Wed Apr 6 11:29:40 2011

Asterisk developer's documentation


astobj2.c

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00001 /*
00002  * astobj2 - replacement containers for asterisk data structures.
00003  *
00004  * Copyright (C) 2006 Marta Carbone, Luigi Rizzo - Univ. di Pisa, Italy
00005  *
00006  * See http://www.asterisk.org for more information about
00007  * the Asterisk project. Please do not directly contact
00008  * any of the maintainers of this project for assistance;
00009  * the project provides a web site, mailing lists and IRC
00010  * channels for your use.
00011  *
00012  * This program is free software, distributed under the terms of
00013  * the GNU General Public License Version 2. See the LICENSE file
00014  * at the top of the source tree.
00015  */
00016 
00017 /*
00018  * Function implementing astobj2 objects.
00019  */
00020 #include "asterisk.h"
00021 
00022 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 298960 $")
00023 
00024 #include "asterisk/_private.h"
00025 #include "asterisk/astobj2.h"
00026 #include "asterisk/utils.h"
00027 #include "asterisk/cli.h"
00028 #define REF_FILE "/tmp/refs"
00029 
00030 /*!
00031  * astobj2 objects are always preceded by this data structure,
00032  * which contains a lock, a reference counter,
00033  * the flags and a pointer to a destructor.
00034  * The refcount is used to decide when it is time to
00035  * invoke the destructor.
00036  * The magic number is used for consistency check.
00037  * XXX the lock is not always needed, and its initialization may be
00038  * expensive. Consider making it external.
00039  */
00040 struct __priv_data {
00041    ast_mutex_t lock;
00042    int ref_counter;
00043    ao2_destructor_fn destructor_fn;
00044    /*! for stats */
00045    size_t data_size;
00046    /*! magic number.  This is used to verify that a pointer passed in is a
00047     *  valid astobj2 */
00048    uint32_t magic;
00049 };
00050 
00051 #define  AO2_MAGIC   0xa570b123
00052 
00053 /*!
00054  * What an astobj2 object looks like: fixed-size private data
00055  * followed by variable-size user data.
00056  */
00057 struct astobj2 {
00058    struct __priv_data priv_data;
00059    void *user_data[0];
00060 };
00061 
00062 #ifdef AST_DEVMODE
00063 #define AO2_DEBUG 1
00064 #endif
00065 
00066 #ifdef AO2_DEBUG
00067 struct ao2_stats {
00068    volatile int total_objects;
00069    volatile int total_mem;
00070    volatile int total_containers;
00071    volatile int total_refs;
00072    volatile int total_locked;
00073 };
00074 
00075 static struct ao2_stats ao2;
00076 #endif
00077 
00078 #ifndef HAVE_BKTR /* backtrace support */
00079 void ao2_bt(void) {}
00080 #else
00081 #include <execinfo.h>    /* for backtrace */
00082 
00083 void ao2_bt(void)
00084 {
00085    int c, i;
00086 #define N1  20
00087    void *addresses[N1];
00088    char **strings;
00089 
00090    c = backtrace(addresses, N1);
00091    strings = ast_bt_get_symbols(addresses,c);
00092    ast_verbose("backtrace returned: %d\n", c);
00093    for(i = 0; i < c; i++) {
00094       ast_verbose("%d: %p %s\n", i, addresses[i], strings[i]);
00095    }
00096    free(strings);
00097 }
00098 #endif
00099 
00100 /*!
00101  * \brief convert from a pointer _p to a user-defined object
00102  *
00103  * \return the pointer to the astobj2 structure
00104  */
00105 static inline struct astobj2 *INTERNAL_OBJ(void *user_data)
00106 {
00107    struct astobj2 *p;
00108 
00109    if (!user_data) {
00110       ast_log(LOG_ERROR, "user_data is NULL\n");
00111       return NULL;
00112    }
00113 
00114    p = (struct astobj2 *) ((char *) user_data - sizeof(*p));
00115    if (AO2_MAGIC != (p->priv_data.magic) ) {
00116       ast_log(LOG_ERROR, "bad magic number 0x%x for %p\n", p->priv_data.magic, p);
00117       p = NULL;
00118    }
00119 
00120    return p;
00121 }
00122 
00123 enum ao2_callback_type {
00124    DEFAULT,
00125    WITH_DATA,
00126 };
00127 
00128 /*!
00129  * \brief convert from a pointer _p to an astobj2 object
00130  *
00131  * \return the pointer to the user-defined portion.
