1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003, 2006, 2008 Free Software Foundation, Inc.
2 *
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
7 *
8 * This library is distributed in the hope that it will be useful,
9 * but 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.
12 *
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 02110-1301 USA
16 */
17
18 /* #define DEBUGINFO */
19
20 #ifdef HAVE_CONFIG_H
21 # include <config.h>
22 #endif
23
24 #include <stdio.h>
25 #include <errno.h>
26 #include <string.h>
27 #include <assert.h>
28
29 #include "libguile/_scm.h"
30 #include "libguile/eval.h"
31 #include "libguile/stime.h"
32 #include "libguile/stackchk.h"
33 #include "libguile/struct.h"
34 #include "libguile/smob.h"
35 #include "libguile/unif.h"
36 #include "libguile/async.h"
37 #include "libguile/ports.h"
38 #include "libguile/root.h"
39 #include "libguile/strings.h"
40 #include "libguile/vectors.h"
41 #include "libguile/weaks.h"
42 #include "libguile/hashtab.h"
43 #include "libguile/tags.h"
44
45 #include "libguile/private-gc.h"
46 #include "libguile/validate.h"
47 #include "libguile/deprecation.h"
48 #include "libguile/gc.h"
49 #include "libguile/dynwind.h"
50
51 #ifdef GUILE_DEBUG_MALLOC
52 #include "libguile/debug-malloc.h"
53 #endif
54
55 #ifdef HAVE_MALLOC_H
56 #include <stdlib.h>
57 #endif
58
59 #ifdef HAVE_UNISTD_H
60 #include <unistd.h>
61 #endif
62
63 /* Lock this mutex before doing lazy sweeping.
64 */
65 scm_i_pthread_mutex_t scm_i_sweep_mutex = SCM_I_PTHREAD_MUTEX_INITIALIZER;
66
67 /* Set this to != 0 if every cell that is accessed shall be checked:
68 */
69 int scm_debug_cell_accesses_p = 0;
70 int scm_expensive_debug_cell_accesses_p = 0;
71
72 /* Set this to 0 if no additional gc's shall be performed, otherwise set it to
73 * the number of cell accesses after which a gc shall be called.
74 */
75 int scm_debug_cells_gc_interval = 0;
76
77 /*
78 Global variable, so you can switch it off at runtime by setting
79 scm_i_cell_validation_already_running.
80 */
81 int scm_i_cell_validation_already_running ;
82
83 #if (SCM_DEBUG_CELL_ACCESSES == 1)
84
85
86 /*
87
88 Assert that the given object is a valid reference to a valid cell. This
89 test involves to determine whether the object is a cell pointer, whether
90 this pointer actually points into a heap segment and whether the cell
91 pointed to is not a free cell. Further, additional garbage collections may
92 get executed after a user defined number of cell accesses. This helps to
93 find places in the C code where references are dropped for extremely short
94 periods.
95
96 */
97 void
scm_i_expensive_validation_check(SCM cell)98 scm_i_expensive_validation_check (SCM cell)
99 {
100 if (!scm_in_heap_p (cell))
101 {
102 fprintf (stderr, "scm_assert_cell_valid: this object does not live in the heap: %lux\n",
103 (unsigned long) SCM_UNPACK (cell));
104 abort ();
105 }
106
107 /* If desired, perform additional garbage collections after a user
108 * defined number of cell accesses.
109 */
110 if (scm_debug_cells_gc_interval)
111 {
112 static unsigned int counter = 0;
113
114 if (counter != 0)
115 {
116 --counter;
117 }
118 else
119 {
120 counter = scm_debug_cells_gc_interval;
121 scm_gc ();
122 }
123 }
124 }
125
126 void
scm_assert_cell_valid(SCM cell)127 scm_assert_cell_valid (SCM cell)
128 {
129 if (!scm_i_cell_validation_already_running && scm_debug_cell_accesses_p)
130 {
131 scm_i_cell_validation_already_running = 1; /* set to avoid recursion */
132
133 /*
134 During GC, no user-code should be run, and the guile core
135 should use non-protected accessors.
136 */
137 if (scm_gc_running_p)
138 return;
139
140 /*
141 Only scm_in_heap_p and rescanning the heap is wildly
142 expensive.
143 */
144 if (scm_expensive_debug_cell_accesses_p)
145 scm_i_expensive_validation_check (cell);
146
147 if (!SCM_GC_MARK_P (cell))
148 {
149 fprintf (stderr,
150 "scm_assert_cell_valid: this object is unmarked. \n"
151 "It has been garbage-collected in the last GC run: "
152 "%lux\n",
153 (unsigned long) SCM_UNPACK (cell));
154 abort ();
155 }
156
157 scm_i_cell_validation_already_running = 0; /* re-enable */
158 }
159 }
160
161
162
163 SCM_DEFINE (scm_set_debug_cell_accesses_x, "set-debug-cell-accesses!", 1, 0, 0,
164 (SCM flag),
165 "If @var{flag} is @code{#f}, cell access checking is disabled.\n"
166 "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n"
167 "but no additional calls to garbage collection are issued.\n"
168 "If @var{flag} is a number, strict cell access checking is enabled,\n"
169 "with an additional garbage collection after the given\n"
170 "number of cell accesses.\n"
171 "This procedure only exists when the compile-time flag\n"
172 "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.")
