Re: [Lockfree] spsc example query

From: Gavin Lambert (boost_at_[hidden])
Date: 2020-08-25 23:09:24

On 26/08/2020 02:17, Sean Farrow wrote:
> I’m just about to start using the spsc queue in a project and whilst 
> reading the example at:
> 
> https://www.boost.org/doc/libs/1_74_0/doc/html/lockfree/examples.html#lockfree.examples.waitfree_single_producer_single_consumer_queue
> 
> looking at the consumer function, there appears to be two while loops 
> retrieving items from the queue inside the outer loop that checks 
> whether the done variable is true.
> 
> Can somebody please explain why this is, or, is it a bug in the example? 
> I would have thought one inner while loop would be enough.

There is only one inner while loop.  The second loop is outside of the 
main "while not done" loop.

The second loop is probably intended as a "post-done cleanup" rather 
than a "normal processing", although that's disguised by the trivial 
nature of the example.