00132  */
00133 #define EXTERNAL_OBJ(_p)   ((_p) == NULL ? NULL : (_p)->user_data)
00134 
00135 /* the underlying functions common to debug and non-debug versions */
00136 
00137 static int internal_ao2_ref(void *user_data, const int delta);
00138 static struct ao2_container *internal_ao2_container_alloc(struct ao2_container *c, const uint n_buckets, ao2_hash_fn *hash_fn,
00139                        ao2_callback_fn *cmp_fn);
00140 static struct bucket_entry *internal_ao2_link(struct ao2_container *c, void *user_data, const char *file, int line, const char *func);
00141 static void *internal_ao2_callback(struct ao2_container *c,
00142                const enum search_flags flags, void *cb_fn, void *arg, void *data, enum ao2_callback_type type,
00143                char *tag, char *file, int line, const char *funcname);
00144 static void *internal_ao2_iterator_next(struct ao2_iterator *a, struct bucket_entry **q);
00145 
00146 int __ao2_lock(void *user_data, const char *file, const char *func, int line, const char *var)
00147 {
00148    struct astobj2 *p = INTERNAL_OBJ(user_data);
00149 
00150    if (p == NULL)
00151       return -1;
00152 
00153 #ifdef AO2_DEBUG
00154    ast_atomic_fetchadd_int(&ao2.total_locked, 1);
00155 #endif
00156 
00157    return __ast_pthread_mutex_lock(file, line, func, var, &p->priv_data.lock);
00158 }
00159 
00160 int __ao2_unlock(void *user_data, const char *file, const char *func, int line, const char *var)
00161 {
00162    struct astobj2 *p = INTERNAL_OBJ(user_data);
00163 
00164    if (p == NULL)
00165       return -1;
00166 
00167 #ifdef AO2_DEBUG
00168    ast_atomic_fetchadd_int(&ao2.total_locked, -1);
00169 #endif
00170 
00171    return __ast_pthread_mutex_unlock(file, line, func, var, &p->priv_data.lock);
00172 }
00173 
00174 int __ao2_trylock(void *user_data, const char *file, const char *func, int line, const char *var)
00175 {
00176    struct astobj2 *p = INTERNAL_OBJ(user_data);
00177    int ret;
00178    
00179    if (p == NULL)
00180       return -1;
00181    ret = __ast_pthread_mutex_trylock(file, line, func, var, &p->priv_data.lock);
00182 
00183 #ifdef AO2_DEBUG
00184    if (!ret)
00185       ast_atomic_fetchadd_int(&ao2.total_locked, 1);
00186 #endif
00187    return ret;
00188 }
00189 
00190 void *ao2_object_get_lockaddr(void *obj)
00191 {
00192    struct astobj2 *p = INTERNAL_OBJ(obj);
00193    
00194    if (p == NULL)
00195       return NULL;
00196 
00197    return &p->priv_data.lock;
00198 }
00199 
00200 /*
00201  * The argument is a pointer to the user portion.
00202  */
00203 
00204 
00205 int __ao2_ref_debug(void *user_data, const int delta, char *tag, char *file, int line, const char *funcname)
00206 {
00207    struct astobj2 *obj = INTERNAL_OBJ(user_data);
00208    
00209    if (obj == NULL)
00210       return -1;
00211 
00212    if (delta != 0) {
00213       FILE *refo = fopen(REF_FILE,"a");
00214       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);
00215       fclose(refo);
00216    }
00217    if (obj->priv_data.ref_counter + delta == 0 && obj->priv_data.destructor_fn != NULL) { /* this isn't protected with lock; just for o/p */
00218          FILE *refo = fopen(REF_FILE,"a");    
00219          fprintf(refo, "%p **call destructor** %s:%d:%s (%s)\n", user_data, file, line, funcname, tag);   
00220          fclose(refo);
00221    }
00222    return internal_ao2_ref(user_data, delta);
00223 }
00224 
00225 int __ao2_ref(void *user_data, const int delta)
00226 {
00227    struct astobj2 *obj = INTERNAL_OBJ(user_data);
00228 
00229    if (obj == NULL)
00230       return -1;
00231 
00232    return internal_ao2_ref(user_data, delta);
00233 }
00234 
00235 static int internal_ao2_ref(void *user_data, const int delta)
00236 {
00237    struct astobj2 *obj = INTERNAL_OBJ(user_data);
00238    int current_value;
00239    int ret;
00240 
00241    if (obj == NULL)
00242       return -1;
00243 
00244    /* if delta is 0, just return the refcount */
00245    if (delta == 0)
00246       return (obj->priv_data.ref_counter);
00247 
00248    /* we modify with an atomic operation the reference counter */
00249    ret = ast_atomic_fetchadd_int(&obj->priv_data.ref_counter, delta);
00250    current_value = ret + delta;
00251 
00252 #ifdef AO2_DEBUG  
00253    ast_atomic_fetchadd_int(&ao2.total_refs, delta);
00254 #endif
00255 
00256    /* this case must never happen */
00257    if (current_value < 0)
00258       ast_log(LOG_ERROR, "refcount %d on object %p\n", current_value, user_data);
00259 
00260    if (current_value <= 0) { /* last reference, destroy the object */
00261       if (obj->priv_data.destructor_fn != NULL) {
00262          obj->priv_data.destructor_fn(user_data);
00263       }
00264 
00265       ast_mutex_destroy(&obj->priv_data.lock);
00266 #ifdef AO2_DEBUG
00267       ast_atomic_fetchadd_int(&ao2.total_mem, - obj->priv_data.data_size);
00268       ast_atomic_fetchadd_int(&ao2.total_objects, -1);
00269 #endif
00270       /* for safety, zero-out the astobj2 header and also the
00271        * first word of the user-data, which we make sure is always
00272        * allocated. */
00273       memset(obj, '\0', sizeof(struct astobj2 *) + sizeof(void *) );
00274       ast_free(obj);
00275    }
00276 
00277    return ret;
00278 }
00279 
00280 /*
00281  * We always alloc at least the size of a void *,
00282  * for debugging purposes.
