[wildfly-dev] Handling history with the build split

[Stuart Douglas]

Hi all,

So something we have been thinking about is how best to handle history 
when doing the split, there were three obvious options that we looked at:

1) Copy the repo for each split, and just delete what is no longer needed.

This means that you have full history, however each repo is 130Mb+, so 
once you have 4 or more repos you are looking at a very large amount of 
data to checkout a full WF server, which will probably put off potential 
contributors.

2) Clean break

Copy the files into a core repo, and just have a clean break, which 
means that if you want to view history you will need to refer to the 
original WF repo, which is not great (I know I use history and git 
annotate a lot). This also means that it looks like the whole server was 
added by one person in a single commit, which is not great.

3) git filter-branch

We use the filer branch command to filter out all non-relevant history. 
This means most history is intact, however you do loose the full context 
of the commit if it modified subsystems that have been moved into 
separate repos.

It looks like it should be possible to append the old commit sha to the 
message on a new line, which will make it easy to look up the old commit 
if you need to see the full context.



The interesting thing is that options 2) and 3) can also be used with a 
little known command called 'git replace' (which is basically a 
replacement for grafts), to basically graft the full history over the 
top of the truncated/rewritten history. Basically if you care about the 
full history you will be able to run a script, and it will graft the 
complete WF history into your repo, so any command that works with 
history will show each commit in its entirety.

I think we should use option 3) combined with 'git replace'. This means 
that the repo will be much smaller, and contain a rewritten version of 
history that should be enough for most people. If anyone needs a full 
history (e.g. when doing backporting) all that will be required is 
running a simple script to replace the fake history with the real thing.

Comments?

Stuart