Re: [container] Proposal for ring queues

From: Gavin Lambert (boost_at_[hidden])
Date: 2020-05-25 03:37:37

On 22/05/2020 10:17, Andrey Semashev wrote:
> Some time ago I have proposed to include ring_queue and small_ring_queue 
> containers to Boost.Container:
> 
> https://github.com/boostorg/container/pull/121
> 
> The ring queues work similarly to std::queue with the main difference 
> being that they use a ring buffer internally to store elements. The 
> small_ring_queue also allows to allocate a static storage for a fixed 
> amount of elements. The benefit of this is that dynamic memory 
> allocations can be practically avoided when the number of enqueued 
> elements does not exceed some limit.

Boost.Lockfree [1] already contains such a queue (which operates similar 
to a ring-buffer when set to fixed capacity, but can be configured to be 
dynamic).

The queue doesn't implement a ring buffer, but can be used as if it did.
The spsc_queue actually uses a ring buffer internally.

They implement "push fails" if the buffer is full when fixed-capacity, 
but (provided you use the multi-consumer version, or prevent concurrent 
access some other way) there's no reason why you couldn't pop and retry 
if you want overwrite-like behaviour.

Usually I personally find that if I care about memory allocation then I 
care about locking as well.

[1]: https://www.boost.org/doc/libs/1_73_0/doc/html/lockfree.html