# &adminguide;

## 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(...)).

## Dependencies

### &kamailio; Modules

The following modules must be loaded before this module:

- tm - transaction management.

- tmx - transaction management extensions.

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- None

## Parameters

### `workers` (int)

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

Default value is 1.

#### Set `workers` parameter

    ...
    modparam("async", "workers", 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 resultion will generate a higher load on the system. If you set ms_timer to 1 you will get a timer with 1 millisecond resultion, a setting of 20 provides a resultion of 20ms.

Default value is 0.

#### Set `ms_timer` parameter

    ...
    modparam("async", "ms_timer", 10)
    ...

## Functions

### `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.

#### `async_route` usage

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

### `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 then 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.

#### `async_ms_route` usage

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

### `async_sleep(seconds)`

Simulate a sleep of 'seconds' and then continue the processing of SIP request with the next action. In case of internal errors, the function returns false.

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.

This function can be used from REQUEST_ROUTE.

#### `async_sleep` usage

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

### `async_ms_sleep(milliseconds)`

Simulate a sleep of 'milliseconds' and then continue the processing of SIP request with the next action. In case of internal errors, the function returns false. This function works only if the ms_timer parameter has a value greater then 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.

#### `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;
    }
    ...

### `async_task_route(routename)`

Continue the processing of the SIP request with the route[routename] in one of the processes from 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.

#### `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.

#### `async_task_route` usage

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