ASYNC Module

Daniel-Constantin Mierla

   <miconda@gmail.com>

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2011-2016 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. workers (int)
              3.2. ms_timer (int)
              3.3. return (int)

        4. Functions

              4.1. async_route(routename, seconds)
              4.2. async_ms_route(routename, milliseconds)
              4.3. async_sleep(seconds)
              4.4. async_ms_sleep(milliseconds)
              4.5. async_task_route(routename)
              4.6. async_task_group_route(routename, groupname)
              4.7. async_task_data(routename, data)
              4.8. async_task_group_data(routename, groupname, data)

   List of Examples

   1.1. Set workers parameter
   1.2. Set ms_timer parameter
   1.3. Set workers parameter
   1.4. async_route usage
   1.5. async_ms_route usage
   1.6. async_sleep usage
   1.7. async_ms_sleep usage
   1.8. async_workers usage
   1.9. async_task_route usage
   1.10. async_task_group_route usage
   1.11. async_task_data usage
   1.12. async_task_group_data 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. workers (int)
        3.2. ms_timer (int)
        3.3. return (int)

   4. Functions

        4.1. async_route(routename, seconds)
        4.2. async_ms_route(routename, milliseconds)
        4.3. async_sleep(seconds)
        4.4. async_ms_sleep(milliseconds)
        4.5. async_task_route(routename)
        4.6. async_task_group_route(routename, groupname)
        4.7. async_task_data(routename, data)
        4.8. async_task_group_data(routename, groupname, data)

1. Overview

   This module provides asynchronous operations for handling SIP requests
   in the configuration file.

   Async uses t_suspend() and t_continue() from the TM and TMX modules.

   Note that after invoking the asynchronous operation, the processing
   will continue later in another application process. Therefore variables
   stored in private memory should not be used, try to use shared memory
   if you want to get values after the processing is resumed (e.g.,
   $avp(...), $xavp(...), $shv(...), htable $sht(...)).

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:
     * tm - transaction management.
     * tmx - transaction management extensions.

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. workers (int)
   3.2. ms_timer (int)
   3.3. return (int)

3.1. workers (int)

   Number of worker processes to be started to handle the asynchronous
   tasks for async_route() and async_sleep().

   Default value is 1.

   Example 1.1. Set workers parameter
...
modparam("async", "workers", 2)
...

3.2. ms_timer (int)

   Enables millisecond timer for async_ms_sleep() and async_ms_route()
   functions. The integer value is the timer resolution in milliseconds. A
   smaller timer resolution will generate a higher load on the system. If
   you set ms_timer to 1 you will get a timer with 1 millisecond
   resolution, a setting of 20 provides a resolution of 20ms.

   Default value is 0.

   Example 1.2. Set ms_timer parameter
...
modparam("async", "ms_timer", 10)
...

3.3. return (int)

   The value to be returned by async functions on success. It does not
   apply for async data functions, only for those that suspend the SIP
   transaction.

   Default value is 0.

   Example 1.3. Set workers parameter
...
modparam("async", "return", 1)
...

4. Functions

   4.1. async_route(routename, seconds)
   4.2. async_ms_route(routename, milliseconds)
   4.3. async_sleep(seconds)
   4.4. async_ms_sleep(milliseconds)
   4.5. async_task_route(routename)
   4.6. async_task_group_route(routename, groupname)
   4.7. async_task_data(routename, data)
   4.8. async_task_group_data(routename, groupname, data)

4.1.  async_route(routename, seconds)

   Simulate a sleep of 'seconds' and then continue the processing of the
   SIP request with the route[routename]. In case of internal errors, the
   function returns false, otherwise the function exits the execution of
   the script at that moment (return 0 behaviour).

   The routename parameter can be a static string or a dynamic string
   value with config variables.

   The sleep parameter represent the number of seconds to suspend the
   processing of a SIP request. Maximum value is 100. The parameter can be
   a static integer or a variable holding an integer.

   Since the SIP request handling is resumed in another process, the
   config file execution state is practically lost. Therefore beware that
   the execution of config after resume will end once the route[routename]
   is finished.

   This function can be used from REQUEST_ROUTE.

   Example 1.4. async_route usage
...
request_route {
    ...
    async_route("RESUME", "4");
    ...
}
route[RESUME] {
   send_reply("404", "Not found");
   exit;
}
...

4.2.  async_ms_route(routename, milliseconds)

   Simulate a sleep of 'milliseconds' and then continue the processing of
   the SIP request with the route[routename]. In case of internal errors,
   the function returns false, otherwise the function exits the execution
   of the script at that moment (return 0 behaviour). This function works
   only if the ms_timer parameter has a value greater than 0.

   The routename parameter can be a static string or a dynamic string
   value with config variables.

   The sleep parameter represent the number of milliseconds to suspend the
   processing of a SIP request. Maximum value is 30000 (30 sec). The
   parameter can be a static integer or a variable holding an integer.

