Mark Needham

Thoughts on Software Development

Archive for the ‘mercurial’ tag

Mercurial: hg push to Google Code

with one comment

I wanted to make a change to add flatMap to Option in totallylazy so I had to clone the repository and make the change.

I thought I’d then be able to just push the change using my Google user name and password but instead ended up with the following error:

➜  mhneedham-totally-lazy  hg push
pushing to https://m.h.needham@code.google.com/r/mhneedham-totally-lazy/
searching for changes
1 changesets found
http authorization required
realm: Google Code hg Repository
user: m.h.needham
password: 
abort: HTTP Error 403: Forbidden

It turns out that you need to specifically set an option to use your Google account from the settings page:

Googlecode

And then it works!

Written by Mark Needham

March 14th, 2012 at 9:25 pm

Posted in Version Control

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Mercurial: Only pushing some local changes

with 8 comments

One problem we’ve come across a few times over the last couple of months while using Mercurial is the situation where we want to quickly commit a local change without committing other local changes that we’ve made.

The example we came across today was where we wanted to make a change to the build file as we’d made a mistake in the target that runs on our continuous integration server and hadn’t noticed for a while during which time we’d accumulated other local changes.

The following is a rough diagram of the situation we had:

mercurial.jpg

We had multiple file changes in our working directory which hadn’t yet been checked in to the local repository or the central repository.

We wanted to push just the change in blue.

My initial thought was that I could check in just that one file into our local repository and then push it to the central one.

hg ci -m "mark: updating build file to fix build" -A /path/to/build.file

I then wanted to push that change but when I went to do so I realised that they were other incoming changes which we hadn’t yet integrated with.

In order to integrate with those changes we need to make sure that we don’t have any locally uncommitted changes which of course in this scenario we do since we deliberately chose not to check in some of our local changes.

One way around this would be to just force the push and ignore the need to integrate with the remote changes but that doesn’t seem the right approach to me but I’m not sure what is.

We ended up just checking in everything we had locally, commenting out the bits that we were currently working on, merging with the remote changes and then pushing everything to the remote repository.

That’s obviously a really poor way of solving the problem so I’d be interested in what a good way to solve this problem would be!

Written by Mark Needham

June 25th, 2010 at 11:32 pm

Posted in Version Control

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Git/Mercurial: Pushing regularly

with 4 comments

I was reading a recent blog post by Gabriel Schenker where he discusses how his team is making use of Git and about half way through he says the following:

When using Git as your SCM it is normal to work for quite a while – maybe for a couple of days – in a local branch and without ever pushing the changes to the origin. Usually we only push when a feature is done or a defect is completely resolved.

We’ve been using Mercurial on the project I’m currently working on over the past few months and although it’s a similar tool we’ve been following a different approach.

We’ve got it setup the same way we would setup Subversion:

dscm.gif

We’ve been trying to push to the central repository as frequently as possible, just as we would if we were using Subversion.

I don’t know the Git workflow that well because I haven’t used it on a project yet but we’ve always found that it’s beneficial to integrate with code being written by others on the team as frequently as possible.

Not doing this can lead to the problems which Martin Fowler outlines in his post about feature branches.

We’ve tried to ensure that after every commit the build still passes although we do sometimes have broken versions in the code committed locally because we don’t run our full test suite before every local check in.

Even if a feature isn’t completed I still think it’s valuable to have what we’ve done so far checked in and it also helps remove the problem with needing to backup local repositories:

Since we are going to work locally potentially for days without pushing to the origin (our central repository) we might well loose our work if we have a hard disk crash or our office is flooded. Thus we need some backup strategy.

We just need to make sure the central repository is being backed up and then the danger of losing our work is significantly reduced.

Written by Mark Needham

June 19th, 2010 at 10:14 pm

Posted in Version Control

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hg: Reverting committed changes

with one comment

Continuing with our learning with Mercurial, yesterday we wanted to revert a couple of change sets that we had previously committed and go back to an old version of the code and continue working from there.

As an example, say we wanted to go back to Revision 1 and had the following changes committed:

Revision 3
Revision 2
Revision 1
Revision 0

My original thought was that we could merge revision 1 with the current tip:

hg merge -r 1

Sadly that won’t work because we can’t merge with an ancestor:

'abort: can't merge with ancestor'

I put the question to twitter and got a few different suggestions.

The first was to use ‘revert’ and go back to revision 1 like so:

hg revert -r 1

This works pretty well although my colleague Chris Turner pointed out that we could also use ‘backout’ like so:

hg backout -merge 3
hg backout -merge 2

The neat thing about that approach is that we get 2 changesets checked in showing the reversing of the changes that we previously checked in. We therefore have a better history of what exactly we’re reverted.

With this approach we could also back out changes which weren’t right near the tip of the repository as was the case in my example.

Another alternative is to clone the repository from the revision that we want to keep:

hg clone -r 1

With this approach we would lose the history of anything beyond that revision but if that’s what we want then it’s another approach to achieve our goal!

