[Yum-devel] [PATCH] Fix _remove_old_deps to deal with chains of revdeps.

[seth vidal]

On Fri, 2011-04-08 at 08:44 -0700, Casey Jao wrote:
> ---
>  yum/__init__.py |   69
> +++++++++++++++++++++++++++++++++++++++++++++++++++----
>  1 files changed, 64 insertions(+), 5 deletions(-)
> 
> diff --git a/yum/__init__.py b/yum/__init__.py
> index cf4d827..bbb5204 100644
> --- a/yum/__init__.py
> +++ b/yum/__init__.py
> @@ -5276,6 +5276,11 @@ class YumBase(depsolve.Depsolve):
>          found_leaves = set()
>          checked = set()
>          beingremoved = [ t.po for t in
> self.tsInfo.getMembersWithState(output_states=TS_REMOVE_STATES) ]
> +        # cache previously examined packages
> +        okay_to_remove = {}
> +        for i in self.rpmdb.returnPackages():
> +            okay_to_remove[i] = True
> +
>          for pkg in beingremoved: # for each package required by the pkg
> being removed
>              #print 'removal: %s' % pkg.name
>              for required in pkg.required_packages():
> @@ -5283,23 +5288,29 @@ class YumBase(depsolve.Depsolve):
>                  #    continue # if we've already checked it, skip it.
>                  #checked.add(required)
>                  if required.yumdb_info.get('reason', '') != 'dep': # if
> the required pkg is not a dep, then skip it
> +                    okay_to_remove[required] = False
>                      continue
>                  if required in beingremoved:
>                      continue
> +                if self._has_needed_revdeps(required, beingremoved,
> okay_to_remove):
> +                    continue
>                  still_needed = False
>                  for requiring in required.requiring_packages(): # so we
> have required deps - look at all the pkgs which require them
>                      if requiring == required: # if they are
> self-requiring skip them
>                          continue
> -                    if requiring not in beingremoved: # if the
> requiring pkg is not in the list of pkgs being removed then it is still
> needed
> -                        still_needed = True
> -                        break
> +                    #if requiring not in beingremoved: # if the
> requiring pkg is not in the list of pkgs being removed then it is still
> needed
> +                        #still_needed = True
> +                        #break
> +
>                  # go through the stuff in the ts to be installed - make
> sure none of that needs the required pkg, either.
>                  for (provn,provf,provevr) in required.provides:
>                      if self.tsInfo.getNewRequires(provn, provf,
> provevr).keys():
>                          still_needed = True
> +                        okay_to_remove[required] = False
>                          break
>                  for fn in required.filelist + required.dirlist:
>                      if self.tsInfo.getNewRequires(fn,
> None,(None,None,None)).keys():
> +                        okay_to_remove[required] = False
>                          still_needed = True
>                          break
> 
> @@ -5319,5 +5330,53 @@ class YumBase(depsolve.Depsolve):
>                              beingremoved.append(txmbr.po)
>                          found_leaves.add(txmbr)
>          self.verbose_logger.log(logginglevels.INFO_2, "Found and
> removing %s unneeded dependencies" % len(found_leaves))
> -
> -
> +
> +    # Checks if pkg has any reverse deps which cannot be removed.
> +    # Currently this only checks the install reason for each revdep,
> +    # but we may want to check for other reasons that would
> +    # prevent the revdep from being removed (e.g. protected)
> +    def _has_needed_revdeps(self, pkg, beingremoved, ok_to_remove):
> +        # check if we've already found this package to have
> user-installed deps
> +        if not ok_to_remove[pkg]:
> +            # Debugging output
> +            #print pkg, "has been visited already and cannot be removed!!!"
> +            return True
> +        # Debugging output
> +        #print "Examining revdeps of", pkg
> +        # track which pkgs we have visited already
> +        visited = {}
> +        for po in self.rpmdb.returnPackages():
> +            visited[po] = False
> +        # no need to consider packages that are already being removed
> +        for po in beingremoved:
> +            visited[po] = True
> +        stack = []
> +        stack.append(pkg)
> +        # depth-first search
> +        while stack:
> +            curpkg = stack[-1]
> +            if not visited[curpkg]:
> +                if not ok_to_remove[curpkg]:
> +                    # Debugging
> +                    #print pkg, "has been visited already and cannot be
> removed!!!"
> +                    ok_to_remove[pkg] = False
> +                    return True
> +                if curpkg.yumdb_info.get('reason', '') != 'dep':
> +                    # Debugging output
> +                    #print pkg, "has revdep", curpkg, "which was
> user-installed."
> +                    ok_to_remove[pkg] = False
> +                    return True
> +                visited[curpkg] = True
> +            all_leaves_visited = True
> +            leaves = curpkg.requiring_packages()
> +            for leaf in leaves:
> +                if not visited[leaf]:
> +                    stack.append(leaf)
> +                    all_leaves_visited = False
> +                    break
> +            if all_leaves_visited:
> +                stack.pop()
> +        # Debugging output
> +        #print pkg, "has no user-installed revdeps"
> +        return False
> +
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Casey,
 This looks pretty good. Can you clean up the debugging comments and
maybe turn them into higher debug-level log calls? Also do you have any
testcases to go along with this?

Thanks,
-sv