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  • /*
     * astobj2 - replacement containers for asterisk data structures.
     *
     * Copyright (C) 2006 Marta Carbone, Luigi Rizzo - Univ. di Pisa, Italy
     *
     * See http://www.asterisk.org for more information about
     * the Asterisk project. Please do not directly contact
     * any of the maintainers of this project for assistance;
     * the project provides a web site, mailing lists and IRC
     * channels for your use.
     *
     * This program is free software, distributed under the terms of
     * the GNU General Public License Version 2. See the LICENSE file
     * at the top of the source tree.
     */
    
    /*
     * Function implementing astobj2 objects.
     */
    #include "asterisk.h"
    
    ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
    
    
    #include "asterisk/_private.h"
    
    #include "asterisk/astobj2.h"
    #include "asterisk/utils.h"
    #include "asterisk/cli.h"
    
     * astobj2 objects are always preceded by this data structure,
    
     * which contains a lock, a reference counter,
     * the flags and a pointer to a destructor.
     * The refcount is used to decide when it is time to
     * invoke the destructor.
     * The magic number is used for consistency check.
     * XXX the lock is not always needed, and its initialization may be
     * expensive. Consider making it external.
     */
    struct __priv_data {
    	ast_mutex_t lock;
    	int ref_counter;
    	ao2_destructor_fn destructor_fn;
    	/*! for stats */
    	size_t data_size;
    	/*! magic number.  This is used to verify that a pointer passed in is a
    	 *  valid astobj2 */
    	uint32_t magic;
    };
    
    #define	AO2_MAGIC	0xa570b123
    
    /*!
     * What an astobj2 object looks like: fixed-size private data
     * followed by variable-size user data.
     */
    struct astobj2 {
    	struct __priv_data priv_data;
    	void *user_data[0];
    };
    
    
    #ifdef AST_DEVMODE
    
    /* #define AO2_DEBUG 1 */
    
    #endif
    
    #ifdef AO2_DEBUG
    
    struct ao2_stats {
    	volatile int total_objects;
    	volatile int total_mem;
    	volatile int total_containers;
    	volatile int total_refs;
    	volatile int total_locked;
    };
    
    static struct ao2_stats ao2;
    
    
    #ifndef HAVE_BKTR	/* backtrace support */
    void ao2_bt(void) {}
    #else
    #include <execinfo.h>    /* for backtrace */
    
    void ao2_bt(void)
    {
    
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    	int c, i;
    
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    	void *addresses[N1];
    	char **strings;
    
    	c = backtrace(addresses, N1);
    
    	strings = ast_bt_get_symbols(addresses,c);
    
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    	ast_verbose("backtrace returned: %d\n", c);
    	for(i = 0; i < c; i++) {
    		ast_verbose("%d: %p %s\n", i, addresses[i], strings[i]);
    	}
    	free(strings);
    
    }
    #endif
    
    /*!
     * \brief convert from a pointer _p to a user-defined object
     *
     * \return the pointer to the astobj2 structure
     */
    static inline struct astobj2 *INTERNAL_OBJ(void *user_data)
    {
    	struct astobj2 *p;
    
    	if (!user_data) {
    		ast_log(LOG_ERROR, "user_data is NULL\n");
    		return NULL;
    	}
    
    	p = (struct astobj2 *) ((char *) user_data - sizeof(*p));
    	if (AO2_MAGIC != (p->priv_data.magic) ) {
    		ast_log(LOG_ERROR, "bad magic number 0x%x for %p\n", p->priv_data.magic, p);
    		p = NULL;
    	}
    
    	return p;
    }
    
    
    /*!
     * \brief convert from a pointer _p to an astobj2 object
     *
     * \return the pointer to the user-defined portion.
     */
    #define EXTERNAL_OBJ(_p)	((_p) == NULL ? NULL : (_p)->user_data)
    
    
    /* the underlying functions common to debug and non-debug versions */
    
    
    static int internal_ao2_ref(void *user_data, const int delta);
    static struct ao2_container *internal_ao2_container_alloc(struct ao2_container *c, const uint n_buckets, ao2_hash_fn *hash_fn,
    							  ao2_callback_fn *cmp_fn);
    
    static struct bucket_entry *internal_ao2_link(struct ao2_container *c, void *user_data, int flags, const char *file, int line, const char *func);
    
    static void *internal_ao2_callback(struct ao2_container *c,
    				   const enum search_flags flags, void *cb_fn, void *arg, void *data, enum ao2_callback_type type,
    				   char *tag, char *file, int line, const char *funcname);
    
    static void *internal_ao2_iterator_next(struct ao2_iterator *a, struct bucket_entry **q);
    
    int __ao2_lock(void *user_data, const char *file, const char *func, int line, const char *var)
    
