Mon Oct 8 12:39:05 2012

Asterisk developer's documentation


taskprocessor.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2007-2008, Digium, Inc.
00005  *
00006  * Dwayne M. Hubbard <dhubbard@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*!
00020  * \file
00021  * \brief Maintain a container of uniquely-named taskprocessor threads that can be shared across modules.
00022  *
00023  * \author Dwayne Hubbard <dhubbard@digium.com>
00024  */
00025 
00026 /*** MODULEINFO
00027    <support_level>core</support_level>
00028  ***/
00029 
00030 #include "asterisk.h"
00031 
00032 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 369001 $")
00033 
00034 #include "asterisk/_private.h"
00035 #include "asterisk/module.h"
00036 #include "asterisk/time.h"
00037 #include "asterisk/astobj2.h"
00038 #include "asterisk/cli.h"
00039 #include "asterisk/taskprocessor.h"
00040 
00041 
00042 /*!
00043  * \brief tps_task structure is queued to a taskprocessor
00044  *
00045  * tps_tasks are processed in FIFO order and freed by the taskprocessing
00046  * thread after the task handler returns.  The callback function that is assigned
00047  * to the execute() function pointer is responsible for releasing datap resources if necessary.
00048  */
00049 struct tps_task {
00050    /*! \brief The execute() task callback function pointer */
00051    int (*execute)(void *datap);
00052    /*! \brief The data pointer for the task execute() function */
00053    void *datap;
00054    /*! \brief AST_LIST_ENTRY overhead */
00055    AST_LIST_ENTRY(tps_task) list;
00056 };
00057 
00058 /*! \brief tps_taskprocessor_stats maintain statistics for a taskprocessor. */
00059 struct tps_taskprocessor_stats {
00060    /*! \brief This is the maximum number of tasks queued at any one time */
00061    unsigned long max_qsize;
00062    /*! \brief This is the current number of tasks processed */
00063    unsigned long _tasks_processed_count;
00064 };
00065 
00066 /*! \brief A ast_taskprocessor structure is a singleton by name */
00067 struct ast_taskprocessor {
00068    /*! \brief Friendly name of the taskprocessor */
00069    const char *name;
00070    /*! \brief Thread poll condition */
00071    ast_cond_t poll_cond;
00072    /*! \brief Taskprocessor thread */
00073    pthread_t poll_thread;
00074    /*! \brief Taskprocessor lock */
00075    ast_mutex_t taskprocessor_lock;
00076    /*! \brief Taskprocesor thread run flag */
00077    unsigned char poll_thread_run;
00078    /*! \brief Taskprocessor statistics */
00079    struct tps_taskprocessor_stats *stats;
00080    /*! \brief Taskprocessor current queue size */
00081    long tps_queue_size;
00082    /*! \brief Taskprocessor queue */
00083    AST_LIST_HEAD_NOLOCK(tps_queue, tps_task) tps_queue;
00084    /*! \brief Taskprocessor singleton list entry */
00085    AST_LIST_ENTRY(ast_taskprocessor) list;
00086 };
00087 #define TPS_MAX_BUCKETS 7
00088 /*! \brief tps_singletons is the astobj2 container for taskprocessor singletons */
00089 static struct ao2_container *tps_singletons;
00090 
00091 /*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> operation requires a ping condition */
00092 static ast_cond_t cli_ping_cond;
00093 
00094 /*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> operation requires a ping condition lock */
00095 AST_MUTEX_DEFINE_STATIC(cli_ping_cond_lock);
00096 
00097 /*! \brief The astobj2 hash callback for taskprocessors */
00098 static int tps_hash_cb(const void *obj, const int flags);
00099 /*! \brief The astobj2 compare callback for taskprocessors */
00100 static int tps_cmp_cb(void *obj, void *arg, int flags);
00101 
00102 /*! \brief The task processing function executed by a taskprocessor */
