Internals

scheduler_node

This Python module implements the scheduler interface for the Robotics in Concert (ROCON) project. It tracks resources and allocates them to ROCON services.

class concert_simple_scheduler.scheduler_node.SimpleSchedulerNode(node_name=u'simple_scheduler', period=rospy.Duration[1000000000])

Simple ROCON scheduler node.

Parameters:

• node_name – (str) Default name of scheduler node.
• period – (rospy.Duration) Rescheduling time quantum.

ready_queue = None

Queue of waiting requests.

blocked_queue = None

Queue of blocked requests.

period = None

Time duration between periodic rescheduling.

notification_set = None

Set of requester identifiers to notify.

lock = None

Big Scheduler Lock.

pool = None

Resource pool of known ROCON clients.

sch = None

Scheduler request handler.

callback(rset)

Scheduler request callback.

Called in the scheduler callback thread holding the Big Scheduler Lock.

See: concert_scheduler_requests.Scheduler documentation.

dispatch()

Grant any available resources to ready requests.

Notifies all affected requesters.

free(request, requester_id)

Free all resources allocated for this request.

Parameters:

• request – (ActiveRequest)
• requester_id – (uuid.UUID) Unique requester identifier.

notify_requesters()

Notify affected requesters.

Pre:self.notification_set contains requesters to notify. Post:self.notification_set is empty.

queue(request, requester_id)

Add request to ready queue, making it wait.

Parameters:

• request (ActiveRequest) – resource request to be queued.
• requester_id (uuid.UUID) – Unique requester identifier.

reject_request(element, exception)

Reject an invalid queue element.

Parameters:

• element (QueueElement) – Queue element to reject.
• exception – Associated exception object.

reschedule(event)

Periodic rescheduling thread.

Moves requests that cannot be satisfied with currently-available resources to the blocked queue. Also checks the blocked queue for requests that can be satisfied due to newly-arrived resources.

Uses the Big Scheduler Lock to serialize these changes with operations done within the scheduler callback thread.

shutdown_requester(requester_id)

Shut down this requester, recovering all resources assigned.

concert_simple_scheduler.scheduler_node.main()

Scheduler node main entry point.