    {
    	struct astobj2 *p = INTERNAL_OBJ(user_data);
    
    	if (p == NULL)
    		return -1;
    
    
    #ifdef AO2_DEBUG
    
    	ast_atomic_fetchadd_int(&ao2.total_locked, 1);
    
    	return __ast_pthread_mutex_lock(file, line, func, var, &p->priv_data.lock);
    
    int __ao2_unlock(void *user_data, const char *file, const char *func, int line, const char *var)
    
    {
    	struct astobj2 *p = INTERNAL_OBJ(user_data);
    
    	if (p == NULL)
    		return -1;
    
    
    #ifdef AO2_DEBUG
    
    	ast_atomic_fetchadd_int(&ao2.total_locked, -1);
    
    	return __ast_pthread_mutex_unlock(file, line, func, var, &p->priv_data.lock);
    
    int __ao2_trylock(void *user_data, const char *file, const char *func, int line, const char *var)
    
    {
    	struct astobj2 *p = INTERNAL_OBJ(user_data);
    	int ret;
    	
    	if (p == NULL)
    		return -1;
    
    	ret = __ast_pthread_mutex_trylock(file, line, func, var, &p->priv_data.lock);
    
    
    #ifdef AO2_DEBUG
    	if (!ret)
    		ast_atomic_fetchadd_int(&ao2.total_locked, 1);
    #endif
    	return ret;
    }
    
    void *ao2_object_get_lockaddr(void *obj)
    {
    	struct astobj2 *p = INTERNAL_OBJ(obj);
    	
    	if (p == NULL)
    		return NULL;
    
    	return &p->priv_data.lock;
    }
    
    
    /*
     * The argument is a pointer to the user portion.
     */
    
    int __ao2_ref_debug(void *user_data, const int delta, char *tag, char *file, int line, const char *funcname)
    
    {
    	struct astobj2 *obj = INTERNAL_OBJ(user_data);
    	
    	if (obj == NULL)
    		return -1;
    
    	if (delta != 0) {
    		FILE *refo = fopen(REF_FILE,"a");
    
    		fprintf(refo, "%p %s%d   %s:%d:%s (%s) [@%d]\n", user_data, (delta<0? "":"+"), delta, file, line, funcname, tag, obj ? obj->priv_data.ref_counter : -1);
    
    		fclose(refo);
    	}
    	if (obj->priv_data.ref_counter + delta == 0 && obj->priv_data.destructor_fn != NULL) { /* this isn't protected with lock; just for o/p */
    			FILE *refo = fopen(REF_FILE,"a"); 	 
    			fprintf(refo, "%p **call destructor** %s:%d:%s (%s)\n", user_data, file, line, funcname, tag); 	 
    			fclose(refo);
    	}
    
    	return internal_ao2_ref(user_data, delta);
    
    int __ao2_ref(void *user_data, const int delta)
    
    {
    	struct astobj2 *obj = INTERNAL_OBJ(user_data);
    
    	if (obj == NULL)
    		return -1;
    
    
    	return internal_ao2_ref(user_data, delta);
    
    static int internal_ao2_ref(void *user_data, const int delta)
    
    {
    	struct astobj2 *obj = INTERNAL_OBJ(user_data);
    	int current_value;
    	int ret;
    
    
    	/* if delta is 0, just return the refcount */
    	if (delta == 0)
    		return (obj->priv_data.ref_counter);
    
    	/* we modify with an atomic operation the reference counter */
    	ret = ast_atomic_fetchadd_int(&obj->priv_data.ref_counter, delta);
    	current_value = ret + delta;
    
    
    #ifdef AO2_DEBUG	
    	ast_atomic_fetchadd_int(&ao2.total_refs, delta);
    #endif
    
