
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.

   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/.
