
693 * the garbage collection. The only purpose of this function is to mark the
694 * gc_async (which will eventually lead to the execution of the
698 mark_gc_async (void * hook_data SCM_UNUSED
,
699 void *fn_data SCM_UNUSED
,
700 void *data SCM_UNUSED
)
702 /* If cell access debugging is enabled, the user may choose to perform
703 * additional garbage collections after an arbitrary number of cell
704 * accesses. We don't want the scheme level after-gc-hook to be performed
705 * for each of these garbage collections for the following reason: The
706 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
707 * after-gc-hook was performed with every gc, and if the gc was performed
708 * after a very small number of cell accesses, then the number of cell
709 * accesses during the execution of the after-gc-hook will suffice to cause
710 * the execution of the next gc. Then, guile would keep executing the
711 * after-gc-hook over and over again, and would never come to do other
714 * To overcome this problem, if cell access debugging with additional
715 * garbage collections is enabled, the after-gc-hook is never run by the
716 * garbage collecter. When running guile with cell access debugging and the
717 * execution of the after-gc-hook is desired, then it is necessary to run
718 * the hook explicitly from the user code. This has the effect, that from
719 * the scheme level point of view it seems that garbage collection is
720 * performed with a much lower frequency than it actually is. Obviously,
721 * this will not work for code that depends on a fixed one to one
722 * relationship between the execution counts of the C level garbage
723 * collection hooks and the execution count of the scheme level
727 #if (SCM_DEBUG_CELL_ACCESSES == 1)
728 if (scm_debug_cells_gc_interval
== 0)
729 scm_system_async_mark (gc_async
);
731 scm_system_async_mark (gc_async
);
738 scm_i_tag_name (scm_t_bits tag
)
742 int k
= 0xff & (tag
>> 8);
743 return (scm_smobs
[k
].name
);
746 switch (tag
) /* 7 bits */
750 case scm_tcs_cons_imcar
:
751 return "cons (immediate car)";
752 case scm_tcs_cons_nimcar
:
753 return "cons (non-immediate car)";
754 case scm_tc7_foreign
:
756 case scm_tc7_hashtable
:
760 case scm_tc7_dynamic_state
:
761 return "dynamic state";
764 case scm_tc7_objcode
:
768 case scm_tc7_vm_cont
:
769 return "vm continuation";
771 return "weak vector";
783 case scm_tc16_complex
:
784 return "complex number";
786 case scm_tc16_fraction
:
794 case scm_tc7_stringbuf
:
795 return "string buffer";
800 case scm_tc7_variable
:
807 return "smob"; /* should not occur. */
820 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
822 scm_after_gc_hook
= scm_make_hook (SCM_INUM0
);
823 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
825 gc_async
= scm_c_make_gsubr ("%gc-thunk", 0, 0, 0, gc_async_thunk
);
827 scm_c_hook_add (&scm_after_gc_c_hook
, mark_gc_async
, NULL
, 0);
829 #include "libguile/gc.x"
835 #define FUNC_NAME "scm_gc_sweep"
838 fprintf (stderr
, "%s: doing nothing\n", FUNC_NAME
);