    
    	/* this case must never happen */
    	if (current_value < 0)
    		ast_log(LOG_ERROR, "refcount %d on object %p\n", current_value, user_data);
    
    	if (current_value <= 0) { /* last reference, destroy the object */
    
    		if (obj->priv_data.destructor_fn != NULL) {
    
    			obj->priv_data.destructor_fn(user_data);
    
    
    		ast_mutex_destroy(&obj->priv_data.lock);
    
    #ifdef AO2_DEBUG
    
    		ast_atomic_fetchadd_int(&ao2.total_mem, - obj->priv_data.data_size);
    
    		ast_atomic_fetchadd_int(&ao2.total_objects, -1);
    #endif
    
    		/* for safety, zero-out the astobj2 header and also the
    		 * first word of the user-data, which we make sure is always
    		 * allocated. */
    
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    		memset(obj, '\0', sizeof(struct astobj2 *) + sizeof(void *) );
    
    	}
    
    	return ret;
    }
    
    /*
     * We always alloc at least the size of a void *,
     * for debugging purposes.
     */
    
    static void *internal_ao2_alloc(size_t data_size, ao2_destructor_fn destructor_fn, const char *file, int line, const char *funcname)
    
    {
    	/* allocation */
    	struct astobj2 *obj;
    
    	if (data_size < sizeof(void *))
    		data_size = sizeof(void *);
    
    
    #if defined(__AST_DEBUG_MALLOC)
    	obj = __ast_calloc(1, sizeof(*obj) + data_size, file, line, funcname);
    #else
    
    	obj = ast_calloc(1, sizeof(*obj) + data_size);
    
    
    	if (obj == NULL)
    		return NULL;
    
    	ast_mutex_init(&obj->priv_data.lock);
    	obj->priv_data.magic = AO2_MAGIC;
    	obj->priv_data.data_size = data_size;
    	obj->priv_data.ref_counter = 1;
    	obj->priv_data.destructor_fn = destructor_fn;	/* can be NULL */
    
    	ast_atomic_fetchadd_int(&ao2.total_objects, 1);
    	ast_atomic_fetchadd_int(&ao2.total_mem, data_size);
    	ast_atomic_fetchadd_int(&ao2.total_refs, 1);
    
    
    	/* return a pointer to the user data */
    	return EXTERNAL_OBJ(obj);
    }
    
    
    void *__ao2_alloc_debug(size_t data_size, ao2_destructor_fn destructor_fn, char *tag,
    			const char *file, int line, const char *funcname, int ref_debug)
    
    	FILE *refo = ref_debug ? fopen(REF_FILE,"a") : NULL;
    
    	if ((obj = internal_ao2_alloc(data_size, destructor_fn, file, line, funcname)) == NULL) {
    		fclose(refo);
    
    	if (refo) {
    		fprintf(refo, "%p =1   %s:%d:%s (%s)\n", obj, file, line, funcname, tag);
    		fclose(refo);
    	}
    
    	/* return a pointer to the user data */
    	return obj;
    }
    
    
    void *__ao2_alloc(size_t data_size, ao2_destructor_fn destructor_fn)
    
    	return internal_ao2_alloc(data_size, destructor_fn, __FILE__, __LINE__, __FUNCTION__);
    
    /* internal callback to destroy a container. */
    static void container_destruct(void *c);
    
    
    /* internal callback to destroy a container. */
    static void container_destruct_debug(void *c);
    
    
    /* each bucket in the container is a tailq. */
    
    AST_LIST_HEAD_NOLOCK(bucket, bucket_entry);
    
    
    /*!
     * A container; stores the hash and callback functions, information on
     * the size, the hash bucket heads, and a version number, starting at 0
     * (for a newly created, empty container)
     * and incremented every time an object is inserted or deleted.
     * The assumption is that an object is never moved in a container,
     * but removed and readded with the new number.
     * The version number is especially useful when implementing iterators.
     * In fact, we can associate a unique, monotonically increasing number to
     * each object, which means that, within an iterator, we can store the
     * version number of the current object, and easily look for the next one,
     * which is the next one in the list with a higher number.
     * Since all objects have a version >0, we can use 0 as a marker for
     * 'we need the first object in the bucket'.
     *
     * \todo Linking and unlink objects is typically expensive, as it
     * involves a malloc() of a small object which is very inefficient.
    
