2 * astobj2 - replacement containers for asterisk data structures.
4 * Copyright (C) 2006 Marta Carbone, Luigi Rizzo - Univ. di Pisa, Italy
6 * See http://www.asterisk.org for more information about
7 * the Asterisk project. Please do not directly contact
8 * any of the maintainers of this project for assistance;
9 * the project provides a web site, mailing lists and IRC
10 * channels for your use.
12 * This program is free software, distributed under the terms of
13 * the GNU General Public License Version 2. See the LICENSE file
14 * at the top of the source tree.
18 * Function implementing astobj2 objects.
22 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
24 #include "asterisk/astobj2.h"
25 #include "asterisk/utils.h"
26 #include "asterisk/cli.h"
29 * astobj2 objects are always preceded by this data structure,
30 * which contains a lock, a reference counter,
31 * the flags and a pointer to a destructor.
32 * The refcount is used to decide when it is time to
33 * invoke the destructor.
34 * The magic number is used for consistency check.
35 * XXX the lock is not always needed, and its initialization may be
36 * expensive. Consider making it external.
41 ao2_destructor_fn destructor_fn;
44 /*! magic number. This is used to verify that a pointer passed in is a
49 #define AO2_MAGIC 0xa570b123
52 * What an astobj2 object looks like: fixed-size private data
53 * followed by variable-size user data.
56 struct __priv_data priv_data;
66 volatile int total_objects;
67 volatile int total_mem;
68 volatile int total_containers;
69 volatile int total_refs;
70 volatile int total_locked;
73 static struct ao2_stats ao2;
76 #ifndef HAVE_BKTR /* backtrace support */
79 #include <execinfo.h> /* for backtrace */
88 c = backtrace(addresses, N1);
89 strings = backtrace_symbols(addresses,c);
90 ast_verbose("backtrace returned: %d\n", c);
91 for(i = 0; i < c; i++) {
92 ast_verbose("%d: %p %s\n", i, addresses[i], strings[i]);
99 * \brief convert from a pointer _p to a user-defined object
101 * \return the pointer to the astobj2 structure
103 static inline struct astobj2 *INTERNAL_OBJ(void *user_data)
108 ast_log(LOG_ERROR, "user_data is NULL\n");
112 p = (struct astobj2 *) ((char *) user_data - sizeof(*p));
113 if (AO2_MAGIC != (p->priv_data.magic) ) {
114 ast_log(LOG_ERROR, "bad magic number 0x%x for %p\n", p->priv_data.magic, p);
122 * \brief convert from a pointer _p to an astobj2 object
124 * \return the pointer to the user-defined portion.
126 #define EXTERNAL_OBJ(_p) ((_p) == NULL ? NULL : (_p)->user_data)
128 int ao2_lock(void *user_data)
130 struct astobj2 *p = INTERNAL_OBJ(user_data);
136 ast_atomic_fetchadd_int(&ao2.total_locked, 1);
139 return ast_mutex_lock(&p->priv_data.lock);
142 int ao2_unlock(void *user_data)
144 struct astobj2 *p = INTERNAL_OBJ(user_data);
150 ast_atomic_fetchadd_int(&ao2.total_locked, -1);
153 return ast_mutex_unlock(&p->priv_data.lock);
157 * The argument is a pointer to the user portion.
159 int ao2_ref(void *user_data, const int delta)
163 struct astobj2 *obj = INTERNAL_OBJ(user_data);
168 /* if delta is 0, just return the refcount */
170 return (obj->priv_data.ref_counter);
172 /* we modify with an atomic operation the reference counter */
173 ret = ast_atomic_fetchadd_int(&obj->priv_data.ref_counter, delta);
174 current_value = ret + delta;
177 ast_atomic_fetchadd_int(&ao2.total_refs, delta);
180 /* this case must never happen */
181 if (current_value < 0)
182 ast_log(LOG_ERROR, "refcount %d on object %p\n", current_value, user_data);
184 if (current_value <= 0) { /* last reference, destroy the object */
185 if (obj->priv_data.destructor_fn != NULL)
186 obj->priv_data.destructor_fn(user_data);
188 ast_mutex_destroy(&obj->priv_data.lock);
190 ast_atomic_fetchadd_int(&ao2.total_mem, - obj->priv_data.data_size);
191 ast_atomic_fetchadd_int(&ao2.total_objects, -1);
193 /* for safety, zero-out the astobj2 header and also the
194 * first word of the user-data, which we make sure is always
196 bzero(obj, sizeof(struct astobj2 *) + sizeof(void *) );
204 * We always alloc at least the size of a void *,
205 * for debugging purposes.