00283  */
00284 static void *internal_ao2_alloc(size_t data_size, ao2_destructor_fn destructor_fn, const char *file, int line, const char *funcname)
00285 {
00286    /* allocation */
00287    struct astobj2 *obj;
00288 
00289    if (data_size < sizeof(void *))
00290       data_size = sizeof(void *);
00291 
00292 #if defined(__AST_DEBUG_MALLOC)
00293    obj = __ast_calloc(1, sizeof(*obj) + data_size, file, line, funcname);
00294 #else
00295    obj = ast_calloc(1, sizeof(*obj) + data_size);
00296 #endif
00297 
00298    if (obj == NULL)
00299       return NULL;
00300 
00301    ast_mutex_init(&obj->priv_data.lock);
00302    obj->priv_data.magic = AO2_MAGIC;
00303    obj->priv_data.data_size = data_size;
00304    obj->priv_data.ref_counter = 1;
00305    obj->priv_data.destructor_fn = destructor_fn;   /* can be NULL */
00306 
00307 #ifdef AO2_DEBUG
00308    ast_atomic_fetchadd_int(&ao2.total_objects, 1);
00309    ast_atomic_fetchadd_int(&ao2.total_mem, data_size);
00310    ast_atomic_fetchadd_int(&ao2.total_refs, 1);
00311 #endif
00312 
00313    /* return a pointer to the user data */
00314    return EXTERNAL_OBJ(obj);
00315 }
00316 
00317 void *__ao2_alloc_debug(size_t data_size, ao2_destructor_fn destructor_fn, char *tag,
00318          const char *file, int line, const char *funcname, int ref_debug)
00319 {
00320    /* allocation */
00321    void *obj;
00322    FILE *refo = ref_debug ? fopen(REF_FILE,"a") : NULL;
00323 
00324    if ((obj = internal_ao2_alloc(data_size, destructor_fn, file, line, funcname)) == NULL) {
00325       fclose(refo);
00326       return NULL;
00327    }
00328 
00329    if (refo) {
00330       fprintf(refo, "%p =1   %s:%d:%s (%s)\n", obj, file, line, funcname, tag);
00331       fclose(refo);
00332    }
00333 
00334    /* return a pointer to the user data */
00335    return obj;
00336 }
00337 
00338 void *__ao2_alloc(size_t data_size, ao2_destructor_fn destructor_fn)
00339 {
00340    return internal_ao2_alloc(data_size, destructor_fn, __FILE__, __LINE__, __FUNCTION__);
00341 }
00342 
00343 
00344 /* internal callback to destroy a container. */
00345 static void container_destruct(void *c);
00346 
00347 /* internal callback to destroy a container. */
00348 static void container_destruct_debug(void *c);
00349 
00350 /* each bucket in the container is a tailq. */
00351 AST_LIST_HEAD_NOLOCK(bucket, bucket_entry);
00352 
00353 /*!
00354  * A container; stores the hash and callback functions, information on
00355  * the size, the hash bucket heads, and a version number, starting at 0
00356  * (for a newly created, empty container)
00357  * and incremented every time an object is inserted or deleted.
00358  * The assumption is that an object is never moved in a container,
00359  * but removed and readded with the new number.
00360  * The version number is especially useful when implementing iterators.
00361  * In fact, we can associate a unique, monotonically increasing number to
00362  * each object, which means that, within an iterator, we can store the
00363  * version number of the current object, and easily look for the next one,
00364  * which is the next one in the list with a higher number.
00365  * Since all objects have a version >0, we can use 0 as a marker for
00366  * 'we need the first object in the bucket'.
00367  *
00368  * \todo Linking and unlink objects is typically expensive, as it
00369  * involves a malloc() of a small object which is very inefficient.
00370  * To optimize this, we allocate larger arrays of bucket_entry's
00371  * when we run out of them, and then manage our own freelist.
00372  * This will be more efficient as we can do the freelist management while
00373  * we hold the lock (that we need anyways).
00374  */
00375 struct ao2_container {
00376    ao2_hash_fn *hash_fn;
00377    ao2_callback_fn *cmp_fn;
00378    int n_buckets;
00379    /*! Number of elements in the container */
00380    int elements;
00381    /*! described above */
00382    int version;
00383    /*! variable size */
00384    struct bucket buckets[0];
00385 };
00386  
00387 /*!
00388  * \brief always zero hash function
00389  *
00390  * it is convenient to have a hash function that always returns 0.
00391  * This is basically used when we want to have a container that is
00392  * a simple linked list.
00393  *
00394  * \returns 0
00395  */
00396 static int hash_zero(const void *user_obj, const int flags)
00397 {
00398    return 0;
00399 }
00400 
00401 /*
00402  * A container is just an object, after all!
00403  */
00404 static struct ao2_container *internal_ao2_container_alloc(struct ao2_container *c, const unsigned int n_buckets, ao2_hash_fn *hash_fn,
00405                        ao2_callback_fn *cmp_fn)
00406 {
00407    /* XXX maybe consistency check on arguments ? */
00408    /* compute the container size */
00409 
00410    if (!c)
00411       return NULL;
00412    
00413    c->version = 1;   /* 0 is a reserved value here */
00414    c->n_buckets = hash_fn ? n_buckets : 1;
00415    c->hash_fn = hash_fn ? hash_fn : hash_zero;
00416    c->cmp_fn = cmp_fn;
00417 
00418 #ifdef AO2_DEBUG
00419    ast_atomic_fetchadd_int(&ao2.total_containers, 1);
00420 #endif
00421 
00422    return c;
00423 }
00424 
00425 struct ao2_container *__ao2_container_alloc_debug(const unsigned int n_buckets, ao2_hash_fn *hash_fn,
00426                     ao2_callback_fn *cmp_fn, char *tag, char *file, int line,
00427                     const char *funcname, int ref_debug)
00428 {
00429    /* XXX maybe consistency check on arguments ? */
00430    /* compute the container size */
00431    const unsigned int num_buckets = hash_fn ? n_buckets : 1;
00432    size_t container_size = sizeof(struct ao2_container) + num_buckets * sizeof(struct bucket);
00433    struct ao2_container *c = __ao2_alloc_debug(container_size, container_destruct_debug, tag, file, line, funcname, ref_debug);
00434 
00435    return internal_ao2_container_alloc(c, num_buckets, hash_fn, cmp_fn);
00436 }
00437 
00438 struct ao2_container *__ao2_container_alloc(const unsigned int n_buckets, ao2_hash_fn *hash_fn,
00439                    ao2_callback_fn *cmp_fn)
00440 {
00441    /* XXX maybe consistency check on arguments ? */
00442    /* compute the container size */
00443 
00444    const unsigned int num_buckets = hash_fn ? n_buckets : 1;
00445    size_t container_size = sizeof(struct ao2_container) + num_buckets * sizeof(struct bucket);
00446    struct ao2_container *c = __ao2_alloc(container_size, container_destruct);
00447 
00448    return internal_ao2_container_alloc(c, num_buckets, hash_fn, cmp_fn);
00449 }
00450 
00451 /*!
