One question that arises at this point - what happens if there's a conflict? If two people submit merge requests, the second could conflict with the first. Obviously the patch queue manager is not an AI; it can't automatically resolve all conflicts. So the simple solution is to just to inform the submitter of the second patch of this fact, and reject the merge request. They can then sync up their tree with the main branch, and resubmit the merge request.

However, textual conflicts aren't the only kind of conflict; you could also have _semantic_ conflicts, where the patches don't touch the exact same portion of code, but taken together they break it. One way to help solve this problem is to run a testsuite before every commit to the main archive. The tla patch queue manager lets you do this with a precommit hook. You can actually do pretty much anything you want inside this hook.

You have two choices for submitting merge requests; one option is to send them via email. arch-pqm supports GPG-signed messages for security.

If it can be arranged for developers to all have write access to the same filesystem (via NFS/SFS, over sftp, etc), then you can have them simply drop merge requests into a special queue directory.

The commands in this section will be easier if we record in a little file which archive is the "upstream". It is recommended you do something like this:

$ echo 'example-dev@example.com'/$(tla parse-package-name --non-arch $(tla tree-version)) > {arch}/+upstream

If you can provide all of the developers with write access to the same filesystem, then you can simply have them place merge request files in the queue directory, using a small shell script such as this:

#!/bin/sh (echo "From: $(tla my-id)"; echo "Subject: $1"; echo; echo
star-merge "$(tla tree-version)" "$(cat {arch}/+upstream)") >
/usr/src/arch-pqm/patch.$(date +%s)
    

Save that as tla-submit-merge. Then you would use this script by saying:

$ tla-submit-merge 'fix lots of bugs'

In the future, we would like to have better support integrated in tla for this kind of thing.

If your site is widely distributed, or giving shell accounts to all developers doesn't work well, you can also use GNUPG-signed email. Here's how you could modify the script above:

#!/bin/sh
echo star-merge "$(tla tree-version)" "$(cat {arch}/+upstream)" | gpg --clearsign | mail -s "$1" "$2"

You might use the above script by saying:

$ tla-submit-merge 'fix bugs' pqm@example.com 	

In order to process requests sent by email, you will likely want to use procmail. If you have an account dedicated to processing merge requests (a good idea), you could use this sample .procmailrc entry:

:0:
| arch-pqm --read
    

If you don't have a dedicated account, you will have to pick a specific Subject: or other header to use to differentiate merge requests from your regular email.

The key command is:

$ arch-pqm --run
      

That simply iterates through the pending merge requests in order (by mtime), and processes them. A good way to use this would be to run it via a cron job.