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)
              3.3. mqueue_name (string)
              3.4. mqueue_size (int)
              3.5. mqueue_addmode (int)

        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
              6.3. mqueue.get_sizes

   List of Examples

   1.1. Set db_url parameter
   1.2. Set mqueue parameter
   1.3. Set mqueue_name parameter
   1.4. Set mqueue_size parameter
   1.5. Set mqueue_addmode parameter
   1.6. mq_add usage
   1.7. mq_fetch usage
   1.8. mq_pv_free usage
   1.9. mq_size usage
   1.10. mqueue.get_size usage
   1.11. mqueue.fetch usage
   1.12. mqueue.get_sizes 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)
        3.3. mqueue_name (string)
        3.4. mqueue_size (int)
        3.5. mqueue_addmode (int)

   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
        6.3. mqueue.get_sizes

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)
   3.3. mqueue_name (string)
   3.4. mqueue_size (int)
   3.5. mqueue_addmode (int)

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 read from
            database at startup and is written to database table when the
            SIP server is stopped (i.e., ensure persistency over
            restarts). If set to 2, it is read at startup but not written
            at shutdown. If set to 3, it is written at shutdown but not
            read at startup. Default value is 0 (no db table interaction).
          + addmode: how to add new (key,value) pairs.
               o 0: Will push all new (key,value) pairs at the end of the
                 queue. (default)
               o 1: Will keep oldest (key,value) pair in the queue, based
                 on the key.
               o 2: Will keep newest (key,value) pair in the queue, based
                 on the key.

   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=myq;size=10000;addmode=2")
modparam("mqueue", "mqueue", "name=qaz")
modparam("mqueue", "mqueue", "name=qaz;addmode=1")
...

3.3. mqueue_name (string)

   Definition of a memory queue, just by name.

   Default value is “none”.

   Value must be a string.

   The parameter can be set many times, each holding the definition of one
   queue. The max size of each queue defined this way will be equal to
   mqueue_size(if mqueue_size configured), or limitless (if mqueue_size
   not configured).

   Example 1.3. Set mqueue_name parameter
...
modparam("mqueue", "mqueue_name", "my_own_queue")
...

3.4. mqueue_size (int)

   Definition of the size of all memory queues defined via "mqueue_name"
   parameter.

   Default value is “0”.

   Value must be an int.

   The parameter should be set before defining any "mqueue_name". If not
   set, the queues defined via "mqueue_name" will be limitless.

   Example 1.4. Set mqueue_size parameter
...
modparam("mqueue", "mqueue_size", 1024)
...

3.5. mqueue_addmode (int)

   Sets the mode to be used when adding a new (key,value) pair in the
   mqueue.
     * 0 Add all new (key,value) at the end of mqueue
     * 1 Unique key, keep oldest (key,value)
     * 2 Unique key, keep newest(key,value)

   Default value is “0”.

   Value must be an int.

   The parameter should be set before defining any "mqueue_name". If not
   set, the queues defined via "mqueue_name" will have default addmode 0.

   Example 1.5. Set mqueue_addmode parameter
...
modparam("mqueue", "mqueue_addmode", 2)
...

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 1.6. 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 1.7. 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 1.8. 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 1.9. 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/wikidocs/.

6. RPC Commands

   6.1. mqueue.get_size
   6.2. mqueue.fetch
   6.3. mqueue.get_sizes

6.1. mqueue.get_size

   Get the size of a memory queue.

   Parameters:
     * name - the name of memory queue

   Example 1.10. 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 1.11. mqueue.fetch usage
...
kamcmd mqueue.fetch xyz
...

6.3. mqueue.get_sizes

   Get the size for all memory queues.

   Parameters: none

   Example 1.12. mqueue.get_sizes usage
...
kamcmd mqueue.get_sizes
...