00103 static void *tps_processing_function(void *data);
00104 
00105 /*! \brief Destroy the taskprocessor when its refcount reaches zero */
00106 static void tps_taskprocessor_destroy(void *tps);
00107 
00108 /*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> handler function */
00109 static int tps_ping_handler(void *datap);
00110 
00111 /*! \brief Remove the front task off the taskprocessor queue */
00112 static struct tps_task *tps_taskprocessor_pop(struct ast_taskprocessor *tps);
00113 
00114 /*! \brief Return the size of the taskprocessor queue */
00115 static int tps_taskprocessor_depth(struct ast_taskprocessor *tps);
00116 
00117 static char *cli_tps_ping(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
00118 static char *cli_tps_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
00119 
00120 static struct ast_cli_entry taskprocessor_clis[] = {
00121    AST_CLI_DEFINE(cli_tps_ping, "Ping a named task processor"),
00122    AST_CLI_DEFINE(cli_tps_report, "List instantiated task processors and statistics"),
00123 };
00124 
00125 /* initialize the taskprocessor container and register CLI operations */
00126 int ast_tps_init(void)
00127 {
00128    if (!(tps_singletons = ao2_container_alloc(TPS_MAX_BUCKETS, tps_hash_cb, tps_cmp_cb))) {
00129       ast_log(LOG_ERROR, "taskprocessor container failed to initialize!\n");
00130       return -1;
00131    }
00132 
00133    ast_cond_init(&cli_ping_cond, NULL);
00134 
00135    ast_cli_register_multiple(taskprocessor_clis, ARRAY_LEN(taskprocessor_clis));
00136    return 0;
00137 }
00138 
00139 /* allocate resources for the task */
00140 static struct tps_task *tps_task_alloc(int (*task_exe)(void *datap), void *datap)
00141 {
00142    struct tps_task *t;
00143    if ((t = ast_calloc(1, sizeof(*t)))) {
00144       t->execute = task_exe;
00145       t->datap = datap;
00146    }
00147    return t;
00148 }
00149 
00150 /* release task resources */  
00151 static void *tps_task_free(struct tps_task *task)
00152 {
00153    if (task) {
00154       ast_free(task);
00155    }
00156    return NULL;
00157 }
00158 
00159 /* taskprocessor tab completion */
00160 static char *tps_taskprocessor_tab_complete(struct ast_taskprocessor *p, struct ast_cli_args *a) 
00161 {
00162    int tklen;
00163    int wordnum = 0;
00164    char *name = NULL;
00165    struct ao2_iterator i;
00166 
00167    if (a->pos != 3)
00168       return NULL;
00169 
00170    tklen = strlen(a->word);
00171    i = ao2_iterator_init(tps_singletons, 0);
00172    while ((p = ao2_iterator_next(&i))) {
00173       if (!strncasecmp(a->word, p->name, tklen) && ++wordnum > a->n) {
00174          name = ast_strdup(p->name);
00175          ao2_ref(p, -1);
00176          break;
00177       }
00178       ao2_ref(p, -1);
00179    }
00180    ao2_iterator_destroy(&i);
00181    return name;
00182 }
00183 
00184 /* ping task handling function */
00185 static int tps_ping_handler(void *datap)
00186 {
00187    ast_mutex_lock(&cli_ping_cond_lock);
00188    ast_cond_signal(&cli_ping_cond);
00189    ast_mutex_unlock(&cli_ping_cond_lock);
00190    return 0;
00191 }
00192 
00193 /* ping the specified taskprocessor and display the ping time on the CLI */
00194 static char *cli_tps_ping(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
00195 {
00196    struct timeval begin, end, delta;
00197    const char *name;
00198    struct timeval when;
00199    struct timespec ts;
00200    struct ast_taskprocessor *tps = NULL;
00201 
00202    switch (cmd) {
00203    case CLI_INIT:
00204       e->command = "core ping taskprocessor";
00205       e->usage = 
00206          "Usage: core ping taskprocessor <taskprocessor>\n"
