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
;
201 /* GC Statistics Keeping
203 unsigned long scm_gc_ports_collected
= 0;
205 static unsigned long protected_obj_count
= 0;
208 SCM_SYMBOL (sym_gc_time_taken
, "gc-time-taken");
209 SCM_SYMBOL (sym_heap_size
, "heap-size");
210 SCM_SYMBOL (sym_heap_free_size
, "heap-free-size");
211 SCM_SYMBOL (sym_heap_total_allocated
, "heap-total-allocated");
212 SCM_SYMBOL (sym_heap_allocated_since_gc
, "heap-allocated-since-gc");
213 SCM_SYMBOL (sym_protected_objects
, "protected-objects");
214 SCM_SYMBOL (sym_times
, "gc-times");
217 /* Number of calls to SCM_NEWCELL since startup. */
218 unsigned scm_newcell_count
;
219 unsigned scm_newcell2_count
;
222 /* {Scheme Interface to GC}
225 tag_table_to_type_alist (void *closure
, SCM key
, SCM val
, SCM acc
)
227 if (scm_is_integer (key
))
229 int c_tag
= scm_to_int (key
);
231 char const * name
= scm_i_tag_name (c_tag
);
234 key
= scm_from_locale_string (name
);
239 sprintf (s
, "tag %d", c_tag
);
240 key
= scm_from_locale_string (s
);
244 return scm_cons (scm_cons (key
, val
), acc
);
247 SCM_DEFINE (scm_gc_live_object_stats
, "gc-live-object-stats", 0, 0, 0,
249 "Return an alist of statistics of the current live objects. ")
250 #define FUNC_NAME s_scm_gc_live_object_stats
252 SCM tab
= scm_make_hash_table (scm_from_int (57));
256 = scm_internal_hash_fold (&tag_table_to_type_alist
, NULL
, SCM_EOL
, tab
);
262 extern int scm_gc_malloc_yield_percentage
;
263 SCM_DEFINE (scm_gc_stats
, "gc-stats", 0, 0, 0,
265 "Return an association list of statistics about Guile's current\n"
267 #define FUNC_NAME s_scm_gc_stats
270 size_t heap_size
, free_bytes
, bytes_since_gc
, total_bytes
;
273 heap_size
= GC_get_heap_size ();
274 free_bytes
= GC_get_free_bytes ();
275 bytes_since_gc
= GC_get_bytes_since_gc ();
276 total_bytes
= GC_get_total_bytes ();
280 scm_list_n (scm_cons (sym_gc_time_taken
, SCM_INUM0
),
281 scm_cons (sym_heap_size
, scm_from_size_t (heap_size
)),
282 scm_cons (sym_heap_free_size
, scm_from_size_t (free_bytes
)),
283 scm_cons (sym_heap_total_allocated
,
284 scm_from_size_t (total_bytes
)),
285 scm_cons (sym_heap_allocated_since_gc
,
286 scm_from_size_t (bytes_since_gc
)),
287 scm_cons (sym_protected_objects
,
288 scm_from_ulong (protected_obj_count
)),
289 scm_cons (sym_times
, scm_from_size_t (gc_times
)),
297 SCM_DEFINE (scm_gc_dump
, "gc-dump", 0, 0, 0,
299 "Dump information about the garbage collector's internal data "
300 "structures and memory usage to the standard output.")
301 #define FUNC_NAME s_scm_gc_dump
305 return SCM_UNSPECIFIED
;
310 SCM_DEFINE (scm_object_address
, "object-address", 1, 0, 0,
312 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
313 "returned by this function for @var{obj}")
314 #define FUNC_NAME s_scm_object_address
316 return scm_from_ulong (SCM_UNPACK (obj
));
321 SCM_DEFINE (scm_gc_disable
, "gc-disable", 0, 0, 0,
323 "Disables the garbage collector. Nested calls are permitted. "
324 "GC is re-enabled once @code{gc-enable} has been called the "
325 "same number of times @code{gc-disable} was called.")