     * To optimize this, we allocate larger arrays of bucket_entry's
    
     * when we run out of them, and then manage our own freelist.
     * This will be more efficient as we can do the freelist management while
     * we hold the lock (that we need anyways).
     */
    
    struct ao2_container {
    
    	ao2_hash_fn *hash_fn;
    	ao2_callback_fn *cmp_fn;
    
    	int n_buckets;
    	/*! Number of elements in the container */
    	int elements;
    	/*! described above */
    	int version;
    	/*! variable size */
    	struct bucket buckets[0];
    };
     
    /*!
     * \brief always zero hash function
     *
     * it is convenient to have a hash function that always returns 0.
     * This is basically used when we want to have a container that is
     * a simple linked list.
     *
     * \returns 0
     */
    static int hash_zero(const void *user_obj, const int flags)
    {
    	return 0;
    }
    
    /*
     * A container is just an object, after all!
     */
    
    static struct ao2_container *internal_ao2_container_alloc(struct ao2_container *c, const unsigned int n_buckets, ao2_hash_fn *hash_fn,
    							  ao2_callback_fn *cmp_fn)
    
    {
    	/* XXX maybe consistency check on arguments ? */
    	/* compute the container size */
    
    	if (!c)
    		return NULL;
    	
    	c->version = 1;	/* 0 is a reserved value here */
    
    	c->n_buckets = hash_fn ? n_buckets : 1;
    
    	c->hash_fn = hash_fn ? hash_fn : hash_zero;
    	c->cmp_fn = cmp_fn;
    
    	ast_atomic_fetchadd_int(&ao2.total_containers, 1);
    
    struct ao2_container *__ao2_container_alloc_debug(const unsigned int n_buckets, ao2_hash_fn *hash_fn,
    
    						  ao2_callback_fn *cmp_fn, char *tag, char *file, int line,
    						  const char *funcname, int ref_debug)
    
    {
    	/* XXX maybe consistency check on arguments ? */
    	/* compute the container size */
    
    	const unsigned int num_buckets = hash_fn ? n_buckets : 1;
    	size_t container_size = sizeof(struct ao2_container) + num_buckets * sizeof(struct bucket);
    
    	struct ao2_container *c = __ao2_alloc_debug(container_size, container_destruct_debug, tag, file, line, funcname, ref_debug);
    
    	return internal_ao2_container_alloc(c, num_buckets, hash_fn, cmp_fn);
    
    struct ao2_container *__ao2_container_alloc(const unsigned int n_buckets, ao2_hash_fn *hash_fn,
    					    ao2_callback_fn *cmp_fn)
    
    {
    	/* XXX maybe consistency check on arguments ? */
    	/* compute the container size */
    
    
    	const unsigned int num_buckets = hash_fn ? n_buckets : 1;
    	size_t container_size = sizeof(struct ao2_container) + num_buckets * sizeof(struct bucket);
    
    	struct ao2_container *c = __ao2_alloc(container_size, container_destruct);
    
    	return internal_ao2_container_alloc(c, num_buckets, hash_fn, cmp_fn);
    
    /*!
     * return the number of elements in the container
     */
    
    int ao2_container_count(struct ao2_container *c)
    
    {
    	return c->elements;
    }
    
    /*!
     * A structure to create a linked list of entries,
     * used within a bucket.
     * XXX \todo this should be private to the container code
     */
    
    struct bucket_entry {
    	AST_LIST_ENTRY(bucket_entry) entry;
    
    	int version;
    	struct astobj2 *astobj;		/* pointer to internal data */
    }; 
    
    /*
     * link an object to a container
     */
    
    static struct bucket_entry *internal_ao2_link(struct ao2_container *c, void *user_data, int flags, const char *file, int line, const char *func)
    
    {
    	int i;
    	/* create a new list entry */
    
    	struct astobj2 *obj = INTERNAL_OBJ(user_data);
    
    		return NULL;
    
    	if (INTERNAL_OBJ(c) == NULL)
    		return NULL;
    
    	p = ast_calloc(1, sizeof(*p));
    	if (!p)
    		return NULL;
    
    
    	i = abs(c->hash_fn(user_data, OBJ_POINTER));
    
    	if (!(flags & OBJ_NOLOCK)) {
    		ao2_lock(c);
    	}
    
    	i %= c->n_buckets;
    	p->astobj = obj;
    	p->version = ast_atomic_fetchadd_int(&c->version, 1);
    
