> -----Original Message----- > From: Sergei Golubchik [mailto:[email protected]] > Sent: Sonntag, 27. März 2011 21:26 > To: [email protected] > Cc: MARK CALLAGHAN; [email protected]; > [email protected] > Subject: Re: [Maria-discuss] client library shared library version changed in > 5.5.10 > > Hi, Monty! > > On Mar 18, Michael Widenius wrote: > > >>>>> "MARK" == MARK CALLAGHAN <[email protected]> writes: > > > > > I think there was discussion about how client library shared library > > > versions during the Lisbon meeting. > > > > >> From http://dev.mysql.com/doc/refman/5.5/en/news-5-5-10.html > > >>>> > > > Incompatible Change: The shared library version of the client library > > > was increased to 18 to reflect ABI changes, and avoid compatibility > > > problems with the client library in MySQL 5.1. Note that this is an > > > incompatible change between 5.5.10 and earlier 5.5 versions, so client > > > programs that use the 5.5 client library should be recompiled against > > > the 5.5.10 client library. > > > > Serg, as you have now probably have full insight into the MariaDB 5.5 > > code, is it possible to keep the API compatible with MariaDB 5.1 / > > MySQL 5.1 to not force all applications to have to be recompiled when > > upgrading to 5.5 ? > > The API incompatibility was caused by migration to CMake. > If you want to keep libraries compatible, if's something that Wlad may > need to look into.
I do not really think it was CMake that broke it. The "official" ABI has not changed, however some people claim that API and ABI are 2 different things ;) For 5.5 the discussion starts here http://bugs.mysql.com/bug.php?id=59078 ([9 Feb 2:26] Clint Byrum, IIRC he works for Debian). His argument that ABI has changed "dramatically" is that for example an exported symbol named TERMINATE has gone, while new symbols PSI_hook and PSI_server were added. He uses "nm" for his argumentation. Clint's claim is that every time an exported symbol is changed/removed or added, shared library version must be bumped. Unix linkers export every global function and variable by default. Which means, if one renames a global variable as part of cleanup, the ABI is changed. Changes like that can happen really in any point release, so I see no other way to maintain the 100% ABI compatibility, rather than restricting visibility to only symbols defined by client API (i.e mysql_xxx stuff) . On some Unixes, it is possible to do with linker version script .On Windows symbols were restricted to the official API from the start on , using with the .def file. This would be a clean solution from my point of view. However, should we go for it, this would result in incompatibilities with Oracle's MySQL, and this has to be worked out somehow (best thing is probably contribute visibility-restricting patch, if they are at all interested) . Besides , Unix users need to be warned that shared and static library are not interchangeable and that it will not be possible to access e.g mysys/strings/dbug functionality using the shared library. Hopefully most of the programs are written using officially documented client API functions, so there won't be many surprises. Regards, Wlad _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp
