taskprocessor.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007-2013, Digium, Inc.
 *
 * Dwayne M. Hubbard <dhubbard@digium.com>
 *
 * 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.
 */
 
/*!
 * \file
 * \brief Maintain a container of uniquely-named taskprocessor threads that can be shared across modules.
 *
 * \author Dwayne Hubbard <dhubbard@digium.com>
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/_private.h"
#include "asterisk/module.h"
#include "asterisk/time.h"
#include "asterisk/astobj2.h"
#include "asterisk/cli.h"
#include "asterisk/taskprocessor.h"
#include "asterisk/sem.h"
 
/*!
 * \brief tps_task structure is queued to a taskprocessor
 *
 * tps_tasks are processed in FIFO order and freed by the taskprocessing
 * thread after the task handler returns.  The callback function that is assigned
 * to the execute() function pointer is responsible for releasing datap resources if necessary.
 */
struct tps_task {
    /*! \brief The execute() task callback function pointer */
    union {
        int (*execute)(void *datap);
        int (*execute_local)(struct ast_taskprocessor_local *local);
    } callback;
    /*! \brief The data pointer for the task execute() function */
    void *datap;
    /*! \brief AST_LIST_ENTRY overhead */
    AST_LIST_ENTRY(tps_task) list;
    unsigned int wants_local:1;
};
 
/*! \brief tps_taskprocessor_stats maintain statistics for a taskprocessor. */
struct tps_taskprocessor_stats {
    /*! \brief This is the maximum number of tasks queued at any one time */
    unsigned long max_qsize;
    /*! \brief This is the current number of tasks processed */
    unsigned long _tasks_processed_count;
};
 
/*! \brief A ast_taskprocessor structure is a singleton by name */
struct ast_taskprocessor {
    /*! \brief Taskprocessor statistics */
    struct tps_taskprocessor_stats stats;
    void *local_data;
    /*! \brief Taskprocessor current queue size */
    long tps_queue_size;
    /*! \brief Taskprocessor low water clear alert level */
    long tps_queue_low;
    /*! \brief Taskprocessor high water alert trigger level */
    long tps_queue_high;
    /*! \brief Taskprocessor queue */
    AST_LIST_HEAD_NOLOCK(tps_queue, tps_task) tps_queue;
    struct ast_taskprocessor_listener *listener;
    /*! Current thread executing the tasks */
    pthread_t thread;
    /*! Indicates if the taskprocessor is currently executing a task */
    unsigned int executing:1;
    /*! Indicates that a high water warning has been issued on this task processor */
    unsigned int high_water_warned:1;
    /*! Indicates that a high water alert is active on this taskprocessor */
    unsigned int high_water_alert:1;
    /*! Indicates if the taskprocessor is currently suspended */
    unsigned int suspended:1;
    /*! \brief Anything before the first '/' in the name (if there is one) */
    char *subsystem;
    /*! \brief Friendly name of the taskprocessor.
     * Subsystem is appended after the name's NULL terminator.
     */
    char name[0];
};
 
/*!
 * \brief A listener for taskprocessors
 *
 * \since 12.0.0
 *
 * When a taskprocessor's state changes, the listener
 * is notified of the change. This allows for tasks
 * to be addressed in whatever way is appropriate for
 * the module using the taskprocessor.
 */
struct ast_taskprocessor_listener {
    /*! The callbacks the taskprocessor calls into to notify of state changes */
    const struct ast_taskprocessor_listener_callbacks *callbacks;
    /*! The taskprocessor that the listener is listening to */
    struct ast_taskprocessor *tps;
    /*! Data private to the listener */
    void *user_data;
};
 
/*!
 * Keep track of which subsystems are in alert
 * and how many of their taskprocessors are overloaded.
 */
struct subsystem_alert {
    unsigned int alert_count;
    char subsystem[0];
};
static AST_VECTOR_RW(subsystem_alert_vector, struct subsystem_alert *) overloaded_subsystems;
 
#ifdef LOW_MEMORY
#define TPS_MAX_BUCKETS 61
#else
/*! \brief Number of buckets in the tps_singletons container. */
#define TPS_MAX_BUCKETS 1567
#endif
 
/*! \brief tps_singletons is the astobj2 container for taskprocessor singletons */
static struct ao2_container *tps_singletons;
 
/*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> operation requires a ping condition */
static ast_cond_t cli_ping_cond;
 
/*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> operation requires a ping condition lock */
AST_MUTEX_DEFINE_STATIC(cli_ping_cond_lock);
 
/*! \brief The astobj2 hash callback for taskprocessors */
static int tps_hash_cb(const void *obj, const int flags);
/*! \brief The astobj2 compare callback for taskprocessors */
static int tps_cmp_cb(void *obj, void *arg, int flags);
 
/*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> handler function */
static int tps_ping_handler(void *datap);
 
static char *cli_tps_ping(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static char *cli_tps_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static char *cli_subsystem_alert_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static char *cli_tps_reset_stats(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static char *cli_tps_reset_stats_all(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
 
static int tps_sort_cb(const void *obj_left, const void *obj_right, int flags);
 
 
static struct ast_cli_entry taskprocessor_clis[] = {
    AST_CLI_DEFINE(cli_tps_ping, "Ping a named task processor"),
    AST_CLI_DEFINE(cli_tps_report, "List instantiated task processors and statistics"),
    AST_CLI_DEFINE(cli_subsystem_alert_report, "List task processor subsystems in alert"),
    AST_CLI_DEFINE(cli_tps_reset_stats, "Reset a named task processor's stats"),
    AST_CLI_DEFINE(cli_tps_reset_stats_all, "Reset all task processors' stats"),
};
 
struct default_taskprocessor_listener_pvt {
    pthread_t poll_thread;
    int dead;
    struct ast_sem sem;
};
 
static void default_listener_pvt_destroy(struct default_taskprocessor_listener_pvt *pvt)
{
    ast_assert(pvt->dead);
    ast_sem_destroy(&pvt->sem);
    ast_free(pvt);
}
 
static void default_listener_pvt_dtor(struct ast_taskprocessor_listener *listener)
{
    struct default_taskprocessor_listener_pvt *pvt = listener->user_data;
 
    default_listener_pvt_destroy(pvt);
 
    listener->user_data = NULL;
}
 
/*!
 * \brief Function that processes tasks in the taskprocessor
 * \internal
 */
static void *default_tps_processing_function(void *data)
{
    struct ast_taskprocessor_listener *listener = data;
    struct ast_taskprocessor *tps = listener->tps;
    struct default_taskprocessor_listener_pvt *pvt = listener->user_data;
    int sem_value;
    int res;
 
    while (!pvt->dead) {
        res = ast_sem_wait(&pvt->sem);
        if (res != 0 && errno != EINTR) {
            ast_log(LOG_ERROR, "ast_sem_wait(): %s\n",
                strerror(errno));
            /* Just give up */
            break;
        }
        ast_taskprocessor_execute(tps);
    }
 
