taskprocessor.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007-2008, 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"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 377839 $")

#include "asterisk/_private.h"
#include "asterisk/module.h"
#include "asterisk/time.h"
#include "asterisk/astobj2.h"
#include "asterisk/cli.h"
#include "asterisk/taskprocessor.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 */
   int (*execute)(void *datap);
   /*! \brief The data pointer for the task execute() function */
   void *datap;
   /*! \brief AST_LIST_ENTRY overhead */
   AST_LIST_ENTRY(tps_task) list;
};

/*! \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 Friendly name of the taskprocessor */
   const char *name;
   /*! \brief Thread poll condition */
   ast_cond_t poll_cond;
   /*! \brief Taskprocessor thread */
   pthread_t poll_thread;
   /*! \brief Taskprocessor lock */
   ast_mutex_t taskprocessor_lock;
   /*! \brief Taskprocesor thread run flag */
   unsigned char poll_thread_run;
   /*! \brief Taskprocessor statistics */
   struct tps_taskprocessor_stats *stats;
   /*! \brief Taskprocessor current queue size */
   long tps_queue_size;
   /*! \brief Taskprocessor queue */
   AST_LIST_HEAD_NOLOCK(tps_queue, tps_task) tps_queue;
   /*! \brief Taskprocessor singleton list entry */
   AST_LIST_ENTRY(ast_taskprocessor) list;
};
#define TPS_MAX_BUCKETS 7
/*! \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 The task processing function executed by a taskprocessor */
static void *tps_processing_function(void *data);

/*! \brief Destroy the taskprocessor when its refcount reaches zero */
static void tps_taskprocessor_destroy(void *tps);

/*! \brief CLI <example>taskprocessor ping &lt;blah&gt;</example> handler function */
static int tps_ping_handler(void *datap);

/*! \brief Remove the front task off the taskprocessor queue */
static struct tps_task *tps_taskprocessor_pop(struct ast_taskprocessor *tps);

/*! \brief Return the size of the taskprocessor queue */
static int tps_taskprocessor_depth(struct ast_taskprocessor *tps);

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 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"),
};

/*!
 * \internal
 * \brief Clean up resources on Asterisk shutdown
 */
static void tps_shutdown(void)
{
   ast_cli_unregister_multiple(taskprocessor_clis, ARRAY_LEN(taskprocessor_clis));
   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)
{
   if (!(tps_singletons = ao2_container_alloc(TPS_MAX_BUCKETS, tps_hash_cb, tps_cmp_cb))) {
      ast_log(LOG_ERROR, "taskprocessor container 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_atexit(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 ((t = ast_calloc(1, sizeof(*t)))) {
      t->execute = task_exe;
      t->datap = datap;
   }
   return t;
}

/* release task resources */
static void *tps_task_free(struct tps_task *task)
{
   if (task) {
      ast_free(task);
   }
   return NULL;
}

/* taskprocessor tab completion */
static char *tps_taskprocessor_tab_complete(struct ast_taskprocessor *p, struct ast_cli_args *a)
{
   int tklen;
   int wordnum = 0;
   char *name = NULL;
   struct ao2_iterator i;

   if (a->pos != 3)
      return NULL;

   tklen = strlen(a->word);
   i = ao2_iterator_init(tps_singletons, 0);
   while ((p = ao2_iterator_next(&i))) {
      if (!strncasecmp(a->word, p->name, tklen) && ++wordnum > a->n) {
         name = ast_strdup(p->name);
         ao2_ref(p, -1);
         break;
      }
      ao2_ref(p, -1);
   }
   ao2_iterator_destroy(&i);
   return name;
}

/* 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 = NULL;