00207          "  Displays the time required for a task to be processed\n";
00208       return NULL;
00209    case CLI_GENERATE:
00210       return tps_taskprocessor_tab_complete(tps, a);
00211    }
00212 
00213    if (a->argc != 4)
00214       return CLI_SHOWUSAGE;
00215 
00216    name = a->argv[3];
00217    if (!(tps = ast_taskprocessor_get(name, TPS_REF_IF_EXISTS))) {
00218       ast_cli(a->fd, "\nping failed: %s not found\n\n", name);
00219       return CLI_SUCCESS;
00220    }
00221    ast_cli(a->fd, "\npinging %s ...", name);
00222    when = ast_tvadd((begin = ast_tvnow()), ast_samp2tv(1000, 1000));
00223    ts.tv_sec = when.tv_sec;
00224    ts.tv_nsec = when.tv_usec * 1000;
00225    ast_mutex_lock(&cli_ping_cond_lock);
00226    if (ast_taskprocessor_push(tps, tps_ping_handler, 0) < 0) {
00227       ast_cli(a->fd, "\nping failed: could not push task to %s\n\n", name);
00228       ao2_ref(tps, -1);
00229       return CLI_FAILURE;
00230    }
00231    ast_cond_timedwait(&cli_ping_cond, &cli_ping_cond_lock, &ts);
00232    ast_mutex_unlock(&cli_ping_cond_lock);
00233    end = ast_tvnow();
00234    delta = ast_tvsub(end, begin);
00235    ast_cli(a->fd, "\n\t%24s ping time: %.1ld.%.6ld sec\n\n", name, (long)delta.tv_sec, (long int)delta.tv_usec);
00236    ao2_ref(tps, -1);
00237    return CLI_SUCCESS;  
00238 }
00239 
00240 static char *cli_tps_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
00241 {
00242    char name[256];
00243    int tcount;
00244    unsigned long qsize;
00245    unsigned long maxqsize;
00246    unsigned long processed;
00247    struct ast_taskprocessor *p;
00248    struct ao2_iterator i;
00249 
00250    switch (cmd) {
00251    case CLI_INIT:
00252       e->command = "core show taskprocessors";
00253       e->usage = 
00254          "Usage: core show taskprocessors\n"
00255          "  Shows a list of instantiated task processors and their statistics\n";
00256       return NULL;
00257    case CLI_GENERATE:
00258       return NULL;   
00259    }
00260 
00261    if (a->argc != e->args)
00262       return CLI_SHOWUSAGE;
00263 
00264    ast_cli(a->fd, "\n\t+----- Processor -----+--- Processed ---+- In Queue -+- Max Depth -+");
00265    i = ao2_iterator_init(tps_singletons, 0);
00266    while ((p = ao2_iterator_next(&i))) {
00267       ast_copy_string(name, p->name, sizeof(name));
00268       qsize = p->tps_queue_size;
00269       maxqsize = p->stats->max_qsize;
00270       processed = p->stats->_tasks_processed_count;
00271       ast_cli(a->fd, "\n%24s   %17ld %12ld %12ld", name, processed, qsize, maxqsize);
00272       ao2_ref(p, -1);
00273    }
00274    ao2_iterator_destroy(&i);
00275    tcount = ao2_container_count(tps_singletons); 
00276    ast_cli(a->fd, "\n\t+---------------------+-----------------+------------+-------------+\n\t%d taskprocessors\n\n", tcount);
00277    return CLI_SUCCESS;  
00278 }
00279 
00280 /* this is the task processing worker function */
00281 static void *tps_processing_function(void *data)
00282 {
00283    struct ast_taskprocessor *i = data;
00284    struct tps_task *t;
00285    int size;
00286 
00287    if (!i) {
00288       ast_log(LOG_ERROR, "cannot start thread_function loop without a ast_taskprocessor structure.\n");
00289       return NULL;
00290    }
00291 
00292    while (i->poll_thread_run) {
00293       ast_mutex_lock(&i->taskprocessor_lock);
00294       if (!i->poll_thread_run) {
00295          ast_mutex_unlock(&i->taskprocessor_lock);
00296          break;
00297       }
00298       if (!(size = tps_taskprocessor_depth(i))) {
00299          ast_cond_wait(&i->poll_cond, &i->taskprocessor_lock);