00452  * return the number of elements in the container
00453  */
00454 int ao2_container_count(struct ao2_container *c)
00455 {
00456    return c->elements;
00457 }
00458 
00459 /*!
00460  * A structure to create a linked list of entries,
00461  * used within a bucket.
00462  * XXX \todo this should be private to the container code
00463  */
00464 struct bucket_entry {
00465    AST_LIST_ENTRY(bucket_entry) entry;
00466    int version;
00467    struct astobj2 *astobj;    /* pointer to internal data */
00468 }; 
00469 
00470 /*
00471  * link an object to a container
00472  */
00473 
00474 static struct bucket_entry *internal_ao2_link(struct ao2_container *c, void *user_data, const char *file, int line, const char *func)
00475 {
00476    int i;
00477    /* create a new list entry */
00478    struct bucket_entry *p;
00479    struct astobj2 *obj = INTERNAL_OBJ(user_data);
00480 
00481    if (obj == NULL)
00482       return NULL;
00483 
00484    if (INTERNAL_OBJ(c) == NULL)
00485       return NULL;
00486 
00487    p = ast_calloc(1, sizeof(*p));
00488    if (!p)
00489       return NULL;
00490 
00491    i = abs(c->hash_fn(user_data, OBJ_POINTER));
00492 
00493    ao2_lock(c);
00494    i %= c->n_buckets;
00495    p->astobj = obj;
00496    p->version = ast_atomic_fetchadd_int(&c->version, 1);
00497    AST_LIST_INSERT_TAIL(&c->buckets[i], p, entry);
00498    ast_atomic_fetchadd_int(&c->elements, 1);
00499 
00500    /* the last two operations (ao2_ref, ao2_unlock) must be done by the calling func */
00501    return p;
00502 }
00503 
00504 void *__ao2_link_debug(struct ao2_container *c, void *user_data, char *tag, char *file, int line, const char *funcname)
00505 {
00506    struct bucket_entry *p = internal_ao2_link(c, user_data, file, line, funcname);
00507 
00508    if (p) {
00509       __ao2_ref_debug(user_data, +1, tag, file, line, funcname);
00510       ao2_unlock(c);
00511    }
00512    return p;
00513 }
00514 
00515 void *__ao2_link(struct ao2_container *c, void *user_data)
00516 {
00517    struct bucket_entry *p = internal_ao2_link(c, user_data, __FILE__, __LINE__, __PRETTY_FUNCTION__);
00518 
00519    if (p) {
00520       __ao2_ref(user_data, +1);
00521       ao2_unlock(c);
00522    }
00523    return p;
00524 }
00525 
00526 /*!
00527  * \brief another convenience function is a callback that matches on address
00528  */
00529 int ao2_match_by_addr(void *user_data, void *arg, int flags)
00530 {
00531    return (user_data == arg) ? (CMP_MATCH | CMP_STOP) : 0;
00532 }
00533 
00534 /*
00535  * Unlink an object from the container
00536  * and destroy the associated * bucket_entry structure.
00537  */
00538 void *__ao2_unlink_debug(struct ao2_container *c, void *user_data, char *tag,
00539           char *file, int line, const char *funcname)
00540 {
00541    if (INTERNAL_OBJ(user_data) == NULL)   /* safety check on the argument */
00542       return NULL;
00543 
00544    __ao2_callback_debug(c, OBJ_UNLINK | OBJ_POINTER | OBJ_NODATA, ao2_match_by_addr, user_data, tag, file, line, funcname);
00545 
00546    return NULL;
00547 }
00548 
00549 void *__ao2_unlink(struct ao2_container *c, void *user_data)
00550 {
00551    if (INTERNAL_OBJ(user_data) == NULL)   /* safety check on the argument */
00552       return NULL;
00553 
00554    __ao2_callback(c, OBJ_UNLINK | OBJ_POINTER | OBJ_NODATA, ao2_match_by_addr, user_data);
00555 
00556    return NULL;
00557 }
00558 
00559 /*! 
00560  * \brief special callback that matches all 
00561  */ 
00562 static int cb_true(void *user_data, void *arg, int flags)
00563 {
00564    return CMP_MATCH;
00565 }
00566 
00567 /*!
00568  * \brief similar to cb_true, but is an ao2_callback_data_fn instead
00569  */
00570 static int cb_true_data(void *user_data, void *arg, void *data, int flags)
00571 {
00572    return CMP_MATCH;
00573 }
00574 
00575 /*!