207 void *ao2_alloc(size_t data_size, ao2_destructor_fn destructor_fn)
212 if (data_size < sizeof(void *))
213 data_size = sizeof(void *);
215 obj = ast_calloc(1, sizeof(*obj) + data_size);
220 ast_mutex_init(&obj->priv_data.lock);
221 obj->priv_data.magic = AO2_MAGIC;
222 obj->priv_data.data_size = data_size;
223 obj->priv_data.ref_counter = 1;
224 obj->priv_data.destructor_fn = destructor_fn; /* can be NULL */
227 ast_atomic_fetchadd_int(&ao2.total_objects, 1);
228 ast_atomic_fetchadd_int(&ao2.total_mem, data_size);
229 ast_atomic_fetchadd_int(&ao2.total_refs, 1);
232 /* return a pointer to the user data */
233 return EXTERNAL_OBJ(obj);
236 /* internal callback to destroy a container. */
237 static void container_destruct(void *c);
239 /* each bucket in the container is a tailq. */
240 AST_LIST_HEAD_NOLOCK(bucket, bucket_list);
243 * A container; stores the hash and callback functions, information on
244 * the size, the hash bucket heads, and a version number, starting at 0
245 * (for a newly created, empty container)
246 * and incremented every time an object is inserted or deleted.
247 * The assumption is that an object is never moved in a container,
248 * but removed and readded with the new number.
249 * The version number is especially useful when implementing iterators.
250 * In fact, we can associate a unique, monotonically increasing number to
251 * each object, which means that, within an iterator, we can store the
252 * version number of the current object, and easily look for the next one,
253 * which is the next one in the list with a higher number.
254 * Since all objects have a version >0, we can use 0 as a marker for
255 * 'we need the first object in the bucket'.
257 * \todo Linking and unlink objects is typically expensive, as it
258 * involves a malloc() of a small object which is very inefficient.
259 * To optimize this, we allocate larger arrays of bucket_list's
260 * when we run out of them, and then manage our own freelist.
261 * This will be more efficient as we can do the freelist management while
262 * we hold the lock (that we need anyways).
264 struct ao2_container {
265 ao2_hash_fn *hash_fn;
266 ao2_callback_fn *cmp_fn;
268 /*! Number of elements in the container */
270 /*! described above */
273 struct bucket buckets[0];
277 * \brief always zero hash function
279 * it is convenient to have a hash function that always returns 0.
280 * This is basically used when we want to have a container that is
281 * a simple linked list.
285 static int hash_zero(const void *user_obj, const int flags)
291 * A container is just an object, after all!
293 struct ao2_container *
294 ao2_container_alloc(const uint n_buckets, ao2_hash_fn *hash_fn,
295 ao2_callback_fn *cmp_fn)
297 /* XXX maybe consistency check on arguments ? */
298 /* compute the container size */
299 size_t container_size = sizeof(struct ao2_container) + n_buckets * sizeof(struct bucket);
301 struct ao2_container *c = ao2_alloc(container_size, container_destruct);
306 c->version = 1; /* 0 is a reserved value here */
307 c->n_buckets = n_buckets;
308 c->hash_fn = hash_fn ? hash_fn : hash_zero;
312 ast_atomic_fetchadd_int(&ao2.total_containers, 1);
319 * return the number of elements in the container
321 int ao2_container_count(struct ao2_container *c)
327 * A structure to create a linked list of entries,
328 * used within a bucket.
329 * XXX \todo this should be private to the container code
332 AST_LIST_ENTRY(bucket_list) entry;
334 struct astobj2 *astobj; /* pointer to internal data */
338 * link an object to a container
340 void *ao2_link(struct ao2_container *c, void *user_data)
343 /* create a new list entry */
344 struct bucket_list *p;
345 struct astobj2 *obj = INTERNAL_OBJ(user_data);
350 if (INTERNAL_OBJ(c) == NULL)
353 p = ast_calloc(1, sizeof(*p));
357 i = c->hash_fn(user_data, OBJ_POINTER);
362 p->version = ast_atomic_fetchadd_int(&c->version, 1);
363 AST_LIST_INSERT_TAIL(&c->buckets[i], p, entry);
364 ast_atomic_fetchadd_int(&c->elements, 1);
371 * \brief another convenience function is a callback that matches on address
373 int ao2_match_by_addr(void *user_data, void *arg, int flags)
375 return (user_data == arg) ? (CMP_MATCH | CMP_STOP) : 0;
379 * Unlink an object from the container
380 * and destroy the associated * ao2_bucket_list structure.
