Writing cronjobs works similar to plugins. The invocation and arguments passed are different though. A minimal cronjob looks like this:
import datetime from debexpo.cronjobs import BaseCronjob class ImportUpload(BaseCronjob): def setup(self): pass def teardown(self): pass def invoke(self): self.log.debug("Hello World") cronjob = ImportUpload schedule = datetime.timedelta(seconds = 10)
A cronjob should be subclassed from BaseCronjob. That ensure API compliant
invocation. A worker thread runs your jobs cyclically, persistence is guaranteed
for the object runtime. Technically, you
must define two objects in your
- cronjob = ImportUpload schedule = datetime.timedelta(seconds = 10)
The ‘cronjob’ attribute is an object reference which should be instantiated upon cronjob invocation. The ‘schedule’ attribute defines how often your cronjob should invoke your worker method. This must be a datetime.timedelta object. This is a soft guarantee. The Worker thread will guarantee you not to run the job more often than you specified, but it will not invoke it precisely for every delta. Your cronjob will not be invoked if another cronjob is still pending or running once your delta expires. Additionally the Worker thread does not execute the worker queue more often than every debexpo.cronjob_delay milliseconds.
Please don’t override the base class constructor, it will call your setup method if you need any setup. The following attributes will be instantiated for your cronjob:
This is a reference to the worker object, which instantiated your cronjob. You can call any method in from there, if necessary.
This is an instantiated configuration object. You can access every Debexpo configuration setting from it.
An instantiated log object, use it to display messages within the worker thread
Similarly to the constructor, don’t override the destructor. Use the teardown method instead
The worker method invocation¶
Implement the invoke method as your working horse. It will be called regularly and run your stuff. The Worker is designed as single threaded application, which means your method will block the entire cron job architecture. Don’t do anything which shall not be run synchronously.