1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
|
/*
Reference Cycle Garbage Collection
==================================
Neil Schemenauer <nas@arctrix.com>
Based on a post on the python-dev list. Ideas from Guido van Rossum,
Eric Tiedemann, and various others.
http://www.arctrix.com/nas/python/gc/
http://www.python.org/pipermail/python-dev/2000-March/003869.html
http://www.python.org/pipermail/python-dev/2000-March/004010.html
http://www.python.org/pipermail/python-dev/2000-March/004022.html
For a highlevel view of the collection process, read the collect
function.
*/
#include "Python.h"
#ifdef WITH_CYCLE_GC
/* Get an object's GC head */
#define AS_GC(o) ((PyGC_Head *)(o)-1)
/* Get the object given the GC head */
#define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1))
/*** Global GC state ***/
/* linked lists of container objects */
PyGC_Head _PyGC_generation0 = {{&_PyGC_generation0, &_PyGC_generation0, 0}};
static PyGC_Head generation1 = {{&generation1, &generation1, 0}};
static PyGC_Head generation2 = {{&generation2, &generation2, 0}};
static int generation = 0; /* current generation being collected */
/* collection frequencies, XXX tune these */
static int enabled = 1; /* automatic collection enabled? */
static int threshold0 = 700; /* net new containers before collection */
static int threshold1 = 10; /* generation0 collections before collecting 1 */
static int threshold2 = 10; /* generation1 collections before collecting 2 */
/* net new objects allocated since last collection */
static int allocated;
/* true if we are currently running the collector */
static int collecting;
/* set for debugging information */
#define DEBUG_STATS (1<<0) /* print collection statistics */
#define DEBUG_COLLECTABLE (1<<1) /* print collectable objects */
#define DEBUG_UNCOLLECTABLE (1<<2) /* print uncollectable objects */
#define DEBUG_INSTANCES (1<<3) /* print instances */
#define DEBUG_OBJECTS (1<<4) /* print other objects */
#define DEBUG_SAVEALL (1<<5) /* save all garbage in gc.garbage */
#define DEBUG_LEAK DEBUG_COLLECTABLE | \
DEBUG_UNCOLLECTABLE | \
DEBUG_INSTANCES | \
DEBUG_OBJECTS | \
DEBUG_SAVEALL
static int debug;
/* Special gc_refs value */
#define GC_MOVED -123
/* list of uncollectable objects */
static PyObject *garbage;
/* Python string to use if unhandled exception occurs */
static PyObject *gc_str;
/*** list functions ***/
static void
gc_list_init(PyGC_Head *list)
{
list->gc.gc_prev = list;
list->gc.gc_next = list;
}
static void
gc_list_append(PyGC_Head *node, PyGC_Head *list)
{
node->gc.gc_next = list;
node->gc.gc_prev = list->gc.gc_prev;
node->gc.gc_prev->gc.gc_next = node;
list->gc.gc_prev = node;
}
static void
gc_list_remove(PyGC_Head *node)
{
node->gc.gc_prev->gc.gc_next = node->gc.gc_next;
node->gc.gc_next->gc.gc_prev = node->gc.gc_prev;
node->gc.gc_next = NULL; /* object is not currently tracked */
}
static void
gc_list_move(PyGC_Head *from, PyGC_Head *to)
{
if (from->gc.gc_next == from) {
/* empty from list */
gc_list_init(to);
}
else {
to->gc.gc_next = from->gc.gc_next;
to->gc.gc_next->gc.gc_prev = to;
to->gc.gc_prev = from->gc.gc_prev;
to->gc.gc_prev->gc.gc_next = to;
}
gc_list_init(from);
}
/* append a list onto another list, from becomes an empty list */
static void
gc_list_merge(PyGC_Head *from, PyGC_Head *to)
{
PyGC_Head *tail;
if (from->gc.gc_next != from) {
tail = to->gc.gc_prev;
tail->gc.gc_next = from->gc.gc_next;
tail->gc.gc_next->gc.gc_prev = tail;
to->gc.gc_prev = from->gc.gc_prev;
to->gc.gc_prev->gc.gc_next = to;
}
gc_list_init(from);
}
static long
gc_list_size(PyGC_Head *list)
{
