On 07/09/2014 15:38, Milosz Tanski wrote: > If you're planning on having plugins that are not shipped with the > host software you have to worry about both API and ABI stability. > Traditionally (and in my personal experience) keeping a C++ ABI > compatible is hard. For those reasons, I would strongly campaign for > having the plugins interface be in C (or et least their interface > would be C linkage). Hi Milosz, That's a good point indeed. > Otherwise here's some things you can read read about C++ ABI stability > (from the KDE people): > https://techbase.kde.org/Policies/Binary_Compatibility_Issues_With_C++ Thanks, I did not even think C++ ABI compatibility was possible at all ;-) The web site is down at the moment but I'll take a look. Cheers > > This are my 2 cents based on my past experience. > > On Sun, Sep 7, 2014 at 4:26 AM, Loic Dachary <loic@xxxxxxxxxxx> wrote: >> Hi Ceph, >> >> There is a need for a cluster to share code such as cls https://github.com/ceph/ceph/tree/master/src/cls or erasure code plugins https://github.com/ceph/ceph/tree/master/src/erasure-code/. >> >> These plugins could have a life cycle independent of Ceph, as long as they comply to the supported API ( https://github.com/ceph/ceph/blob/master/src/erasure-code/ErasureCodeInterface.h ). For erasure code plugins it currently works this way (or it will as soon as https://github.com/ceph/ceph/pull/2397 is merged): >> >> a) upgrade from Hammer to I* half the OSD nodes. The new I* have new erasure code plugins >> b) the MON will refuse to create an erasure coded pool using the new I* plugins, otherwise the Hammer nodes will find themselves unable to participate in the pool >> >> Instead it could work this way: >> >> a) upgrade from Hammer to I* half the OSD nodes. The new I* have new erasure code plugins >> b) the new erasure code plugins are uploaded to a "plugins" pool >> c) an erasure coded pool is created using a new plugin from I* >> d) the Hammer OSD downloads the plugin from the pool and can participate in the pool >> >> It is easier said than done and there are a lot of details to consider. However it not different from maintaining an Operating System that includes shared libraries and the path to do so properly is well known. >> >> Thoughts ? >> >> Cheers >> >> -- >> Loïc Dachary, Artisan Logiciel Libre >> > > > -- Loïc Dachary, Artisan Logiciel Libre
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