Splitting out multiple intermediate changes in Mercurial - mercurial

We have a very unfortunate situation where a new feature branch was made from a second, unrelated feature branch that had been put on hold rather than from default. There's multiple changesets within both feature branches and while most changed files are unrelated several high level project files that have edits on both branches. Default has also had several updates and merges during this time too. Thankfully the intermediate feature hasn't been updated concurrently with the new feature. I've looked into various commands and options available and lost how to best fix this situation. The tree currently looks roughly like:
Default -- Various edits and merges -- tip
\
\-- Named Branch 1 (15 changes) -- Named Branch 2 (30 edits)
I want to get to a point where default has the changes from Named Branch 2 but none from Named Branch 1. I also want a branch that has the changes from Named Branch 1 available for when we return to this feature.
I suspect there's no nice easy way to do this, and there's going to be some messy parts in the history, however I am at a loss at how to start going about this task.

hg graft can cherry-pick changesets from one branch to another. Update to the destination branch, then graft the revisions you want to copy by running, for example:
hg graft 8 9 10
Conflicts will be handled using the normal merge process.
If you use TortoiseHg, select the changesets to graft to the current selected changeset, then right-click and select Graft Selected to local...:
Result:

Since you want to move the entire branch 2, you could consider using rebase. Make a clone of the repository and try this:
hg rebase --source <first branch2 rev> --dest <new parent in default> --keepbranches
This will in principle transform the history to what it should have been. However:
You may have to resolve conflicts arising when <first branch2 ver> gets moved to a new parent.
Since rebase rewrites history, you'll have to get everyone to cooperate in synchronizing their repositories. Whether that's feasible or worth the trouble in your case I can't say, but it's not that difficult: Assuming everyone has pushed any changes in branch 2, they can pull the new history and then get rid of the obsolete version of branch 2 with hg strip:
hg strip <first branch2 rev>

Related

Create new mercurial repository cloning SINCE revision

I have a HUGE mercurial repository.
Cloning and some operations are starting to be slow.
I would like to get rid of old commits, but keep the history of revisions since a specific date.
Is there any way to keep the commits SINCE a specific commit on a single branch, and collapse all the older parent commits in a single one?
R1 -> R2 ->R3 ->R4 ->R5 -> R6 -> R7 ->R8 ->Tip
[R1-5] ->R6 ->R7 ->R8 ->Tip
I tried to do such thing using GRAFT, but it did not work (maybe I don't now how to do it properly).
Optional: Is there such an option on Sourcetree?
You cannot clone it to achieve this. But you have basically two options:
history rewrite using histedit (it's an default extension, but needs enabling)
It gives you the option to fold commits, that is combine several one to a single.
convert (which in essence is also a history rewrite)
This gives you the chance to create a new repository with only the selected commits and branches. Thus you can simply leave out the first 4 commits and start with the 5th.
For each also checkout the help shipped with mercurial (hg help histedit, hg help convert).

Is there a way to set a custom base version when merging with Mercurial?

I'm confronted with a Mercurial repository that has originally been a CVS repository. It has recently been migrated to Mercurial with cvs2hg.
The CVS repository had a couple of branches, lets call two of them "main" and "feature". "feature" has been branched off "main" a very long time ago. Between the branches, changes have frequently been "merged" by checking in changes committed in one branch into the other. There are frequently tagged "merge" revisions where "main" and "feature" have been equal.
When I try to do the first (real) merge in Mercurial, the three-way merge assumes that the "base" version is the revision when "feature" was originally branched off. This means that there is a lot of visual cluster with conflicts where "main" and "feature" are almost equivalent to each other but very different to the "base" version. This is so bad that the merge would take a very long time and would be error prone.
I'm wondering if there is a way to tell Mercurial that the base version is one of the tagged "merge" revisions, e.g.
hg up feature;
hg merge main --base "tag-xyz"
In this case, the merge would be easy.
I would recommend fixing your recent history. This is somewhat messy, but once finished, Mercurial's merges should work correctly out of the box.
First, find the most recent point at which the feature and main branches were exactly the same. Merge the equivalent commits (merge main into feature). This should create a new head with two parents (one from feature, one from main). Furthermore, that head should be on the feature branch, not the main branch. Since the commits are exactly the same, you should not experience conflicts. Next, you will need to rebase the rest of the feature branch onto this head.
Suppose the new head is commit abc. Again, this head has two parents, one of which is on the feature branch. That feature parent has a second child, which is also on the feature branch. Suppose that second child is commit def. Then you can perform the rebase as follows:
hg phase -f -d 'def::' # Unnecessary if you've never pushed
hg rebase -s def -d abc
This will change the commit numbers for def and all its descendants. If you have multiple instances of the repository, they will need to undergo this same fixup, or you will need to re-clone them. Otherwise, your repositories will get very messy when people push and pull.
Once you've done this, merging should "just work."

