Re: Futex Stack...

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:
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[...]
To tidy things up a little, the flush_wait can look like this:
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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;
}
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Also, I made a spelling error wrt:
     unsigned long g_ct_work_alloations = 0;
     unsigned long g_ct_work_dealloations = 0;
grrrrr!