    /* No posting to a dead taskprocessor! */
    res = ast_sem_getvalue(&pvt->sem, &sem_value);
    ast_assert(res == 0 && sem_value == 0);
 
    /* Free the shutdown reference (see default_listener_shutdown) */
    ao2_t_ref(listener->tps, -1, "tps-shutdown");
 
    return NULL;
}
 
static int default_listener_start(struct ast_taskprocessor_listener *listener)
{
    struct default_taskprocessor_listener_pvt *pvt = listener->user_data;
 
    if (ast_pthread_create(&pvt->poll_thread, NULL, default_tps_processing_function, listener)) {
        return -1;
    }
 
    return 0;
}
 
static void default_task_pushed(struct ast_taskprocessor_listener *listener, int was_empty)
{
    struct default_taskprocessor_listener_pvt *pvt = listener->user_data;
 
    if (ast_sem_post(&pvt->sem) != 0) {
        ast_log(LOG_ERROR, "Failed to notify of enqueued task: %s\n",
            strerror(errno));
    }
}
 
static int default_listener_die(void *data)
{
    struct default_taskprocessor_listener_pvt *pvt = data;
    pvt->dead = 1;
    return 0;
}
 
static void default_listener_shutdown(struct ast_taskprocessor_listener *listener)
{
    struct default_taskprocessor_listener_pvt *pvt = listener->user_data;
    int res;
 
    /* Hold a reference during shutdown */
    ao2_t_ref(listener->tps, +1, "tps-shutdown");
 
    if (ast_taskprocessor_push(listener->tps, default_listener_die, pvt)) {
        /* This will cause the thread to exit early without completing tasks already
         * in the queue.  This is probably the least bad option in this situation. */
        default_listener_die(pvt);
    }
 
    ast_assert(pvt->poll_thread != AST_PTHREADT_NULL);
 
    if (pthread_equal(pthread_self(), pvt->poll_thread)) {
        res = pthread_detach(pvt->poll_thread);
        if (res != 0) {
            ast_log(LOG_ERROR, "pthread_detach(): %s\n", strerror(errno));
        }
    } else {
        res = pthread_join(pvt->poll_thread, NULL);
        if (res != 0) {
            ast_log(LOG_ERROR, "pthread_join(): %s\n", strerror(errno));
        }
    }
    pvt->poll_thread = AST_PTHREADT_NULL;
}
 
static const struct ast_taskprocessor_listener_callbacks default_listener_callbacks = {
    .start = default_listener_start,
    .task_pushed = default_task_pushed,
    .shutdown = default_listener_shutdown,
    .dtor = default_listener_pvt_dtor,
};
 
/*! \brief How many seconds to wait for running taskprocessors to finish on shutdown. */
#define AST_TASKPROCESSOR_SHUTDOWN_MAX_WAIT 10
 
/*!
 * \internal
 * \brief Clean up resources on Asterisk shutdown
 */
static void tps_shutdown(void)
{
    int objcount;
    int tries;
    struct ao2_container *sorted_tps;
    struct ast_taskprocessor *tps;
    struct ao2_iterator iter;
    struct timespec delay = {1, 0};
 
    /* During shutdown there may still be taskprocessor threads running and those
     * tasprocessors reference tps_singletons.  When those taskprocessors finish
     * they will call ast_taskprocessor_unreference, creating a race condition which
     * can result in tps_singletons being referenced after being deleted. To try and
     * avoid this we check the container count and if greater than zero, give the
     * running taskprocessors a chance to finish */
    objcount = ao2_container_count(tps_singletons);
    if (objcount > 0) {
        ast_log(LOG_DEBUG,
            "waiting for taskprocessor shutdown, %d tps object(s) still allocated.\n",
            objcount);
 
        /* give the running taskprocessors a chance to finish, up to
         * AST_TASKPROCESSOR_SHUTDOWN_MAX_WAIT seconds */
        for (tries = 0; tries < AST_TASKPROCESSOR_SHUTDOWN_MAX_WAIT; tries++) {
            while (nanosleep(&delay, &delay));
            objcount = ao2_container_count(tps_singletons);
            /* if count is 0, we are done waiting */
            if (objcount == 0) {
                break;
            }
            delay.tv_sec = 1;
            delay.tv_nsec = 0;
            ast_log(LOG_DEBUG,
                "waiting for taskprocessor shutdown, %d tps object(s) still allocated.\n",
                objcount);
        }
    }
 
    /* rather than try forever, risk an assertion on shutdown.  This probably indicates
     * a taskprocessor was not cleaned up somewhere */
    if (objcount > 0) {
        ast_log(LOG_ERROR,
            "Asertion may occur, the following taskprocessors are still runing:\n");
 
        sorted_tps = ao2_container_alloc_rbtree(AO2_ALLOC_OPT_LOCK_NOLOCK, 0, tps_sort_cb,
            NULL);
        if (!sorted_tps || ao2_container_dup(sorted_tps, tps_singletons, 0)) {
            ast_log(LOG_ERROR, "unable to get sorted list of taskprocessors");
        }
        else {
            iter = ao2_iterator_init(sorted_tps, AO2_ITERATOR_UNLINK);
            while ((tps = ao2_iterator_next(&iter))) {
                ast_log(LOG_ERROR, "taskprocessor '%s'\n", tps->name);
            }
        }
 
        ao2_cleanup(sorted_tps);
    }
    else {
        ast_log(LOG_DEBUG,
                "All waiting taskprocessors cleared!\n");
    }
 
    ast_cli_unregister_multiple(taskprocessor_clis, ARRAY_LEN(taskprocessor_clis));
    AST_VECTOR_CALLBACK_VOID(&overloaded_subsystems, ast_free);
    AST_VECTOR_RW_FREE(&overloaded_subsystems);
    ao2_t_ref(tps_singletons, -1, "Unref tps_singletons in shutdown");
    tps_singletons = NULL;
}
 
