Re: [boost] Announcing LEAF, a new error handling library suitable for low latency applications

Subject: Re: [boost] Announcing LEAF, a new error handling library suitable for low latency applications
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2018-11-15 01:30:36

On Wed, Nov 14, 2018 at 5:19 PM Gavin Lambert via Boost <
boost_at_[hidden]> wrote:

> On 15/11/2018 12:29, Emil Dotchevski wrote:
> > It uses thread_local raw pointers, one per error type. This is needed in
> > order to decouple result<T> from the static type of error objects being
> > propagated, which I consider critical, see
> > https://zajo.github.io/leaf/#rationale.
> >
> >> Is it compatible with coroutines or fibers or other non-thread-based
> stacks?
> >
> > Good question. I'm not sure, but I'm interested to know what are the
> issues.
>
> In general AFAIK, any use of thread-local storage is entirely
> incompatible with coroutines or fibers.  (Unless the mechanisms for both
> cooperate with each other, which is theoretically possible but I'm not
> aware of it occurring in the wild.)
>

The LEAF machinery that is used for multi-thread support can probably be
used as-is for coroutines as well.

It should be possible to explicitly support coroutines context switching,
which would be much faster, involving only setting raw pointers, possibly
exactly one raw pointer.