326 #define FUNC_NAME s_scm_gc_disable
329 return SCM_UNSPECIFIED
;
333 SCM_DEFINE (scm_gc_enable
, "gc-enable", 0, 0, 0,
335 "Enables the garbage collector.")
336 #define FUNC_NAME s_scm_gc_enable
339 return SCM_UNSPECIFIED
;
344 SCM_DEFINE (scm_gc
, "gc", 0, 0, 0,
346 "Scans all of SCM objects and reclaims for further use those that are\n"
347 "no longer accessible.")
348 #define FUNC_NAME s_scm_gc
351 return SCM_UNSPECIFIED
;
356 scm_i_gc (const char *what
)
363 /* {GC Protection Helper Functions}
368 * If within a function you need to protect one or more scheme objects from
369 * garbage collection, pass them as parameters to one of the
370 * scm_remember_upto_here* functions below. These functions don't do
371 * anything, but since the compiler does not know that they are actually
372 * no-ops, it will generate code that calls these functions with the given
373 * parameters. Therefore, you can be sure that the compiler will keep those
374 * scheme values alive (on the stack or in a register) up to the point where
375 * scm_remember_upto_here* is called. In other words, place the call to
376 * scm_remember_upto_here* _behind_ the last code in your function, that
377 * depends on the scheme object to exist.
379 * Example: We want to make sure that the string object str does not get
380 * garbage collected during the execution of 'some_function' in the code
381 * below, because otherwise the characters belonging to str would be freed and
382 * 'some_function' might access freed memory. To make sure that the compiler
383 * keeps str alive on the stack or in a register such that it is visible to
384 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
385 * call to 'some_function'. Note that this would not be necessary if str was
386 * used anyway after the call to 'some_function'.
387 * char *chars = scm_i_string_chars (str);
388 * some_function (chars);
389 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
392 /* Remove any macro versions of these while defining the functions.
393 Functions are always included in the library, for upward binary
394 compatibility and in case combinations of GCC and non-GCC are used. */
395 #undef scm_remember_upto_here_1
396 #undef scm_remember_upto_here_2
399 scm_remember_upto_here_1 (SCM obj SCM_UNUSED
)
401 /* Empty. Protects a single object from garbage collection. */
405 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED
, SCM obj2 SCM_UNUSED
)
407 /* Empty. Protects two objects from garbage collection. */
411 scm_remember_upto_here (SCM obj SCM_UNUSED
, ...)
413 /* Empty. Protects any number of objects from garbage collection. */
417 These crazy functions prevent garbage collection
418 of arguments after the first argument by
419 ensuring they remain live throughout the
420 function because they are used in the last
421 line of the code block.
422 It'd be better to have a nice compiler hint to
423 aid the conservative stack-scanning GC. --03/09/00 gjb */
425 scm_return_first (SCM elt
, ...)
431 scm_return_first_int (int i
, ...)
438 scm_permanent_object (SCM obj
)
440 return (scm_gc_protect_object (obj
));
444 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
445 other references are dropped, until the object is unprotected by calling
446 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
447 i. e. it is possible to protect the same object several times, but it is
448 necessary to unprotect the object the same number of times to actually get
449 the object unprotected. It is an error to unprotect an object more often
450 than it has been protected before. The function scm_protect_object returns
454 /* Implementation note: For every object X, there is a counter which
455 scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements.
461 scm_gc_protect_object (SCM obj
)
465 /* This critical section barrier will be replaced by a mutex. */
466 /* njrev: Indeed; if my comment above is correct, there is the same
467 critsec/mutex inconsistency here. */
468 SCM_CRITICAL_SECTION_START
;
470 handle
= scm_hashq_create_handle_x (scm_protects
, obj
, scm_from_int (0));
471 SCM_SETCDR (handle
, scm_sum (SCM_CDR (handle
), scm_from_int (1)));
473 protected_obj_count
++;
475 SCM_CRITICAL_SECTION_END
;
481 /* Remove any protection for OBJ established by a prior call to
482 scm_protect_object. This function returns OBJ.