how to undo a commit pull

I faced today my first mercurial problem. I was in my repo, I modified a file and I did a
hg commit
hg pull
followed by
hg update
hg rollback
to repair what I've done, (but actually I didn't push anything)
The problem is that when I did the pull (that I should do before the commit, the head changed and so hg heads looks like :
- Modif from yesterday
- My modif
- Modif from last week
and now I see that someone also did another modification (via the http interface). What should I do to repair my local repo, (if possible modifying my summary) and push it after the 2 others modifications.
Thanks a lot. Quiet confusing, was easier on my "one-man" repo..
Your local repo doesn't need "repairing". This is a very standard case that you will see often if you use Mercurial a lot.
The issue is multiple heads.
You can either merge your heads, assuming your working directory is your version and there is only the other head:
hg merge
This will result in a merge changeset (same as if you were merging across branches).
Or you can enable the rebase extension to re-base your version onto the tip of the branch (the other head):
hg rebase --source<YourVersionNumber> --dest<TipVersionNumber>
This will not result in a merge changeset, and will simply transplant your changes on top of the changeset you specify as if they were born of that changeset all along (hence rebase or "new"basing).
Multiple heads is a funny sort of inner-branch branching... you can continue checking stuff in against your own head and change between heads using hg update. We block multiple heads per branch on our server, so our push would fail. I'd advise keeping multiple heads local as they are less clear-cut than branches.
I tend to work with Mercurial in one of two ways:
If the work is large in scale I will branch it off and follow Continuous Integration practices (constantly merging the main branch into my own etc). I then re-merge back into main when I am happy with the end result.
If the work is small in scale I will simply work against main branch and "merge" heads every so often. I say "merge" as I usually use rebase. Re-basing works great if the changes are simple and conflicts are unlikely.
My hard and fast rule: if I can't use rebase I put it on a branch born of main.

How can I create a branch for a non-tip revision in Mercurial?

In my repo, I have the revisions 1 to 10. I've pushed up to 5 (so the next hg push would publish revisions 6-10).
But I have to interrupt my work now and the result isn't 100% complete. So I'd like to move the revisions 6-10 into a new "experimental" branch to allow someone else to complete the work without disrupting the sources for everyone.
How can I add a branch to a non-tip revision (in my case: Starting with revision 6)? Or should I use a completely different approach?
You cannot apply a branch name after the fact without modifying your history.
The most simple approach is to ask the other users to use revision 5 as the parent for any changes they create. For example, the other users would:
hg clone <your repo> or even hg clone --rev 5
hg update -r 5
work, work, work
hg commit
When they commit a change, it will create a second head on the default branch, but that should not create any problems. You will simply need to merge the two heads together once your experimental changes are complete.
That being said, moving your changesets onto a branch can be accomplished using Mercurial Queues (MQ). The following sequence shows how it be done:
hg qinit (Create a new patch queue)
hg qimport --rev 6:10 (import r6-10 into a new patch queue)
hg qpop -a (remove all patches from your working copy)
hg branch <branch name> (create your new experimental branch)
hg qpush -a (apply all the patches to your branch)
hg qfinish -a (convert all patches to permanent changesets)
Tim already has good suggestions. Additionally you could push your experimental changes into a distinct experimental clone on your central server (I guess you use one). This clone could also be used by other developers to push their not-yet-finished work in order to let others review or continue it. It is also clear that this clone's code is not ready to be used. Once some task is finished, the corresponding changesets can be pushed to the stable repository.
Actually named branches are a good idea for your case, but the fact that their names are burned into history mostly is more a problem than a feature. IMHO Git's branch names are more practically. However, to some extend you could also handle your case with bookmarks, which are pushable since Mercurial 1.7 (not sure here). That is you bookmark revision 5 with something like stable (or whatever you agree on in your team) and revision 10 gets bookmarked with something like Aarons-not-finished-work. The other developers would then just pull stable, except your colleague who is supposed to continue your work, who would pull the other bookmark. However, personally I did not use a such workflow yet, so I cannot say if it performs well in practice.