PyGC_Head *gc;
long n = 0;
for (gc = list->gc.gc_next; gc != list; gc = gc->gc.gc_next) {
n++;
}
return n;
}
/*** end of list stuff ***/
/* Set all gc_refs = ob_refcnt */
static void
update_refs(PyGC_Head *containers)
{
PyGC_Head *gc = containers->gc.gc_next;
for (; gc != containers; gc=gc->gc.gc_next) {
gc->gc.gc_refs = FROM_GC(gc)->ob_refcnt;
}
}
static int
visit_decref(PyObject *op, void *data)
{
if (op && PyObject_IS_GC(op)) {
PyGC_Head *gc = AS_GC(op);
if (gc->gc.gc_next != NULL)
AS_GC(op)->gc.gc_refs--;
}
return 0;
}
/* Subtract internal references from gc_refs */
static void
subtract_refs(PyGC_Head *containers)
{
traverseproc traverse;
PyGC_Head *gc = containers->gc.gc_next;
for (; gc != containers; gc=gc->gc.gc_next) {
traverse = FROM_GC(gc)->ob_type->tp_traverse;
(void) traverse(FROM_GC(gc),
(visitproc)visit_decref,
NULL);
}
}
/* Append objects with gc_refs > 0 to roots list */
static void
move_roots(PyGC_Head *containers, PyGC_Head *roots)
{
PyGC_Head *next;
PyGC_Head *gc = containers->gc.gc_next;
while (gc != containers) {
next = gc->gc.gc_next;
if (gc->gc.gc_refs > 0) {
gc_list_remove(gc);
gc_list_append(gc, roots);
gc->gc.gc_refs = GC_MOVED;
}
gc = next;
}
}
static int
visit_move(PyObject *op, PyGC_Head *tolist)
{
if (PyObject_IS_GC(op)) {
PyGC_Head *gc = AS_GC(op);
if (gc->gc.gc_next != NULL && gc->gc.gc_refs != GC_MOVED) {
gc_list_remove(gc);
gc_list_append(gc, tolist);
gc->gc.gc_refs = GC_MOVED;
}
}
return 0;
}
/* Move objects referenced from reachable to reachable set. */
static void
move_root_reachable(PyGC_Head *reachable)
{
traverseproc traverse;
PyGC_Head *gc = reachable->gc.gc_next;
for (; gc != reachable; gc=gc->gc.gc_next) {
/* careful, reachable list is growing here */
PyObject *op = FROM_GC(gc);
traverse = op->ob_type->tp_traverse;
(void) traverse(op,
(visitproc)visit_move,
(void *)reachable);
}
}
/* return true of object has a finalization method */
static int
has_finalizer(PyObject *op)
{
static PyObject *delstr = NULL;
if (delstr == NULL) {
delstr = PyString_InternFromString("__del__");
if (delstr == NULL)
Py_FatalError("PyGC: can't initialize __del__ string");
}
return (PyInstance_Check(op) ||
PyType_HasFeature(op->ob_type, Py_TPFLAGS_HEAPTYPE))
&& PyObject_HasAttr(op, delstr);
}
/* Move all objects with finalizers (instances with __del__) */
static void
move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
{
PyGC_Head *next;
PyGC_Head *gc = unreachable->gc.gc_next;
for (; gc != unreachable; gc=next) {
PyObject *op = FROM_GC(gc);
next = gc->gc.gc_next;
if (has_finalizer(op)) {
gc_list_remove(gc);
gc_list_append(gc, finalizers);
}
}
}
/* Move objects referenced from roots to roots */
static void
move_finalizer_reachable(PyGC_Head *finalizers)
{
traverseproc traverse;
PyGC_Head *gc = finalizers->gc.gc_next;
for (; gc != finalizers; gc=gc->gc.gc_next) {
/* careful, finalizers list is growing here */
traverse = FROM_GC(gc)->ob_type->tp_traverse;
(void) traverse(FROM_GC(gc),
(visitproc)visit_move,
(void *)finalizers);
}
}
static void
debug_instance(char *msg, PyInstanceObject *inst)
{
char *cname;
/* simple version of instance_repr */
PyObject *classname = inst->in_class->cl_name;
if (classname != NULL && PyString_Check(classname))
cname = PyString_AsString(classname);
else
cname = "?";
PySys_WriteStderr("gc: %.100s <%.100s instance at %p>\n",
msg, cname, inst);
}
static void
debug_cycle(char *msg, PyObject *op)
{
if ((debug & DEBUG_INSTANCES) && PyInstance_Check(op)) {
debug_instance(msg, (PyInstanceObject *)op);
}
else if (debug & DEBUG_OBJECTS) {
PySys_WriteStderr("gc: %.100s <%.100s %p>\n",
