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
;
93 #if (SCM_DEBUG_CELL_ACCESSES == 1)
98 Assert that the given object is a valid reference to a valid cell. This
99 test involves to determine whether the object is a cell pointer, whether
100 this pointer actually points into a heap segment and whether the cell
101 pointed to is not a free cell. Further, additional garbage collections may
102 get executed after a user defined number of cell accesses. This helps to
103 find places in the C code where references are dropped for extremely short
108 scm_i_expensive_validation_check (SCM cell
)
110 /* If desired, perform additional garbage collections after a user
111 * defined number of cell accesses.
113 if (scm_debug_cells_gc_interval
)
115 static unsigned int counter
= 0;
123 counter
= scm_debug_cells_gc_interval
;
130 scm_assert_cell_valid (SCM cell
)
132 if (!scm_i_cell_validation_already_running
&& scm_debug_cell_accesses_p
)
134 scm_i_cell_validation_already_running
= 1; /* set to avoid recursion */
137 During GC, no user-code should be run, and the guile core
138 should use non-protected accessors.
140 if (scm_gc_running_p
)
144 Only scm_in_heap_p and rescanning the heap is wildly
147 if (scm_expensive_debug_cell_accesses_p
)
148 scm_i_expensive_validation_check (cell
);
150 scm_i_cell_validation_already_running
= 0; /* re-enable */
156 SCM_DEFINE (scm_set_debug_cell_accesses_x
, "set-debug-cell-accesses!", 1, 0, 0,
158 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
159 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
160 "but no additional calls to garbage collection are issued.\n"
161 "If @var{flag} is a number, strict cell access checking is enabled,\n"
162 "with an additional garbage collection after the given\n"
163 "number of cell accesses.\n"
164 "This procedure only exists when the compile-time flag\n"
165 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
166 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
168 if (scm_is_false (flag
))
170 scm_debug_cell_accesses_p
= 0;
172 else if (scm_is_eq (flag
, SCM_BOOL_T
))
174 scm_debug_cells_gc_interval
= 0;
175 scm_debug_cell_accesses_p
= 1;
176 scm_expensive_debug_cell_accesses_p
= 0;
180 scm_debug_cells_gc_interval
= scm_to_signed_integer (flag
, 0, INT_MAX
);
181 scm_debug_cell_accesses_p
= 1;
182 scm_expensive_debug_cell_accesses_p
= 1;
184 return SCM_UNSPECIFIED
;
189 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
193 scm_t_c_hook scm_before_gc_c_hook
;
194 scm_t_c_hook scm_before_mark_c_hook
;
195 scm_t_c_hook scm_before_sweep_c_hook
;
196 scm_t_c_hook scm_after_sweep_c_hook
;
197 scm_t_c_hook scm_after_gc_c_hook
;
200 /* GC Statistics Keeping
202 unsigned long scm_gc_ports_collected
= 0;
204 static unsigned long protected_obj_count
= 0;
207 SCM_SYMBOL (sym_cells_allocated
, "cells-allocated");
208 SCM_SYMBOL (sym_heap_size
, "heap-size");
209 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
210 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
211 SCM_SYMBOL (sym_mallocated
, "bytes-malloced");
212 SCM_SYMBOL (sym_mtrigger
, "gc-malloc-threshold");
213 SCM_SYMBOL (sym_heap_segments
, "cell-heap-segments");
214 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
215 SCM_SYMBOL (sym_gc_mark_time_taken
, "gc-mark-time-taken");
216 SCM_SYMBOL (sym_times
, "gc-times");
217 SCM_SYMBOL (sym_cells_marked
, "cells-marked");
218 SCM_SYMBOL (sym_cells_marked_conservatively
, "cells-marked-conservatively");
219 SCM_SYMBOL (sym_cells_swept
, "cells-swept");
220 SCM_SYMBOL (sym_malloc_yield
, "malloc-yield");
221 SCM_SYMBOL (sym_cell_yield
, "cell-yield");
222 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
223 SCM_SYMBOL (sym_total_cells_allocated
, "total-cells-allocated");
226 /* Number of calls to SCM_NEWCELL since startup. */
227 unsigned scm_newcell_count
;
228 unsigned scm_newcell2_count
;
231 /* {Scheme Interface to GC}
234 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
236 if (scm_is_integer (key
))
238 int c_tag
= scm_to_int (key
);
240 char const * name
= scm_i_tag_name (c_tag
);
243 key
= scm_from_locale_string (name
);
248 sprintf (s
, "tag %d", c_tag
);
249 key
= scm_from_locale_string (s
);
253 return scm_cons (scm_cons (key
, val
), acc
);
256 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
258 "Return an alist of statistics of the current live objects. ")
259 #define FUNC_NAME s_scm_gc_live_object_stats