00576  * Browse the container using different stategies accoding the flags.
00577  * \return Is a pointer to an object or to a list of object if OBJ_MULTIPLE is 
00578  * specified.
00579  * Luckily, for debug purposes, the added args (tag, file, line, funcname)
00580  * aren't an excessive load to the system, as the callback should not be
00581  * called as often as, say, the ao2_ref func is called.
00582  */
00583 static void *internal_ao2_callback(struct ao2_container *c,
00584                const enum search_flags flags, void *cb_fn, void *arg, void *data, enum ao2_callback_type type,
00585                char *tag, char *file, int line, const char *funcname)
00586 {
00587    int i, start, last;  /* search boundaries */
00588    void *ret = NULL;
00589    ao2_callback_fn *cb_default = NULL;
00590    ao2_callback_data_fn *cb_withdata = NULL;
00591    struct ao2_container *multi_container = NULL;
00592    struct ao2_iterator *multi_iterator = NULL;
00593 
00594    if (INTERNAL_OBJ(c) == NULL)  /* safety check on the argument */
00595       return NULL;
00596 
00597    /*
00598     * This logic is used so we can support OBJ_MULTIPLE with OBJ_NODATA
00599     * turned off.  This if statement checks for the special condition
00600     * where multiple items may need to be returned.
00601     */
00602    if ((flags & (OBJ_MULTIPLE | OBJ_NODATA)) == OBJ_MULTIPLE) {
00603       /* we need to return an ao2_iterator with the results,
00604        * as there could be more than one. the iterator will
00605        * hold the only reference to a container that has all the
00606        * matching objects linked into it, so when the iterator
00607        * is destroyed, the container will be automatically
00608        * destroyed as well.
00609        */
00610       if (!(multi_container = __ao2_container_alloc(1, NULL, NULL))) {
00611          return NULL;
00612       }
00613       if (!(multi_iterator = ast_calloc(1, sizeof(*multi_iterator)))) {
00614          ao2_ref(multi_container, -1);
00615          return NULL;
00616       }
00617    }
00618 
00619    /* override the match function if necessary */
00620    if (cb_fn == NULL) { /* if NULL, match everything */
00621       if (type == WITH_DATA) {
00622          cb_withdata = cb_true_data;
00623       } else {
00624          cb_default = cb_true;
00625       }
00626    } else {
00627       /* We do this here to avoid the per object casting penalty (even though
00628          that is probably optimized away anyway). */
00629       if (type == WITH_DATA) {
00630          cb_withdata = cb_fn;
00631       } else {
00632          cb_default = cb_fn;
00633       }
00634    }
00635 
00636    /*
00637     * XXX this can be optimized.
00638     * If we have a hash function and lookup by pointer,
00639     * run the hash function. Otherwise, scan the whole container
00640     * (this only for the time being. We need to optimize this.)
00641     */
00642    if ((flags & OBJ_POINTER)) /* we know hash can handle this case */
00643       start = i = c->hash_fn(arg, flags & OBJ_POINTER) % c->n_buckets;
00644    else        /* don't know, let's scan all buckets */
00645       start = i = -1;      /* XXX this must be fixed later. */
00646 
00647    /* determine the search boundaries: i..last-1 */
00648    if (i < 0) {
00649       start = i = 0;
00650       last = c->n_buckets;
00651    } else if ((flags & OBJ_CONTINUE)) {
00652       last = c->n_buckets;
00653    } else {
00654       last = i + 1;
00655    }
00656 
00657    ao2_lock(c);   /* avoid modifications to the content */
00658 
00659    for (; i < last ; i++) {
00660       /* scan the list with prev-cur pointers */
00661       struct bucket_entry *cur;
00662 
00663       AST_LIST_TRAVERSE_SAFE_BEGIN(&c->buckets[i], cur, entry) {
00664          int match = (CMP_MATCH | CMP_STOP);
00665 
00666          if (type == WITH_DATA) {
00667             match &= cb_withdata(EXTERNAL_OBJ(cur->astobj), arg, data, flags);
00668          } else {
00669             match &= cb_default(EXTERNAL_OBJ(cur->astobj), arg, flags);
00670          }
00671 
00672          /* we found the object, performing operations according flags */
00673          if (match == 0) { /* no match, no stop, continue */
00674             continue;
00675          } else if (match == CMP_STOP) {  /* no match but stop, we are done */
00676             i = last;
00677             break;
00678          }
00679 
00680          /* we have a match (CMP_MATCH) here */
00681          if (!(flags & OBJ_NODATA)) {  /* if must return the object, record the value */
00682             /* it is important to handle this case before the unlink */
00683             ret = EXTERNAL_OBJ(cur->astobj);
00684             if (!(flags & (OBJ_UNLINK | OBJ_MULTIPLE))) {
00685                if (tag)
00686                   __ao2_ref_debug(ret, 1, tag, file, line, funcname);
00687                else
00688                   __ao2_ref(ret, 1);
00689             }
00690          }
00691 
00692          /* If we are in OBJ_MULTIPLE mode and OBJ_NODATE is off, 
00693           * link the object into the container that will hold the results.
00694           */
00695          if (ret && (multi_container != NULL)) {
00696             __ao2_link(multi_container, ret);
00697             ret = NULL;
00698          }
00699 
00700          if (flags & OBJ_UNLINK) {  /* must unlink */
00701             /* we are going to modify the container, so update version */
00702             ast_atomic_fetchadd_int(&c->version, 1);
00703             AST_LIST_REMOVE_CURRENT(entry);
00704             /* update number of elements */
00705             ast_atomic_fetchadd_int(&c->elements, -1);
00706 
00707             /* - When unlinking and not returning the result, (OBJ_NODATA), the ref from the container
00708              * must be decremented.