173 #define FUNC_NAME s_scm_set_debug_cell_accesses_x
174 {
175 if (scm_is_false (flag))
176 {
177 scm_debug_cell_accesses_p = 0;
178 }
179 else if (scm_is_eq (flag, SCM_BOOL_T))
180 {
181 scm_debug_cells_gc_interval = 0;
182 scm_debug_cell_accesses_p = 1;
183 scm_expensive_debug_cell_accesses_p = 0;
184 }
185 else
186 {
187 scm_debug_cells_gc_interval = scm_to_signed_integer (flag, 0, INT_MAX);
188 scm_debug_cell_accesses_p = 1;
189 scm_expensive_debug_cell_accesses_p = 1;
190 }
191 return SCM_UNSPECIFIED;
192 }
193 #undef FUNC_NAME
194
195
196 #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */
197
198
199
200
201 /* scm_mtrigger
202 * is the number of bytes of malloc allocation needed to trigger gc.
203 */
204 unsigned long scm_mtrigger;
205
206 /* GC Statistics Keeping
207 */
208 unsigned long scm_cells_allocated = 0;
209 unsigned long scm_last_cells_allocated;
210 unsigned long scm_mallocated = 0;
211 unsigned long scm_gc_cells_collected;
212 unsigned long scm_gc_cells_collected_1 = 0; /* previous GC yield */
213 unsigned long scm_gc_malloc_collected;
214 unsigned long scm_gc_ports_collected;
215 unsigned long scm_gc_time_taken = 0;
216 static unsigned long t_before_gc;
217 unsigned long scm_gc_mark_time_taken = 0;
218 unsigned long scm_gc_times = 0;
219 unsigned long scm_gc_cells_swept = 0;
220 double scm_gc_cells_marked_acc = 0.;
221 double scm_gc_cells_swept_acc = 0.;
222 double scm_gc_cells_allocated_acc = 0.;
223 int scm_gc_cell_yield_percentage =0;
224 int scm_gc_malloc_yield_percentage = 0;
225 unsigned long protected_obj_count = 0;
226
227
228 SCM_SYMBOL (sym_cells_allocated, "cells-allocated");
229 SCM_SYMBOL (sym_heap_size, "cell-heap-size");
230 SCM_SYMBOL (sym_mallocated, "bytes-malloced");
231 SCM_SYMBOL (sym_mtrigger, "gc-malloc-threshold");
232 SCM_SYMBOL (sym_heap_segments, "cell-heap-segments");
233 SCM_SYMBOL (sym_gc_time_taken, "gc-time-taken");
234 SCM_SYMBOL (sym_gc_mark_time_taken, "gc-mark-time-taken");
235 SCM_SYMBOL (sym_times, "gc-times");
236 SCM_SYMBOL (sym_cells_marked, "cells-marked");
237 SCM_SYMBOL (sym_cells_swept, "cells-swept");
238 SCM_SYMBOL (sym_malloc_yield, "malloc-yield");
239 SCM_SYMBOL (sym_cell_yield, "cell-yield");
240 SCM_SYMBOL (sym_protected_objects, "protected-objects");
241 SCM_SYMBOL (sym_total_cells_allocated, "total-cells-allocated");
242
243
244
245
246 /* Number of calls to SCM_NEWCELL since startup. */
247 unsigned scm_newcell_count;
248 unsigned scm_newcell2_count;
249
250
251 /* {Scheme Interface to GC}
252 */
253 static SCM
tag_table_to_type_alist(void * closure,SCM key,SCM val,SCM acc)254 tag_table_to_type_alist (void *closure, SCM key, SCM val, SCM acc)
255 {
256 if (scm_is_integer (key))
257 {
258 int c_tag = scm_to_int (key);
259
260 char const * name = scm_i_tag_name (c_tag);
261 if (name != NULL)
262 {
263 key = scm_from_locale_string (name);
264 }
265 else
266 {
267 char s[100];
268 sprintf (s, "tag %d", c_tag);
269 key = scm_from_locale_string (s);
270 }
271 }
272
273 return scm_cons (scm_cons (key, val), acc);
274 }
275
276 SCM_DEFINE (scm_gc_live_object_stats, "gc-live-object-stats", 0, 0, 0,
277 (),
278 "Return an alist of statistics of the current live objects. ")
279 #define FUNC_NAME s_scm_gc_live_object_stats
280 {
281 SCM tab = scm_make_hash_table (scm_from_int (57));
282 SCM alist;
283
284 scm_i_all_segments_statistics (tab);
285
286 alist
287 = scm_internal_hash_fold (&tag_table_to_type_alist, NULL, SCM_EOL, tab);
288
289 return alist;
290 }
291 #undef FUNC_NAME
292
293 extern int scm_gc_malloc_yield_percentage;
294 SCM_DEFINE (scm_gc_stats, "gc-stats", 0, 0, 0,
295 (),
296 "Return an association list of statistics about Guile's current\n"
297 "use of storage.\n")
298 #define FUNC_NAME s_scm_gc_stats
299 {
300 long i = 0;
301 SCM heap_segs = SCM_EOL ;
302 unsigned long int local_scm_mtrigger;
303 unsigned long int local_scm_mallocated;
304 unsigned long int local_scm_heap_size;
305 int local_scm_gc_cell_yield_percentage;
306 int local_scm_gc_malloc_yield_percentage;
307 unsigned long int local_scm_cells_allocated;
308 unsigned long int local_scm_gc_time_taken;
309 unsigned long int local_scm_gc_times;
310 unsigned long int local_scm_gc_mark_time_taken;
311 unsigned long int local_protected_obj_count;
312 double local_scm_gc_cells_swept;
313 double local_scm_gc_cells_marked;
314 double local_scm_total_cells_allocated;
315 SCM answer;
316 unsigned long *bounds = 0;
317 int table_size = scm_i_heap_segment_table_size;
318 SCM_CRITICAL_SECTION_START;
319
320 /*
321 temporarily store the numbers, so as not to cause GC.
