stasis_message.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * David M. Lee, II <[email protected]>
 *
 * 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 Stasis Message API.
 *
 * \author David M. Lee, II <[email protected]>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/astobj2.h"
#include "asterisk/stasis.h"
#include "asterisk/utils.h"
#include "asterisk/hashtab.h"

/*! \internal */
struct stasis_message_type {
   struct stasis_message_vtable *vtable;
   char *name;
   unsigned int hash;
   int id;
   enum stasis_subscription_message_formatters available_formatters;
};

static struct stasis_message_vtable null_vtable = {};
static int message_type_id;

static void message_type_dtor(void *obj)
{
   struct stasis_message_type *type = obj;
   ast_free(type->name);
   type->name = NULL;
}

int stasis_message_type_create(const char *name,
   struct stasis_message_vtable *vtable,
   struct stasis_message_type **result)
{
   struct stasis_message_type *type;

   /* Check for declination */
   if (name && stasis_message_type_declined(name)) {
      return STASIS_MESSAGE_TYPE_DECLINED;
   }

   type = ao2_t_alloc_options(sizeof(*type), message_type_dtor,
      AO2_ALLOC_OPT_LOCK_NOLOCK, name ?: "");
   if (!type) {
      return STASIS_MESSAGE_TYPE_ERROR;
   }
   if (!vtable) {
      /* Null object pattern, FTW! */
      vtable = &null_vtable;
   }

   type->name = ast_strdup(name);
   if (!type->name) {
      ao2_cleanup(type);
      return STASIS_MESSAGE_TYPE_ERROR;
   }
   type->hash = ast_hashtab_hash_string(name);
   type->vtable = vtable;
   if (vtable->to_json) {
      type->available_formatters |= STASIS_SUBSCRIPTION_FORMATTER_JSON;
   }
   if (vtable->to_ami) {
      type->available_formatters |= STASIS_SUBSCRIPTION_FORMATTER_AMI;
   }
   if (vtable->to_event) {
      type->available_formatters |= STASIS_SUBSCRIPTION_FORMATTER_EVENT;
   }
   type->id = ast_atomic_fetchadd_int(&message_type_id, +1);
   *result = type;

   return STASIS_MESSAGE_TYPE_SUCCESS;
}

const char *stasis_message_type_name(const struct stasis_message_type *type)
{
   return type->name;
}

unsigned int stasis_message_type_hash(const struct stasis_message_type *type)
{
   return type->hash;
}

int stasis_message_type_id(const struct stasis_message_type *type)
{
   return type->id;
}

enum stasis_subscription_message_formatters stasis_message_type_available_formatters(
   const struct stasis_message_type *type)
{
   return type->available_formatters;
}

/*! \internal */
struct stasis_message {
   /*! Time the message was created */
   struct timeval timestamp;
   /*! Type of the message */
   struct stasis_message_type *type;
   /*! Where this message originated.  NULL if aggregate message. */
   const struct ast_eid *eid_ptr;
   /*! Message content */
   void *data;
   /*! Where this message originated. */
   struct ast_eid eid;
};

static void stasis_message_dtor(void *obj)
{
   struct stasis_message *message = obj;
   ao2_cleanup(message->data);
}

struct stasis_message *stasis_message_create_full(struct stasis_message_type *type, void *data, const struct ast_eid *eid)
{
   struct stasis_message *message;

   if (type == NULL || data == NULL) {
      return NULL;
   }

   message = ao2_t_alloc_options(sizeof(*message), stasis_message_dtor,
      AO2_ALLOC_OPT_LOCK_NOLOCK, type->name);
   if (message == NULL) {
      return NULL;
   }

   message->timestamp = ast_tvnow();
   /*
    * XXX Normal ao2 ref counting rules says we should increment the message
    * type ref here and decrement it in stasis_message_dtor().  However, the
    * stasis message could be cached and legitimately cause the type ref count
    * to hit the excessive ref count assertion.  Since the message type
    * practically has to be a global object anyway, we can get away with not
    * holding a ref in the stasis message.
    */
   message->type = type;
   ao2_ref(data, +1);
   message->data = data;
   if (eid) {
      message->eid_ptr = &message->eid;
      message->eid = *eid;
   }

   return message;
}

struct stasis_message *stasis_message_create(struct stasis_message_type *type, void *data)
{
   return stasis_message_create_full(type, data, &ast_eid_default);
}

const struct ast_eid *stasis_message_eid(const struct stasis_message *msg)
{
   if (msg == NULL) {
      return NULL;
   }
   return msg->eid_ptr;
}

struct stasis_message_type *stasis_message_type(const struct stasis_message *msg)
{
   if (msg == NULL) {
      return NULL;
   }
   return msg->type;
}

void *stasis_message_data(const struct stasis_message *msg)
{
   if (msg == NULL) {
      return NULL;
   }
   return msg->data;
}

const struct timeval *stasis_message_timestamp(const struct stasis_message *msg)
{
   if (msg == NULL) {
      return NULL;
   }
   return &msg->timestamp;
}

#define INVOKE_VIRTUAL(fn, ...)              \
   ({                               \
      if (!msg) {                      \
         return NULL;                  \
      }                             \
      ast_assert(msg->type != NULL);         \
      ast_assert(msg->type->vtable != NULL); \
      if (!msg->type->vtable->fn) {       \
         return NULL;                  \
      }                             \
      msg->type->vtable->fn(__VA_ARGS__);    \
   })

struct ast_manager_event_blob *stasis_message_to_ami(struct stasis_message *msg)
{
   return INVOKE_VIRTUAL(to_ami, msg);
}

struct ast_json *stasis_message_to_json(
   struct stasis_message *msg,
   struct stasis_message_sanitizer *sanitize)
{
   return INVOKE_VIRTUAL(to_json, msg, sanitize);
}

struct ast_event *stasis_message_to_event(struct stasis_message *msg)
{
   return INVOKE_VIRTUAL(to_event, msg);
}

#define HAS_VIRTUAL(fn, msg)              \
   ({                               \
      if (!msg) {                      \
         return 0;                     \
      }                             \
      ast_assert(msg->type != NULL);         \
      ast_assert(msg->type->vtable != NULL); \
      !!msg->type->vtable->fn;            \
   })

int stasis_message_can_be_ami(struct stasis_message *msg)
{
   return HAS_VIRTUAL(to_ami, msg);
}