261 SCM tab
= scm_make_hash_table (scm_from_int (57));
265 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
271 extern int scm_gc_malloc_yield_percentage
;
272 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
274 "Return an association list of statistics about Guile's current\n"
276 #define FUNC_NAME s_scm_gc_stats
279 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
282 heap_size
= GC_get_heap_size ();
283 free_bytes
= GC_get_free_bytes ();
284 bytes_since_gc
= GC_get_bytes_since_gc ();
285 total_bytes
= GC_get_total_bytes ();
288 /* njrev: can any of these scm_cons's or scm_list_n signal a memory
289 error? If so we need a frame here. */
291 scm_list_n (scm_cons (sym_gc_time_taken
, SCM_INUM0
),
293 scm_cons (sym_cells_allocated
,
294 scm_from_ulong (local_scm_cells_allocated
)),
295 scm_cons (sym_mallocated
,
296 scm_from_ulong (local_scm_mallocated
)),
297 scm_cons (sym_mtrigger
,
298 scm_from_ulong (local_scm_mtrigger
)),
299 scm_cons (sym_gc_mark_time_taken
,
300 scm_from_ulong (local_scm_gc_mark_time_taken
)),
301 scm_cons (sym_cells_marked
,
302 scm_from_double (local_scm_gc_cells_marked
)),
303 scm_cons (sym_cells_swept
,
304 scm_from_double (local_scm_gc_cells_swept
)),
305 scm_cons (sym_malloc_yield
,
306 scm_from_long (local_scm_gc_malloc_yield_percentage
)),
307 scm_cons (sym_cell_yield
,
308 scm_from_long (local_scm_gc_cell_yield_percentage
)),
309 scm_cons (sym_heap_segments
, heap_segs
),
311 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
312 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
313 scm_cons (sym_heap_total_allocated
,
314 scm_from_size_t (total_bytes
)),
315 scm_cons (sym_protected_objects
,
316 scm_from_ulong (protected_obj_count
)),
317 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
325 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
327 "Dump information about the garbage collector's internal data "
328 "structures and memory usage to the standard output.")
329 #define FUNC_NAME s_scm_gc_dump
333 return SCM_UNSPECIFIED
;
338 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
340 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
341 "returned by this function for @var{obj}")
342 #define FUNC_NAME s_scm_object_address
344 return scm_from_ulong (SCM_UNPACK (obj
));
349 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
351 "Disables the garbage collector. Nested calls are permitted. "
352 "GC is re-enabled once @code{gc-enable} has been called the "
353 "same number of times @code{gc-disable} was called.")
354 #define FUNC_NAME s_scm_gc_disable
357 return SCM_UNSPECIFIED
;
361 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
363 "Enables the garbage collector.")
364 #define FUNC_NAME s_scm_gc_enable
367 return SCM_UNSPECIFIED
;
372 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
374 "Scans all of SCM objects and reclaims for further use those that are\n"
375 "no longer accessible.")
376 #define FUNC_NAME s_scm_gc
378 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex
);
380 /* njrev: It looks as though other places, e.g. scm_realloc,
381 can call scm_i_gc without acquiring the sweep mutex. Does this
382 matter? Also scm_i_gc (or its descendants) touch the
383 scm_sys_protects, which are protected in some cases
384 (e.g. scm_permobjs above in scm_gc_stats) by a critical section,
385 not by the sweep mutex. Shouldn't all the GC-relevant objects be
386 protected in the same way? */
387 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex
);
388 scm_c_hook_run (&scm_after_gc_c_hook
, 0);
389 return SCM_UNSPECIFIED
;
394 scm_i_gc (const char *what
)
401 /* {GC Protection Helper Functions}
406 * If within a function you need to protect one or more scheme objects from
407 * garbage collection, pass them as parameters to one of the
408 * scm_remember_upto_here* functions below. These functions don't do
409 * anything, but since the compiler does not know that they are actually
410 * no-ops, it will generate code that calls these functions with the given
411 * parameters. Therefore, you can be sure that the compiler will keep those
412 * scheme values alive (on the stack or in a register) up to the point where
413 * scm_remember_upto_here* is called. In other words, place the call to
414 * scm_remember_upto_here* _behind_ the last code in your function, that
415 * depends on the scheme object to exist.
