mqueue Module

Elena-Ramona Modroiu

   asipto.com

Edited by

Elena-Ramona Modroiu

   <ramona@asipto.com>

Alex Balashov

   Evariste Systems
   <abalashov@evaristesys.com>

Ovidiu Sas

   VoIP Embedded, Inc.
   <osas@voipembedded.com>

Julien Chavanton

   <jchavanton@gmail.com>

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

   Copyright © 2018-2020 Julien chavanton, Flowroute
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. db_url (str)
              3.2. 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 Variables
        6. RPC Commands

              6.1. mqueue.get_size
              6.2. mqueue.fetch

   List of Examples

   1.1. Set db_url parameter
   1.2. Set mqueue parameter
   1.3. mq_add usage
   1.4. mq_fetch usage
   1.5. mq_pv_free usage
   1.6. mq_size usage
   1.7. mqueue.get_size usage
   1.8. mqueue.fetch 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. db_url (str)
        3.2. 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 Variables
   6. RPC Commands

        6.1. mqueue.get_size
        6.2. mqueue.fetch

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. db_url (str)
   3.2. mqueue (string)

3.1. db_url (str)

   The URL to connect to database for loading values in mqueue table at
   start up and/or saving values at shutdown.

   Default value is NULL (do not connect).

   Example 1.1. Set db_url parameter
...
modparam("mqueue", "db_url", "mysql://kamailio:kamailiorw@localhost/kamailio")

# Example of table in sqlite, you have the set the fields to support the length
according to the data that will be present in the mqueue
CREATE TABLE mqueue_name (
id INTEGER PRIMARY KEY AUTOINCREMENT,
key character varying(64) DEFAULT "" NOT NULL,
val character varying(4096) DEFAULT "" NOT NULL
);
...

3.2. mqueue (string)

   Definition of a memory queue

   Default value is “none”.

   Value must be a list of parameters: attr=value;...
     * Mandatory attributes:
          + name: name of the queue.
     * Optional attributes:
          + size: size of the queue. Specifies the maximum number of items
            in queue. If exceeded the oldest one is removed. If not set
            the queue will be limitless.
          + dbmode: If set to 1, the content of the queue is written to
            database table when the SIP server is stopped (i.e., ensure
            persistency over restarts). If set to 2, it is written at
            shutdown but not read at startup. If set to 3, it is read at
            sartup but not written at shutdown. Default value is 0 (no db
            table interaction).

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

   Example 1.2. 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 1.3. 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 1.4. 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 1.5. 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 1.6. mq_size usage
...
$var(q_size) = mq_size("queue");
xlog("L_INFO", "Size of queue is: $var(q_size)\n");
...

5. Exported Variables

     * $mqk(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
   https://www.kamailio.org/wiki/.

6. RPC Commands

   6.1. mqueue.get_size
   6.2. mqueue.fetch

6.1. mqueue.get_size

   Get the size of a memory queue.

   Parameters:
     * name - the name of memory queue

   Example 1.7. mqueue.get_size usage
...
kamcmd mqueue.get_size xyz
...

6.2. mqueue.fetch

   Fetch a key-value pair from a memory queue.

   Parameters:
     * name - the name of memory queue

   Example 1.8. mqueue.fetch usage
...
kamcmd mqueue.fetch xyz
...