484 See scm_protect_object for more information. */
486 scm_gc_unprotect_object (SCM obj
)
490 /* This critical section barrier will be replaced by a mutex. */
491 /* njrev: and again. */
492 SCM_CRITICAL_SECTION_START
;
494 if (scm_gc_running_p
)
496 fprintf (stderr
, "scm_unprotect_object called during GC.\n");
500 handle
= scm_hashq_get_handle (scm_protects
, obj
);
502 if (scm_is_false (handle
))
504 fprintf (stderr
, "scm_unprotect_object called on unprotected object\n");
509 SCM count
= scm_difference (SCM_CDR (handle
), scm_from_int (1));
510 if (scm_is_eq (count
, scm_from_int (0)))
511 scm_hashq_remove_x (scm_protects
, obj
);
513 SCM_SETCDR (handle
, count
);
515 protected_obj_count
--;
517 SCM_CRITICAL_SECTION_END
;
523 scm_gc_register_root (SCM
*p
)
529 scm_gc_unregister_root (SCM
*p
)
535 scm_gc_register_roots (SCM
*b
, unsigned long n
)
538 for (; p
< b
+ n
; ++p
)
539 scm_gc_register_root (p
);
543 scm_gc_unregister_roots (SCM
*b
, unsigned long n
)
546 for (; p
< b
+ n
; ++p
)
547 scm_gc_unregister_root (p
);
551 run_before_gc_c_hook (void)
553 scm_c_hook_run (&scm_before_gc_c_hook
, NULL
);
560 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
563 /* Get an integer from an environment variable. */
565 scm_getenv_int (const char *var
, int def
)
568 char *val
= getenv (var
);
572 res
= strtol (val
, &end
, 10);
579 scm_storage_prehistory ()
581 GC_all_interior_pointers
= 0;
582 GC_set_free_space_divisor (scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3));
586 #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \
587 && (defined SCM_I_GSC_USE_PTHREAD_THREADS)
588 /* When using GC 6.8, this call is required to initialize thread-local
589 freelists (shouldn't be necessary with GC 7.0). */
593 GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2
);
595 /* We only need to register a displacement for those types for which the
596 higher bits of the type tag are used to store a pointer (that is, a
597 pointer to an 8-octet aligned region). For `scm_tc3_struct', this is
598 handled in `scm_alloc_struct ()'. */
599 GC_REGISTER_DISPLACEMENT (scm_tc3_cons
);
600 /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */
603 if (!GC_is_visible (&scm_protects
))
606 scm_c_hook_init (&scm_before_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
607 scm_c_hook_init (&scm_before_mark_c_hook
, 0, SCM_C_HOOK_NORMAL
);
608 scm_c_hook_init (&scm_before_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
609 scm_c_hook_init (&scm_after_sweep_c_hook
, 0, SCM_C_HOOK_NORMAL
);
610 scm_c_hook_init (&scm_after_gc_c_hook
, 0, SCM_C_HOOK_NORMAL
);
613 scm_i_pthread_mutex_t scm_i_gc_admin_mutex
= SCM_I_PTHREAD_MUTEX_INITIALIZER
;
616 scm_init_gc_protect_object ()
618 scm_protects
= scm_c_make_hash_table (31);
621 /* We can't have a cleanup handler since we have no thread to run it
628 on_exit (cleanup
, 0);
637 SCM scm_after_gc_hook
;
639 static SCM after_gc_async_cell
;
641 /* The function after_gc_async_thunk causes the execution of the
642 * after-gc-hook. It is run after the gc, as soon as the asynchronous
643 * events are handled by the evaluator.