   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:
      return tps_taskprocessor_tab_complete(tps, 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, "\nping failed: %s not found\n\n", name);
      return CLI_SUCCESS;
   }
   ast_cli(a->fd, "\npinging %s ...", name);
   when = ast_tvadd((begin = ast_tvnow()), ast_samp2tv(1000, 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_cli(a->fd, "\nping failed: could not push task to %s\n\n", name);
      ao2_ref(tps, -1);
      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);
   ao2_ref(tps, -1);
   return CLI_SUCCESS;
}

static char *cli_tps_report(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   char name[256];
   int tcount;
   unsigned long qsize;
   unsigned long maxqsize;
   unsigned long processed;
   struct ast_taskprocessor *p;
   struct ao2_iterator i;

   switch (cmd) {
   case CLI_INIT:
      e->command = "core show taskprocessors";
      e->usage =
         "Usage: core show taskprocessors\n"
         "  Shows a list of instantiated task processors and their statistics\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   }

   if (a->argc != e->args)
      return CLI_SHOWUSAGE;

   ast_cli(a->fd, "\n\t+----- Processor -----+--- Processed ---+- In Queue -+- Max Depth -+");
   i = ao2_iterator_init(tps_singletons, 0);
   while ((p = ao2_iterator_next(&i))) {
      ast_copy_string(name, p->name, sizeof(name));
      qsize = p->tps_queue_size;
      maxqsize = p->stats->max_qsize;
      processed = p->stats->_tasks_processed_count;
      ast_cli(a->fd, "\n%24s   %17ld %12ld %12ld", name, processed, qsize, maxqsize);
      ao2_ref(p, -1);
   }
   ao2_iterator_destroy(&i);
   tcount = ao2_container_count(tps_singletons);
   ast_cli(a->fd, "\n\t+---------------------+-----------------+------------+-------------+\n\t%d taskprocessors\n\n", tcount);
   return CLI_SUCCESS;
}

/* this is the task processing worker function */
static void *tps_processing_function(void *data)
{
   struct ast_taskprocessor *i = data;
   struct tps_task *t;
   int size;

   if (!i) {
      ast_log(LOG_ERROR, "cannot start thread_function loop without a ast_taskprocessor structure.\n");
      return NULL;
   }

   while (i->poll_thread_run) {
      ast_mutex_lock(&i->taskprocessor_lock);
      if (!i->poll_thread_run) {
         ast_mutex_unlock(&i->taskprocessor_lock);
         break;
      }
      if (!(size = tps_taskprocessor_depth(i))) {
         ast_cond_wait(&i->poll_cond, &i->taskprocessor_lock);
         if (!i->poll_thread_run) {
            ast_mutex_unlock(&i->taskprocessor_lock);
            break;
         }
      }
      ast_mutex_unlock(&i->taskprocessor_lock);
      /* stuff is in the queue */
      if (!(t = tps_taskprocessor_pop(i))) {
         ast_log(LOG_ERROR, "Wtf?? %d tasks in the queue, but we're popping blanks!\n", size);
         continue;
      }
      if (!t->execute) {
         ast_log(LOG_WARNING, "Task is missing a function to execute!\n");
         tps_task_free(t);
         continue;
      }
      t->execute(t->datap);

      ast_mutex_lock(&i->taskprocessor_lock);
      if (i->stats) {
         i->stats->_tasks_processed_count++;
         if (size > i->stats->max_qsize) {
            i->stats->max_qsize = size;
         }
      }
      ast_mutex_unlock(&i->taskprocessor_lock);

      tps_task_free(t);
   }
   while ((t = tps_taskprocessor_pop(i))) {
      tps_task_free(t);
   }
   return NULL;
}

/* hash callback for astobj2 */
static int tps_hash_cb(const void *obj, const int flags)
{
   const struct ast_taskprocessor *tps = obj;

   return ast_str_case_hash(tps->name);
}

/* compare callback for astobj2 */
static int tps_cmp_cb(void *obj, void *arg, int flags)
{
   struct ast_taskprocessor *lhs = obj, *rhs = arg;

   return !strcasecmp(lhs->name, rhs->name) ? CMP_MATCH | CMP_STOP : 0;
}

/* destroy the taskprocessor */
static void tps_taskprocessor_destroy(void *tps)
{
   struct ast_taskprocessor *t = tps;

   if (!tps) {
      ast_log(LOG_ERROR, "missing taskprocessor\n");
      return;
   }
   ast_debug(1, "destroying taskprocessor '%s'\n", t->name);
   /* kill it */
   ast_mutex_lock(&t->taskprocessor_lock);
   t->poll_thread_run = 0;
   ast_cond_signal(&t->poll_cond);
   ast_mutex_unlock(&t->taskprocessor_lock);
   pthread_join(t->poll_thread, NULL);
   t->poll_thread = AST_PTHREADT_NULL;
   ast_mutex_destroy(&t->taskprocessor_lock);
   ast_cond_destroy(&t->poll_cond);
   /* free it */
   if (t->stats) {
      ast_free(t->stats);
      t->stats = NULL;
   }
   ast_free((char *) t->name);
}