/* initialize the taskprocessor container and register CLI operations */
int ast_tps_init(void)
{
    tps_singletons = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
        TPS_MAX_BUCKETS, tps_hash_cb, NULL, tps_cmp_cb);
    if (!tps_singletons) {
        ast_log(LOG_ERROR, "taskprocessor container failed to initialize!\n");
        return -1;
    }
 
    if (AST_VECTOR_RW_INIT(&overloaded_subsystems, 10)) {
        ao2_ref(tps_singletons, -1);
        ast_log(LOG_ERROR, "taskprocessor subsystems vector failed to initialize!\n");
        return -1;
    }
 
    ast_cond_init(&cli_ping_cond, NULL);
 
    ast_cli_register_multiple(taskprocessor_clis, ARRAY_LEN(taskprocessor_clis));
 
    ast_register_cleanup(tps_shutdown);
 
    return 0;
}
 
/* allocate resources for the task */
static struct tps_task *tps_task_alloc(int (*task_exe)(void *datap), void *datap)
{
    struct tps_task *t;
    if (!task_exe) {
        ast_log(LOG_ERROR, "task_exe is NULL!\n");
        return NULL;
    }
 
    t = ast_calloc(1, sizeof(*t));
    if (!t) {
        ast_log(LOG_ERROR, "failed to allocate task!\n");
        return NULL;
    }
 
    t->callback.execute = task_exe;
    t->datap = datap;
 
    return t;
}
 
static struct tps_task *tps_task_alloc_local(int (*task_exe)(struct ast_taskprocessor_local *local), void *datap)
{
    struct tps_task *t;
    if (!task_exe) {
        ast_log(LOG_ERROR, "task_exe is NULL!\n");
        return NULL;
    }
 
    t = ast_calloc(1, sizeof(*t));
    if (!t) {
        ast_log(LOG_ERROR, "failed to allocate task!\n");
        return NULL;
    }
 
    t->callback.execute_local = task_exe;
    t->datap = datap;
    t->wants_local = 1;
 
    return t;
}
 
/* release task resources */
static void *tps_task_free(struct tps_task *task)
{
    ast_free(task);
    return NULL;
}
 
/* Taskprocessor tab completion.
 *
 * The caller of this function is responsible for argument
 * position checks prior to calling.
 */
static char *tps_taskprocessor_tab_complete(struct ast_cli_args *a)
{
    int tklen;
    struct ast_taskprocessor *p;
    struct ao2_iterator i;
 
    tklen = strlen(a->word);
    i = ao2_iterator_init(tps_singletons, 0);
    while ((p = ao2_iterator_next(&i))) {
        if (!strncasecmp(a->word, p->name, tklen)) {
            if (ast_cli_completion_add(ast_strdup(p->name))) {
                ast_taskprocessor_unreference(p);
                break;
            }
        }
        ast_taskprocessor_unreference(p);
    }
    ao2_iterator_destroy(&i);
 
    return NULL;
}
 
/* ping task handling function */
static int tps_ping_handler(void *datap)
{
    ast_mutex_lock(&cli_ping_cond_lock);
    ast_cond_signal(&cli_ping_cond);
    ast_mutex_unlock(&cli_ping_cond_lock);
    return 0;
}
 
/* ping the specified taskprocessor and display the ping time on the CLI */
static char *cli_tps_ping(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
    struct timeval begin, end, delta;
    const char *name;
    struct timeval when;
    struct timespec ts;
    struct ast_taskprocessor *tps;
 
    switch (cmd) {
    case CLI_INIT:
        e->command = "core ping taskprocessor";
        e->usage =
            "Usage: core ping taskprocessor <taskprocessor>\n"
            "   Displays the time required for a task to be processed\n";
        return NULL;
    case CLI_GENERATE:
        if (a->pos == 3) {
            return tps_taskprocessor_tab_complete(a);
        } else {
            return NULL;
        }
    }
 
    if (a->argc != 4)
        return CLI_SHOWUSAGE;
 
    name = a->argv[3];
    if (!(tps = ast_taskprocessor_get(name, TPS_REF_IF_EXISTS))) {
        ast_cli(a->fd, "\nping failed: %s not found\n\n", name);
        return CLI_SUCCESS;
    }
    ast_cli(a->fd, "\npinging %s ...", name);
 
    /*
     * Wait up to 5 seconds for a ping reply.
     *
     * On a very busy system it could take awhile to get a
     * ping response from some taskprocessors.
     */
    begin = ast_tvnow();
    when = ast_tvadd(begin, ast_samp2tv(5000, 1000));
    ts.tv_sec = when.tv_sec;
    ts.tv_nsec = when.tv_usec * 1000;
 
    ast_mutex_lock(&cli_ping_cond_lock);
    if (ast_taskprocessor_push(tps, tps_ping_handler, 0) < 0) {
        ast_mutex_unlock(&cli_ping_cond_lock);
        ast_cli(a->fd, "\nping failed: could not push task to %s\n\n", name);
        ast_taskprocessor_unreference(tps);
        return CLI_FAILURE;
    }
    ast_cond_timedwait(&cli_ping_cond, &cli_ping_cond_lock, &ts);
    ast_mutex_unlock(&cli_ping_cond_lock);
 
    end = ast_tvnow();
    delta = ast_tvsub(end, begin);
    ast_cli(a->fd, "\n\t%24s ping time: %.1ld.%.6ld sec\n\n", name, (long)delta.tv_sec, (long int)delta.tv_usec);
    ast_taskprocessor_unreference(tps);
    return CLI_SUCCESS;
}
 