msg, op->ob_type->tp_name, op);
}
}
/* Handle uncollectable garbage (cycles with finalizers). */
static void
handle_finalizers(PyGC_Head *finalizers, PyGC_Head *old)
{
PyGC_Head *gc;
if (garbage == NULL) {
garbage = PyList_New(0);
}
for (gc = finalizers->gc.gc_next; gc != finalizers;
gc = finalizers->gc.gc_next) {
PyObject *op = FROM_GC(gc);
if ((debug & DEBUG_SAVEALL) || has_finalizer(op)) {
/* If SAVEALL is not set then just append objects with
* finalizers to the list of garbage. All objects in
* the finalizers list are reachable from those
* objects. */
PyList_Append(garbage, op);
}
/* object is now reachable again */
gc_list_remove(gc);
gc_list_append(gc, old);
}
}
/* Break reference cycles by clearing the containers involved. This is
* tricky business as the lists can be changing and we don't know which
* objects may be freed. It is possible I screwed something up here. */
static void
delete_garbage(PyGC_Head *unreachable, PyGC_Head *old)
{
inquiry clear;
while (unreachable->gc.gc_next != unreachable) {
PyGC_Head *gc = unreachable->gc.gc_next;
PyObject *op = FROM_GC(gc);
if (debug & DEBUG_SAVEALL) {
PyList_Append(garbage, op);
}
else {
if ((clear = op->ob_type->tp_clear) != NULL) {
Py_INCREF(op);
clear((PyObject *)op);
Py_DECREF(op);
}
}
if (unreachable->gc.gc_next == gc) {
/* object is still alive, move it, it may die later */
gc_list_remove(gc);
gc_list_append(gc, old);
}
}
}
/* This is the main function. Read this to understand how the
* collection process works. */
static long
collect(PyGC_Head *young, PyGC_Head *old)
{
long n = 0;
long m = 0;
PyGC_Head reachable;
PyGC_Head unreachable;
PyGC_Head finalizers;
PyGC_Head *gc;
if (debug & DEBUG_STATS) {
PySys_WriteStderr(
"gc: collecting generation %d...\n"
"gc: objects in each generation: %ld %ld %ld\n",
generation,
gc_list_size(&_PyGC_generation0),
gc_list_size(&generation1),
gc_list_size(&generation2));
}
/* Using ob_refcnt and gc_refs, calculate which objects in the
* container set are reachable from outside the set (ie. have a
* refcount greater than 0 when all the references within the
* set are taken into account */
update_refs(young);
subtract_refs(young);
/* Move everything reachable from outside the set into the
* reachable set (ie. gc_refs > 0). Next, move everything
* reachable from objects in the reachable set. */
gc_list_init(&reachable);
move_roots(young, &reachable);
move_root_reachable(&reachable);
/* move unreachable objects to a temporary list, new objects can be
* allocated after this point */
gc_list_init(&unreachable);
gc_list_move(young, &unreachable);
/* move reachable objects to next generation */
gc_list_merge(&reachable, old);
/* Move objects reachable from finalizers, we can't safely delete
* them. Python programmers should take care not to create such
* things. For Python finalizers means instance objects with
* __del__ methods. */
gc_list_init(&finalizers);
move_finalizers(&unreachable, &finalizers);
move_finalizer_reachable(&finalizers);
/* Collect statistics on collectable objects found and print
* debugging information. */
for (gc = unreachable.gc.gc_next; gc != &unreachable;
gc = gc->gc.gc_next) {
m++;
if (debug & DEBUG_COLLECTABLE) {
debug_cycle("collectable", FROM_GC(gc));
}
}
/* call tp_clear on objects in the collectable set. This will cause
* the reference cycles to be broken. It may also cause some objects in
* finalizers to be freed */
delete_garbage(&unreachable, old);
/* Collect statistics on uncollectable objects found and print
* debugging information. */
for (gc = finalizers.gc.gc_next; gc != &finalizers;
