Application Interface

For the application API autocron provides the decorators cron and delay and the functions start(), stop() and get_results(). After importing autocron the decorators and function are accessible like i.e. autocron.start().

Functions decorated with delay will get executes later in a separate process. Functions decorated with cron will get executed periodically.

To start the autocron background workers, the function start() must get called somewere in the code. The function stop() will stop the workers. It is not necessary to call stop() because autocron stops the workers on shutdown of the main application.

cron

A function decorated with cron should get never called from the application. Instead it will get called from autocron periodically. Because of this a cron-decorated function should not get arguments. The decorator can directly imported from autocron:

from autocron import cron

To register a cron-function (that means autocron is aware of the decorated function) the module where the function is defined must get imported from the application.

Example

Let’s consider a newsletter should get send on Monday and Wednesday at 9:30 am. This could be configured by means of a cron-string:

@cron("30 9 0,2 * *")
def send_newsletter():
    ...

and could also be configured by keyword-arguments:

@cron(minutes=[30], hours=[9], dow=[0, 2])
def send_newsletter():
    ...

delay

To use the delay decorator autocron provides a shortcut for import:

from autocron import delay

Functions decorated with delay will return a Result instance (see below), wrapping the result. It is safe to ignore the return value. autocron will clean up the database from time to time to delete outdated results.

Result

A delay-decorated function returns a Result instance. This is a wrapper around the delayed result. The instance provide attributes like is_waiting to indicate whether a result is available:

@delay
def do_this_later():
    # code here ...

task_result = do_this_later()
...
if task_result.waiting:
    # try to get the result later
else:
    result = task_result.function_result

If autocron is inactive the decorated function will also return a TaskResult instance with the return value of the function.

start and stop

To start the autocron background workers, call autocron.start(<filename>) with a database-filename as argument. The number of workers can be set by the admin-interface.