mqueue Module

Elena-Ramona Modroiu

   asipto.com

Edited by

Elena-Ramona Modroiu

   <ramona@asipto.com>

Edited by

Alex Balashov

   Evariste Systems
   <abalashov@evaristesys.com>

   Copyright © 2010 Elena-Ramona Modroiu (asipto.com)
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. mqueue (string)

        4. Functions

              4.1. mq_add(queue, key, value)
              4.2. mq_fetch(queue)
              4.3. mq_pv_free(queue)
              4.4. mq_size(queue)

        5. Exported Pseudo-variables

   List of Examples

   1.1. Set mqueue parameter
   1.2. mq_add usage
   1.3. mq_fetch usage
   1.4. mq_pv_free usage
   1.5. mq_size usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. mqueue (string)

   4. Functions

        4.1. mq_add(queue, key, value)
        4.2. mq_fetch(queue)
        4.3. mq_pv_free(queue)
        4.4. mq_size(queue)

   5. Exported Pseudo-variables

1. Overview

   The mqueue module offers a generic message queue system in shared
   memory for inter-process communication using the config file. One
   example of usage is to send time consuming operations to one or several
   timer processes that consumes items in the queue, without affecting SIP
   message handling in the socket-listening process.

   There can be many defined queues. Access to queued values is done via
   pseudo variables.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * None.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * None.

3. Parameters

   3.1. mqueue (string)

3.1. mqueue (string)

   Definition of a memory queue

   Default value is “none”.

   Value must be a list of parameters: attr=value;... The attribute 'name'
   is mandatory, defining the name of the queue. Optional attribute 'size'
   specifies the maximum number of items in queue, if it is execeeded the
   oldest one is removed.

   The parameter can be set many times, each holding the definition of one
   queue.

   Example 1.1. Set mqueue parameter
...
modparam("mqueue", "mqueue", "name=myq;size=20;")
modparam("mqueue", "mqueue", "name=qaz")
...

4. Functions

   4.1. mq_add(queue, key, value)
   4.2. mq_fetch(queue)
   4.3. mq_pv_free(queue)
   4.4. mq_size(queue)

4.1.  mq_add(queue, key, value)

   Add a new item (key, value) in the queue. If max size of queue is
   exceeded, the oldest one is removed.

   Example 1.2. mq_add usage
...
mq_add("myq", "$rU", "call from $fU");
...

4.2.  mq_fetch(queue)

   Take oldest item from queue and fill $mqk(queue) and $mqv(queue) pseudo
   variables.

   Return: true on success (1); false on failure (-1) or no item fetched
   (-2).

   Example 1.3. mq_fetch usage
...
while(mq_fetch("myq"))
{
   xlog("$mqk(myq) - $mqv(myq)\n");
}
...

4.3.  mq_pv_free(queue)

   Free the item fetched in pseudo-variables. It is optional, a new fetch
   frees the previous values.

   Example 1.4. mq_pv_free usage
...
mq_pv_free("myq");
...

4.4.  mq_size(queue)

   Returns the current number of elements in the mqueue.

   If the mqueue is empty, the function returns -1. If the mqueue is not
   found, the function returns -2.

   Example 1.5. mq_size usage
...
$var(q_size) = mq_size("queue");
xlog("L_INFO", "Size of queue is: $var(q_size)\n");
...

5. Exported Pseudo-variables

     * $mqv(mqueue) - the most recent item key fetched from the specified
       mqueue
     * $mqv(mqueue) - the most recent item value fetched from the
       specified mqueue
     * $mq_size(mqueue) - the size of the specified mqueue

   Exported pseudo-variables are documented at
   http://www.kamailio.org/wiki/.