322 */
323
324 bounds = malloc (sizeof (unsigned long) * table_size * 2);
325 if (!bounds)
326 abort();
327 for (i = table_size; i--; )
328 {
329 bounds[2*i] = (unsigned long)scm_i_heap_segment_table[i]->bounds[0];
330 bounds[2*i+1] = (unsigned long)scm_i_heap_segment_table[i]->bounds[1];
331 }
332
333
334 /* Below, we cons to produce the resulting list. We want a snapshot of
335 * the heap situation before consing.
336 */
337 local_scm_mtrigger = scm_mtrigger;
338 local_scm_mallocated = scm_mallocated;
339 local_scm_heap_size = SCM_HEAP_SIZE;
340
341 local_scm_cells_allocated = scm_cells_allocated;
342
343 local_scm_gc_time_taken = scm_gc_time_taken;
344 local_scm_gc_mark_time_taken = scm_gc_mark_time_taken;
345 local_scm_gc_times = scm_gc_times;
346 local_scm_gc_malloc_yield_percentage = scm_gc_malloc_yield_percentage;
347 local_scm_gc_cell_yield_percentage= scm_gc_cell_yield_percentage;
348 local_protected_obj_count = protected_obj_count;
349 local_scm_gc_cells_swept =
350 (double) scm_gc_cells_swept_acc
351 + (double) scm_gc_cells_swept;
352 local_scm_gc_cells_marked = scm_gc_cells_marked_acc
353 +(double) scm_gc_cells_swept
354 -(double) scm_gc_cells_collected;
355
356 local_scm_total_cells_allocated = scm_gc_cells_allocated_acc
357 + (double) (scm_cells_allocated - scm_last_cells_allocated);
358
359 for (i = table_size; i--;)
360 {
361 heap_segs = scm_cons (scm_cons (scm_from_ulong (bounds[2*i]),
362 scm_from_ulong (bounds[2*i+1])),
363 heap_segs);
364 }
365 /* njrev: can any of these scm_cons's or scm_list_n signal a memory
366 error? If so we need a frame here. */
367 answer =
368 scm_list_n (scm_cons (sym_gc_time_taken,
369 scm_from_ulong (local_scm_gc_time_taken)),
370 scm_cons (sym_cells_allocated,
371 scm_from_ulong (local_scm_cells_allocated)),
372 scm_cons (sym_total_cells_allocated,
373 scm_from_ulong (local_scm_total_cells_allocated)),
374 scm_cons (sym_heap_size,
375 scm_from_ulong (local_scm_heap_size)),
376 scm_cons (sym_mallocated,
377 scm_from_ulong (local_scm_mallocated)),
378 scm_cons (sym_mtrigger,
379 scm_from_ulong (local_scm_mtrigger)),
380 scm_cons (sym_times,
381 scm_from_ulong (local_scm_gc_times)),
382 scm_cons (sym_gc_mark_time_taken,
383 scm_from_ulong (local_scm_gc_mark_time_taken)),
384 scm_cons (sym_cells_marked,
385 scm_from_double (local_scm_gc_cells_marked)),
386 scm_cons (sym_cells_swept,
387 scm_from_double (local_scm_gc_cells_swept)),
388 scm_cons (sym_malloc_yield,
389 scm_from_long(local_scm_gc_malloc_yield_percentage)),
390 scm_cons (sym_cell_yield,
391 scm_from_long (local_scm_gc_cell_yield_percentage)),
392 scm_cons (sym_protected_objects,
393 scm_from_ulong (local_protected_obj_count)),
394 scm_cons (sym_heap_segments, heap_segs),
395 SCM_UNDEFINED);
396 SCM_CRITICAL_SECTION_END;
397
398 free (bounds);
399 return answer;
400 }
401 #undef FUNC_NAME
402
403 static void
gc_start_stats(const char * what SCM_UNUSED)404 gc_start_stats (const char *what SCM_UNUSED)
405 {
406 t_before_gc = scm_c_get_internal_run_time ();
407
408 scm_gc_cells_marked_acc += (double) scm_gc_cells_swept
409 - (double) scm_gc_cells_collected;
410 scm_gc_cells_swept_acc += (double) scm_gc_cells_swept;
411
412 scm_gc_cell_yield_percentage = ( scm_gc_cells_collected * 100 ) / SCM_HEAP_SIZE;
413
414 scm_gc_cells_swept = 0;
415 scm_gc_cells_collected_1 = scm_gc_cells_collected;
416
417 /*
418 CELLS SWEPT is another word for the number of cells that were
419 examined during GC. YIELD is the number that we cleaned
420 out. MARKED is the number that weren't cleaned.