417 * Example: We want to make sure that the string object str does not get
418 * garbage collected during the execution of 'some_function' in the code
419 * below, because otherwise the characters belonging to str would be freed and
420 * 'some_function' might access freed memory. To make sure that the compiler
421 * keeps str alive on the stack or in a register such that it is visible to
422 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
423 * call to 'some_function'. Note that this would not be necessary if str was
424 * used anyway after the call to 'some_function'.
425 * char *chars = scm_i_string_chars (str);
426 * some_function (chars);
427 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
430 /* Remove any macro versions of these while defining the functions.
431 Functions are always included in the library, for upward binary
432 compatibility and in case combinations of GCC and non-GCC are used. */
433 #undef scm_remember_upto_here_1
434 #undef scm_remember_upto_here_2
437 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
439 /* Empty. Protects a single object from garbage collection. */
443 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
445 /* Empty. Protects two objects from garbage collection. */
449 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
451 /* Empty. Protects any number of objects from garbage collection. */
455 These crazy functions prevent garbage collection
456 of arguments after the first argument by
457 ensuring they remain live throughout the
458 function because they are used in the last
459 line of the code block.
460 It'd be better to have a nice compiler hint to
461 aid the conservative stack-scanning GC. --03/09/00 gjb */
463 scm_return_first (SCM elt
, ...)
469 scm_return_first_int (int i
, ...)
476 scm_permanent_object (SCM obj
)
478 return (scm_gc_protect_object (obj
));
482 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
483 other references are dropped, until the object is unprotected by calling
484 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
485 i. e. it is possible to protect the same object several times, but it is
486 necessary to unprotect the object the same number of times to actually get
487 the object unprotected. It is an error to unprotect an object more often
488 than it has been protected before. The function scm_protect_object returns
492 /* Implementation note: For every object X, there is a counter which
493 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
499 scm_gc_protect_object (SCM obj
)
503 /* This critical section barrier will be replaced by a mutex. */
504 /* njrev: Indeed; if my comment above is correct, there is the same
505 critsec/mutex inconsistency here. */
506 SCM_CRITICAL_SECTION_START
;
508 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
509 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
511 protected_obj_count
++;
513 SCM_CRITICAL_SECTION_END
;
519 /* Remove any protection for OBJ established by a prior call to
520 scm_protect_object. This function returns OBJ.
522 See scm_protect_object for more information. */
524 scm_gc_unprotect_object (SCM obj
)
528 /* This critical section barrier will be replaced by a mutex. */
529 /* njrev: and again. */
530 SCM_CRITICAL_SECTION_START
;
532 if (scm_gc_running_p
)
534 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
538 handle
= scm_hashq_get_handle (scm_protects
, obj
);
540 if (scm_is_false (handle
))
542 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
547 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
548 if (scm_is_eq (count
, scm_from_int (0)))
549 scm_hashq_remove_x (scm_protects
, obj
);
551 SCM_SETCDR (handle
, count
);
553 protected_obj_count
--;
555 SCM_CRITICAL_SECTION_END
;
561 scm_gc_register_root (SCM
*p
)
567 scm_gc_unregister_root (SCM
*p
)
573 scm_gc_register_roots (SCM
*b
, unsigned long n
)
576 for (; p
< b
+ n
; ++p
)
577 scm_gc_register_root (p
);
581 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
584 for (; p
< b
+ n
; ++p
)
585 scm_gc_unregister_root (p
);
588 int scm_i_terminating
;
594 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
597 /* Get an integer from an environment variable. */
599 scm_getenv_int (const char *var
, int def
)
602 char *val
= getenv (var
);
606 res
= strtol (val
, &end
, 10);
613 scm_storage_prehistory ()
615 GC_all_interior_pointers
= 0;
616 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
620 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
