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.

I've been refining the shell script shown below for a few years now. 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.

To push code into ClearCase takes two steps. First, I clone my working repository into /home/pronovic/mercurial/MyProject. Then, I run the script below. The script takes /home/pronovic/mercurial/MyProject and pushes it into /vobs/ken/MyProject. Mercurial is the source, and the import process adds and removes files as necessary to make the vob target match the Mercurial source.

You'll find that clearfsimport is kind of clunky. The arguments are not really "source" and "target". They're more like "source" and "target directory". So, you really tell it: "please import /home/pronovic/mercurial/MyProject into /vobs/ken" and that ends up creating or modifying /vobs/ken/MyProject.

-- KennethPronovici

# Sync configuration
typeset -x MERCURIALDIR="/home/pronovic/mercurial"
typeset -x VOBDIR="/vobs/ken"
typeset -x SOURCE="${MERCURIALDIR}/MyProject"
typeset -x TARGET="${VOBDIR}/MyProject"
typeset -x COMMENT="$1"

# Script configuration
typeset -x IMPORT="/usr/atria/bin/clearfsimport"
typeset -x STANDARD_OPTIONS="-nsetevent -recurse -rmname"
typeset -x PREVIEW_OPTION="-preview"

# Handle commend line
if [[ $# -eq 1 ]]
then
   typeset -x PREVIEW="false"
   typeset -x COMMENT="$1"
   typeset -x OPTIONS="$STANDARD_OPTIONS"
elif [[ $# -eq 2 ]]
then
   if [[ "$1" != "--preview" ]]
   then
      print "Usage: sync-mercurial [--preview] comment"
      print "Syncs $SOURCE into $VOBDIR"
      exit 1
   fi

   print "*** Operating in preview mode..."

   typeset -x PREVIEW="true"
   typeset -x COMMENT="$2"
   typeset -x OPTIONS="$STANDARD_OPTIONS $PREVIEW_OPTION"
else
   print "Usage: sync-mercurial [--preview] comment"
   print "Syncs $SOURCE into $VOBDIR"
   exit 1
fi

# Invoke clearfsimport to get things into ClearCase
"$IMPORT" $OPTIONS -c "$COMMENT" "$SOURCE" "$VOBDIR" 

# Check that the two repositories are indeed equivalent
if [[ "$PREVIEW" != "true" ]]
then
   if [[ $(diff -Naur "$SOURCE" "$TARGET" | wc -l) -ne 0 ]]
   then
      print "Error: recursive diff yielded inconsistencies between source and target!"
      print "To compare, use 'diff -Naur $SOURCE $TARGET"
   fi
fi