Title: Code Contributions

Slug: code-contributions

All of the Instant Messaging Freedom related projects use

[Review Board](https://reviewboard.org/) for handling contributions at

[reviews.imfreedom.org](https://reviews.imfreedom.org).

There are a few things you'll need to set up to be able to submit a code

review to these projects. This includes installing

[RBTools](https://www.reviewboard.org/downloads/rbtools/)

as well as some additional

[Mercurial](https://www.mercurial-scm.org/)

configuration.

The recommended way to install RBTools is via pip and can be done with the

following command.

pip3 install --user "RBTools>=3.0"

Once RBTools is installed you need to make sure that `rbt` is available on your

`$PATH`. To do this, you may need to add `$HOME/.local/bin` to your `$PATH`.

The exact procedure to do this is dependent on your setup and outside of the

scope of this document.

This configuration for Mercurial is to make your life as a contributor easier.

There a few different ways to configure Mercurial, but these instructions will

update your user specific configuration in `$HOME/.hgrc`.

The first thing we need to do is to install the evolve extension. This

extension makes rewriting history safe and we use it extensively in our

repositories. You can install it with a simple `pip3 install --user hg-evolve`.

We will enable it below with some other bundled extensions, but you can find

more information about it

[here](https://www.mercurial-scm.org/wiki/EvolveExtension).

When working with Mercurial repositories it is very important to make sure that

your username is set properly as it is added to every commit you make. To set

your username you must add it to the `[ui]` section in your `$HOME/.hgrc` like

the following example.

Next we need to make sure that the ***evolve*** and ***rebase*** extensions are

loaded. To do so add the lines in the following example. You do not need to put

anything after the `=` as this will tell Mercurial to look for them in the

default places for extensions.

Next we're going to create a ***revsetalias*** named `wip` which is short for

"Work In Progress". This will be used to make it easier to look at your history

and submit your review request.

This alias will show us just the commits that are on our working branch and not

on the `default` branch. The `default` branch is where all accepted code

contributions go. Optionally, you can add the `wip` command alias below which

will show you the revision history of what you are working on.

There are quite a few other useful configuration changes you can make, and a

few examples can be found below.

Below is all of the above configuration settings to make it easier to

copy/paste.

To be able to submit a review request you need to have an account on our

JetBrains Hub instance at [hub.imfreedom.org](https://hub.imfreedom.org). You

can create an account here in a number of ways and even turn on two factor

authentication. But please note that if you turn on two factor authentication

you will need to create an [application

password](https://www.jetbrains.com/help/hub/application-passwords.html) to be

able to login to Review Board.

Once you have that account you can use it to login our Review Board instance at

[reviews.imfreedom.org](https://reviews.imfreedom.org). Please note, you will

have to login via the web interface before being able to use RBTools.

Once you have an account and have logged into our Review Board site, you can

begin using RBTools. In your shell, navigate to a Mercurial clone of one of the

Instant Messaging Freedom related projects, then run the `rbt login` command.

You should only need to do this once, unless you change your password or have

run the `rbt logout` command.

Before starting a new review request, you should make sure that your

local copy of the repository is up to date. To do so, make sure you are

on the ***default*** branch via `hg update default`. Once you are on the

***default*** branch, you can update your copy with `hg pull --update`. Now

that you're starting with the most recent code, you can proceed with your

contributions.

While it's not mandatory, it is highly recommended that you work on your

contributions via a branch. If you don't go this path, you will have

issues after your review request is merged. This branch name can be

whatever you like as it will not end up in the main repositories, and

you can delete it from your local repository after it is merged. See

[cleanup](#cleanup) for more information.

You can create the branch with the following command:

hg branch my-new-branch-name

Now that you have a branch started, you can go ahead and work like you normally

would, committing your code at logical times, etc. Once you have some work

committed and you are ready to create a new review request, you can type `rbt

post wip` and you should be good to go. This will create a new review request

using all of the committed work in your repository and will output something

like below.

Review request #403 posted.

https://reviews.imfreedom.org/r/403/

https://reviews.imfreedom.org/r/403/diff/

At this point, your review request has been posted, but it is not yet

published. This means no one can review it yet. To do that, you need to go to

the URL that was output from your `rbt post` command and verify that everything

looks correct. If this review request fixes any bugs, please make sure to enter

their numbers in the bugs field on the right. Also, be sure to review the

actual diff yourself to make sure it includes what you intended it to and

nothing extra.

Once you are happy with the review request, you can hit the publish button

which will make the review request public and alert the reviewers of its

creation. Optionally you can pass `--open` to `rbt post` in the future to

automatically open the draft review in your web browser.

`rbt post` has a ton of options, so be sure to check them out with `rbt post

--help`. There are even options to automatically fill out the bugs fixed fields

among other things.

Typically with a code review, you're going to need to make some updates.

However there's also a good chance that your original branching point has

changed as other contributions are accepted. To deal with this you'll need to

rebase your branch on top of the new changes.

Rebasing, as the name suggests is the act of replaying your previous

commits on top of a new base revision. Mercurial makes this pretty easy.

First, make sure you are on your branch with `hg up my-branch-name`. Now you

can preview the rebase with

`hg rebase --dest default --keepbranches --dry-run`. We prefer doing a dry-run

just to make sure there aren't any major surprises. You may run into some

conflicts, but those will have to be fixed regardless.

