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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: [general] c help needed
Date Wed, 09 Apr 2008 14:00:47 GMT
Right.

To avoid the CAS loop, you can use Mutex.

mutex_lock();
//critical section;
mutex_unlock();

Thanks,
xiaofeng

On Wed, Apr 9, 2008 at 8:35 PM, Aleksey Shipilev
<aleksey.shipilev@gmail.com> wrote:
> IMHO here:
>
>  1. Using CAS infers using busy-loop, e.g. "we are trying until
>  operation succeed". You might tolerate spinning there by using PAUSE
>  instruction or some other way.
>  2. How about "static int counter = 0; #define INC() counter++;"? It
>  will be done in runtime though.
>
>  Thanks,
>  Aleksey.
>
>
>
>  On Wed, Apr 9, 2008 at 3:57 PM, Alexei Fedotov <alexei.fedotov@gmail.com> wrote:
>  > Hello folks,
>  >  Could you please help?
>  >
>  >  1. Is it possible to add to a thread safe linked list using CAS
>  >  without a busy loop?
>  >
>  >  void add_site(LogSite* log_site) {
>  >     LogSite** p_site_head = (LogSite**) &get_logger()->log_site;
>  >     LogSite* old_value = *p_site_head;
>  >     do {
>  >         log_site->next = (LogSite*) old_value;
>  >         (LogSite*) old_value = (LogSite*) apr_atomic_casptr((volatile
>  >  void **) p_site_head,
>  >             (void*) log_site, log_site->next);
>  >     } while (old_value != log_site->next); // busy loop
>  >  }
>  >
>  >  2. Is it possible to create an auto-increment macro within a
>  >  compilation unit using C preprocessor?
>  >
>  >  #define INC() ...
>  >
>  >     INC() // == 1
>  >     INC() // == 2
>  >     ...
>  >
>  >  Thank you for sharing your expertise.
>  >  --
>  >  With best regards,
>  >  Alexei
>  >
>



-- 
http://xiao-feng.blogspot.com

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