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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.lang.c++
Subject: Re: Futex Stack Test...
Date: Sat, 3 May 2025 18:57:11 -0700
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On 5/3/2025 12:58 PM, Chris M. Thomasson wrote:
> On 5/3/2025 11:19 AM, Bonita Montero wrote:
>> Am 03.05.2025 um 20:02 schrieb Chris M. Thomasson:
>>
>>> Now, its fun to be able to get a lock-free stack with only single 
>>> word exchange and cas, and have the ability to use it with a futex to 
>>> allow one to wait on empty conditions.
>>
>> Is a lock-free stack with a single word CAS really possible without an
>> ABA-problem ?
> 
> Will get back to you. Need to run a bunch of errands. If you omit single 
> item pop, yup. It's also possible to get rid of the cas in push.

The ABA problem _and_ memory issue is only there in on the single node 
pop for a lock-free stack. If you just whack it with a nullptr aka flush 
_all_ nodes, then you are all right and ready to roll.

Actually, IBM had/has a nice write up of it in an appendix for the 
principles of operations iirc. I think it might of been in appendix 40 
ish or something. God it's been a while since I read that Bonita. Then 
they have a rather nifty PLO, or perform locked operation, again iirc...

The futex is fun to use because it allows one to wait on an empty 
condition...

Actually, I remember Joe Seigh taking all the nodes in an exchange, 
reversing them, and BAM, its FIFO. ;^)

> [...]