   Since the SIP request handling is resumed in another process, the
   config file execution state is practically lost. Therefore beware that
   the execution of config after resume will end once the route[routename]
   is finished.

   This function can be used from REQUEST_ROUTE.

   Example 1.5. async_ms_route usage
...
request_route {
    ...
    async_ms_route("RESUME", "250");
    ...
}
route[RESUME] {
   send_reply("404", "Not found");
   exit;
}
...

4.3.  async_sleep(seconds)

   Simulate a sleep of 'seconds' and then continue the processing of SIP
   request with the next action. Note that the processing continues till
   the last action in the current route block. Consider using
   async_route() instead if you want to control better what is executed
   after the wait time. Beacuse the execution is resumed in another
   process, do not use private memory variables before and after the async
   sleep.

   The sleep parameter represent the number of seconds to suspend the
   processing of SIP request. Maximum value is 100. The parameter can be a
   static integer or a variable holding an integer.

   In case of internal errors, the function returns false.

   This function can be used from REQUEST_ROUTE.

   Example 1.6. async_sleep usage
...
async_sleep("4");
send_reply("404", "Not found");
exit;
...

4.4.  async_ms_sleep(milliseconds)

   Similar to async_sleep(), but with a 'milliseconds' parameter. This
   function works only if the ms_timer parameter has a value greater than
   0.

   The sleep parameter represent the number of milliseconds to suspend the
   processing of SIP request. Maximum value is 30000 (30 sec). The
   parameter can be a static integer or a variable holding an integer.

   This function can be used from REQUEST_ROUTE.

   Example 1.7. async_ms_sleep usage
...
route[REQUESTSHAPER] {
        $var(res) = http_connect("leakybucket",
                        "/add?key=$fd", $null, $null,"$avp(delay)");
        $var(d) = $(avp(delay){s.int});
        if ($var(d) > 0) {
                # Delay the request by $avp(delay) ms
                async_ms_sleep("$var(d)");
                if (!t_relay()) {
                        sl_reply_error();
                }
                exit;
        }
        # No delay
        if (!t_relay()) {
                sl_reply_error();
        }
        exit;
}
...

4.5.  async_task_route(routename)

   Continue the processing of the SIP request with the route[routename] in
   one of the processes from first group of core asynchronous framework.
   The core parameter async_workers has to be set to enable asynchronous
   framework. The task is executed as soon as a process from asynchronous
   framework is idle, there is no wait time for the task like for
   async_route(...).

   To enable the core asynchronous framework, you need to set the
   async_workers core parameter in the configuration file. See the core
   cookbook for more information.

   Example 1.8. async_workers usage
...
# Enable 8 worker processes used by async and other modules
async_workers=8
...

   In case of internal errors, the function returns false, otherwise the
   function exits the execution of the script at that moment (return 0
   behaviour).

   The routename parameter can be a static string or a dynamic string
   value with config variables.

   Since the SIP request handling is resumed in another process, the
   config file execution state is practically lost. Therefore beware that
   the execution of config after resume will end once the route[routename]
   is finished.

   This function can be used from REQUEST_ROUTE.

   Example 1.9. async_task_route usage
...
request_route {
    ...
    async_task_route("RESUME");
    ...
}
route[RESUME] {
   t_relay();
   exit;
}
...

4.6.  async_task_group_route(routename, groupname)

   Similar to async_task_route(), but allows to specify the name of the
   group for asynchronous workers. See also 'async_workers_group' core
   global parameter.

   This function can be used from REQUEST_ROUTE.

   Example 1.10. async_task_group_route usage
...
async_workers_group="name=abc;workers=4;nonblock=0;usleep=0"
...
request_route {
    ...
    async_task_route("RESUME", "abc");
    ...
}
route[RESUME] {
   t_relay();
   exit;
}
...

4.7.  async_task_data(routename, data)

   Send the data to an asynchronous task process (in the first group) that
   executes the route[rountename] and makes the data available via
   $async(data).

   The current SIP message is not suspended and it is not available in the
   asynchronous task process, a local faked SIP request is used there.

   The parameters can contain variables.

   This function can be used from ANY_ROUTE.

   Example 1.11. async_task_data usage
...
async_workers_group="name=abc;workers=4;nonblock=0;usleep=0"
...
request_route {
    ...
    async_task_data("RESUME", "caller: $fU - callee: $tU");
    ...
}
route[RESUME] {
   xinfo("$async(data)\n");
   exit;
}
...

4.8.  async_task_group_data(routename, groupname, data)

   Similar to async_task_route(), but allows to specify the name of the
   group for asynchronous workers. See also 'async_workers_group' core
   global parameter.

   This function can be used from ANY_ROUTE.

   Example 1.12. async_task_group_data usage
...
async_workers_group="name=abc;workers=4;nonblock=0;usleep=0"
...
request_route {
    ...
    async_task_data("RESUME", "abc", "caller: $fU - callee: $tU");
    ...
}
route[RESUME] {
   xinfo("$async(data)\n");
   exit;
}
...
