[kea-dev] Is it possible for hooks to hande server shutdown?

Thomas Markwalder tmark at isc.org
Fri Oct 6 10:59:28 UTC 2017


On 10/5/17 8:57 PM, Dave Cole wrote:
>> The load and unload points are in the same file wrapped in the same extern "C". 
>>
>> In my in-expect browsing of the code I could not see any way that the unload hook was being called on server exit.  I was just hoping someone with a clue would confirm that for me, and maybe suggest a way to achieve the same effect.
>>
>> Using onexit is not going to work since a hook reload would almost certainly cause a segfault during server exit.
> I do not pretend to understand what is going on, but when I built my hook on centos7, the unload callback is being invoked during server shutdown.
>
> Oh well...
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Hi Dave:

Each configured hook library is owned by an instance of
isc::hooks::LibraryManager.  Whenever a library needs to unloaded, it is
done through: 

LibraryManager::unloadLibrary() -> LibraryManager::runUnload() ->
SomeHookLib::unload().

This chain is invoked by LibraryManager's destructor, so during a
shutdown the hook library unloads are automatically called, as each
LibraryManager gets destroyed.

Hope that answers your question.

Regards,

Thomas Markwalder
ISC Software Engineering








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