rebase planning: determining blobs changed by multiple branches

We have 15 branches that are unmerged, but are based on the same published history. They branched off at different points in the history. Each branch is comprised of a single squashed commit (except for master). How can I compare all 15 branches with the tip of master to see which file merges (blobs) they have in common?

a-------b-------c-------d-------e-------f-------g-------i-------j-------k-------l
|           |            |           |           |                      | 
|          |           |---k1
|           |            |           |           |                      | 
|          |---j1
|           |            |           |           |                      | 
|---i1
|           |            |           |           | 
|---g1
|           |            |           |           |---e1
|           |            |           |           |---e2
|           |            |           |           |---e3
|           |            |           |---d1
|           |            |           |---d2
|           |            |           |---d3
|           |            |---c1
|           |            |---c2
|           |---b1
|           |---b2
|---a1

The goal is to create a sane plan for rebasing. If the question is insane as it is stated, then please advise on any sane ways to approach this besides just rebasing one-by-one and making the last poor branch wait till the end to rebase with a ton of conflicts. I'm dealing with users who refuse to do frequent rebases, so a plan the minimizes rebases while getting the most out of each rebase is desired, if practical.

v/r, Neal

Hi Neal,

I'm not quite sure what you want to do? rebase all branches on top of commit l so that they are up to date?

Why do you want to find common blobs? If the same conflict happens you could use gitrere and reuse a conflict resolution.

git ls-files --with $HASH gives you a list of files

git diff --name-only should give you a nice list of modified files.

So using the intersection of ls-files of branch and tip should give you common files. Substracting changed files using --name-only should yield the files which were not modified. Maybe there are nicer solutions though.

Rebasing is always bad. Have you considered using top-git? This way you can merge with tip and create the rebased patches using the export function.

Marc Weber

On 2/7/2011 6:59 PM, Marc Weber wrote:

Our master represents our new system and we want to have a linear history so we use rebase. Each branch is a project. If a project does not have any merges with other projects then it can rebase with little impact. If projects are changing alot of the same blobs then they will have alot of merged blobs and can be rebased on eachother in throw-away-integration branches. In this way the branches can be grouped into appropriate rebase groups so the merge-conflict resolutions of these groups can be resolved simultaneously in different integration repos. So lets say you have 5 groups, then you can rebase those 5 integration-branches onto master one-by-one instead of doing 15 project branches one-by-one. I thought maybe git had a cool command for analyzing this in one fell swoop.

v/r, Neal