/*!
 * \internal
 * \brief Taskprocessor ao2 container sort function.
 * \since 13.8.0
 *
 * \param obj_left pointer to the (user-defined part) of an object.
 * \param obj_right pointer to the (user-defined part) of an object.
 * \param flags flags from ao2_callback()
 *   OBJ_SEARCH_OBJECT - if set, 'obj_right', is an object.
 *   OBJ_SEARCH_KEY - if set, 'obj_right', is a search key item that is not an object.
 *   OBJ_SEARCH_PARTIAL_KEY - if set, 'obj_right', is a partial search key item that is not an object.
 *
 * \retval negative if obj_left < obj_right
 * \retval 0 if obj_left == obj_right
 * \retval positive if obj_left > obj_right
 */
static int tps_sort_cb(const void *obj_left, const void *obj_right, int flags)
{
    const struct ast_taskprocessor *tps_left = obj_left;
    const struct ast_taskprocessor *tps_right = obj_right;
    const char *right_key = obj_right;
    int cmp;
 
    switch (flags & OBJ_SEARCH_MASK) {
    default:
    case OBJ_SEARCH_OBJECT:
        right_key = tps_right->name;
        /* Fall through */
    case OBJ_SEARCH_KEY:
        cmp = strcasecmp(tps_left->name, right_key);
        break;
    case OBJ_SEARCH_PARTIAL_KEY:
        cmp = strncasecmp(tps_left->name, right_key, strlen(right_key));
        break;
    }
    return cmp;
}
 
#define FMT_HEADERS     "%-70s %10s %10s %10s %10s %10s\n"
#define FMT_FIELDS      "%-70s %10lu %10lu %10lu %10lu %10lu\n"
 
/*!
 * \internal
 * \brief Print taskprocessor information to CLI.
 * \since 13.30.0
 *
 * \param fd the file descriptor
 * \param tps the taskprocessor
 */
static void tps_report_taskprocessor_list_helper(int fd, struct ast_taskprocessor *tps)
{
    ast_cli(fd, FMT_FIELDS, tps->name, tps->stats._tasks_processed_count,
        tps->tps_queue_size, tps->stats.max_qsize, tps->tps_queue_low,
        tps->tps_queue_high);
}
 
/*!
 * \internal
 * \brief Prints an optionally narrowed down list of taskprocessors to the CLI.
 * \since 13.30.0
 *
 * \param fd the file descriptor
 * \param like the string we are matching on
 *
 * \return number of taskprocessors on success
 * \retval 0 otherwise
 */
static int tps_report_taskprocessor_list(int fd, const char *like)
{
    int tps_count = 0;
    int word_len;
    struct ao2_container *sorted_tps;
    struct ast_taskprocessor *tps;
    struct ao2_iterator iter;
 
    sorted_tps = ao2_container_alloc_rbtree(AO2_ALLOC_OPT_LOCK_NOLOCK, 0, tps_sort_cb,
        NULL);
    if (!sorted_tps
        || ao2_container_dup(sorted_tps, tps_singletons, 0)) {
        ast_debug(1, "Failed to retrieve sorted taskprocessors\n");
        ao2_cleanup(sorted_tps);
        return 0;
    }
 
    word_len = strlen(like);
    iter = ao2_iterator_init(sorted_tps, AO2_ITERATOR_UNLINK);
    while ((tps = ao2_iterator_next(&iter))) {
        if (like) {
            if (!strncasecmp(like, tps->name, word_len)) {
                tps_report_taskprocessor_list_helper(fd, tps);
                tps_count++;
            }
        } else {
            tps_report_taskprocessor_list_helper(fd, tps);
            tps_count++;
        }
        ast_taskprocessor_unreference(tps);
    }
    ao2_iterator_destroy(&iter);
    ao2_ref(sorted_tps, -1);
 
    return tps_count;
}
 
static char *cli_tps_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
    const char *like;
 
    switch (cmd) {
    case CLI_INIT:
        e->command = "core show taskprocessors [like]";
        e->usage =
            "Usage: core show taskprocessors [like keyword]\n"
            "   Shows a list of instantiated task processors and their statistics\n";
        return NULL;
    case CLI_GENERATE:
        if (a->pos == e->args) {
            return tps_taskprocessor_tab_complete(a);
        } else {
            return NULL;
        }
    }
 
    if (a->argc == e->args - 1) {
        like = "";
    } else if (a->argc == e->args + 1 && !strcasecmp(a->argv[e->args-1], "like")) {
        like = a->argv[e->args];
    } else {
        return CLI_SHOWUSAGE;
    }
 
    ast_cli(a->fd, "\n" FMT_HEADERS, "Processor", "Processed", "In Queue", "Max Depth", "Low water", "High water");
    ast_cli(a->fd, "\n%d taskprocessors\n\n", tps_report_taskprocessor_list(a->fd, like));
 
    return CLI_SUCCESS;
}
 
/* hash callback for astobj2 */
static int tps_hash_cb(const void *obj, const int flags)
{
    const struct ast_taskprocessor *tps = obj;
    const char *name = flags & OBJ_KEY ? obj : tps->name;
 
    return ast_str_case_hash(name);
}
 
/* compare callback for astobj2 */
static int tps_cmp_cb(void *obj, void *arg, int flags)
{
    struct ast_taskprocessor *lhs = obj, *rhs = arg;
    const char *rhsname = flags & OBJ_KEY ? arg : rhs->name;
 
    return !strcasecmp(lhs->name, rhsname) ? CMP_MATCH | CMP_STOP : 0;
}
 
static int subsystem_match(struct subsystem_alert *alert, const char *subsystem)
{
    return !strcmp(alert->subsystem, subsystem);
}
 
static int subsystem_cmp(struct subsystem_alert *a, struct subsystem_alert *b)
{
    return strcmp(a->subsystem, b->subsystem);
}
 
unsigned int ast_taskprocessor_get_subsystem_alert(const char *subsystem)
{
    struct subsystem_alert *alert;
    unsigned int count = 0;
    int idx;
 
