Incremental builds

[Indhu <in...@gmail.com>]

Hi,

We all have the experience of making a small change in a PR and waiting for
a couple of hours or more for the continuous integration builds to finish.
This is because at the moment, all builds (even if it only fixes a typo in
a comment) is built from scratch as a clean build. I was wondering if we
can do incremental builds instead for changes to PRs. So, a clean build
will still happen when a PR is submitted for the first time. But every time
a change is made to the PR, we should be able to do an incremental build
from the previous build that was done for that PR. This will drastically
reduce the waiting time for developers.

I have an idea to do this which involves creating a separate directory in
jenkins slaves for each PR and doing the build for that PR under its own
directory. These directories can be created in EFS and they can be deleted
when the PR is closed. I'm wondering if there is a better/easier way to do
this. Please let me know if you know of any.

Thanks,
Indu