421 */
422 scm_gc_cells_collected = 0;
423 scm_gc_malloc_collected = 0;
424 scm_gc_ports_collected = 0;
425 }
426
427 static void
gc_end_stats()428 gc_end_stats ()
429 {
430 unsigned long t = scm_c_get_internal_run_time ();
431 scm_gc_time_taken += (t - t_before_gc);
432
433 ++scm_gc_times;
434 }
435
436
437 SCM_DEFINE (scm_object_address, "object-address", 1, 0, 0,
438 (SCM obj),
439 "Return an integer that for the lifetime of @var{obj} is uniquely\n"
440 "returned by this function for @var{obj}")
441 #define FUNC_NAME s_scm_object_address
442 {
443 return scm_from_ulong (SCM_UNPACK (obj));
444 }
445 #undef FUNC_NAME
446
447
448 SCM_DEFINE (scm_gc, "gc", 0, 0, 0,
449 (),
450 "Scans all of SCM objects and reclaims for further use those that are\n"
451 "no longer accessible.")
452 #define FUNC_NAME s_scm_gc
453 {
454 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex);
455 scm_gc_running_p = 1;
456 scm_i_gc ("call");
457 /* njrev: It looks as though other places, e.g. scm_realloc,
458 can call scm_i_gc without acquiring the sweep mutex. Does this
459 matter? Also scm_i_gc (or its descendants) touch the
460 scm_sys_protects, which are protected in some cases
461 (e.g. scm_permobjs above in scm_gc_stats) by a critical section,
462 not by the sweep mutex. Shouldn't all the GC-relevant objects be
463 protected in the same way? */
464 scm_gc_running_p = 0;
465 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex);
466 scm_c_hook_run (&scm_after_gc_c_hook, 0);
467 return SCM_UNSPECIFIED;
468 }
469 #undef FUNC_NAME
470
471
472
473
474 /* The master is global and common while the freelist will be
475 * individual for each thread.
476 */
477
478 SCM
scm_gc_for_newcell(scm_t_cell_type_statistics * freelist,SCM * free_cells)479 scm_gc_for_newcell (scm_t_cell_type_statistics *freelist, SCM *free_cells)
480 {
481 SCM cell;
482 int did_gc = 0;
483
484 scm_i_scm_pthread_mutex_lock (&scm_i_sweep_mutex);
485 scm_gc_running_p = 1;
486
487 *free_cells = scm_i_sweep_some_segments (freelist);
488 if (*free_cells == SCM_EOL && scm_i_gc_grow_heap_p (freelist))
489 {
490 freelist->heap_segment_idx = scm_i_get_new_heap_segment (freelist, abort_on_error);
491 *free_cells = scm_i_sweep_some_segments (freelist);
492 }
493
494 if (*free_cells == SCM_EOL)
495 {
496 /*
497 with the advent of lazy sweep, GC yield is only known just
498 before doing the GC.
499 */
500 scm_i_adjust_min_yield (freelist);
501
502 /*
503 out of fresh cells. Try to get some new ones.
504 */
505
506 did_gc = 1;
507 scm_i_gc ("cells");
508
509 *free_cells = scm_i_sweep_some_segments (freelist);
510 }
511
512 if (*free_cells == SCM_EOL)
513 {
514 /*
515 failed getting new cells. Get new juice or die.
516 */
517 freelist->heap_segment_idx = scm_i_get_new_heap_segment (freelist, abort_on_error);
518 *free_cells = scm_i_sweep_some_segments (freelist);
519 }
520
521 if (*free_cells == SCM_EOL)
522 abort ();
523
524 cell = *free_cells;
525
526 *free_cells = SCM_FREE_CELL_CDR (cell);
527
528 scm_gc_running_p = 0;
529 scm_i_pthread_mutex_unlock (&scm_i_sweep_mutex);
530
531 if (did_gc)
532 scm_c_hook_run (&scm_after_gc_c_hook, 0);
533
534 return cell;
535 }
536
537
538 scm_t_c_hook scm_before_gc_c_hook;
539 scm_t_c_hook scm_before_mark_c_hook;
540 scm_t_c_hook scm_before_sweep_c_hook;
541 scm_t_c_hook scm_after_sweep_c_hook;
542 scm_t_c_hook scm_after_gc_c_hook;
543
544 /* Must be called while holding scm_i_sweep_mutex.
