XrdCks does not use XrdOss

[apeters1971]

It is very unfortunate that the preconfigured checksum plugin uses POSIX calls to scan files and to get/set attributes to store the checksum.

If XrdCksManager would use XrdOss functions one would get checksumming automatically supported for any XrdOss implementation. Can this be changed?

[abh3]

The problem that we have here is that your request requires an ABI change that it is generally anathema for EPEL and we have to abide by EPEL rules. Why is it that you cannot use the plugin architecture for check sums to get around this problem? Your should just substitute the checksum manager witch your own plugin even if it makes use of the existing check sum packages.

[apeters1971]

"just substitute" ... I can, but I have to rewrite/duplicate the whole logic for each checksum flavour I want.

XrdCks should be the plugin for the algorithm, while XrdOss is the plugin for the low-level IO ... so I think it makes a lot of sense. Maybe there is a way to get the Oss object into the Cks object without modification of the public API ?!?!?

[abh3]

This is largely the fallout of needing to use the class in various contexts, some of which do not have an oss present. One solution is to change XrdCks and pass it the oss class so that it would use it. Of course, adding an additional constructor may be considered an ABI change (need to explore that). Of course, there are non-OO ways around that. That said, this is just one of the problems since Cks also uses the Fattr classes to get and set extended attributes. These also do not use the oss. Of course, the brute force solution is to simply over-ride CksManager with your own plugin if direct POSIX calls are an issue. Let's talk about this the week of the 22nd or earlier.

[abh3]

We have a solution on the way.