Re: [boost] lightweight_once

From: Anthony Williams (anthony_w.geo_at_[hidden])
Date: 2007-09-20 11:46:11

Andrey Semashev <andysem_at_[hidden]> writes:

> Hello Anthony,
>
> Tuesday, August 28, 2007, 12:17:45 PM, you wrote:
>
>> "Peter Dimov" <pdimov_at_[hidden]> writes:
>
>>> Hasn't Anthony Williams already implemented a header-only call_once? I'm not 
>>> sure I see a reason to reinvent that particular wheel. Once boost::mutex is 
>>> made header-only, there'd be no need for lightweight_mutex either and I'll 
>>> be able to retire it as well. 
>
>> I have implemented a header-only call_once for Windows --- on the
>> thread_rewrite branch in SVN. I plan to get to pthreads sometime in the near
>> future.
>
>> The win32 implementation of mutex is also header-only, and I plan to add a
>> header-only pthreads implementation too.
>
> Would you be interested to take a look at my implementation? Maybe
> after some cleaning up it could be moved to your official library?

Sorry for the delay in replying.

I've looked at the implementation in FSM.zip from the vault --- is that the
one you meant? --- and with a quick glance it looks like you've opted for a
check/sleep/check/sleep loop for threads that are waiting for another thread
to finish running the routine. This is a bad idea. Blocking of this nature
should be done by waiting on an OS primitive rather than with a wait loop.

Anthony
-- 
Anthony Williams
Just Software Solutions Ltd - http://www.justsoftwaresolutions.co.uk
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