R – Which version control tool is best suited to handle reflective or cyclic merging? SVN, Git

gitsvnversion control

Reflective/Cyclic Merging

This is easiest to explain with an example. Suppose you are working on a feature branch copied from your trunk. During the development process you regularly merge ''all'' new changes from trunk to your branch so that the branch stays in "synch" with the work occurring on trunk. When you eventually merge your branch back to trunk, that is called a reflective (or cyclic) merge.

Refer to Subversion merge reintegrate article on http://blogs.open.collab.net/svn/2008/07/subversion-merg.html for more details.
You can also refer to http://jugalps.wordpress.com/2009/07/31/svn-branching-and-merging-in-scrum/ to get an overview of a typical reflective merge process.
My personal experience with SVN is not good enough when dealing with such kind of scenarios.

Does any one have experience working with any other version control tool apart from SVN for reflective merging?

Best Answer

Git has always been designed with this ability in mind. It was my first VCS, and to me, this type of workflow is totally routine. In general, the merge (a push or requested pull) back to origin ("trunk") is trivial, since by regularly merging from origin, you have ensured that your HEAD (branch tip) has origin's HEAD in its past, so when origin merges your work, it merely has to move forward through the history, rather than actually perform a merge (git calls this a "fast forward").

Git's rebase capability can also be used to make the history even prettier. If you adopt this workflow, you can always rebase your work on top of whatever you pull from origin, rather than merging them. (This is rewriting history so you have to be sure not to do it with anything already published) That way, all of your merges from origin are fast forwards, and your work is just a single sequence of commits on top of origin's HEAD. This makes the history more direct - hopefully a straight line, instead of a series of lots of merges.

Now you want to commit onto the SVN server

[Eventually] stash the modifications you don't want to see committed on the SVN server (often you commented some code in the main file just because you want to accelerate the compilation and focus on a given feature)
```
(work)$> git stash
```
rebase the master branch with the SVN repository (to update from the SVN server)
```
(work)$> git checkout master
(master)$> git svn rebase
```

go back to the work branch and rebase with master

(master)$> git checkout work
(work)$> git rebase master

Ensure everything is fine using, for instance:

(work)$> git log --graph --oneline --decorate

Now it's time to merge all three commits from the "work" branch into "master" using this wonderful --no-ff option
```
(work)$> git checkout master
(master)$> git merge --no-ff work
```

You can notice the status of the logs:

(master)$> git log --graph --oneline --decorate
* 56a779b (work, master) Merge branch 'work'
|\  
| * af6f7ae msg 3
| * 8750643 msg 2
| * 08464ae msg 1
|/  
* 21e20fa (git-svn) last svn commit

Now you probably want to edit (amend) the last commit for your SVN dudes (otherwise they will only see a single commit with the message "Merge branch 'work'"
```
(master)$> git commit --amend
```
Finally commit on the SVN server
```
(master)$> git svn dcommit
```
Go back to work and eventually recover your stashed files:
```
(master)$> git checkout work
(work)$> git stash pop
```

Using TortoiseSVN how to merge changes from the trunk to a branch and vice versa

I couldn't properly follow the other answers, here's more of a dummies guide...

You can do this either way round to go trunk -> branch or branch -> trunk. I always first do trunk -> branch fix any conflicts there and then merge branch -> trunk.

Merge trunk into a branch / tag

Checkout the branch / tag
Right-click on the root of the branch | Tortoise SVN | Merge ...
Merge Type: Merge a range of revisions | Click 'Next'
Merge revision range: Select the URL of the trunk directory that you copied to the branch / tag. Enter the revisions to merge or leave the field empty to merge all revisions | click 'Next'
Merge options: I just left these as default | click 'Merge'
This will merge the revisions into the checked out branch / tag
Then commit the merged changes to the branch / tag

Best Answer

Related Solutions

Git – Is git-svn dcommit after merging in git dangerous

Now you want to commit onto the SVN server

Using TortoiseSVN how to merge changes from the trunk to a branch and vice versa

Merge trunk into a branch / tag

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