It’d be interesting to hear your opinions on which approach you take and if there are any others to solve the problem I described.

Written by Mark Needham

April 15th, 2010 at 10:35 pm

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Mercurial: Early thoughts

with 4 comments

We’re using Mercurial as our source control system on the project I’m working on at the moment and since I’ve not yet used a distributed source control system on a team I thought it’d be interesting to note some of my initial thoughts.

One of the neat things about having a local repository and a central one is that you can check in lots of times locally and then push those changes to the central repository when you want everyone else to get the changes that you’ve made.

So far we’ve been pushing much more frequently than would usually be the case using something like Subversion. For example I checked in after doing some tidy up on unused references whereas with Subversion I’d probably have included that as part of another checkin.

It actually makes development more fun and reminds me of a kata I did while checking in almost every minute last year.

We’re all still very much learning Mercurial but these are some of the commands that we’ve found ourselves using a lot so far:

  • To check if there are any changes to pull from the central repository:

    hg incoming
    hg in
  • To check if we have any changes that we haven’t pushed to the central repository:

    hg outgoing
    hg out
  • To add any unversioned files and remove any missing files:

    hg addremove
  • To remove a file from the repository and from the file system:

    hg remove /file/name
  • To remove a file from the repository on the next commit but not remove it from the file system:

    hg forget /file/name
  • To pull any changes from the remote repository and update your repository with them:

    hg pull -u

    This one only completely works if you don’t have any changes locally on the files you’re pulling in. Otherwise you’ll need to do a ‘hg merge’ afterwards.

    It seems like there’s a lot more merging to do when using Mercurial than with Subversion which we’re still getting used to but seems to be more natural as we use Mercurial more.

  • To undo committing a file locally:

    hg rollback
    hg ci -X /file/to/not/commit -m"message and so on"

I’ve found Mercurial: The Definitive Guide by Bryan Sullivan and Joel’s hginit to be useful resources for learning more about this tool.

Written by Mark Needham

April 10th, 2010 at 11:43 am

Posted in Version Control

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Mercurial: hg bisect

with 3 comments

We’ve been using Mercurial locally on the project I’ve been working on and Phil showed me a cool feature called ‘bisect‘ a couple of weeks ago which can be helpful for working out which revision we managed to break our code in.

It’s been ported across from Git and is included in Mercurial from version 1.0.0 rather than just being an extension.

From the bisect extension page:

Its behaviour is fairly simple: it takes a first revision known to be correct (i.e. without the bug) and a last revision known to be bad (i.e. with the bug). The bisect extension ouputs a revision halfway between the good and the bad ones and lets you test it. If this revision is a good one, you mark it as good with hg bisect good, otherwise you mark it as bad with hg bisect bad. In both cases, bisect outputs a new revision to test, halfway between the good and the bad ones. You repeat until only one revision is left: the culprit.

The usage has changed a bit now that it’s included as part of the initial download.

I was working on something yesterday and checking in fairly regularly before realising that I’d broken something.

I was fairly sure that the break had happened in the tip (revision 98) but I could only remember it definitely working in revision 96.

I defined the good and bad revisions like this:

hg bisect -b tip
hg bisect -g 96

In this case revision 97 was now checked out and I checked that the code was working with that revision before marking it:

hg bisect -g

It’s now able to work out that the problem is in fact in revision 98:

The first bad revision is:
changeset:   98:86260809c309
tag:         tip
user:        mneedham
date:        Fri Nov 13 16:31:02 2009 +1100
summary:     seem to have screwed up the graphs. Not sure how

I managed to mess up setting up the good and bad revisions a few times – I somehow had the impression that I needed to manually update to the original good and bad revisions which isn’t the case.

The reset command was my friend before I worked out what I was doing wrong:

hg bisect -r

It seems like a neat little feature. I’m sure there are lots of other cool things like this in Mercurial so if you know any let me know!

* Update *
As Rob points out in the comments the command is ‘bisect’ rather than ‘bisec’ as I had it originally. Both commands work for the moment though!

Written by Mark Needham

November 14th, 2009 at 11:20 am

Posted in Version Control

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Mercurial: Pulling from behind a proxy

with 10 comments

I’ve been playing around with Mercurial and the mercurial hosting website bitbucket a bit this year and recently wanted to pull from a repository from behind a proxy server.

With a bit of help from the mercurial mailing list and the documentation this is how I was able to pull the repository for the Hambread project I’ve been doing a bit of work on:

hg --config http_proxy.host=ipOfYourProxyServer:portOfYourProxyServer --config http_proxy.user=user --config http_proxy.passwd=password pull http://bitbucket.org/markhneedham/hambread

After that command a ‘hg update’ updates your local repository with all the changes that have just been pulled.

What I found strange was that you needed to define the ‘– config’ part of the command three times as far as I can tell in order to pass each of the different properties related to the proxy.

I tried just defining it once and just setting the properties individually but that just produced errors.

Written by Mark Needham

May 13th, 2009 at 7:49 am

Posted in Version Control

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