If everything looks good, you can run the actual rebase with

`hg rebase --dest default --keepbranches`. Again if you run into any conflicts,

you will have to resolve them and they will cause the dry-run to fail. Once you

have fixed the merge conflicts, you'll then need to mark the files as resolved

with `hg resolve --mark filename`. When you have resolved all of the conflicted

files you can continue the rebase with `hg rebase --continue`. You may run into

multiple conflicts, so just repeat until you're done. If you've lost track of

where you are in resolving conflicts you can use `hg resolve --list` to see the

current state.

After rebasing you can start addressing the comments in your review and commit

them. Once they are committed, you can update your existing review request

with `rbt post --update`. If for some reason `rbt` can not figure out the

proper review request to update, you can pass the number in via

`rbt post --review-request-id #`. Note that when using `--review-request-id`

you no longer need to specify `--update`.

Just like an initial `rbt post`, the updated version will be in a draft state

until you publish it. So again, you'll need to visit the URL that was output,

verify everything, and click the publish button.

This will typically only be done by the maintainers with push access. If you

want to test a patch from a review request, please see the

[Testing Patches Locally](#testing-patches-locally) section below.

It is ***HIGHLY*** recommended that you use a separate clone of the repository

in question when you want to land review requests. This makes it much easier

to avoid accidentally pushing development work to the canonical repository

which makes everyone's life easier. Also, the mainline repositories now auto

publish, so if you do not selectively push commits, all of your draft commits

will be published. You can name this additional clone whatever you like, but

using something like `pidgin-clean` is a fairly common practice. This makes it

easy for you to know that this clone is only meant for landing review requests,

and other administrative work like updating the `ChangeLog` and `COPYRIGHT`

files.

When you are ready to land a review request you need to make sure you are on

the proper branch. In most cases this will be the branch named ***default***

and can be verified by running the command `hg branch`. Next you need to make

sure that your local copy is up to date. You can do this by running

`hg pull --update`.

Please note, if you run `hg pull` and then immediately run `hg pull --update`

you will ***not*** update to the most recent commit as this new invocation of

`hg pull` has not actually pulled in any new commits. To properly update,

you'll need to run `hg update` instead.

Once your local copy is up to date you can land the review request with

`rbt land --no-push --review-request-id #` where `#` is the number of the

review request you are landing. The `--no-push` argument is to disable pushing

this commit immediately. Most of our configuration already enables this flag

for you, but if you're in doubt, please use the `--no-push` argument.

Once the review request has been landed, make sure to verify that the revision

history looks correct, run a test build as well as the unit tests, and if

everything looks good, you can continue with the housekeeping before we finally

push the new commits.

The housekeeping we need to do entails a few things. If this is a big new

feature or bug fix, we should be documenting this in the `ChangeLog` file for

the repository. Please follow the existing convention of mentioning the

contributor as well as the issues addressed and the review request number.

Likewise, if this is someone's first contribution you will need to add them to

the `COPYRIGHT` file in the repository as well. If you had to update either of

these files, review your changes and commit them directly.

Now that any updates to `ChangeLog` and `COPYRIGHT` are completed, we can

actually start pushing the changes back to the canonical repository. Currently

not all of the canonical repositories are publishing repositories so we'll need

to manually mark the commits as public. This is easily accomplished with

`hg phase --public`. ***Note***, if you are not using a separate clone of the

canonical repository you will need to specify a revision to avoid publishing

every commit in your repository. If you run into issues or have more questions

about phases see the

[official documentation](https://www.mercurial-scm.org/wiki/Phases).

Now that the changes have been made public, we can finally push to the

canonical repository with `hg push`. Once that is done, you'll also need to go

and mark the review request as ***Submitted*** in the Review Board web

interface.

***Note*** This section is meant for testing patches for existing review

requests. If you are updating a review request, you should be following the

[Updating an existing review request](#updating-an-existing-review-request)

section above.

If you want to test a patch locally for any reason, you first need to make sure

that you are on the target branch for the review request which is listed on the

review request page. In most cases this will be the ***default*** branch.

Regardless you'll need to run `hg up branch-name` before applying the patch.

Now that you are on the correct branch, you can apply the patch with

`rbt patch #` where `#` is the id of the review request you want to test. This

will apply the patch from the review request to your working copy without

committing it.

Once you're done with your testing you can remove the changes with `hg revert

--no-backup --all`. This will return your repository to exactly what it was

before the patch was applied. The `--no-backup` argument says to not save the

changes that you are reverting and the `--all` argument tells Mercurial to

revert all files.

Whether or not your pull request has been accepted, you probably want to clean

it up from your local repository. To do so, you need to update to a branch

other than the branch you built it on. In the following example, we're going to

remove the branch named ***my-new-branch-name*** that we used to create a

review request.

If you review request was merged, you can tell Mercurial the revision that has

become the successor to your revision. You can do this by running

`hg log --graph` to find the land commit's hash. In the example below, we found

a commit has of `abc123`.

hg up default

hg prune --rev 'branch(my-new-branch-name)' --successor abc123

If you just want to remove the branch and not tell Mercurial why it was

deleted, you can just prune the branch entirely without specifying a successor.

hg up default

hg prune --rev 'branch(my-new-branch-name)'

Now, all commits that were on the ***my-new-branch-name*** branch will have

their contents removed but internally Mercurial keeps track that these revisions

have been deleted.

You can repeat this for any other branches you need to clean up, and you're

done!