00709              * - When unlinking with OBJ_MULTIPLE the ref from the original container
00710              * must be decremented regardless if OBJ_NODATA is used. This is because the result is
00711              * returned in a new container that already holds its own ref for the object. If the ref
00712              * from the original container is not accounted for here a memory leak occurs. */
00713             if (flags & (OBJ_NODATA | OBJ_MULTIPLE)) {
00714                if (tag)
00715                   __ao2_ref_debug(EXTERNAL_OBJ(cur->astobj), -1, tag, file, line, funcname);
00716                else
00717                   __ao2_ref(EXTERNAL_OBJ(cur->astobj), -1);
00718             }
00719             ast_free(cur); /* free the link record */
00720          }
00721 
00722          if ((match & CMP_STOP) || !(flags & OBJ_MULTIPLE)) {
00723             /* We found our only (or last) match, so force an exit from
00724                the outside loop. */
00725             i = last;
00726             break;
00727          }
00728       }
00729       AST_LIST_TRAVERSE_SAFE_END;
00730 
00731       if (ret) {
00732          break;
00733       }
00734 
00735       if (i == c->n_buckets - 1 && (flags & OBJ_POINTER) && (flags & OBJ_CONTINUE)) {
00736          /* Move to the beginning to ensure we check every bucket */
00737          i = -1;
00738          last = start;
00739       }
00740    }
00741    ao2_unlock(c);
00742 
00743    /* if multi_container was created, we are returning multiple objects */
00744    if (multi_container != NULL) {
00745       *multi_iterator = ao2_iterator_init(multi_container,
00746                       AO2_ITERATOR_DONTLOCK | AO2_ITERATOR_UNLINK | AO2_ITERATOR_MALLOCD);
00747       ao2_ref(multi_container, -1);
00748       return multi_iterator;
00749    } else {
00750       return ret;
00751    }
00752 }
00753 
00754 void *__ao2_callback_debug(struct ao2_container *c,
00755             const enum search_flags flags,
00756             ao2_callback_fn *cb_fn, void *arg,
00757             char *tag, char *file, int line, const char *funcname)
00758 {
00759    return internal_ao2_callback(c,flags, cb_fn, arg, NULL, DEFAULT, tag, file, line, funcname);
00760 }
00761 
00762 void *__ao2_callback(struct ao2_container *c, const enum search_flags flags,
00763            ao2_callback_fn *cb_fn, void *arg)
00764 {
00765    return internal_ao2_callback(c,flags, cb_fn, arg, NULL, DEFAULT, NULL, NULL, 0, NULL);
00766 }
00767 
00768 void *__ao2_callback_data_debug(struct ao2_container *c,
00769             const enum search_flags flags,
00770             ao2_callback_data_fn *cb_fn, void *arg, void *data,
00771             char *tag, char *file, int line, const char *funcname)
00772 {
00773    return internal_ao2_callback(c, flags, cb_fn, arg, data, WITH_DATA, tag, file, line, funcname);
00774 }
00775 
00776 void *__ao2_callback_data(struct ao2_container *c, const enum search_flags flags,
00777            ao2_callback_data_fn *cb_fn, void *arg, void *data)
00778 {
00779    return internal_ao2_callback(c, flags, cb_fn, arg, data, WITH_DATA, NULL, NULL, 0, NULL);
00780 }
00781 
00782 /*!
00783  * the find function just invokes the default callback with some reasonable flags.
00784  */
00785 void *__ao2_find_debug(struct ao2_container *c, void *arg, enum search_flags flags, char *tag, char *file, int line, const char *funcname)
00786 {
00787    return __ao2_callback_debug(c, flags, c->cmp_fn, arg, tag, file, line, funcname);
00788 }
00789 
00790 void *__ao2_find(struct ao2_container *c, void *arg, enum search_flags flags)
00791 {
00792    return __ao2_callback(c, flags, c->cmp_fn, arg);
00793 }
00794 
00795 /*!
00796  * initialize an iterator so we start from the first object
00797  */
00798 struct ao2_iterator ao2_iterator_init(struct ao2_container *c, int flags)
00799 {
00800    struct ao2_iterator a = {
00801       .c = c,
00802       .flags = flags
00803    };
00804 
00805    ao2_ref(c, +1);
00806    
00807    return a;
00808 }
00809 
00810 /*!
00811  * destroy an iterator
00812  */
00813 void ao2_iterator_destroy(struct ao2_iterator *i)
00814 {
00815    ao2_ref(i->c, -1);
00816    if (i->flags & AO2_ITERATOR_MALLOCD) {
00817       ast_free(i);
00818    } else {
00819       i->c = NULL;
00820    }
00821 }
00822 
00823 /*
00824  * move to the next element in the container.
00825  */
00826 static void *internal_ao2_iterator_next(struct ao2_iterator *a, struct bucket_entry **q)
00827 {
00828    int lim;
00829    struct bucket_entry *p = NULL;
00830    void *ret = NULL;
00831 
00832    *q = NULL;
00833    
00834    if (INTERNAL_OBJ(a->c) == NULL)
00835       return NULL;
00836 
00837    if (!(a->flags & AO2_ITERATOR_DONTLOCK))
00838       ao2_lock(a->c);
00839 
00840    /* optimization. If the container is unchanged and
00841     * we have a pointer, try follow it
00842     */
00843    if (a->c->version == a->c_version && (p = a->obj)) {
00844       if ((p = AST_LIST_NEXT(p, entry)))
00845          goto found;
00846       /* nope, start from the next bucket */
00847       a->bucket++;
00848       a->version = 0;
00849       a->obj = NULL;
00850    }
00851 
00852    lim = a->c->n_buckets;
00853 
00854    /* Browse the buckets array, moving to the next
00855     * buckets if we don't find the entry in the current one.
