Plugin Decorators

The Hoppr framework provides two Python decorators to simplify the development of plugin processes.

1. @hoppr_process

The @hoppr_process decorator handles several tasks that any implementation of pre_stage_process, process_component, or post_stage_process must perform. These include:

• Creation of a logger (accessible via the get_logger() method) to which information may be written regarding the execution of the process. This is an "in-memory" logger, which is copied to stdout at the completion of the processes, thereby preventing interleaving log messages from multiple processes running in parallel.

• Logging of certain standard events: start and completion of the process, run time, and result.

• For process_component (or any method that passes an argument of type Component), check that the process is appropriate to the PURL type of the component.

• At process completion, close the logger, and dump its contents to stdout.

2. @hoppr_rerunner

The @hoppr_rerunner decorator runs a process repeatedly, up to the value max_attempts specified in the Context, waiting for retry_wait_seconds (also from the Context) seconds between attempts.

3. Combining the decorators

The two decorators can (and often will be) combined for a single method. We recommend that the order be:

    @hoppr_process
    @hoppr_rerunner
    def process_component(....)

caution

Reversing the decorator order will still work, but will be slightly less efficient - creating and destroying loggers and logging data for each attempt.