646 after_gc_async_thunk (void)
648 /* Fun, no? Hook-run *and* run-hook? */
649 scm_c_hook_run (&scm_after_gc_c_hook
, NULL
);
650 scm_c_run_hook (scm_after_gc_hook
, SCM_EOL
);
651 return SCM_UNSPECIFIED
;
655 /* The function queue_after_gc_hook is run by the scm_before_gc_c_hook
656 * at the end of the garbage collection. The only purpose of this
657 * function is to mark the after_gc_async (which will eventually lead to
658 * the execution of the after_gc_async_thunk).
661 queue_after_gc_hook (void * hook_data SCM_UNUSED
,
662 void *fn_data SCM_UNUSED
,
663 void *data SCM_UNUSED
)
665 /* If cell access debugging is enabled, the user may choose to perform
666 * additional garbage collections after an arbitrary number of cell
667 * accesses. We don't want the scheme level after-gc-hook to be performed
668 * for each of these garbage collections for the following reason: The
669 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
670 * after-gc-hook was performed with every gc, and if the gc was performed
671 * after a very small number of cell accesses, then the number of cell
672 * accesses during the execution of the after-gc-hook will suffice to cause
673 * the execution of the next gc. Then, guile would keep executing the
674 * after-gc-hook over and over again, and would never come to do other
677 * To overcome this problem, if cell access debugging with additional
678 * garbage collections is enabled, the after-gc-hook is never run by the
679 * garbage collecter. When running guile with cell access debugging and the
680 * execution of the after-gc-hook is desired, then it is necessary to run
681 * the hook explicitly from the user code. This has the effect, that from
682 * the scheme level point of view it seems that garbage collection is
683 * performed with a much lower frequency than it actually is. Obviously,
684 * this will not work for code that depends on a fixed one to one
685 * relationship between the execution counts of the C level garbage
686 * collection hooks and the execution count of the scheme level
690 #if (SCM_DEBUG_CELL_ACCESSES == 1)
691 if (scm_debug_cells_gc_interval
== 0)
694 scm_i_thread
*t
= SCM_I_CURRENT_THREAD
;
696 if (scm_is_false (SCM_CDR (after_gc_async_cell
)))
698 SCM_SETCDR (after_gc_async_cell
, t
->active_asyncs
);
699 t
->active_asyncs
= after_gc_async_cell
;
700 t
->pending_asyncs
= 1;
708 scm_i_tag_name (scm_t_bits tag
)
712 int k
= 0xff & (tag
>> 8);
713 return (scm_smobs
[k
].name
);
716 switch (tag
) /* 7 bits */
720 case scm_tcs_cons_imcar
:
721 return "cons (immediate car)";
722 case scm_tcs_cons_nimcar
:
723 return "cons (non-immediate car)";
724 case scm_tc7_pointer
:
726 case scm_tc7_hashtable
:
730 case scm_tc7_dynamic_state
:
731 return "dynamic state";
734 case scm_tc7_objcode
:
738 case scm_tc7_vm_cont
:
739 return "vm continuation";
741 return "weak vector";
753 case scm_tc16_complex
:
754 return "complex number";
756 case scm_tc16_fraction
:
764 case scm_tc7_stringbuf
:
765 return "string buffer";
770 case scm_tc7_variable
:
777 return "smob"; /* should not occur. */
790 /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */
792 scm_after_gc_hook
= scm_make_hook (SCM_INUM0
);
793 scm_c_define ("after-gc-hook", scm_after_gc_hook
);
795 /* When the async is to run, the cdr of the gc_async pair gets set to
796 the asyncs queue of the current thread. */
797 after_gc_async_cell
= scm_cons (scm_c_make_gsubr ("%after-gc-thunk", 0, 0, 0,
798 after_gc_async_thunk
),
801 scm_c_hook_add (&scm_before_gc_c_hook
, queue_after_gc_hook
, NULL
, 0);
802 GC_set_start_callback (run_before_gc_c_hook
);
804 #include "libguile/gc.x"
810 #define FUNC_NAME "scm_gc_sweep"
813 fprintf (stderr
, "%s: doing nothing\n", FUNC_NAME
);