00856     * Stop when we find an element with version number greater
00857     * than the current one (we reset the version to 0 when we
00858     * switch buckets).
00859     */
00860    for (; a->bucket < lim; a->bucket++, a->version = 0) {
00861       /* scan the current bucket */
00862       AST_LIST_TRAVERSE(&a->c->buckets[a->bucket], p, entry) {
00863          if (p->version > a->version)
00864             goto found;
00865       }
00866    }
00867 
00868 found:
00869    if (p) {
00870       ret = EXTERNAL_OBJ(p->astobj);
00871       if (a->flags & AO2_ITERATOR_UNLINK) {
00872          /* we are going to modify the container, so update version */
00873          ast_atomic_fetchadd_int(&a->c->version, 1);
00874          AST_LIST_REMOVE(&a->c->buckets[a->bucket], p, entry);
00875          /* update number of elements */
00876          ast_atomic_fetchadd_int(&a->c->elements, -1);
00877          a->version = 0;
00878          a->obj = NULL;
00879          a->c_version = a->c->version;
00880          ast_free(p);
00881       } else {
00882          a->version = p->version;
00883          a->obj = p;
00884          a->c_version = a->c->version;
00885          /* inc refcount of returned object */
00886          *q = p;
00887       }
00888    }
00889 
00890    return ret;
00891 }
00892 
00893 void *__ao2_iterator_next_debug(struct ao2_iterator *a, char *tag, char *file, int line, const char *funcname)
00894 {
00895    struct bucket_entry *p;
00896    void *ret = NULL;
00897 
00898    ret = internal_ao2_iterator_next(a, &p);
00899    
00900    if (p) {
00901       /* inc refcount of returned object */
00902       __ao2_ref_debug(ret, 1, tag, file, line, funcname);
00903    }
00904 
00905    if (!(a->flags & AO2_ITERATOR_DONTLOCK))
00906       ao2_unlock(a->c);
00907 
00908    return ret;
00909 }
00910 
00911 void *__ao2_iterator_next(struct ao2_iterator *a)
00912 {
00913    struct bucket_entry *p = NULL;
00914    void *ret = NULL;
00915 
00916    ret = internal_ao2_iterator_next(a, &p);
00917    
00918    if (p) {
00919       /* inc refcount of returned object */
00920       __ao2_ref(ret, 1);
00921    }
00922 
00923    if (!(a->flags & AO2_ITERATOR_DONTLOCK))
00924       ao2_unlock(a->c);
00925 
00926    return ret;
00927 }
00928 
00929 /* callback for destroying container.
00930  * we can make it simple as we know what it does
00931  */
00932 static int cd_cb(void *obj, void *arg, int flag)
00933 {
00934    __ao2_ref(obj, -1);
00935    return 0;
00936 }
00937    
00938 static int cd_cb_debug(void *obj, void *arg, int flag)
00939 {
00940    __ao2_ref_debug(obj, -1, "deref object via container destroy",  __FILE__, __LINE__, __PRETTY_FUNCTION__);
00941    return 0;
00942 }
00943    
00944 static void container_destruct(void *_c)
00945 {
00946    struct ao2_container *c = _c;
00947    int i;
00948 
00949    __ao2_callback(c, OBJ_UNLINK, cd_cb, NULL);
00950 
00951    for (i = 0; i < c->n_buckets; i++) {
00952       struct bucket_entry *current;
00953 
00954       while ((current = AST_LIST_REMOVE_HEAD(&c->buckets[i], entry))) {
00955          ast_free(current);
00956       }
00957    }
00958 
00959 #ifdef AO2_DEBUG
00960    ast_atomic_fetchadd_int(&ao2.total_containers, -1);
00961 #endif
00962 }
00963 
00964 static void container_destruct_debug(void *_c)
00965 {
00966    struct ao2_container *c = _c;
00967    int i;
00968 
00969    __ao2_callback_debug(c, OBJ_UNLINK, cd_cb_debug, NULL, "container_destruct_debug called", __FILE__, __LINE__, __PRETTY_FUNCTION__);
00970 
00971    for (i = 0; i < c->n_buckets; i++) {
00972       struct bucket_entry *current;
00973 
00974       while ((current = AST_LIST_REMOVE_HEAD(&c->buckets[i], entry))) {
00975          ast_free(current);
00976       }
00977    }
00978 
00979 #ifdef AO2_DEBUG
00980    ast_atomic_fetchadd_int(&ao2.total_containers, -1);
00981 #endif
00982 }
00983 
00984 #ifdef AO2_DEBUG
00985 static int print_cb(void *obj, void *arg, int flag)
00986 {
00987    struct ast_cli_args *a = (struct ast_cli_args *) arg;
00988    char *s = (char *)obj;
00989 
00990    ast_cli(a->fd, "string <%s>\n", s);
00991    return 0;
00992 }
00993 
00994 /*
00995  * Print stats
00996  */
00997 static char *handle_astobj2_stats(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
00998 {
00999    switch (cmd) {
01000    case CLI_INIT:
01001       e->command = "astobj2 show stats";
01002       e->usage = "Usage: astobj2 show stats\n"
01003             "       Show astobj2 show stats\n";
01004       return NULL;
01005    case CLI_GENERATE:
01006       return NULL;