545 */
546
547 void
scm_i_gc(const char * what)548 scm_i_gc (const char *what)
549 {
550 scm_i_thread_put_to_sleep ();
551
552 scm_c_hook_run (&scm_before_gc_c_hook, 0);
553
554 #ifdef DEBUGINFO
555 fprintf (stderr,"gc reason %s\n", what);
556
557 fprintf (stderr,
558 scm_is_null (*SCM_FREELIST_LOC (scm_i_freelist))
559 ? "*"
560 : (scm_is_null (*SCM_FREELIST_LOC (scm_i_freelist2)) ? "o" : "m"));
561 #endif
562
563 gc_start_stats (what);
564
565 /*
566 Set freelists to NULL so scm_cons() always triggers gc, causing
567 the assertion above to fail.
568 */
569 *SCM_FREELIST_LOC (scm_i_freelist) = SCM_EOL;
570 *SCM_FREELIST_LOC (scm_i_freelist2) = SCM_EOL;
571
572 /*
573 Let's finish the sweep. The conservative GC might point into the
574 garbage, and marking that would create a mess.
575 */
576 scm_i_sweep_all_segments("GC");
577 if (scm_mallocated < scm_i_deprecated_memory_return)
578 {
579 /* The byte count of allocated objects has underflowed. This is
580 probably because you forgot to report the sizes of objects you
581 have allocated, by calling scm_done_malloc or some such. When
582 the GC freed them, it subtracted their size from
583 scm_mallocated, which underflowed. */
584 fprintf (stderr,
585 "scm_gc_sweep: Byte count of allocated objects has underflowed.\n"
586 "This is probably because the GC hasn't been correctly informed\n"
587 "about object sizes\n");
588 abort ();
589 }
590 scm_mallocated -= scm_i_deprecated_memory_return;
591
592
593 /* Mark */
594
595 scm_c_hook_run (&scm_before_mark_c_hook, 0);
596 scm_mark_all ();
597 scm_gc_mark_time_taken += (scm_c_get_internal_run_time () - t_before_gc);
598
599 /* Sweep
600
601 TODO: the after_sweep hook should probably be moved to just before
602 the mark, since that's where the sweep is finished in lazy
603 sweeping.
604
605 MDJ 030219 <djurfeldt@nada.kth.se>: No, probably not. The
606 original meaning implied at least two things: that it would be
607 called when
608
609 1. the freelist is re-initialized (no evaluation possible, though)
610
611 and
612
613 2. the heap is "fresh"
614 (it is well-defined what data is used and what is not)
615
616 Neither of these conditions would hold just before the mark phase.
617
618 Of course, the lazy sweeping has muddled the distinction between
619 scm_before_sweep_c_hook and scm_after_sweep_c_hook, but even if
620 there were no difference, it would still be useful to have two
621 distinct classes of hook functions since this can prevent some
622 bad interference when several modules adds gc hooks.
623 */
624
625 scm_c_hook_run (&scm_before_sweep_c_hook, 0);
626 scm_gc_sweep ();
627 scm_c_hook_run (&scm_after_sweep_c_hook, 0);
628
629 gc_end_stats ();
630
631 scm_i_thread_wake_up ();
632
633 /*
634 For debugging purposes, you could do
635 scm_i_sweep_all_segments("debug"), but then the remains of the
636 cell aren't left to analyse.
637 */
638 }
639
640
641 /* {GC Protection Helper Functions}
642 */
643
644
645 /*
646 * If within a function you need to protect one or more scheme objects from
647 * garbage collection, pass them as parameters to one of the
648 * scm_remember_upto_here* functions below. These functions don't do
649 * anything, but since the compiler does not know that they are actually
650 * no-ops, it will generate code that calls these functions with the given
651 * parameters. Therefore, you can be sure that the compiler will keep those
652 * scheme values alive (on the stack or in a register) up to the point where
653 * scm_remember_upto_here* is called. In other words, place the call to
654 * scm_remember_upto_here* _behind_ the last code in your function, that
655 * depends on the scheme object to exist.
656 *
657 * Example: We want to make sure that the string object str does not get
658 * garbage collected during the execution of 'some_function' in the code
659 * below, because otherwise the characters belonging to str would be freed and
660 * 'some_function' might access freed memory. To make sure that the compiler
661 * keeps str alive on the stack or in a register such that it is visible to
662 * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the
663 * call to 'some_function'. Note that this would not be necessary if str was
664 * used anyway after the call to 'some_function'.
665 * char *chars = scm_i_string_chars (str);
666 * some_function (chars);
667 * scm_remember_upto_here_1 (str); // str will be alive up to this point.
668 */
669
670 /* Remove any macro versions of these while defining the functions.
671 Functions are always included in the library, for upward binary
672 compatibility and in case combinations of GCC and non-GCC are used. */
673 #undef scm_remember_upto_here_1
674 #undef scm_remember_upto_here_2
675
676 void
scm_remember_upto_here_1(SCM obj SCM_UNUSED)677 scm_remember_upto_here_1 (SCM obj SCM_UNUSED)
678 {
679 /* Empty. Protects a single object from garbage collection. */
680 }
681
682 void
scm_remember_upto_here_2(SCM obj1 SCM_UNUSED,SCM obj2 SCM_UNUSED)683 scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED, SCM obj2 SCM_UNUSED)
684 {
685 /* Empty. Protects two objects from garbage collection. */
686 }
687
688 void
scm_remember_upto_here(SCM obj SCM_UNUSED,...)689 scm_remember_upto_here (SCM obj SCM_UNUSED, ...)