382 void *ao2_unlink(struct ao2_container *c, void *user_data)
384 if (INTERNAL_OBJ(user_data) == NULL) /* safety check on the argument */
387 ao2_callback(c, OBJ_UNLINK | OBJ_POINTER | OBJ_NODATA, ao2_match_by_addr, user_data);
393 * \brief special callback that matches all
395 static int cb_true(void *user_data, void *arg, int flags)
401 * Browse the container using different stategies accoding the flags.
402 * \return Is a pointer to an object or to a list of object if OBJ_MULTIPLE is
405 void *ao2_callback(struct ao2_container *c,
406 const enum search_flags flags,
407 ao2_callback_fn *cb_fn, void *arg)
409 int i, last; /* search boundaries */
412 if (INTERNAL_OBJ(c) == NULL) /* safety check on the argument */
415 if ((flags & (OBJ_MULTIPLE | OBJ_NODATA)) == OBJ_MULTIPLE) {
416 ast_log(LOG_WARNING, "multiple data return not implemented yet (flags %x)\n", flags);
420 /* override the match function if necessary */
421 if (cb_fn == NULL) /* if NULL, match everything */
424 * XXX this can be optimized.
425 * If we have a hash function and lookup by pointer,
426 * run the hash function. Otherwise, scan the whole container
427 * (this only for the time being. We need to optimize this.)
429 if ((flags & OBJ_POINTER)) /* we know hash can handle this case */
430 i = c->hash_fn(arg, flags & OBJ_POINTER) % c->n_buckets;
431 else /* don't know, let's scan all buckets */
432 i = -1; /* XXX this must be fixed later. */
434 /* determine the search boundaries: i..last-1 */
442 ao2_lock(c); /* avoid modifications to the content */
444 for (; i < last ; i++) {
445 /* scan the list with prev-cur pointers */
446 struct bucket_list *cur;
448 AST_LIST_TRAVERSE_SAFE_BEGIN(&c->buckets[i], cur, entry) {
449 int match = cb_fn(EXTERNAL_OBJ(cur->astobj), arg, flags) & (CMP_MATCH | CMP_STOP);
451 /* we found the object, performing operations according flags */
452 if (match == 0) { /* no match, no stop, continue */
454 } else if (match == CMP_STOP) { /* no match but stop, we are done */
458 /* we have a match (CMP_MATCH) here */
459 if (!(flags & OBJ_NODATA)) { /* if must return the object, record the value */
460 /* it is important to handle this case before the unlink */
461 ret = EXTERNAL_OBJ(cur->astobj);
465 if (flags & OBJ_UNLINK) { /* must unlink */
466 struct bucket_list *x = cur;
468 /* we are going to modify the container, so update version */
469 ast_atomic_fetchadd_int(&c->version, 1);
470 AST_LIST_REMOVE_CURRENT(&c->buckets[i], entry);
471 /* update number of elements and version */
472 ast_atomic_fetchadd_int(&c->elements, -1);
473 ao2_ref(EXTERNAL_OBJ(x->astobj), -1);
474 free(x); /* free the link record */
477 if ((match & CMP_STOP) || (flags & OBJ_MULTIPLE) == 0) {
478 /* We found the only match we need */
479 i = last; /* force exit from outer loop */
482 if (!(flags & OBJ_NODATA)) {
483 #if 0 /* XXX to be completed */
485 * This is the multiple-return case. We need to link
486 * the object in a list. The refcount is already increased.
491 AST_LIST_TRAVERSE_SAFE_END
498 * the find function just invokes the default callback with some reasonable flags.
500 void *ao2_find(struct ao2_container *c, void *arg, enum search_flags flags)
502 return ao2_callback(c, flags, c->cmp_fn, arg);
506 * initialize an iterator so we start from the first object
508 struct ao2_iterator ao2_iterator_init(struct ao2_container *c, int flags)
510 struct ao2_iterator a = {
519 * move to the next element in the container.
521 void * ao2_iterator_next(struct ao2_iterator *a)
524 struct bucket_list *p = NULL;
527 if (INTERNAL_OBJ(a->c) == NULL)
530 if (!(a->flags & F_AO2I_DONTLOCK))
533 /* optimization. If the container is unchanged and
534 * we have a pointer, try follow it
536 if (a->c->version == a->c_version && (p = a->obj) ) {
537 if ( (p = AST_LIST_NEXT(p, entry)) )
539 /* nope, start from the next bucket */
545 lim = a->c->n_buckets;
547 /* Browse the buckets array, moving to the next
548 * buckets if we don't find the entry in the current one.