    AST_VECTOR_RW_RDLOCK(&overloaded_subsystems);
    idx = AST_VECTOR_GET_INDEX(&overloaded_subsystems, subsystem, subsystem_match);
    if (idx >= 0) {
        alert = AST_VECTOR_GET(&overloaded_subsystems, idx);
        count = alert->alert_count;
    }
    AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
 
    return count;
}
 
static void subsystem_alert_increment(const char *subsystem)
{
    struct subsystem_alert *alert;
    int idx;
 
    if (ast_strlen_zero(subsystem)) {
        return;
    }
 
    AST_VECTOR_RW_WRLOCK(&overloaded_subsystems);
    idx = AST_VECTOR_GET_INDEX(&overloaded_subsystems, subsystem, subsystem_match);
    if (idx >= 0) {
        alert = AST_VECTOR_GET(&overloaded_subsystems, idx);
        alert->alert_count++;
        AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
        return;
    }
 
    alert = ast_malloc(sizeof(*alert) + strlen(subsystem) + 1);
    if (!alert) {
        AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
        return;
    }
    alert->alert_count = 1;
    strcpy(alert->subsystem, subsystem); /* Safe */
 
    if (AST_VECTOR_APPEND(&overloaded_subsystems, alert)) {
        ast_free(alert);
    }
    AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
}
 
static void subsystem_alert_decrement(const char *subsystem)
{
    struct subsystem_alert *alert;
    int idx;
 
    if (ast_strlen_zero(subsystem)) {
        return;
    }
 
    AST_VECTOR_RW_WRLOCK(&overloaded_subsystems);
    idx = AST_VECTOR_GET_INDEX(&overloaded_subsystems, subsystem, subsystem_match);
    if (idx < 0) {
        ast_log(LOG_ERROR,
            "Can't decrement alert count for subsystem '%s' as it wasn't in alert\n", subsystem);
        AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
        return;
    }
    alert = AST_VECTOR_GET(&overloaded_subsystems, idx);
 
    alert->alert_count--;
    if (alert->alert_count <= 0) {
        AST_VECTOR_REMOVE(&overloaded_subsystems, idx, 0);
        ast_free(alert);
    }
 
    AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
}
 
static void subsystem_copy(struct subsystem_alert *alert,
    struct subsystem_alert_vector *vector)
{
    struct subsystem_alert *alert_copy;
    alert_copy = ast_malloc(sizeof(*alert_copy) + strlen(alert->subsystem) + 1);
    if (!alert_copy) {
        return;
    }
    alert_copy->alert_count = alert->alert_count;
    strcpy(alert_copy->subsystem, alert->subsystem); /* Safe */
    if (AST_VECTOR_ADD_SORTED(vector, alert_copy, subsystem_cmp)) {
        ast_free(alert_copy);
    }
}
 
static char *cli_subsystem_alert_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
    struct subsystem_alert_vector sorted_subsystems;
    int i;
 
#define FMT_HEADERS_SUBSYSTEM       "%-32s %12s\n"
#define FMT_FIELDS_SUBSYSTEM        "%-32s %12u\n"
 
    switch (cmd) {
    case CLI_INIT:
        e->command = "core show taskprocessor alerted subsystems";
        e->usage =
            "Usage: core show taskprocessor alerted subsystems\n"
            "   Shows a list of task processor subsystems that are currently alerted\n";
        return NULL;
    case CLI_GENERATE:
        return NULL;
    }
 
    if (a->argc != e->args) {
        return CLI_SHOWUSAGE;
    }
 
    if (AST_VECTOR_INIT(&sorted_subsystems, AST_VECTOR_SIZE(&overloaded_subsystems))) {
        return CLI_FAILURE;
    }
 
    AST_VECTOR_RW_RDLOCK(&overloaded_subsystems);
    for (i = 0; i < AST_VECTOR_SIZE(&overloaded_subsystems); i++) {
        subsystem_copy(AST_VECTOR_GET(&overloaded_subsystems, i), &sorted_subsystems);
    }
    AST_VECTOR_RW_UNLOCK(&overloaded_subsystems);
 
    ast_cli(a->fd, "\n" FMT_HEADERS_SUBSYSTEM, "Subsystem", "Alert Count");
 
    for (i = 0; i < AST_VECTOR_SIZE(&sorted_subsystems); i++) {
        struct subsystem_alert *alert = AST_VECTOR_GET(&sorted_subsystems, i);
        ast_cli(a->fd, FMT_FIELDS_SUBSYSTEM, alert->subsystem, alert->alert_count);
    }
 
    ast_cli(a->fd, "\n%zu subsystems\n\n", AST_VECTOR_SIZE(&sorted_subsystems));
 
    AST_VECTOR_CALLBACK_VOID(&sorted_subsystems, ast_free);
    AST_VECTOR_FREE(&sorted_subsystems);
 
    return CLI_SUCCESS;
}
 
 
/*! Count of the number of taskprocessors in high water alert. */
static unsigned int tps_alert_count;
 
/*! Access protection for tps_alert_count */
AST_RWLOCK_DEFINE_STATIC(tps_alert_lock);
 