690 {
691 /* Empty. Protects any number of objects from garbage collection. */
692 }
693
694 /*
695 These crazy functions prevent garbage collection
696 of arguments after the first argument by
697 ensuring they remain live throughout the
698 function because they are used in the last
699 line of the code block.
700 It'd be better to have a nice compiler hint to
701 aid the conservative stack-scanning GC. --03/09/00 gjb */
702 SCM
scm_return_first(SCM elt,...)703 scm_return_first (SCM elt, ...)
704 {
705 return elt;
706 }
707
708 int
scm_return_first_int(int i,...)709 scm_return_first_int (int i, ...)
710 {
711 return i;
712 }
713
714
715 SCM
scm_permanent_object(SCM obj)716 scm_permanent_object (SCM obj)
717 {
718 SCM cell = scm_cons (obj, SCM_EOL);
719 SCM_CRITICAL_SECTION_START;
720 SCM_SETCDR (cell, scm_permobjs);
721 scm_permobjs = cell;
722 SCM_CRITICAL_SECTION_END;
723 return obj;
724 }
725
726
727 /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all
728 other references are dropped, until the object is unprotected by calling
729 scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest,
730 i. e. it is possible to protect the same object several times, but it is
731 necessary to unprotect the object the same number of times to actually get
732 the object unprotected. It is an error to unprotect an object more often
733 than it has been protected before. The function scm_protect_object returns
734 OBJ.
735 */
736
737 /* Implementation note: For every object X, there is a counter which
738 scm_gc_protect_object(X) increments and scm_gc_unprotect_object(X) decrements.
739 */
740
741
742
743 SCM
scm_gc_protect_object(SCM obj)744 scm_gc_protect_object (SCM obj)
745 {
746 SCM handle;
747
748 /* This critical section barrier will be replaced by a mutex. */
749 /* njrev: Indeed; if my comment above is correct, there is the same
750 critsec/mutex inconsistency here. */
751 SCM_CRITICAL_SECTION_START;
752
753 handle = scm_hashq_create_handle_x (scm_protects, obj, scm_from_int (0));
754 SCM_SETCDR (handle, scm_sum (SCM_CDR (handle), scm_from_int (1)));
755
756 protected_obj_count ++;
757
758 SCM_CRITICAL_SECTION_END;
759
760 return obj;
761 }
762
763
764 /* Remove any protection for OBJ established by a prior call to
765 scm_protect_object. This function returns OBJ.
766
767 See scm_protect_object for more information. */
768 SCM
scm_gc_unprotect_object(SCM obj)769 scm_gc_unprotect_object (SCM obj)
770 {
771 SCM handle;
772
773 /* This critical section barrier will be replaced by a mutex. */
774 /* njrev: and again. */
775 SCM_CRITICAL_SECTION_START;
776
777 if (scm_gc_running_p)
778 {
779 fprintf (stderr, "scm_unprotect_object called during GC.\n");
780 abort ();
781 }
782
783 handle = scm_hashq_get_handle (scm_protects, obj);
784
785 if (scm_is_false (handle))
786 {
787 fprintf (stderr, "scm_unprotect_object called on unprotected object\n");
788 abort ();
789 }
790 else
791 {
792 SCM count = scm_difference (SCM_CDR (handle), scm_from_int (1));
793 if (scm_is_eq (count, scm_from_int (0)))
794 scm_hashq_remove_x (scm_protects, obj);
795 else
796 SCM_SETCDR (handle, count);
797 }
798 protected_obj_count --;
799
800 SCM_CRITICAL_SECTION_END;
801
802 return obj;
803 }
804
805 void
scm_gc_register_root(SCM * p)806 scm_gc_register_root (SCM *p)
807 {
808 SCM handle;
809 SCM key = scm_from_ulong ((unsigned long) p);
810
811 /* This critical section barrier will be replaced by a mutex. */
812 /* njrev: and again. */
813 SCM_CRITICAL_SECTION_START;
814
815 handle = scm_hashv_create_handle_x (scm_gc_registered_roots, key,
816 scm_from_int (0));
817 /* njrev: note also that the above can probably signal an error */
818 SCM_SETCDR (handle, scm_sum (SCM_CDR (handle), scm_from_int (1)));
819
820 SCM_CRITICAL_SECTION_END;
821 }
822
823 void
scm_gc_unregister_root(SCM * p)824 scm_gc_unregister_root (SCM *p)
825 {
826 SCM handle;
827 SCM key = scm_from_ulong ((unsigned long) p);
828
829 /* This critical section barrier will be replaced by a mutex. */
830 /* njrev: and again. */
831 SCM_CRITICAL_SECTION_START;
832
833 handle = scm_hashv_get_handle (scm_gc_registered_roots, key);
834
835 if (scm_is_false (handle))
836 {
837 fprintf (stderr, "scm_gc_unregister_root called on unregistered root\n");
838 abort ();
839 }
840 else
841 {
842 SCM count = scm_difference (SCM_CDR (handle), scm_from_int (1));
843 if (scm_is_eq (count, scm_from_int (0)))
844 scm_hashv_remove_x (scm_gc_registered_roots, key);
845 else
846 SCM_SETCDR (handle, count);
847 }
848
849 SCM_CRITICAL_SECTION_END;
850 }
851
852 void
scm_gc_register_roots(SCM * b,unsigned long n)853 scm_gc_register_roots (SCM *b, unsigned long n)
854 {
855 SCM *p = b;
856 for (; p < b + n; ++p)
857 scm_gc_register_root (p);
858 }
859
860 void
scm_gc_unregister_roots(SCM * b,unsigned long n)861 scm_gc_unregister_roots (SCM *b, unsigned long n)
862 {
863 SCM *p = b;
864 for (; p < b + n; ++p)
865 scm_gc_unregister_root (p);
866 }
867
868 int scm_i_terminating;
