Implemented Worker-Specific Task Assignment Capabilities.

[tejaschauhan373]

Bug / Requirement Description

• Implemented Worker-Specific Task Assignment Capabilities.

Solution description

• Added default parameter workers_name to store uid of workers in Task.
• Added variable is_picked_up to keep track of task assignment in Task.
• Added dictionary queue_map in TaskQueue to keep separate task queue for all workers in case of need, or else it will be stored in default queue.
• If there is non-empty workers_name given in Task object, means task needs to run by given uid workers only, else it can be run by anyone.
• Create separate queue for each uid of workers_name & manage it through queue_map.
• While assigning Task to Worker and popping from queue, check if task is picked up by another worker already or not through Task.is_picked_up variable.
• If Task.is_picked_up is True then don't assign anything for that pull request, else assign it & mark Task.is_picked_up True.
• While _handle_taskresults, _decommission_worker, _discard_task, discard_pending_tasks, mark Task.is_picked_up False.

Checklist:

• Test

[Pyifan]

Generally speaking, doing worker-specific task assignment is against pool design principle. With pool execution, we expect all workers are equivalent, and all tasks isolated.

[Pyifan]

I'm open to have traits on both worker & task as assignment constraints (like jenkins selector), if we have a valid use case.