Re: tasking design considerations

["Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>]

On 01/20/2017 09:07 AM, rrr.eee.27@gmail.com wrote:
>
> For the ease of reasoning you can assume typically around 0 .. 20 messages
> (the maximum certainly << 1000 messages) per time frame T. The cycle time of
> T is fixed now to 1 minute, but might go down in the future to 1 second.
> Channel B of course has exactly one message per T.  The channels are TCP
> sockets. Reception of a single complete message in channel A activates
> callback function in my program.

Callbacks are usually a mechanism used to deal with concurrency in a sequential 
language. When you have a concurrent language, use of callbacks is usually a 
poor design.

> I want now create a protected object stack. The callbacks from channel A fill
> the stack on the top. A cyclic task with a cycle time T reads and removes all
> collected messages from the bottom of the stack. The task processes the
> messages and sends out the result.

This is a queue, not a stack.

This seems like a reasonable design. The only question is how task B decides 
which messages to include for a time frame. If B reads until the queue is empty, 
it may read msgs that belong in the next time frame. One way to avoid this is to 
have B obtain the length of the Q and read that many msgs. Another is for B to 
invoke an operation that gives B a copy of the Q and clears the Q.

-- 
Jeff Carter
"Frankie Wolf, wanted by Federal authorities for
dancing with a mailman."
Take the Money and Run
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