    	AST_LIST_INSERT_TAIL(&c->buckets[i], p, entry);
    
    	ast_atomic_fetchadd_int(&c->elements, 1);
    
    
    	/* the last two operations (ao2_ref, ao2_unlock) must be done by the calling func */
    	return p;
    }
    
    
    void *__ao2_link_debug(struct ao2_container *c, void *user_data, int flags, char *tag, char *file, int line, const char *funcname)
    
    	struct bucket_entry *p = internal_ao2_link(c, user_data, flags, file, line, funcname);
    
    		__ao2_ref_debug(user_data, +1, tag, file, line, funcname);
    
    		if (!(flags & OBJ_NOLOCK)) {
    			ao2_unlock(c);
    		}
    
    void *__ao2_link(struct ao2_container *c, void *user_data, int flags)
    
    	struct bucket_entry *p = internal_ao2_link(c, user_data, flags, __FILE__, __LINE__, __PRETTY_FUNCTION__);
    
    		__ao2_ref(user_data, +1);
    
    		if (!(flags & OBJ_NOLOCK)) {
    			ao2_unlock(c);
    		}
    
    	return p;
    }
    
    /*!
     * \brief another convenience function is a callback that matches on address
     */
    
    int ao2_match_by_addr(void *user_data, void *arg, int flags)
    
    {
    	return (user_data == arg) ? (CMP_MATCH | CMP_STOP) : 0;
    }
    
    /*
     * Unlink an object from the container
    
     * and destroy the associated * bucket_entry structure.
    
    void *__ao2_unlink_debug(struct ao2_container *c, void *user_data, int flags, char *tag,
    
    			 char *file, int line, const char *funcname)
    
    {
    	if (INTERNAL_OBJ(user_data) == NULL)	/* safety check on the argument */
    		return NULL;
    
    
    	flags |= (OBJ_UNLINK | OBJ_POINTER | OBJ_NODATA);
    
    	__ao2_callback_debug(c, flags, ao2_match_by_addr, user_data, tag, file, line, funcname);
    
    void *__ao2_unlink(struct ao2_container *c, void *user_data, int flags)
    
    {
    	if (INTERNAL_OBJ(user_data) == NULL)	/* safety check on the argument */
    		return NULL;
    
    
    	flags |= (OBJ_UNLINK | OBJ_POINTER | OBJ_NODATA);
    	__ao2_callback(c, flags, ao2_match_by_addr, user_data);
    
    
    	return NULL;
    }
    
    /*! 
     * \brief special callback that matches all 
     */ 
    
    static int cb_true(void *user_data, void *arg, int flags)
    {
    	return CMP_MATCH;
    }
    
    /*!
     * \brief similar to cb_true, but is an ao2_callback_data_fn instead
     */
    static int cb_true_data(void *user_data, void *arg, void *data, int flags)
    
    {
    	return CMP_MATCH;
    }
    
    /*!
     * Browse the container using different stategies accoding the flags.
     * \return Is a pointer to an object or to a list of object if OBJ_MULTIPLE is 
     * specified.
    
     * Luckily, for debug purposes, the added args (tag, file, line, funcname)
     * aren't an excessive load to the system, as the callback should not be
     * called as often as, say, the ao2_ref func is called.
    
    static void *internal_ao2_callback(struct ao2_container *c,
    				   const enum search_flags flags, void *cb_fn, void *arg, void *data, enum ao2_callback_type type,
    				   char *tag, char *file, int line, const char *funcname)
    
    	int i, start, last;	/* search boundaries */
    
    	void *ret = NULL;
    
    	ao2_callback_fn *cb_default = NULL;
    	ao2_callback_data_fn *cb_withdata = NULL;
    
    	struct ao2_container *multi_container = NULL;
    	struct ao2_iterator *multi_iterator = NULL;
    
    
    	if (INTERNAL_OBJ(c) == NULL)	/* safety check on the argument */
    		return NULL;
    
    
    	/*
    	 * This logic is used so we can support OBJ_MULTIPLE with OBJ_NODATA
    	 * turned off.  This if statement checks for the special condition
    	 * where multiple items may need to be returned.
    	 */
    	if ((flags & (OBJ_MULTIPLE | OBJ_NODATA)) == OBJ_MULTIPLE) {
    