/*!
 * \internal
 * \brief Add a delta to tps_alert_count with protection.
 * \since 13.10.0
 *
 * \param tps Taskprocessor updating queue water mark alert trigger.
 * \param delta The amount to add to tps_alert_count.
 */
static void tps_alert_add(struct ast_taskprocessor *tps, int delta)
{
    unsigned int old;
 
    ast_rwlock_wrlock(&tps_alert_lock);
    old = tps_alert_count;
    tps_alert_count += delta;
    if (DEBUG_ATLEAST(3)
        /* and tps_alert_count becomes zero or non-zero */
        && !old != !tps_alert_count) {
        ast_log(LOG_DEBUG, "Taskprocessor '%s' %s the high water alert.\n",
            tps->name, tps_alert_count ? "triggered" : "cleared");
    }
 
    if (tps->subsystem[0] != '\0') {
        if (delta > 0) {
            subsystem_alert_increment(tps->subsystem);
        } else {
            subsystem_alert_decrement(tps->subsystem);
        }
    }
 
    ast_rwlock_unlock(&tps_alert_lock);
}
 
unsigned int ast_taskprocessor_alert_get(void)
{
    unsigned int count;
 
    ast_rwlock_rdlock(&tps_alert_lock);
    count = tps_alert_count;
    ast_rwlock_unlock(&tps_alert_lock);
 
    return count;
}
 
int ast_taskprocessor_alert_set_levels(struct ast_taskprocessor *tps, long low_water, long high_water)
{
    if (!tps || high_water < 0 || high_water < low_water) {
        return -1;
    }
 
    if (low_water < 0) {
        /* Set low water level to 90% of high water level */
        low_water = (high_water * 9) / 10;
    }
 
    ao2_lock(tps);
 
    tps->tps_queue_low = low_water;
    tps->tps_queue_high = high_water;
 
    if (tps->high_water_alert) {
        if (!tps->tps_queue_size || tps->tps_queue_size < low_water) {
            /* Update water mark alert immediately */
            tps->high_water_alert = 0;
            tps_alert_add(tps, -1);
        }
    } else {
        if (high_water < tps->tps_queue_size) {
            /* Update water mark alert immediately */
            tps->high_water_alert = 1;
            tps_alert_add(tps, +1);
        }
    }
 
    ao2_unlock(tps);
 
    return 0;
}
 
/* destroy the taskprocessor */
static void tps_taskprocessor_dtor(void *tps)
{
    struct ast_taskprocessor *t = tps;
    struct tps_task *task;
 
    while ((task = AST_LIST_REMOVE_HEAD(&t->tps_queue, list))) {
        tps_task_free(task);
    }
    t->tps_queue_size = 0;
 
    if (t->high_water_alert) {
        t->high_water_alert = 0;
        tps_alert_add(t, -1);
    }
 
    ao2_cleanup(t->listener);
    t->listener = NULL;
}
 
/* pop the front task and return it */
static struct tps_task *tps_taskprocessor_pop(struct ast_taskprocessor *tps)
{
    struct tps_task *task;
 
    if ((task = AST_LIST_REMOVE_HEAD(&tps->tps_queue, list))) {
        --tps->tps_queue_size;
        if (tps->high_water_alert && tps->tps_queue_size <= tps->tps_queue_low) {
            tps->high_water_alert = 0;
            tps_alert_add(tps, -1);
        }
    }
    return task;
}
 
long ast_taskprocessor_size(struct ast_taskprocessor *tps)
{
    return (tps) ? tps->tps_queue_size : -1;
}
 
/* taskprocessor name accessor */
const char *ast_taskprocessor_name(struct ast_taskprocessor *tps)
{
    if (!tps) {
        ast_log(LOG_ERROR, "no taskprocessor specified!\n");
        return NULL;
    }
    return tps->name;
}
 
static void listener_shutdown(struct ast_taskprocessor_listener *listener)
{
    listener->callbacks->shutdown(listener);
    ao2_ref(listener->tps, -1);
}
 
static void taskprocessor_listener_dtor(void *obj)
{
    struct ast_taskprocessor_listener *listener = obj;
 
    if (listener->callbacks->dtor) {
        listener->callbacks->dtor(listener);
    }
}
 
struct ast_taskprocessor_listener *ast_taskprocessor_listener_alloc(const struct ast_taskprocessor_listener_callbacks *callbacks, void *user_data)
{
    struct ast_taskprocessor_listener *listener;
 
    listener = ao2_alloc(sizeof(*listener), taskprocessor_listener_dtor);
    if (!listener) {
        return NULL;
    }
    listener->callbacks = callbacks;
    listener->user_data = user_data;
 
    return listener;
}
 
struct ast_taskprocessor *ast_taskprocessor_listener_get_tps(const struct ast_taskprocessor_listener *listener)
{
    ao2_ref(listener->tps, +1);
    return listener->tps;
}
 
void *ast_taskprocessor_listener_get_user_data(const struct ast_taskprocessor_listener *listener)
{
    return listener->user_data;
}
 
static void *default_listener_pvt_alloc(void)
{
    struct default_taskprocessor_listener_pvt *pvt;
 
    pvt = ast_calloc(1, sizeof(*pvt));
    if (!pvt) {
        return NULL;
    }
    pvt->poll_thread = AST_PTHREADT_NULL;
    if (ast_sem_init(&pvt->sem, 0, 0) != 0) {
        ast_log(LOG_ERROR, "ast_sem_init(): %s\n", strerror(errno));
        ast_free(pvt);
        return NULL;
    }
    return pvt;
}
 
/*!
 * \internal
 * \brief Allocate a task processor structure
 *
 * \param name Name of the task processor.
 * \param listener Listener to associate with the task processor.
 *
 * \return The newly allocated task processor.
 *
 * \pre tps_singletons must be locked by the caller.
 */
static struct ast_taskprocessor *__allocate_taskprocessor(const char *name, struct ast_taskprocessor_listener *listener)
{
    struct ast_taskprocessor *p;
    char *subsystem_separator;
    size_t subsystem_length = 0;
    size_t name_length;
 
    name_length = strlen(name);
    subsystem_separator = strchr(name, '/');
    if (subsystem_separator) {
        subsystem_length = subsystem_separator - name;
    }
 
    p = ao2_alloc(sizeof(*p) + name_length + subsystem_length + 2, tps_taskprocessor_dtor);
    if (!p) {
        ast_log(LOG_WARNING, "failed to create taskprocessor '%s'\n", name);
        return NULL;
    }
 
