Re: Workqueues in Ada

[Simon Wright <simon.j.wright@mac.com>]

Wiktor Moskwa <wiktorDOTmoskwa@gmail.com> writes:

> My idea of using a circular list is to call Delete and Append only
> when new node joins the system or an old one leaves. During normal
> operations a task will request new unit of work without deleting it
> from the queue.  It will be only marked as "currently in use". Other
> tasks will skip this node - Next_To_Service pointer will move
> clockwise skipping nodes that are serviced at the moment.

Sounds very complicated & fragile to me, it no longer resembles
anything one would recognise as a 'queue'.

Would it help to have a queue of pointer-to-work-item? (depends on how
big a work-item is, because (I have a strong impression that)
Ada.Containers containers allocate/deallocate on Append/Delete).

It's hard to see how to avoid this with unbounded containers. You
could look at alternative container packages? (I normally wouldn't
suggest this, given Ada.Containers, but a BC.Comtainers.Queues.Bounded
from http://booch95.sf.net doesn't allocate .. but you have to know
the maximum number of elements you are going to need.)