gc = gc->gc.gc_next) {
n++;
if (debug & DEBUG_UNCOLLECTABLE) {
debug_cycle("uncollectable", FROM_GC(gc));
}
}
if (debug & DEBUG_STATS) {
if (m == 0 && n == 0) {
PySys_WriteStderr("gc: done.\n");
}
else {
PySys_WriteStderr(
"gc: done, %ld unreachable, %ld uncollectable.\n",
n+m, n);
}
}
/* Append instances in the uncollectable set to a Python
* reachable list of garbage. The programmer has to deal with
* this if they insist on creating this type of structure. */
handle_finalizers(&finalizers, old);
if (PyErr_Occurred()) {
if (gc_str == NULL) {
gc_str = PyString_FromString("garbage collection");
}
PyErr_WriteUnraisable(gc_str);
Py_FatalError("unexpected exception during garbage collection");
}
allocated = 0;
return n+m;
}
static long
collect_generations(void)
{
static long collections0 = 0;
static long collections1 = 0;
long n = 0;
if (collections1 > threshold2) {
generation = 2;
gc_list_merge(&_PyGC_generation0, &generation2);
gc_list_merge(&generation1, &generation2);
if (generation2.gc.gc_next != &generation2) {
n = collect(&generation2, &generation2);
}
collections1 = 0;
}
else if (collections0 > threshold1) {
generation = 1;
collections1++;
gc_list_merge(&_PyGC_generation0, &generation1);
if (generation1.gc.gc_next != &generation1) {
n = collect(&generation1, &generation2);
}
collections0 = 0;
}
else {
generation = 0;
collections0++;
if (_PyGC_generation0.gc.gc_next != &_PyGC_generation0) {
n = collect(&_PyGC_generation0, &generation1);
}
}
return n;
}
static char gc_enable__doc__[] =
"enable() -> None\n"
"\n"
"Enable automatic garbage collection.\n"
;
static PyObject *
gc_enable(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, ":enable")) /* check no args */
return NULL;
enabled = 1;
Py_INCREF(Py_None);
return Py_None;
}
static char gc_disable__doc__[] =
"disable() -> None\n"
"\n"
"Disable automatic garbage collection.\n"
;
static PyObject *
gc_disable(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, ":disable")) /* check no args */
return NULL;
enabled = 0;
Py_INCREF(Py_None);
return Py_None;
}
static char gc_isenabled__doc__[] =
"isenabled() -> status\n"
"\n"
"Returns true if automatic garbage collection is enabled.\n"
;
static PyObject *
gc_isenabled(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, ":isenabled")) /* check no args */
return NULL;
return Py_BuildValue("i", enabled);
}
static char gc_collect__doc__[] =
"collect() -> n\n"
"\n"
"Run a full collection. The number of unreachable objects is returned.\n"
;
static PyObject *
gc_collect(PyObject *self, PyObject *args)
{
long n;
if (!PyArg_ParseTuple(args, ":collect")) /* check no args */
return NULL;
if (collecting) {
n = 0; /* already collecting, don't do anything */
}
else {
collecting = 1;
generation = 2;
gc_list_merge(&_PyGC_generation0, &generation2);
gc_list_merge(&generation1, &generation2);
n = collect(&generation2, &generation2);
collecting = 0;
}
return Py_BuildValue("l", n);
}
static char gc_set_debug__doc__[] =
"set_debug(flags) -> None\n"
"\n"
"Set the garbage collection debugging flags. Debugging information is\n"
"written to sys.stderr.\n"
"\n"
"flags is an integer and can have the following bits turned on:\n"
"\n"
" DEBUG_STATS - Print statistics during collection.\n"
" DEBUG_COLLECTABLE - Print collectable objects found.\n"
" DEBUG_UNCOLLECTABLE - Print unreachable but uncollectable objects found.\n"
" DEBUG_INSTANCES - Print instance objects.\n"
" DEBUG_OBJECTS - Print objects other than instances.\n"
" DEBUG_SAVEALL - Save objects to gc.garbage rather than freeing them.\n"
" DEBUG_LEAK - Debug leaking programs (everything but STATS).\n"