    /* Set default congestion water level alert triggers. */
    p->tps_queue_low = (AST_TASKPROCESSOR_HIGH_WATER_LEVEL * 9) / 10;
    p->tps_queue_high = AST_TASKPROCESSOR_HIGH_WATER_LEVEL;
 
    strcpy(p->name, name); /* Safe */
    p->subsystem = p->name + name_length + 1;
    ast_copy_string(p->subsystem, name, subsystem_length + 1);
 
    ao2_ref(listener, +1);
    p->listener = listener;
 
    p->thread = AST_PTHREADT_NULL;
 
    ao2_ref(p, +1);
    listener->tps = p;
 
    if (!(ao2_link_flags(tps_singletons, p, OBJ_NOLOCK))) {
        ast_log(LOG_ERROR, "Failed to add taskprocessor '%s' to container\n", p->name);
        listener->tps = NULL;
        ao2_ref(p, -2);
        return NULL;
    }
 
    return p;
}
 
static struct ast_taskprocessor *__start_taskprocessor(struct ast_taskprocessor *p)
{
    if (p && p->listener->callbacks->start(p->listener)) {
        ast_log(LOG_ERROR, "Unable to start taskprocessor listener for taskprocessor %s\n",
            p->name);
        ast_taskprocessor_unreference(p);
 
        return NULL;
    }
 
    return p;
}
 
/* Provide a reference to a taskprocessor.  Create the taskprocessor if necessary, but don't
 * create the taskprocessor if we were told via ast_tps_options to return a reference only
 * if it already exists */
struct ast_taskprocessor *ast_taskprocessor_get(const char *name, enum ast_tps_options create)
{
    struct ast_taskprocessor *p;
    struct ast_taskprocessor_listener *listener;
    struct default_taskprocessor_listener_pvt *pvt;
 
    if (ast_strlen_zero(name)) {
        ast_log(LOG_ERROR, "requesting a nameless taskprocessor!!!\n");
        return NULL;
    }
    ao2_lock(tps_singletons);
    p = ao2_find(tps_singletons, name, OBJ_KEY | OBJ_NOLOCK);
    if (p || (create & TPS_REF_IF_EXISTS)) {
        /* calling function does not want a new taskprocessor to be created if it doesn't already exist */
        ao2_unlock(tps_singletons);
        return p;
    }
 
    /* Create a new taskprocessor. Start by creating a default listener */
    pvt = default_listener_pvt_alloc();
    if (!pvt) {
        ao2_unlock(tps_singletons);
        return NULL;
    }
    listener = ast_taskprocessor_listener_alloc(&default_listener_callbacks, pvt);
    if (!listener) {
        ao2_unlock(tps_singletons);
        default_listener_pvt_destroy(pvt);
        return NULL;
    }
 
    p = __allocate_taskprocessor(name, listener);
    ao2_unlock(tps_singletons);
    p = __start_taskprocessor(p);
    ao2_ref(listener, -1);
 
    return p;
}
 
struct ast_taskprocessor *ast_taskprocessor_create_with_listener(const char *name, struct ast_taskprocessor_listener *listener)
{
    struct ast_taskprocessor *p;
 
    ao2_lock(tps_singletons);
    p = ao2_find(tps_singletons, name, OBJ_KEY | OBJ_NOLOCK);
    if (p) {
        ao2_unlock(tps_singletons);
        ast_taskprocessor_unreference(p);
        return NULL;
    }
 
    p = __allocate_taskprocessor(name, listener);
    ao2_unlock(tps_singletons);
 
    return __start_taskprocessor(p);
}
 
void ast_taskprocessor_set_local(struct ast_taskprocessor *tps,
    void *local_data)
{
    SCOPED_AO2LOCK(lock, tps);
    tps->local_data = local_data;
}
 
/* decrement the taskprocessor reference count and unlink from the container if necessary */
void *ast_taskprocessor_unreference(struct ast_taskprocessor *tps)
{
    if (!tps) {
        return NULL;
    }
 
    /* To prevent another thread from finding and getting a reference to this
     * taskprocessor we hold the singletons lock. If we didn't do this then
     * they may acquire it and find that the listener has been shut down.
     */
    ao2_lock(tps_singletons);
 
    if (ao2_ref(tps, -1) > 3) {
        ao2_unlock(tps_singletons);
        return NULL;
    }
 
    /* If we're down to 3 references, then those must be:
     * 1. The reference we just got rid of
     * 2. The container
     * 3. The listener
     */
    ao2_unlink_flags(tps_singletons, tps, OBJ_NOLOCK);
    ao2_unlock(tps_singletons);
 
    listener_shutdown(tps->listener);
    return NULL;
}
 
/* push the task into the taskprocessor queue */
static int taskprocessor_push(struct ast_taskprocessor *tps, struct tps_task *t)
{
    int previous_size;
    int was_empty;
 
    if (!tps) {
        ast_log(LOG_ERROR, "tps is NULL!\n");
        return -1;
    }
 
    if (!t) {
        ast_log(LOG_ERROR, "t is NULL!\n");
        return -1;
    }
 
    ao2_lock(tps);
    AST_LIST_INSERT_TAIL(&tps->tps_queue, t, list);
    previous_size = tps->tps_queue_size++;
 
    if (tps->tps_queue_high <= tps->tps_queue_size) {
        if (!tps->high_water_alert) {
            ast_log(LOG_WARNING, "The '%s' task processor queue reached %ld scheduled tasks%s.\n",
                tps->name, tps->tps_queue_size, tps->high_water_warned ? " again" : "");
            tps->high_water_warned = 1;
            tps->high_water_alert = 1;
            tps_alert_add(tps, +1);
        }
    }
 