00300          if (!i->poll_thread_run) {
00301             ast_mutex_unlock(&i->taskprocessor_lock);
00302             break;
00303          }
00304       }
00305       ast_mutex_unlock(&i->taskprocessor_lock);
00306       /* stuff is in the queue */
00307       if (!(t = tps_taskprocessor_pop(i))) {
00308          ast_log(LOG_ERROR, "Wtf?? %d tasks in the queue, but we're popping blanks!\n", size);
00309          continue;
00310       }
00311       if (!t->execute) {
00312          ast_log(LOG_WARNING, "Task is missing a function to execute!\n");
00313          tps_task_free(t);
00314          continue;
00315       }
00316       t->execute(t->datap);
00317  
00318       ast_mutex_lock(&i->taskprocessor_lock);
00319       if (i->stats) {
00320          i->stats->_tasks_processed_count++;
00321          if (size > i->stats->max_qsize) {
00322             i->stats->max_qsize = size;
00323          }
00324       }
00325       ast_mutex_unlock(&i->taskprocessor_lock);
00326  
00327       tps_task_free(t);
00328    }
00329    while ((t = tps_taskprocessor_pop(i))) {
00330       tps_task_free(t);
00331    }
00332    return NULL;
00333 }
00334 
00335 /* hash callback for astobj2 */
00336 static int tps_hash_cb(const void *obj, const int flags)
00337 {
00338    const struct ast_taskprocessor *tps = obj;
00339 
00340    return ast_str_case_hash(tps->name);
00341 }
00342 
00343 /* compare callback for astobj2 */
00344 static int tps_cmp_cb(void *obj, void *arg, int flags)
00345 {
00346    struct ast_taskprocessor *lhs = obj, *rhs = arg;
00347 
00348    return !strcasecmp(lhs->name, rhs->name) ? CMP_MATCH | CMP_STOP : 0;
00349 }
00350 
00351 /* destroy the taskprocessor */
00352 static void tps_taskprocessor_destroy(void *tps)
00353 {
00354    struct ast_taskprocessor *t = tps;
00355    
00356    if (!tps) {
00357       ast_log(LOG_ERROR, "missing taskprocessor\n");
00358       return;
00359    }
00360    ast_log(LOG_DEBUG, "destroying taskprocessor '%s'\n", t->name);
00361    /* kill it */  
00362    ast_mutex_lock(&t->taskprocessor_lock);
00363    t->poll_thread_run = 0;
00364    ast_cond_signal(&t->poll_cond);
00365    ast_mutex_unlock(&t->taskprocessor_lock);
00366    pthread_join(t->poll_thread, NULL);
00367    t->poll_thread = AST_PTHREADT_NULL;
00368    ast_mutex_destroy(&t->taskprocessor_lock);
00369    ast_cond_destroy(&t->poll_cond);
00370    /* free it */
00371    if (t->stats) {
00372       ast_free(t->stats);
00373       t->stats = NULL;
00374    }
00375    ast_free((char *) t->name);
00376 }
00377 
00378 /* pop the front task and return it */
00379 static struct tps_task *tps_taskprocessor_pop(struct ast_taskprocessor *tps)
00380 {
00381    struct tps_task *task;
00382 
00383    if (!tps) {
00384       ast_log(LOG_ERROR, "missing taskprocessor\n");
00385       return NULL;
00386    }
00387    ast_mutex_lock(&tps->taskprocessor_lock);
00388    if ((task = AST_LIST_REMOVE_HEAD(&tps->tps_queue, list))) {
00389       tps->tps_queue_size--;
00390    }
00391    ast_mutex_unlock(&tps->taskprocessor_lock);
00392    return task;
00393 }
00394 
00395 static int tps_taskprocessor_depth(struct ast_taskprocessor *tps)
00396 {
00397    return (tps) ? tps->tps_queue_size : -1;
00398 }
00399 
00400 /* taskprocessor name accessor */
00401 const char *ast_taskprocessor_name(struct ast_taskprocessor *tps)
00402 {
00403    if (!tps) {
00404       ast_log(LOG_ERROR, "no taskprocessor specified!\n");
00405       return NULL;
00406    }
00407    return tps->name;
00408 }
00409 
00410 /* Provide a reference to a taskprocessor.  Create the taskprocessor if necessary, but don't
00411  * create the taskprocessor if we were told via ast_tps_options to return a reference only 
