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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.arch
Subject: Re: Futex Stack...
Date: Tue, 8 Apr 2025 23:07:11 -0700
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On 3/25/2025 12:11 AM, Chris M. Thomasson wrote:
> This is a little C++20 test using a futex to allow one to wait on a 
> lock-free stack. The main stack logic is in struct ct_stack. Well, can 
> you get to compile and run? Thanks... There is no need for DWCAS here. 
> It uses just XCHG and CMPXCHG.
> 
> 
> My code:
> ______________________________________

[...]

To tidy things up a little, the flush_wait can look like this:
____________________
ct_node*
flush_wait()
{
     ct_node* head = m_head.exchange(nullptr, std::memory_order_acquire);

     while (! head || head == CT_WAIT)
     {
         // slow path...
         head = m_head.exchange(CT_WAIT, std::memory_order_acquire);

         if (! head || head == CT_WAIT)
         {
             m_head.wait(CT_WAIT, std::memory_order_relaxed);
         }
     }

     assert(head && head != CT_WAIT);

     return head;
}

____________________

Also, I made a spelling error wrt:

     unsigned long g_ct_work_alloations = 0;
     unsigned long g_ct_work_dealloations = 0;

grrrrr!