/* pop the front task and return it */
static struct tps_task *tps_taskprocessor_pop(struct ast_taskprocessor *tps)
{
   struct tps_task *task;

   if (!tps) {
      ast_log(LOG_ERROR, "missing taskprocessor\n");
      return NULL;
   }
   ast_mutex_lock(&tps->taskprocessor_lock);
   if ((task = AST_LIST_REMOVE_HEAD(&tps->tps_queue, list))) {
      tps->tps_queue_size--;
   }
   ast_mutex_unlock(&tps->taskprocessor_lock);
   return task;
}

static int tps_taskprocessor_depth(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;
}

/* 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, tmp_tps = {
      .name = name,
   };

   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, &tmp_tps, OBJ_POINTER);
   if (p) {
      ao2_unlock(tps_singletons);
      return p;
   }
   if (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 NULL;
   }
   /* create a new taskprocessor */
   if (!(p = ao2_alloc(sizeof(*p), tps_taskprocessor_destroy))) {
      ao2_unlock(tps_singletons);
      ast_log(LOG_WARNING, "failed to create taskprocessor '%s'\n", name);
      return NULL;
   }

   ast_cond_init(&p->poll_cond, NULL);
   ast_mutex_init(&p->taskprocessor_lock);

   if (!(p->stats = ast_calloc(1, sizeof(*p->stats)))) {
      ao2_unlock(tps_singletons);
      ast_log(LOG_WARNING, "failed to create taskprocessor stats for '%s'\n", name);
      ao2_ref(p, -1);
      return NULL;
   }
   if (!(p->name = ast_strdup(name))) {
      ao2_unlock(tps_singletons);
      ao2_ref(p, -1);
      return NULL;
   }
   p->poll_thread_run = 1;
   p->poll_thread = AST_PTHREADT_NULL;
   if (ast_pthread_create(&p->poll_thread, NULL, tps_processing_function, p) < 0) {
      ao2_unlock(tps_singletons);
      ast_log(LOG_ERROR, "Taskprocessor '%s' failed to create the processing thread.\n", p->name);
      ao2_ref(p, -1);
      return NULL;
   }
   if (!(ao2_link(tps_singletons, p))) {
      ao2_unlock(tps_singletons);
      ast_log(LOG_ERROR, "Failed to add taskprocessor '%s' to container\n", p->name);
      ao2_ref(p, -1);
      return NULL;
   }
   ao2_unlock(tps_singletons);
   return p;
}

/* decrement the taskprocessor reference count and unlink from the container if necessary */
void *ast_taskprocessor_unreference(struct ast_taskprocessor *tps)
{
   if (tps) {
      ao2_lock(tps_singletons);
      ao2_unlink(tps_singletons, tps);
      if (ao2_ref(tps, -1) > 1) {
         ao2_link(tps_singletons, tps);
      }
      ao2_unlock(tps_singletons);
   }
   return NULL;
}

/* push the task into the taskprocessor queue */
int ast_taskprocessor_push(struct ast_taskprocessor *tps, int (*task_exe)(void *datap), void *datap)
{
   struct tps_task *t;

   if (!tps || !task_exe) {
      ast_log(LOG_ERROR, "%s is missing!!\n", (tps) ? "task callback" : "taskprocessor");
      return -1;
   }
   if (!(t = tps_task_alloc(task_exe, datap))) {
      ast_log(LOG_ERROR, "failed to allocate task!  Can't push to '%s'\n", tps->name);
      return -1;
   }
   ast_mutex_lock(&tps->taskprocessor_lock);
   AST_LIST_INSERT_TAIL(&tps->tps_queue, t, list);
   tps->tps_queue_size++;
   ast_cond_signal(&tps->poll_cond);
   ast_mutex_unlock(&tps->taskprocessor_lock);
   return 0;
}