Ceph » rgw

Actually we do implement the If-Modified-Since, if it's not working that's a bug. One difference is that we don't return 304, but some other error code. Does Amazon S3 return 304 in such a case?

Yes, Amazon does that. The RFC specifies that when you do so, you have to return a 304 Not Modified header.

Like you said there is already some work for this, but the correct header isn't set, this should be done then.

There is some more to this and it might need some more work to do so.

Right now, all the times stored by the RADOS gateway are in the timezone where the gateway is, but all the HTTP RFC's specify that GMT should be used.

When working with the "If-Modified-Since" header (or the If-Unmodified-Since) the "mtime" coming from RADOS has to be converted to GMT.

But the same goes for displaying the "Last-Modified" header, the time coming from RADOS first has to be converted to GMT, which then makes it prone to errors.

I would suggest saving all the dates in GMT, so no conversion has to be made to them, but this has a drawback. The time_t datatype in C++ is always to be converted according to the local system timezone, this is done by mktime, localtime and gmtime. So this makes the time conversions a bit unreliable.

To do so we would have to switch to a different method of saving times inside the gateway, but i think this goes even deeper then the gateway, it goes down all the way to librados i assume.

Right now i'm hacking around in the code to get the If-Modified-Since working, but i keep coming up with the timezone difference. I'm in GMT +2, so it takes 2 hours before i get the "304 Not Modified" response on a file.

Later today i'll post a patch which would solve the issue, but i still think we will have to go deeper then just converting all the times, imho, all the times saved should be GMT and converted from there on.

The patch seems fine, just a small issue is that you changed the return code in the unmodified-since case. This would make it incompatible with the error codes described in the amazon S3 API documentation.