549 * Stop when we find an element with version number greater
550 * than the current one (we reset the version to 0 when we
553 for (; a->bucket < lim; a->bucket++, a->version = 0) {
554 /* scan the current bucket */
555 AST_LIST_TRAVERSE(&a->c->buckets[a->bucket], p, entry) {
556 if (p->version > a->version)
563 a->version = p->version;
565 a->c_version = a->c->version;
566 ret = EXTERNAL_OBJ(p->astobj);
567 /* inc refcount of returned object */
571 if (!(a->flags & F_AO2I_DONTLOCK))
577 /* callback for destroying container.
578 * we can make it simple as we know what it does
580 static int cd_cb(void *obj, void *arg, int flag)
586 static void container_destruct(void *_c)
588 struct ao2_container *c = _c;
590 ao2_callback(c, OBJ_UNLINK, cd_cb, NULL);
593 ast_atomic_fetchadd_int(&ao2.total_containers, -1);
598 static int print_cb(void *obj, void *arg, int flag)
601 char *s = (char *)obj;
603 ast_cli(*fd, "string <%s>\n", s);
610 static int handle_astobj2_stats(int fd, int argc, char *argv[])
612 ast_cli(fd, "Objects : %d\n", ao2.total_objects);
613 ast_cli(fd, "Containers : %d\n", ao2.total_containers);
614 ast_cli(fd, "Memory : %d\n", ao2.total_mem);
615 ast_cli(fd, "Locked : %d\n", ao2.total_locked);
616 ast_cli(fd, "Refs : %d\n", ao2.total_refs);
621 * This is testing code for astobj
623 static int handle_astobj2_test(int fd, int argc, char *argv[])
625 struct ao2_container *c1;
628 static int prof_id = -1;
631 prof_id = ast_add_profile("ao2_alloc", 0);
633 ast_cli(fd, "argc %d argv %s %s %s\n", argc, argv[0], argv[1], argv[2]);
635 ast_cli(fd, "called astobj_test\n");
637 handle_astobj2_stats(fd, 0, NULL);
639 * allocate a container with no default callback, and no hash function.
640 * No hash means everything goes in the same bucket.
642 c1 = ao2_container_alloc(100, NULL /* no callback */, NULL /* no hash */);
643 ast_cli(fd, "container allocated as %p\n", c1);
646 * fill the container with objects.
647 * ao2_alloc() gives us a reference which we pass to the
648 * container when we do the insert.
650 for (i = 0; i < lim; i++) {
651 ast_mark(prof_id, 1 /* start */);
652 obj = ao2_alloc(80, NULL);
653 ast_mark(prof_id, 0 /* stop */);
654 ast_cli(fd, "object %d allocated as %p\n", i, obj);
655 sprintf(obj, "-- this is obj %d --", i);
658 ast_cli(fd, "testing callbacks\n");
659 ao2_callback(c1, 0, print_cb, &fd);
661 ast_cli(fd, "testing iterators, remove every second object\n");
663 struct ao2_iterator ai;
666 ai = ao2_iterator_init(c1, 0);
667 while ( (obj = ao2_iterator_next(&ai)) ) {
668 ast_cli(fd, "iterator on <%s>\n", obj);
673 ast_cli(fd, "testing iterators again\n");
674 ai = ao2_iterator_init(c1, 0);
675 while ( (obj = ao2_iterator_next(&ai)) ) {
676 ast_cli(fd, "iterator on <%s>\n", obj);
680 ast_cli(fd, "testing callbacks again\n");
681 ao2_callback(c1, 0, print_cb, &fd);
683 ast_verbose("now you should see an error message:\n");
684 ao2_ref(&i, -1); /* i is not a valid object so we print an error here */
686 ast_cli(fd, "destroy container\n");
687 ao2_ref(c1, -1); /* destroy container */
688 handle_astobj2_stats(fd, 0, NULL);
692 static struct ast_cli_entry cli_astobj2[] = {
693 { { "astobj2", "stats", NULL },
694 handle_astobj2_stats, "Print astobj2 statistics", },
695 { { "astobj2", "test", NULL } , handle_astobj2_test, "Test astobj2", },
697 #endif /* AO2_DEBUG */
699 int astobj2_init(void)
702 ast_cli_register_multiple(cli_astobj2, ARRAY_LEN(cli_astobj2));