621 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
622 /* When using GC 6.8, this call is required to initialize thread-local
623 freelists (shouldn't be necessary with GC 7.0). */
627 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
629 /* We only need to register a displacement for those types for which the
630 higher bits of the type tag are used to store a pointer (that is, a
631 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
632 handled in `scm_alloc_struct ()'. */
633 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
634 GC_REGISTER_DISPLACEMENT (scm_tc3_closure
);
637 if (!GC_is_visible (scm_sys_protects
))
640 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
641 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
642 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
643 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
644 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
647 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
654 j
= SCM_NUM_PROTECTS
;
656 scm_sys_protects
[--j
] = SCM_BOOL_F
;
659 /* We can't have a cleanup handler since we have no thread to run it
666 on_exit (cleanup
, 0);
672 scm_protects
= scm_c_make_hash_table (31);
679 SCM scm_after_gc_hook
;
683 /* The function gc_async_thunk causes the execution of the after-gc-hook. It
684 * is run after the gc, as soon as the asynchronous events are handled by the
688 gc_async_thunk (void)
690 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
691 return SCM_UNSPECIFIED
;
695 /* The function mark_gc_async is run by the scm_after_gc_c_hook at the end of
696 * the garbage collection. The only purpose of this function is to mark the
697 * gc_async (which will eventually lead to the execution of the
701 mark_gc_async (void * hook_data SCM_UNUSED
,
702 void *fn_data SCM_UNUSED
,
703 void *data SCM_UNUSED
)
705 /* If cell access debugging is enabled, the user may choose to perform
706 * additional garbage collections after an arbitrary number of cell
707 * accesses. We don't want the scheme level after-gc-hook to be performed
708 * for each of these garbage collections for the following reason: The
709 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
710 * after-gc-hook was performed with every gc, and if the gc was performed
711 * after a very small number of cell accesses, then the number of cell
712 * accesses during the execution of the after-gc-hook will suffice to cause
713 * the execution of the next gc. Then, guile would keep executing the
714 * after-gc-hook over and over again, and would never come to do other
717 * To overcome this problem, if cell access debugging with additional
718 * garbage collections is enabled, the after-gc-hook is never run by the
719 * garbage collecter. When running guile with cell access debugging and the
720 * execution of the after-gc-hook is desired, then it is necessary to run
721 * the hook explicitly from the user code. This has the effect, that from
722 * the scheme level point of view it seems that garbage collection is
723 * performed with a much lower frequency than it actually is. Obviously,
724 * this will not work for code that depends on a fixed one to one
725 * relationship between the execution counts of the C level garbage
726 * collection hooks and the execution count of the scheme level
730 #if (SCM_DEBUG_CELL_ACCESSES == 1)
731 if (scm_debug_cells_gc_interval
== 0)
732 scm_system_async_mark (gc_async
);
734 scm_system_async_mark (gc_async
);
741 scm_i_tag_name (scm_t_bits tag
)
745 int k
= 0xff & (tag
>> 8);
746 return (scm_smobs
[k
].name
);
749 switch (tag
) /* 7 bits */
753 case scm_tcs_cons_imcar
:
754 return "cons (immediate car)";
755 case scm_tcs_cons_nimcar
:
756 return "cons (non-immediate car)";
757 case scm_tcs_closures
:
762 return "weak vector";
767 return "compiled closure";
778 case scm_tc16_complex
:
779 return "complex number";
781 case scm_tc16_fraction
:
789 case scm_tc7_stringbuf
:
790 return "string buffer";
795 case scm_tc7_variable
:
805 return "smob"; /* should not occur. */
818 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
820 scm_after_gc_hook
= scm_permanent_object (scm_make_hook (SCM_INUM0
));
821 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
823 gc_async
= scm_c_make_subr ("%gc-thunk", scm_tc7_subr_0
,
826 scm_c_hook_add (&scm_after_gc_c_hook
, mark_gc_async
, NULL
, 0);
828 #include "libguile/gc.x"
834 #define FUNC_NAME "scm_gc_sweep"
837 fprintf (stderr
, "%s: doing nothing\n", __FUNCTION__
);