869
870
871
872
873 /*
874 MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC.
875 */
876
877 /* Get an integer from an environment variable. */
878 int
scm_getenv_int(const char * var,int def)879 scm_getenv_int (const char *var, int def)
880 {
881 char *end = 0;
882 char *val = getenv (var);
883 long res = def;
884 if (!val)
885 return def;
886 res = strtol (val, &end, 10);
887 if (end == val)
888 return def;
889 return res;
890 }
891
892 void
scm_storage_prehistory()893 scm_storage_prehistory ()
894 {
895 scm_c_hook_init (&scm_before_gc_c_hook, 0, SCM_C_HOOK_NORMAL);
896 scm_c_hook_init (&scm_before_mark_c_hook, 0, SCM_C_HOOK_NORMAL);
897 scm_c_hook_init (&scm_before_sweep_c_hook, 0, SCM_C_HOOK_NORMAL);
898 scm_c_hook_init (&scm_after_sweep_c_hook, 0, SCM_C_HOOK_NORMAL);
899 scm_c_hook_init (&scm_after_gc_c_hook, 0, SCM_C_HOOK_NORMAL);
900 }
901
902 scm_i_pthread_mutex_t scm_i_gc_admin_mutex = SCM_I_PTHREAD_MUTEX_INITIALIZER;
903
904 int
scm_init_storage()905 scm_init_storage ()
906 {
907 size_t j;
908
909 j = SCM_NUM_PROTECTS;
910 while (j)
911 scm_sys_protects[--j] = SCM_BOOL_F;
912
913 scm_gc_init_freelist();
914 scm_gc_init_malloc ();
915
916 j = SCM_HEAP_SEG_SIZE;
917
918
919 /* Initialise the list of ports. */
920 scm_i_port_table = (scm_t_port **)
921 malloc (sizeof (scm_t_port *) * scm_i_port_table_room);
922 if (!scm_i_port_table)
923 return 1;
924
925 #if 0
926 /* We can't have a cleanup handler since we have no thread to run it
927 in. */
928
929 #ifdef HAVE_ATEXIT
930 atexit (cleanup);
931 #else
932 #ifdef HAVE_ON_EXIT
933 on_exit (cleanup, 0);
934 #endif
935 #endif
936
937 #endif
938
939 scm_stand_in_procs = scm_make_weak_key_hash_table (scm_from_int (257));
940 scm_permobjs = SCM_EOL;
941 scm_protects = scm_c_make_hash_table (31);
942 scm_gc_registered_roots = scm_c_make_hash_table (31);
943
944 return 0;
945 }
946
947
948
949 SCM scm_after_gc_hook;
950
951 static SCM gc_async;
952
953 /* The function gc_async_thunk causes the execution of the after-gc-hook. It
954 * is run after the gc, as soon as the asynchronous events are handled by the
955 * evaluator.
956 */
957 static SCM
gc_async_thunk(void)958 gc_async_thunk (void)
959 {
960 scm_c_run_hook (scm_after_gc_hook, SCM_EOL);
961 return SCM_UNSPECIFIED;
962 }
963
964
965 /* The function mark_gc_async is run by the scm_after_gc_c_hook at the end of
966 * the garbage collection. The only purpose of this function is to mark the
967 * gc_async (which will eventually lead to the execution of the
968 * gc_async_thunk).
969 */
970 static void *
mark_gc_async(void * hook_data SCM_UNUSED,void * fn_data SCM_UNUSED,void * data SCM_UNUSED)971 mark_gc_async (void * hook_data SCM_UNUSED,
972 void *fn_data SCM_UNUSED,
973 void *data SCM_UNUSED)
974 {
975 /* If cell access debugging is enabled, the user may choose to perform
976 * additional garbage collections after an arbitrary number of cell
977 * accesses. We don't want the scheme level after-gc-hook to be performed
978 * for each of these garbage collections for the following reason: The
979 * execution of the after-gc-hook causes cell accesses itself. Thus, if the
980 * after-gc-hook was performed with every gc, and if the gc was performed
981 * after a very small number of cell accesses, then the number of cell
982 * accesses during the execution of the after-gc-hook will suffice to cause
983 * the execution of the next gc. Then, guile would keep executing the
984 * after-gc-hook over and over again, and would never come to do other
985 * things.