    		/* we need to return an ao2_iterator with the results,
    		 * as there could be more than one. the iterator will
    		 * hold the only reference to a container that has all the
    		 * matching objects linked into it, so when the iterator
    		 * is destroyed, the container will be automatically
    		 * destroyed as well.
    		 */
    		if (!(multi_container = __ao2_container_alloc(1, NULL, NULL))) {
    			return NULL;
    		}
    		if (!(multi_iterator = ast_calloc(1, sizeof(*multi_iterator)))) {
    			ao2_ref(multi_container, -1);
    			return NULL;
    		}
    
    	}
    
    	/* override the match function if necessary */
    
    	if (cb_fn == NULL) { /* if NULL, match everything */
    		if (type == WITH_DATA) {
    			cb_withdata = cb_true_data;
    		} else {
    			cb_default = cb_true;
    		}
    	} else {
    		/* We do this here to avoid the per object casting penalty (even though
    
    		if (type == WITH_DATA) {
    			cb_withdata = cb_fn;
    		} else {
    			cb_default = cb_fn;
    		}
    	}
    
    
    	/*
    	 * XXX this can be optimized.
    	 * If we have a hash function and lookup by pointer,
    	 * run the hash function. Otherwise, scan the whole container
    	 * (this only for the time being. We need to optimize this.)
    	 */
    	if ((flags & OBJ_POINTER))	/* we know hash can handle this case */
    
    		start = i = c->hash_fn(arg, flags & OBJ_POINTER) % c->n_buckets;
    
    	else			/* don't know, let's scan all buckets */
    
    		start = i = -1;		/* XXX this must be fixed later. */
    
    
    	/* determine the search boundaries: i..last-1 */
    	if (i < 0) {
    
    		start = i = 0;
    		last = c->n_buckets;
    	} else if ((flags & OBJ_CONTINUE)) {
    
    		last = c->n_buckets;
    	} else {
    		last = i + 1;
    	}
    
    
    
    	if (!(flags & OBJ_NOLOCK)) {
    		ao2_lock(c);	/* avoid modifications to the content */
    	}
    
    
    	for (; i < last ; i++) {
    		/* scan the list with prev-cur pointers */
    
    
    		AST_LIST_TRAVERSE_SAFE_BEGIN(&c->buckets[i], cur, entry) {
    
    			int match = (CMP_MATCH | CMP_STOP);
    
    			if (type == WITH_DATA) {
    				match &= cb_withdata(EXTERNAL_OBJ(cur->astobj), arg, data, flags);
    			} else {
    				match &= cb_default(EXTERNAL_OBJ(cur->astobj), arg, flags);
    			}
    
    			/* we found the object, performing operations according flags */
    
    			if (match == 0) {	/* no match, no stop, continue */
    				continue;
    			} else if (match == CMP_STOP) {	/* no match but stop, we are done */
    				i = last;
    				break;
    			}
    
    			/* we have a match (CMP_MATCH) here */
    			if (!(flags & OBJ_NODATA)) {	/* if must return the object, record the value */
    				/* it is important to handle this case before the unlink */
    				ret = EXTERNAL_OBJ(cur->astobj);
    
    				if (!(flags & (OBJ_UNLINK | OBJ_MULTIPLE))) {
    					if (tag)
    						__ao2_ref_debug(ret, 1, tag, file, line, funcname);
    					else
    						__ao2_ref(ret, 1);
    				}
    
    			/* If we are in OBJ_MULTIPLE mode and OBJ_NODATE is off, 
    			 * link the object into the container that will hold the results.
    
    			if (ret && (multi_container != NULL)) {
    
    				if (tag) {
    					__ao2_link_debug(multi_container, ret, flags, tag, file, line, funcname);
    				} else {
    					__ao2_link(multi_container, ret, flags);
    				}
    
    				/* we are going to modify the container, so update version */
    				ast_atomic_fetchadd_int(&c->version, 1);
    
    				AST_LIST_REMOVE_CURRENT(entry);
    
    				ast_atomic_fetchadd_int(&c->elements, -1);
    