00412  * if it already exists */
00413 struct ast_taskprocessor *ast_taskprocessor_get(const char *name, enum ast_tps_options create)
00414 {
00415    struct ast_taskprocessor *p, tmp_tps = {
00416       .name = name,
00417    };
00418       
00419    if (ast_strlen_zero(name)) {
00420       ast_log(LOG_ERROR, "requesting a nameless taskprocessor!!!\n");
00421       return NULL;
00422    }
00423    ao2_lock(tps_singletons);
00424    p = ao2_find(tps_singletons, &tmp_tps, OBJ_POINTER);
00425    if (p) {
00426       ao2_unlock(tps_singletons);
00427       return p;
00428    }
00429    if (create & TPS_REF_IF_EXISTS) {
00430       /* calling function does not want a new taskprocessor to be created if it doesn't already exist */
00431       ao2_unlock(tps_singletons);
00432       return NULL;
00433    }
00434    /* create a new taskprocessor */
00435    if (!(p = ao2_alloc(sizeof(*p), tps_taskprocessor_destroy))) {
00436       ao2_unlock(tps_singletons);
00437       ast_log(LOG_WARNING, "failed to create taskprocessor '%s'\n", name);
00438       return NULL;
00439    }
00440 
00441    ast_cond_init(&p->poll_cond, NULL);
00442    ast_mutex_init(&p->taskprocessor_lock);
00443 
00444    if (!(p->stats = ast_calloc(1, sizeof(*p->stats)))) {
00445       ao2_unlock(tps_singletons);
00446       ast_log(LOG_WARNING, "failed to create taskprocessor stats for '%s'\n", name);
00447       ao2_ref(p, -1);
00448       return NULL;
00449    }
00450    if (!(p->name = ast_strdup(name))) {
00451       ao2_unlock(tps_singletons);
00452       ao2_ref(p, -1);
00453       return NULL;
00454    }
00455    p->poll_thread_run = 1;
00456    p->poll_thread = AST_PTHREADT_NULL;
00457    if (ast_pthread_create(&p->poll_thread, NULL, tps_processing_function, p) < 0) {
00458       ao2_unlock(tps_singletons);
00459       ast_log(LOG_ERROR, "Taskprocessor '%s' failed to create the processing thread.\n", p->name);
00460       ao2_ref(p, -1);
00461       return NULL;
00462    }
00463    if (!(ao2_link(tps_singletons, p))) {
00464       ao2_unlock(tps_singletons);
00465       ast_log(LOG_ERROR, "Failed to add taskprocessor '%s' to container\n", p->name);
00466       ao2_ref(p, -1);
00467       return NULL;
00468    }
00469    ao2_unlock(tps_singletons);
00470    return p;
00471 }
00472 
00473 /* decrement the taskprocessor reference count and unlink from the container if necessary */
00474 void *ast_taskprocessor_unreference(struct ast_taskprocessor *tps)
00475 {
00476    if (tps) {
00477       ao2_lock(tps_singletons);
00478       ao2_unlink(tps_singletons, tps);
00479       if (ao2_ref(tps, -1) > 1) {
00480          ao2_link(tps_singletons, tps);
00481       }
00482       ao2_unlock(tps_singletons);
00483    }
00484    return NULL;
00485 }
00486 
00487 /* push the task into the taskprocessor queue */   
00488 int ast_taskprocessor_push(struct ast_taskprocessor *tps, int (*task_exe)(void *datap), void *datap)
00489 {
00490    struct tps_task *t;
00491 
00492    if (!tps || !task_exe) {
00493       ast_log(LOG_ERROR, "%s is missing!!\n", (tps) ? "task callback" : "taskprocessor");
00494       return -1;
00495    }
00496    if (!(t = tps_task_alloc(task_exe, datap))) {
00497       ast_log(LOG_ERROR, "failed to allocate task!  Can't push to '%s'\n", tps->name);
00498       return -1;
00499    }
00500    ast_mutex_lock(&tps->taskprocessor_lock);
00501    AST_LIST_INSERT_TAIL(&tps->tps_queue, t, list);
00502    tps->tps_queue_size++;
00503    ast_cond_signal(&tps->poll_cond);
00504    ast_mutex_unlock(&tps->taskprocessor_lock);
00505    return 0;
00506 }
00507 

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