Given the Keys to Merge

Today we were told that the Dev on Production Support will be responsible for merging branches. Branching here is a little different than I’m used to. Usually, there is a trunk, main, or master branch that acts as the root that release or feature branches are branched off of. Here release branching is not done from trunk, but a previous branch. So, if we are currently working on release 5.0 and need to start on release 5.1, an new branch will be created off of the 5.0 branch. If there is concurrent development in both branches then the new 5.1 branch needs to be kept in synch with the 5.0 branch, so we merge the 5.0 changes to the 5.1 branch. I am not sure how or even if we merge everything back to trunk or even if we use trunk.

With this scheme when there is a stockpile of changes it is difficult to reconcile all of the potential merge conflicts. If there was a change to the same file of the branches being merged, the merge can get a little hairy trying to reconcile everything. It was decided to merge more often so you don’t have to face a mountain of merge issues. The Production Support Dev will merge branches preferably daily. Since we all rotate Production Support duties, that means the entire team has the keys to merges.

My little brain always has questions and my thought was why don’t we just merge when we have a change complete. If you make a change in a branch, you should issue a merge request to the team (ala Git, even thought we are an SVN shop). A merge request is simply a message to the team asking them to code review the change. If the change passes coded review, the Dev can merge changes related branches. Well it seems that merging is time consuming in our environment. I haven’t done it yet, but our tech lead said that we could merge our own changes if we have time. I assume that this means that under the pressure to get the release complete there is usually no time to merge. I will try it myself and record the time, if I have time :). Although, my production code dev days are limited, so I won’t have a chance to get a lot of opportunities to put it to the test.

Main Line Development

At my previous employer we did main line development. This basically means we developed directly in main (i.e. trunk). Main wasn’t stable and always had the latest changes of the next release. When we deployed a release we would cut a release tag off of the commit in main that was deployed to production. There would always be a tag that contains the currently deployed code.

Any branching outside of the tag release branching was frowned upon and were asked to limit branching (e.g. you better not branch) because merging was thought to be evil. So, we didn’t do concurrent development on multiple releases. The focus was entirely on the current release. When the release was QA validated, we’d cut the release branch and move on to the next release. This meant that as the release slowly came to a close we were sometimes left twiddling our thumbs while we waited on QA validation and release branching.

If we need to do a production hotfix, we would cut branch off of the current production release tag, make the fix, QA validate it, cut a new release tag, merge changes to main.

It was a very clean process, but I remember having a strong desire to cut feature branches so I could work on the next thing.

Feature Toggles

Which bring up Feature Toggles/Flags. Feature Toggles would allow us to get the best of both worlds. Basically, you add a bit of code to indicate if a particular change is active. In fact the active state can be set in configuration, so IT Operations could actually enable and disable new features and changes with a simple config change. With Feature Toggles we get to do main line and concurrent development at the same time. I have only heard of Feature Toggles in the context of other development stacks like Java. I wonder if there are any .Net shops out there successfully using Feature Toggles?

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