986 *
987 * To overcome this problem, if cell access debugging with additional
988 * garbage collections is enabled, the after-gc-hook is never run by the
989 * garbage collecter. When running guile with cell access debugging and the
990 * execution of the after-gc-hook is desired, then it is necessary to run
991 * the hook explicitly from the user code. This has the effect, that from
992 * the scheme level point of view it seems that garbage collection is
993 * performed with a much lower frequency than it actually is. Obviously,
994 * this will not work for code that depends on a fixed one to one
995 * relationship between the execution counts of the C level garbage
996 * collection hooks and the execution count of the scheme level
997 * after-gc-hook.
998 */
999
1000 #if (SCM_DEBUG_CELL_ACCESSES == 1)
1001 if (scm_debug_cells_gc_interval == 0)
1002 scm_system_async_mark (gc_async);
1003 #else
1004 scm_system_async_mark (gc_async);
1005 #endif
1006
1007 return NULL;
1008 }
1009
1010 void
scm_init_gc()1011 scm_init_gc ()
1012 {
1013 scm_gc_init_mark ();
1014
1015 scm_after_gc_hook = scm_permanent_object (scm_make_hook (SCM_INUM0));
1016 scm_c_define ("after-gc-hook", scm_after_gc_hook);
1017
1018 gc_async = scm_c_make_subr ("%gc-thunk", scm_tc7_subr_0,
1019 gc_async_thunk);
1020
1021 scm_c_hook_add (&scm_after_gc_c_hook, mark_gc_async, NULL, 0);
1022
1023 #include "libguile/gc.x"
1024 }
1025
1026 #ifdef __ia64__
1027 # ifdef __hpux
1028 # include <sys/param.h>
1029 # include <sys/pstat.h>
1030 void *
scm_ia64_register_backing_store_base(void)1031 scm_ia64_register_backing_store_base (void)
1032 {
1033 struct pst_vm_status vm_status;
1034 int i = 0;
1035 while (pstat_getprocvm (&vm_status, sizeof (vm_status), 0, i++) == 1)
1036 if (vm_status.pst_type == PS_RSESTACK)
1037 return (void *) vm_status.pst_vaddr;
1038 abort ();
1039 }
1040 void *
scm_ia64_ar_bsp(const void * ctx)1041 scm_ia64_ar_bsp (const void *ctx)
1042 {
1043 uint64_t bsp;
1044 __uc_get_ar_bsp(ctx, &bsp);
1045 return (void *) bsp;
1046 }
1047 # endif /* hpux */
1048 # ifdef linux
1049 # include <ucontext.h>
1050 void *
scm_ia64_register_backing_store_base(void)1051 scm_ia64_register_backing_store_base (void)
1052 {
1053 extern void *__libc_ia64_register_backing_store_base;
1054 return __libc_ia64_register_backing_store_base;
1055 }
1056 void *
scm_ia64_ar_bsp(const void * opaque)1057 scm_ia64_ar_bsp (const void *opaque)
1058 {
1059 const ucontext_t *ctx = opaque;
1060 return (void *) ctx->uc_mcontext.sc_ar_bsp;
1061 }
1062 # endif /* linux */
1063 # ifdef __FreeBSD__
1064 # include <ucontext.h>
1065 void *
scm_ia64_register_backing_store_base(void)1066 scm_ia64_register_backing_store_base (void)
1067 {
1068 return (void *)0x8000000000000000;
1069 }
1070 void *
scm_ia64_ar_bsp(const void * opaque)1071 scm_ia64_ar_bsp (const void *opaque)
1072 {
1073 const ucontext_t *ctx = opaque;
1074 return (void *)(ctx->uc_mcontext.mc_special.bspstore + ctx->uc_mcontext.mc_special.ndirty);
1075 }
1076 # endif /* __FreeBSD__ */
1077 #endif /* __ia64__ */
1078
1079 void
scm_gc_sweep(void)1080 scm_gc_sweep (void)
1081 #define FUNC_NAME "scm_gc_sweep"
1082 {
1083 scm_i_deprecated_memory_return = 0;
1084
1085 scm_i_gc_sweep_freelist_reset (&scm_i_master_freelist);
1086 scm_i_gc_sweep_freelist_reset (&scm_i_master_freelist2);
1087
1088 /*
1089 NOTHING HERE: LAZY SWEEPING !
1090 */
1091 scm_i_reset_segments ();
1092
1093 *SCM_FREELIST_LOC (scm_i_freelist) = SCM_EOL;
1094 *SCM_FREELIST_LOC (scm_i_freelist2) = SCM_EOL;
1095
1096 /* Invalidate the freelists of other threads. */
1097 scm_i_thread_invalidate_freelists ();
1098 }
1099
1100 #undef FUNC_NAME
1101
1102
1103
1104 /*
1105 Local Variables:
1106 c-file-style: "gnu"
1107 End:
1108 */
1109