;
static PyObject *
gc_set_debug(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, "i:set_debug", &debug))
return NULL;
Py_INCREF(Py_None);
return Py_None;
}
static char gc_get_debug__doc__[] =
"get_debug() -> flags\n"
"\n"
"Get the garbage collection debugging flags.\n"
;
static PyObject *
gc_get_debug(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, ":get_debug")) /* no args */
return NULL;
return Py_BuildValue("i", debug);
}
static char gc_set_thresh__doc__[] =
"set_threshold(threshold0, [threhold1, threshold2]) -> None\n"
"\n"
"Sets the collection thresholds. Setting threshold0 to zero disables\n"
"collection.\n"
;
static PyObject *
gc_set_thresh(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, "i|ii:set_threshold", &threshold0,
&threshold1, &threshold2))
return NULL;
Py_INCREF(Py_None);
return Py_None;
}
static char gc_get_thresh__doc__[] =
"get_threshold() -> (threshold0, threshold1, threshold2)\n"
"\n"
"Return the current collection thresholds\n"
;
static PyObject *
gc_get_thresh(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, ":get_threshold")) /* no args */
return NULL;
return Py_BuildValue("(iii)", threshold0, threshold1, threshold2);
}
static int
referrersvisit(PyObject* obj, PyObject *objs)
{
int i;
for (i = 0; i < PyTuple_GET_SIZE(objs); i++)
if (PyTuple_GET_ITEM(objs, i) == obj)
return 1;
return 0;
}
static int
gc_referrers_for(PyObject *objs, PyGC_Head *list, PyObject *resultlist)
{
PyGC_Head *gc;
PyObject *obj;
traverseproc traverse;
for (gc = list->gc.gc_next; gc != list; gc = gc->gc.gc_next) {
obj = FROM_GC(gc);
traverse = obj->ob_type->tp_traverse;
if (obj == objs || obj == resultlist)
continue;
if (traverse(obj, (visitproc)referrersvisit, objs)) {
if (PyList_Append(resultlist, obj) < 0)
return 0; /* error */
}
}
return 1; /* no error */
}
static char gc_get_referrers__doc__[]=
"get_referrers(*objs) -> list\n\
Return the list of objects that directly refer to any of objs.";
static PyObject *
gc_get_referrers(PyObject *self, PyObject *args)
{
PyObject *result = PyList_New(0);
if (!(gc_referrers_for(args, &_PyGC_generation0, result) &&
gc_referrers_for(args, &generation1, result) &&
gc_referrers_for(args, &generation2, result))) {
Py_DECREF(result);
return NULL;
}
return result;
}
static char gc_get_objects__doc__[] =
"get_objects() -> [...]\n"
"\n"
"Return a list of objects tracked by the collector (excluding the list\n"
"returned).\n"
;
/* appending objects in a GC list to a Python list */
static void
append_objects(PyObject *py_list, PyGC_Head *gc_list)
{
PyGC_Head *gc;
for (gc = gc_list->gc.gc_next; gc != gc_list; gc = gc->gc.gc_next) {
PyObject *op = FROM_GC(gc);
if (op != py_list) {
Py_INCREF(op);
PyList_Append(py_list, op);
}
}
}
static PyObject *
gc_get_objects(PyObject *self, PyObject *args)
{
PyObject* result;
if (!PyArg_ParseTuple(args, ":get_objects")) /* check no args */
return NULL;
result = PyList_New(0);
append_objects(result, &_PyGC_generation0);
append_objects(result, &generation1);
append_objects(result, &generation2);
return result;
}
static char gc__doc__ [] =
"This module provides access to the garbage collector for reference cycles.\n"
"\n"
"enable() -- Enable automatic garbage collection.\n"
"disable() -- Disable automatic garbage collection.\n"
"isenabled() -- Returns true if automatic collection is enabled.\n"
"collect() -- Do a full collection right now.\n"
"set_debug() -- Set debugging flags.\n"
"get_debug() -- Get debugging flags.\n"
"set_threshold() -- Set the collection thresholds.\n"
"get_threshold() -- Return the current the collection thresholds.\n"
