Hi, I have made some investigations about file locks and mmap.
On Linux file locks are useless for our alleged problem because all applications have to be "cooperative". There is a paper on kernel.org which describes a mandatory locking, but I have not managed to get it working with ubuntu. http://kernel.org/doc/Documentation/filesystems/mandatory-locking.txt But the original problem on Bug #728197 was different. Mixxx corrupts its own mmap buffer in SoundSourceMp3 due to its own metatdata writes. Unfortunately the Qt implementation uses the MAP_SHARED flag. But in my test writes from a different process to the original file does not effect the mmap buffer. Is this true in general? Conclusion: * we have to verify that all track files are read mmaped by Mixxx. * we have to figure out if my test results are valid for Linux Mac Os and Windows in general * If so, we need not to be worried about external processes that writes metatdata to the files. * If the Mixxx mmap buffer is still untouched due writes from a forked() process in face of Qts MAP_SHARED flag, it should be save to write metadata to a track file using an external process. What do you think? Kind regards, Daniel -- Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Get Mixxx, the #1 Free MP3 DJ Mixing software Today http://mixxx.org Mixxx-devel mailing list Mixxx-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mixxx-devel
