Information for Clearcase/UCM Users

Clearcase/UCM Concepts

Syncing with a Mercurial Repository

It's simple enough to have a stream in Clearcase coexist with a Mercurial repository. All you need is to create a snapshot view on the stream in question. After the files are updated and on a local disk, turn the snapshot view into a Mercurial repository.

hg init
hg addremove
hg ci -m "Initial checkin"

From there you can push the repository anywhere you like.

Clearcase to Hg

As you pick up updates via rebasing in Clearcase and updating your snapshot view, hg status will tell you what is out of sync with your repository. hg addremove is a wonderful command to keep files in sync with respect to new files and deleted files.

Hg to Clearcase

This is a little tougher.

Clearcase, quite incorrectly, likes to own the mode on files, and keeps them read-only until they're checked-out. To update from Hg, I do the following

# I use cygwin for this on win32
find . -type f | xargs chmod u+w
hg pull
hg up

From Clearcase's perspective, you've just hijacked some files. If you update from clearcase using the gui, it will prompt you to check them out and check them in again.

ct update -graphical

To batch process this is more difficult, and that doesn't even cover files being renamed, removed, added, etc.

Another Alternative

If you can live with a one-way push from Mercurial into ClearCase (i.e. if ClearCase is your ultimate source of record, but all checkins happen in Mercurial), then you can also make this work with a dynamic view rather than a snapshot view. The trick is to use the clearfsimport command to import your changes from Mercurial to ClearCase.

The kshell script shown below is what I have been using for the last several months. Lately, I have been using it on a Solaris box, but with a slight tweak (commented out below), it works with Cygwin. It's not the prettiest thing in the world, but hopefully it will offer a decent starting point for others in the same boat as me.

This is the general process I follow:

1. Clone the Mercurial repository

2. Run clearfsimport on the cloned repository

3. Check for top-level elements that differ (and issue a warning)
4. Confirm that source and target contents are identical

Unfortunately, the clearfsimport program is kind of clunky, and you can't just say "import this entire directory into a VOB". Instead, you have to specify each and every file or directory to be imported. This makes it a bit painful if your top-level elements change frequently. You can easily add the new top-level elements, but it's harder to notice when the obsolete elements in the VOB should be removed. This is why step #3 is needed. (If someone knows of a way around this, I would love to hear about it... I've tried a number of different things, but I can't make it consistently work except as shown below.)

In any case, I have found that for Eclipse projects, top-level files don't change very often. So, it works OK to just issue a warning when it does happen. I then just remove the obsolete file or directory by hand. Another alternative might be to structure your projects so that there is just one top-level directory that contains everything else (but that wouldn't work for me in Eclipse).

-- KennethPronovici

# !/bin/ksh

# Sync configuration
typeset -x TARGET="/vobs/projects/xxx"
typeset -x SYNC="/home/projects/xxx/mercurial"
typeset -x PROJECTS="Project1 Project2"
typeset -x COMMENT="Merge in changes from Mercurial via sync script"

# Script configuration
typeset -x FIND="find"  # note: we need GNU find 
typeset -x MERCURIAL="hg"
typeset -x IMPORT="/usr/atria/bin/clearfsimport"
#typeset -x OPTIONS="-nsetevent -preview -recurse -rmname"  # preview mode
typeset -x OPTIONS="-nsetevent -recurse -rmname" # non-preview mode
typeset -x TMPCLONE=${TMPDIR-/tmp}/clone.$$
typeset -x TMPSOURCE=${TMPDIR-/tmp}/source.$$
typeset -x TMPTARGET=${TMPDIR-/tmp}/target.$$
typeset -x IGNORE="^clearfsimport: Error: Unable to determine absolute pathname for|^Changed protection on|Skipping element|directory unchanged|^No change in version|^Validating element|^Validating directory|^Closing directories"

# Sync each project
for project in $PROJECTS
do
   # Let the user know what we're doing
   print "*** Syncing $project"

   # Clone the project so we get the latest changes
   "$MERCURIAL" clone --quiet "$SYNC/$project" "$TMPCLONE"

   # Invoke clearfsimport to get things into ClearCase (non-Cygwin version)
   typeset -x FILES=$("$FIND" "$TMPCLONE" -maxdepth 1 -mindepth 1 -not -name ".hg")
   "$IMPORT" $OPTIONS -c "$COMMENT" $FILES "$TARGET/$project" 2>&1 | egrep -v "$IGNORE"

   # Invoke clearfsimport to get things into ClearCase (Cygwin version)
   # The clearfsimport command is very picky -- it won't work with names containing spaces.
   # That's why we use cygpath -d to convert the paths to DOS 8+3 paths, which never contain whitespace.
   #typeset -x FILES=$("$FIND" "$TMPCLONE" -maxdepth 1 -mindepth 1 -not -name ".hg" -exec cygpath -d \{} \;)
   #"$IMPORT" $OPTIONS -c "$COMMENT" $FILES "$(cygpath -m $TARGET/$project)" | egrep -v "$IGNORE"

   # Check that we have the correct top-level members
   # This is important because ClearCase can't notice if we remove top-level members
   "$FIND" "$TMPCLONE" -maxdepth 1 -mindepth 1 -not -name ".hg" -not -name "target" -printf "%f\n" | sort > "$TMPSOURCE"
   "$FIND" "$TARGET/$project" -maxdepth 1 -mindepth 1 -not -name ".hg" -not -name "target" -printf "%f\n" | sort > "$TMPTARGET"
   diff -q "$TMPSOURCE" "$TMPTARGET" > /dev/null
   if [[ $? != 0 ]]
   then
      print "Warning: some top-level elements differ in source and target"
      print "You may need to remove obsolete top-level members by hand:"
      diff -Naur "${TMPSOURCE}" "${TMPTARGET}"
   else
      # Check that the two repositories are indeed equivalent
      if [[ $(diff --exclude=.hg -Naur "$TMPCLONE" "$TARGET/$project" | wc -l) != 0 ]]
      then
         print "Error: recursive diff yielded inconsistencies between Mercurial and ClearCase!"
         print "To compare differences, make your own clone of $project and use 'diff --exclude=.hg -Naur'."
      fi
   fi

   # Clean up our temp files
   rm -f "${TMPSOURCE}" "${TMPTARGET}"
   rm -rf "${TMPCLONE}"
done