"get_objects() -- Return a list of all objects tracked by the collector.\n"
"get_referrers() -- Return the list of objects that refer to an object.\n"
;
static PyMethodDef GcMethods[] = {
{"enable", gc_enable, METH_VARARGS, gc_enable__doc__},
{"disable", gc_disable, METH_VARARGS, gc_disable__doc__},
{"isenabled", gc_isenabled, METH_VARARGS, gc_isenabled__doc__},
{"set_debug", gc_set_debug, METH_VARARGS, gc_set_debug__doc__},
{"get_debug", gc_get_debug, METH_VARARGS, gc_get_debug__doc__},
{"set_threshold", gc_set_thresh, METH_VARARGS, gc_set_thresh__doc__},
{"get_threshold", gc_get_thresh, METH_VARARGS, gc_get_thresh__doc__},
{"collect", gc_collect, METH_VARARGS, gc_collect__doc__},
{"get_objects", gc_get_objects,METH_VARARGS, gc_get_objects__doc__},
{"get_referrers", gc_get_referrers, METH_VARARGS,
gc_get_referrers__doc__},
{NULL, NULL} /* Sentinel */
};
void
initgc(void)
{
PyObject *m;
PyObject *d;
m = Py_InitModule4("gc",
GcMethods,
gc__doc__,
NULL,
PYTHON_API_VERSION);
d = PyModule_GetDict(m);
if (garbage == NULL) {
garbage = PyList_New(0);
}
PyDict_SetItemString(d, "garbage", garbage);
PyDict_SetItemString(d, "DEBUG_STATS",
PyInt_FromLong(DEBUG_STATS));
PyDict_SetItemString(d, "DEBUG_COLLECTABLE",
PyInt_FromLong(DEBUG_COLLECTABLE));
PyDict_SetItemString(d, "DEBUG_UNCOLLECTABLE",
PyInt_FromLong(DEBUG_UNCOLLECTABLE));
PyDict_SetItemString(d, "DEBUG_INSTANCES",
PyInt_FromLong(DEBUG_INSTANCES));
PyDict_SetItemString(d, "DEBUG_OBJECTS",
PyInt_FromLong(DEBUG_OBJECTS));
PyDict_SetItemString(d, "DEBUG_SAVEALL",
PyInt_FromLong(DEBUG_SAVEALL));
PyDict_SetItemString(d, "DEBUG_LEAK",
PyInt_FromLong(DEBUG_LEAK));
}
/* for debugging */
void _PyGC_Dump(PyGC_Head *g)
{
_PyObject_Dump(FROM_GC(g));
}
#endif /* WITH_CYCLE_GC */
/* extension modules might be compiled with GC support so these
functions must always be available */
void
_PyObject_GC_Track(PyObject *op)
{
_PyObject_GC_TRACK(op);
}
void
_PyObject_GC_UnTrack(PyObject *op)
{
_PyObject_GC_UNTRACK(op);
}
PyObject *
_PyObject_GC_Malloc(PyTypeObject *tp, int nitems)
{
PyObject *op;
const size_t basicsize = _PyObject_VAR_SIZE(tp, nitems);
#ifdef WITH_CYCLE_GC
const size_t nbytes = sizeof(PyGC_Head) + basicsize;
PyGC_Head *g = PyObject_MALLOC(nbytes);
if (g == NULL)
return (PyObject *)PyErr_NoMemory();
g->gc.gc_next = NULL;
allocated++;
if (allocated > threshold0 &&
enabled &&
threshold0 &&
!collecting &&
!PyErr_Occurred()) {
collecting = 1;
collect_generations();
collecting = 0;
}
op = FROM_GC(g);
#else
op = PyObject_MALLOC(basicsize);
if (op == NULL)
return (PyObject *)PyErr_NoMemory();
#endif
return op;
}
PyObject *
_PyObject_GC_New(PyTypeObject *tp)
{
PyObject *op = _PyObject_GC_Malloc(tp, 0);
return PyObject_INIT(op, tp);
}
PyVarObject *
_PyObject_GC_NewVar(PyTypeObject *tp, int nitems)
{
PyVarObject *op = (PyVarObject *) _PyObject_GC_Malloc(tp, nitems);
return PyObject_INIT_VAR(op, tp, nitems);
}
PyVarObject *
_PyObject_GC_Resize(PyVarObject *op, int nitems)
{
const size_t basicsize = _PyObject_VAR_SIZE(op->ob_type, nitems);
#ifdef WITH_CYCLE_GC
PyGC_Head *g = AS_GC(op);
g = PyObject_REALLOC(g, sizeof(PyGC_Head) + basicsize);
if (g == NULL)
return (PyVarObject *)PyErr_NoMemory();
op = (PyVarObject *) FROM_GC(g);
#else
op = PyObject_REALLOC(op, basicsize);
if (op == NULL)
return (PyVarObject *)PyErr_NoMemory();
#endif
op->ob_size = nitems;
return op;
}
void
_PyObject_GC_Del(PyObject *op)
{
#ifdef WITH_CYCLE_GC
PyGC_Head *g = AS_GC(op);
if (g->gc.gc_next != NULL)
gc_list_remove(g);
if (allocated > 0) {
allocated--;
}
PyObject_FREE(g);
#else
PyObject_FREE(op);
#endif
}
|