    
    				/* - When unlinking and not returning the result, (OBJ_NODATA), the ref from the container
    				 * must be decremented.
    				 * - When unlinking with OBJ_MULTIPLE the ref from the original container
    				 * must be decremented regardless if OBJ_NODATA is used. This is because the result is
    				 * returned in a new container that already holds its own ref for the object. If the ref
    				 * from the original container is not accounted for here a memory leak occurs. */
    				if (flags & (OBJ_NODATA | OBJ_MULTIPLE)) {
    
    					if (tag)
    						__ao2_ref_debug(EXTERNAL_OBJ(cur->astobj), -1, tag, file, line, funcname);
    					else
    						__ao2_ref(EXTERNAL_OBJ(cur->astobj), -1);
    				}
    
    			if ((match & CMP_STOP) || !(flags & OBJ_MULTIPLE)) {
    
    				/* We found our only (or last) match, so force an exit from
    				   the outside loop. */
    				i = last;
    
    		AST_LIST_TRAVERSE_SAFE_END;
    
    
    		if (ret) {
    			break;
    		}
    
    		if (i == c->n_buckets - 1 && (flags & OBJ_POINTER) && (flags & OBJ_CONTINUE)) {
    			/* Move to the beginning to ensure we check every bucket */
    			i = -1;
    			last = start;
    		}
    
    
    	/* if multi_container was created, we are returning multiple objects */
    	if (multi_container != NULL) {
    
    		*multi_iterator = ao2_iterator_init(multi_container,
    						    AO2_ITERATOR_DONTLOCK | AO2_ITERATOR_UNLINK | AO2_ITERATOR_MALLOCD);
    		ao2_ref(multi_container, -1);
    		return multi_iterator;
    	} else {
    		return ret;
    	}
    
    void *__ao2_callback_debug(struct ao2_container *c,
    			   const enum search_flags flags,
    			   ao2_callback_fn *cb_fn, void *arg,
    			   char *tag, char *file, int line, const char *funcname)
    
    	return internal_ao2_callback(c,flags, cb_fn, arg, NULL, DEFAULT, tag, file, line, funcname);
    
    void *__ao2_callback(struct ao2_container *c, const enum search_flags flags,
    		     ao2_callback_fn *cb_fn, void *arg)
    
    	return internal_ao2_callback(c,flags, cb_fn, arg, NULL, DEFAULT, NULL, NULL, 0, NULL);
    
    void *__ao2_callback_data_debug(struct ao2_container *c,
    				const enum search_flags flags,
    				ao2_callback_data_fn *cb_fn, void *arg, void *data,
    				char *tag, char *file, int line, const char *funcname)
    
    	return internal_ao2_callback(c, flags, cb_fn, arg, data, WITH_DATA, tag, file, line, funcname);
    
    void *__ao2_callback_data(struct ao2_container *c, const enum search_flags flags,
    			  ao2_callback_data_fn *cb_fn, void *arg, void *data)
    
    	return internal_ao2_callback(c, flags, cb_fn, arg, data, WITH_DATA, NULL, NULL, 0, NULL);
    
    /*!
     * the find function just invokes the default callback with some reasonable flags.
     */
    
    void *__ao2_find_debug(struct ao2_container *c, void *arg, enum search_flags flags, char *tag, char *file, int line, const char *funcname)
    
    	return __ao2_callback_debug(c, flags, c->cmp_fn, arg, tag, file, line, funcname);
    
    void *__ao2_find(struct ao2_container *c, void *arg, enum search_flags flags)
    
    	return __ao2_callback(c, flags, c->cmp_fn, arg);
    
    }
    
    /*!
     * initialize an iterator so we start from the first object
     */
    
    struct ao2_iterator ao2_iterator_init(struct ao2_container *c, int flags)
    
    	struct ao2_iterator a = {
    
    		.c = c,
    		.flags = flags
    	};
    
    /*!
     * destroy an iterator
     */
    void ao2_iterator_destroy(struct ao2_iterator *i)
    {
    	ao2_ref(i->c, -1);
    
    	if (i->flags & AO2_ITERATOR_MALLOCD) {
    		ast_free(i);
    	} else {
    		i->c = NULL;
    	}
    
    /*
     * move to the next element in the container.
     */
    
    static void *internal_ao2_iterator_next(struct ao2_iterator *a, struct bucket_entry **q)
    
    	struct bucket_entry *p = NULL;
    
    	if (INTERNAL_OBJ(a->c) == NULL)
    		return NULL;
    
    
    	if (!(a->flags & AO2_ITERATOR_DONTLOCK))
    
    		ao2_lock(a->c);
    
