On Wed, Jul 30, 2014 at 10:45 AM, Andrey Semashev <andrey.semashev@gmail.com
wrote:
I'm not sure I fully understood the idea but is it implementable in RCU manner?
Thanks for the keyword, I think it's indeed related but I wasn't aware of the idea. I'll have to read more (http://en.wikipedia.org/wiki/Read-copy-update) to be sure.
I think you can have a mutex-protected shared_ptr to the value, which every reader can obtain and use. When the reader is not using the value it demotes it to weak_ptr. Next time the reader wants to use the object it attempts to promote it to shared_ptr, which will only succeed if the value has not expired.
That's close to the implementation I was thinking about but I also would like to avoid any lock if avoidable. (I lack practice in this domain to say if it's avoidable).
This approach does not involve any callbacks, which might be a good or bad thing depending on the use case.
I think in my case the writes are so rarely changed but have so much impact, I'm assuming that it's more efficient if a callback is called once the value is written so that the systems don't have to test the value regularly. I might be wrong though, my application is not complete yet.
In any case, I think this would be a fairly high level primitive (especially if async callbacks are involved), so I'm not sure Boost.Sync is the right place for it.
I was assuming it would be close to synchronized_value but it's a bit more high-level indeed.
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