    /* The currently executing task counts as still in queue */
    was_empty = tps->executing ? 0 : previous_size == 0;
    ao2_unlock(tps);
    tps->listener->callbacks->task_pushed(tps->listener, was_empty);
    return 0;
}
 
int ast_taskprocessor_push(struct ast_taskprocessor *tps, int (*task_exe)(void *datap), void *datap)
{
    return taskprocessor_push(tps, tps_task_alloc(task_exe, datap));
}
 
int ast_taskprocessor_push_local(struct ast_taskprocessor *tps, int (*task_exe)(struct ast_taskprocessor_local *datap), void *datap)
{
    return taskprocessor_push(tps, tps_task_alloc_local(task_exe, datap));
}
 
int ast_taskprocessor_suspend(struct ast_taskprocessor *tps)
{
    if (tps) {
        ao2_lock(tps);
        tps->suspended = 1;
        ao2_unlock(tps);
        return 0;
    }
    return -1;
}
 
int ast_taskprocessor_unsuspend(struct ast_taskprocessor *tps)
{
    if (tps) {
        ao2_lock(tps);
        tps->suspended = 0;
        ao2_unlock(tps);
        return 0;
    }
    return -1;
}
 
int ast_taskprocessor_is_suspended(struct ast_taskprocessor *tps)
{
    return tps ? tps->suspended : -1;
}
 
int ast_taskprocessor_execute(struct ast_taskprocessor *tps)
{
    struct ast_taskprocessor_local local;
    struct tps_task *t;
    long size;
 
    ao2_lock(tps);
    t = tps_taskprocessor_pop(tps);
    if (!t) {
        ao2_unlock(tps);
        return 0;
    }
 
    tps->thread = pthread_self();
    tps->executing = 1;
 
    if (t->wants_local) {
        local.local_data = tps->local_data;
        local.data = t->datap;
    }
    ao2_unlock(tps);
 
    if (t->wants_local) {
        t->callback.execute_local(&local);
    } else {
        t->callback.execute(t->datap);
    }
    tps_task_free(t);
 
    ao2_lock(tps);
    tps->thread = AST_PTHREADT_NULL;
    /* We need to check size in the same critical section where we reset the
     * executing bit. Avoids a race condition where a task is pushed right
     * after we pop an empty stack.
     */
    tps->executing = 0;
    size = ast_taskprocessor_size(tps);
 
    /* Update the stats */
    ++tps->stats._tasks_processed_count;
 
    /* Include the task we just executed as part of the queue size. */
    if (size >= tps->stats.max_qsize) {
        tps->stats.max_qsize = size + 1;
    }
    ao2_unlock(tps);
 
    /* If we executed a task, check for the transition to empty */
    if (size == 0 && tps->listener->callbacks->emptied) {
        tps->listener->callbacks->emptied(tps->listener);
    }
    return size > 0;
}
 
int ast_taskprocessor_is_task(struct ast_taskprocessor *tps)
{
    int is_task;
 
    ao2_lock(tps);
    is_task = pthread_equal(tps->thread, pthread_self());
    ao2_unlock(tps);
    return is_task;
}
 
unsigned int ast_taskprocessor_seq_num(void)
{
    static int seq_num;
 
    return (unsigned int) ast_atomic_fetchadd_int(&seq_num, +1);
}
 
#define SEQ_STR_SIZE (1 + 8 + 1)    /* Dash plus 8 hex digits plus null terminator */
 
void ast_taskprocessor_name_append(char *buf, unsigned int size, const char *name)
{
    int final_size = strlen(name) + SEQ_STR_SIZE;
 
    ast_assert(buf != NULL && name != NULL);
    ast_assert(final_size <= size);
 
    snprintf(buf, final_size, "%s-%08x", name, ast_taskprocessor_seq_num());
}
 
void ast_taskprocessor_build_name(char *buf, unsigned int size, const char *format, ...)
{
    va_list ap;
    int user_size;
 
    ast_assert(buf != NULL);
    ast_assert(SEQ_STR_SIZE <= size);
 
    va_start(ap, format);
    user_size = vsnprintf(buf, size - (SEQ_STR_SIZE - 1), format, ap);
    va_end(ap);
    if (user_size < 0) {
        /*
         * Wow!  We got an output error to a memory buffer.
         * Assume no user part of name written.
         */
        user_size = 0;
    } else if (size < user_size + SEQ_STR_SIZE) {
        /* Truncate user part of name to make sequence number fit. */
        user_size = size - SEQ_STR_SIZE;
    }
 
    /* Append sequence number to end of user name. */
    snprintf(buf + user_size, SEQ_STR_SIZE, "-%08x", ast_taskprocessor_seq_num());
}
 
static void tps_reset_stats(struct ast_taskprocessor *tps)
{
    ao2_lock(tps);
    tps->stats._tasks_processed_count = 0;
    tps->stats.max_qsize = 0;
    ao2_unlock(tps);
}
 
static char *cli_tps_reset_stats(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
    const char *name;
    struct ast_taskprocessor *tps;
 
    switch (cmd) {
    case CLI_INIT:
        e->command = "core reset taskprocessor";
        e->usage =
            "Usage: core reset taskprocessor <taskprocessor>\n"
            "    Resets stats for the specified taskprocessor\n";
        return NULL;
    case CLI_GENERATE:
        return tps_taskprocessor_tab_complete(a);
    }
 
    if (a->argc != 4) {
        return CLI_SHOWUSAGE;
    }
 
    name = a->argv[3];
    if (!(tps = ast_taskprocessor_get(name, TPS_REF_IF_EXISTS))) {
        ast_cli(a->fd, "\nReset failed: %s not found\n\n", name);
        return CLI_SUCCESS;
    }
    ast_cli(a->fd, "\nResetting %s\n\n", name);
 
    tps_reset_stats(tps);
 
    ast_taskprocessor_unreference(tps);
 
    return CLI_SUCCESS;
}
 
static char *cli_tps_reset_stats_all(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
    struct ast_taskprocessor *tps;
    struct ao2_iterator iter;
 
    switch (cmd) {
    case CLI_INIT:
        e->command = "core reset taskprocessors";
        e->usage =
            "Usage: core reset taskprocessors\n"
            "    Resets stats for all taskprocessors\n";
        return NULL;
    case CLI_GENERATE:
        return NULL;
    }
 
    if (a->argc != e->args) {
        return CLI_SHOWUSAGE;
    }
 
    ast_cli(a->fd, "\nResetting stats for all taskprocessors\n\n");
 
    iter = ao2_iterator_init(tps_singletons, 0);
    while ((tps = ao2_iterator_next(&iter))) {
        tps_reset_stats(tps);
        ast_taskprocessor_unreference(tps);
    }
    ao2_iterator_destroy(&iter);
 
    return CLI_SUCCESS;
}