    	/* optimization. If the container is unchanged and
    	 * we have a pointer, try follow it
    	 */
    
    	if (a->c->version == a->c_version && (p = a->obj)) {
    		if ((p = AST_LIST_NEXT(p, entry)))
    
    			goto found;
    		/* nope, start from the next bucket */
    		a->bucket++;
    		a->version = 0;
    		a->obj = NULL;
    	}
    
    	lim = a->c->n_buckets;
    
    	/* Browse the buckets array, moving to the next
    	 * buckets if we don't find the entry in the current one.
    	 * Stop when we find an element with version number greater
    	 * than the current one (we reset the version to 0 when we
    	 * switch buckets).
    	 */
    	for (; a->bucket < lim; a->bucket++, a->version = 0) {
    		/* scan the current bucket */
    		AST_LIST_TRAVERSE(&a->c->buckets[a->bucket], p, entry) {
    			if (p->version > a->version)
    				goto found;
    		}
    	}
    
    found:
    	if (p) {
    
    		if (a->flags & AO2_ITERATOR_UNLINK) {
    			/* we are going to modify the container, so update version */
    			ast_atomic_fetchadd_int(&a->c->version, 1);
    			AST_LIST_REMOVE(&a->c->buckets[a->bucket], p, entry);
    			/* update number of elements */
    			ast_atomic_fetchadd_int(&a->c->elements, -1);
    			a->version = 0;
    			a->obj = NULL;
    			a->c_version = a->c->version;
    			ast_free(p);
    		} else {
    			a->version = p->version;
    			a->obj = p;
    			a->c_version = a->c->version;
    			/* inc refcount of returned object */
    			*q = p;
    		}
    
    void *__ao2_iterator_next_debug(struct ao2_iterator *a, char *tag, char *file, int line, const char *funcname)
    
    	ret = internal_ao2_iterator_next(a, &p);
    
    	
    	if (p) {
    		/* inc refcount of returned object */
    
    		__ao2_ref_debug(ret, 1, tag, file, line, funcname);
    
    	if (!(a->flags & AO2_ITERATOR_DONTLOCK))
    
    void *__ao2_iterator_next(struct ao2_iterator *a)
    
    	struct bucket_entry *p = NULL;
    
    	ret = internal_ao2_iterator_next(a, &p);
    
    	
    	if (p) {
    		/* inc refcount of returned object */
    
    		__ao2_ref(ret, 1);
    
    	if (!(a->flags & AO2_ITERATOR_DONTLOCK))
    
    }
    
    /* callback for destroying container.
     * we can make it simple as we know what it does
     */
    
    static int cd_cb(void *obj, void *arg, int flag)
    
    	__ao2_ref(obj, -1);
    
    static int cd_cb_debug(void *obj, void *arg, int flag)
    
    	__ao2_ref_debug(obj, -1, "deref object via container destroy",  __FILE__, __LINE__, __PRETTY_FUNCTION__);
    
    	return 0;
    }
    	
    static void container_destruct(void *_c)
    {
    
    	struct ao2_container *c = _c;
    
    	__ao2_callback(c, OBJ_UNLINK, cd_cb, NULL);
    
    	for (i = 0; i < c->n_buckets; i++) {
    
    		struct bucket_entry *current;
    
    		while ((current = AST_LIST_REMOVE_HEAD(&c->buckets[i], entry))) {
    			ast_free(current);
    
    #ifdef AO2_DEBUG
    	ast_atomic_fetchadd_int(&ao2.total_containers, -1);
    #endif
    }
    
    static void container_destruct_debug(void *_c)
    {
    	struct ao2_container *c = _c;
    
    	__ao2_callback_debug(c, OBJ_UNLINK, cd_cb_debug, NULL, "container_destruct_debug called", __FILE__, __LINE__, __PRETTY_FUNCTION__);
    
    	for (i = 0; i < c->n_buckets; i++) {
    
    		struct bucket_entry *current;
    
    		while ((current = AST_LIST_REMOVE_HEAD(&c->buckets[i], entry))) {
    			ast_free(current);
    
    #ifdef AO2_DEBUG
    
    	ast_atomic_fetchadd_int(&ao2.total_containers, -1);