01007    }
01008    ast_cli(a->fd, "Objects    : %d\n", ao2.total_objects);
01009    ast_cli(a->fd, "Containers : %d\n", ao2.total_containers);
01010    ast_cli(a->fd, "Memory     : %d\n", ao2.total_mem);
01011    ast_cli(a->fd, "Locked     : %d\n", ao2.total_locked);
01012    ast_cli(a->fd, "Refs       : %d\n", ao2.total_refs);
01013    return CLI_SUCCESS;
01014 }
01015 
01016 /*
01017  * This is testing code for astobj
01018  */
01019 static char *handle_astobj2_test(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
01020 {
01021    struct ao2_container *c1;
01022    int i, lim;
01023    char *obj;
01024    static int prof_id = -1;
01025    struct ast_cli_args fake_args = { a->fd, 0, NULL };
01026 
01027    switch (cmd) {
01028    case CLI_INIT:
01029       e->command = "astobj2 test";
01030       e->usage = "Usage: astobj2 test <num>\n"
01031             "       Runs astobj2 test. Creates 'num' objects,\n"
01032             "       and test iterators, callbacks and may be other stuff\n";
01033       return NULL;
01034    case CLI_GENERATE:
01035       return NULL;
01036    }
01037 
01038    if (a->argc != 3) {
01039       return CLI_SHOWUSAGE;
01040    }
01041 
01042    if (prof_id == -1)
01043       prof_id = ast_add_profile("ao2_alloc", 0);
01044 
01045    ast_cli(a->fd, "argc %d argv %s %s %s\n", a->argc, a->argv[0], a->argv[1], a->argv[2]);
01046    lim = atoi(a->argv[2]);
01047    ast_cli(a->fd, "called astobj_test\n");
01048 
01049    handle_astobj2_stats(e, CLI_HANDLER, &fake_args);
01050    /*
01051     * allocate a container with no default callback, and no hash function.
01052     * No hash means everything goes in the same bucket.
01053     */
01054    c1 = ao2_t_container_alloc(100, NULL /* no callback */, NULL /* no hash */,"test");
01055    ast_cli(a->fd, "container allocated as %p\n", c1);
01056 
01057    /*
01058     * fill the container with objects.
01059     * ao2_alloc() gives us a reference which we pass to the
01060     * container when we do the insert.
01061     */
01062    for (i = 0; i < lim; i++) {
01063       ast_mark(prof_id, 1 /* start */);
01064       obj = ao2_t_alloc(80, NULL,"test");
01065       ast_mark(prof_id, 0 /* stop */);
01066       ast_cli(a->fd, "object %d allocated as %p\n", i, obj);
01067       sprintf(obj, "-- this is obj %d --", i);
01068       ao2_link(c1, obj);
01069       /* At this point, the refcount on obj is 2 due to the allocation
01070        * and linking. We can go ahead and reduce the refcount by 1
01071        * right here so that when the container is unreffed later, the
01072        * objects will be freed
01073        */
01074       ao2_t_ref(obj, -1, "test");
01075    }
01076    ast_cli(a->fd, "testing callbacks\n");
01077    ao2_t_callback(c1, 0, print_cb, a, "test callback");
01078    ast_cli(a->fd, "testing iterators, remove every second object\n");
01079    {
01080       struct ao2_iterator ai;
01081       int x = 0;
01082 
01083       ai = ao2_iterator_init(c1, 0);
01084       while ( (obj = ao2_t_iterator_next(&ai,"test")) ) {
01085          ast_cli(a->fd, "iterator on <%s>\n", obj);
01086          if (x++ & 1)
01087             ao2_t_unlink(c1, obj,"test");
01088          ao2_t_ref(obj, -1,"test");
01089       }
01090       ao2_iterator_destroy(&ai);
01091       ast_cli(a->fd, "testing iterators again\n");
01092       ai = ao2_iterator_init(c1, 0);
01093       while ( (obj = ao2_t_iterator_next(&ai,"test")) ) {
01094          ast_cli(a->fd, "iterator on <%s>\n", obj);
01095          ao2_t_ref(obj, -1,"test");
01096       }
01097       ao2_iterator_destroy(&ai);
01098    }
01099    ast_cli(a->fd, "testing callbacks again\n");
01100    ao2_t_callback(c1, 0, print_cb, a, "test callback");
01101 
01102    ast_verbose("now you should see an error message:\n");
01103    ao2_t_ref(&i, -1, "");  /* i is not a valid object so we print an error here */
01104 
01105    ast_cli(a->fd, "destroy container\n");
01106    ao2_t_ref(c1, -1, "");  /* destroy container */
01107    handle_astobj2_stats(e, CLI_HANDLER, &fake_args);
01108    return CLI_SUCCESS;
01109 }
01110 
01111 static struct ast_cli_entry cli_astobj2[] = {
01112    AST_CLI_DEFINE(handle_astobj2_stats, "Print astobj2 statistics"),
01113    AST_CLI_DEFINE(handle_astobj2_test, "Test astobj2"),
01114 };
01115 #endif /* AO2_DEBUG */
01116 
01117 int astobj2_init(void)
01118 {
01119 #ifdef AO2_DEBUG
01120    ast_cli_register_multiple(cli_astobj2, ARRAY_LEN(cli_astobj2));
01121 #endif
01122 
01123    return 0;
01124 }

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