Re: [boost] [next gen future-promise] What to callthemonadicreturntype?

Subject: Re: [boost] [next gen future-promise] What to callthemonadicreturntype?
From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2015-05-26 14:27:23

On Tue, May 26, 2015 at 6:36 AM, Peter Dimov <lists_at_[hidden]> wrote:
> Gottlob Frege wrote:
>
>> Can't use a spinlock pool.  Because you might hold the spin lock when
>> moving/copying T, and T could be anything, then, in theory at least, T's
>> constructor might also use a future/promise, etc, etc, such that a collision
>> could cause a deadlock.
>
>
> Yes, good point. Need recursive spinlocks.
>

I don't think a pool of recursive spinlocks works, because T could
decide to wait on another thread, which is waiting on a future, which
could - behind the scenes - be using the same spinlock as the original
thread.

You could probably still use a pool somehow, with more management, but
it gets complicated.  You probably either need at least as many locks
as threads, or a fall back of allocating a lock if none are available
- but the original point was to not allocate...

(Or a way to know that Thread A is waiting on Thread B...)

Tony