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  1. Subversion
  2. SVN-766

make RA->do_switch less anemic

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Details

    • Improvement
    • Status: Closed
    • Major
    • Resolution: Fixed
    • all
    • unscheduled
    • libsvn_ra
    • None

    Description

      The fundamental problem is that RA->do_switch() is anemic.  It doesn't
      work on a single file, because dir_delta() can't do a single file
      switch either: dir_delta wants to delete the old basename and re-add
      the new basename, not simply switch the contents.
      
      Thus svn_client_switch() has a hacky workaround at the moment.  If
      switching a directory, run RA->do_switch().  If switching a file, call
      RA->get_file() and manually install the new contents.
      
      The other user of RA->do_switch(), namely the codepath for "svn
      diff/merge URL1 URL2", doesn't have this hacky workaround.  Instead,
      it's attempting to switch to a fileURL, and we have semi-confusing
      code in mod_dav_svn/update.c to detect this case and send back a
      reasonable update report.
      
      The correct long-term solution is to make dir_delta() comfortable with
      single-file switches.  Cmpilato sez:
      
         Make svn_repos_dir_delta() understand how to handle switches.  How?
         Well, first, consider what switch wants.  Switch wants to be told
         how to make PATH_A look exactly like PATH_B while still being named
         PATH_A.  So an option to PRESERVE_BASENAME would be nice, and would
         work in such a way that svn_repos_dir_delta would, if tempted to
         delete()+add() a top-level thing, would be sure to re-add the thing
         using SRC's basename (as opposed to DST's basename, which is the
         usual case), and *then* recursively deltify.
      
         I'm pretty sure this means that instead of just having a source path
         and a target path (for the internal support functions used by
         svn_repos_dir_delta), we would also need an `edit_path' that looks
         just like the target path, but has source-path's basename.
      
      Once dir_delta() can do this, then we don't any more special cases in
      mod_dav_svn, or in svn_client_switch either.  It *also* means that
      RA->do_switch() will be able to change dirs into files, or files into
      dirs, just like RA->do_update() does.  This is a hole gstein pointed
      out a while ago.
      

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            Unassigned Unassigned
            sussman Ben Collins-Sussman
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              Updated:
              Resolved:

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