Mercurial push problem

I've just got a problem with hg push command. What I did - Firstly I created 2 branches hot-fix-1 and hot-fix-2 made some changes in each branche, merged it back to default and closed those branches with the command:
hg commit --close-branch
If I start hg branches I have the following output:
default 29:e62a2c57b17c
hg branches -c gives me:
default 29:e62a2c57b17c
hot-fix-2 27:42f7bf715392 (closed)
hot-fix-1 26:dd98f50934b0 (closed)
Thus hot-fix-* branches seems to be closed. However if I try to push the changes I have the next error message:
pushing to /Users/user1/projects/mercurial/mytag
searching for changes
abort: push creates new remote branches: hot-fix-1, hot-fix-2!
(use 'hg push --new-branch' to create new remote branches)
and it does not matter which command I use hg push -b . or hg push -b default
So the question is how I can push those changes to repository without creating new branches.
P.S I used to work with git and was hoping that similar branching model can be used in Mercurial. Thanks
First, as many others have pointed out, using a named branch for short lived work is not a recommended practice. Named branches are predominantly for long lived features, or for release management.
Given that you are in this situation, there are a few options available. All of them involve modifying history (as you're obviously trying to change something you've done).
One is to just push the branches as is, learn from the experience, and move on. If the rest of the team is fine with this, then it's a case of adding --new-branch to your push command.
If the rest of the team, or you, really want the history to be clean, then you'll need to dig deeper.
If you aren't pushing, then definitely make a clone of your current repo. This way you have a copy of the original work to fall back on.
I see 2 main approaches here. Strip off the merges and rebase your branches onto default. This will get rid of the named branches or graft/transplant your changes. Both will be the same end result, but the implementation is slightly different.
If you merely want to use graft, that is now a built-in function starting with HG 2.0. It replaces the transplant plugin, and is much nicer to work with as it uses your usual merge tool if there are conflicts.
To use it, update to the default branch. Then, use the command:
hg graft -D "2085::2093 and not 2091"
the string after -D is an hg revision selection query. In your case, you'd likely only need '{start}::{end}' where start is the changeset at the start of the branch, and end is the end changeset of the branch (ignoring the merge).
If you did several merges, you'd have to pick and choose the changesets more precisely.
The other option is to strip the final merges, and use the rebase command that is part of the mq plugin.
You'll have to strip your merge changesets to get rid of them, and then update to the tip of the branch you want to keep. Select the start of the first named branch, and do a rebase. This will change the parentage of the branch (if you're familiar with Git, then this is very much like it's rebase).
Then repeat for the second branch. You should now have one long branch with the name default.
Just do the:
hg push --new-branch
It will send over those branches, but they'll be closed on the receiving end too, so no one should be bothered.
See my comment on the question for why Named Branches are best saved for long-lived entities like 'stable' and anonymous branches, bookmarks, or clones are more suitable for short lived things like hot-fixes and new features.
Your hot-fix changes were made on branches. Regardless of whether the branch is active or closed, it does exist.
To push the changes to the server (without rewriting history), you must use the --new-branch option (e.g. hg push --new-branch`).
Since you merged the branches into default, there will still only be one head (as you have already seen in your local repo).
If you really can't live with pushing the branches to the server, then you must rewrite your local history as suggested in Mikezx6r's answer.
In addition to the methods he mentioned, you can also import the changesets into a patch queue and apply them to the tip of your default.