Task Rewrite of JobQueue?

This is a list of goals for the rewrite of the JobQueue?.

MythSystem?

• Expand myth_system to a full featured class, to replace existing uses of myth_system, popen, and QProcess.
• Support both direct execution, and execution through bourne shell.
• Support input and output pipes, as well as buffered output (for 64KB pipe limit) managed by the reaper.
• Allow independent timeouts for wait call and automatic termination.
• (optional) Expand reaper to pull CPU usage.
• (optional) Allow CPU time limits on processes in addition to real time limits.

JobQueue?

• Move user job definition out of settings table and into dedicated table, to allow an arbitrary amount of user jobs.
• Allow per-machine, per-command time constraints for jobs to run between, with the option to forcefully terminate when the run window has closed.
• Remove special handling of transcode and commflag jobs. Each transcode profile would be given an independent command, and any custom status updates should be performed by the external command.
• Set master backend as a job scheduler, doling out tasks to available connected machines. The existing system is effectively a 'free-for-all'.
• (optional) Migrate mythfilldatabase and any other external 'housekeeping' processes to the jobqueue.
• (optional) Improve support for use of jobqueue in MythVideo?, and other non-recording related tasks.
• (optional) Allow maximum CPU time limits, and termination of idle tasks, to prevent deadlocked tasks.
• (optional) Allow automatic scaling of concurrent jobqueue tasks. Preferably this would run properly without configuration, and can track both CPU and IO usage.
• (optional) Force all communication to happen over the backend protocol, removing the need for database access for child queues, to facilitate a future move to an embedded database.
• (optional) Break the jobqueue out of the backend completely in favor of mythjobqueue. The master backend would subsequently exist only as a job scheduler.
• (very optional) Create repository for job scripts, similar to the new theme downloader.