vtk-m/vtkm/thirdparty/UPDATING.md

Updating Third Party Projects

When updating a third party project, any changes to the imported project itself (e.g., the diy/vtkmdiy directory for diy), should go through the update.sh framework. This framework ensures that all patches to the third party projects are tracked externally and available for (preferably) upstream or other projects also embedding the library.

Updating a Project

Once converted, a project should be updated by applying patches to the repository specified in its update.sh script. Once the changes are merged, pulling the changes involves running the update.sh script. This will update the local copy of the project to the version specified in update.sh (usually a for/foo branch, like for/vtk-m for example, but may be master or any other Git reference) and merge it into the main tree.

This requires a Git 2.5 or higher due the worktree tool being used to simplify the availability of the commits to the main checkout.

Here's an example of updating the diy project from tag v2.0 to v2.1, starting with updating the third-party repo

$ cd diy
$ git checkout for/vtk-m
$ git fetch origin
$ git rebase --onto v2.1 v2.0
$ git push

Now import into VTK-m

$ cd vtkm/ThirdParty/diy
$ git checkout -b update_diy
$ ./update.sh

Now you can review the change and make a merge request from the branch as normal.

Porting a Project

When converting a project, if there are any local patches, a project should be created on GitLab to track it. If the upstream project does not use Git, it should be imported into Git (there may be existing conversions available on Github already). The project's description should indicate where the source repository lives.

Once a mirror of the project is created, a branch named for/foo should be created where patches for the foo project will be applied (i.e., for/vtk-m for VTK-m's patches to the project). Usually, changes to the build system, the source code for mangling, the addition of .gitattributes files, and other changes belong here. Functional changes should be submitted upstream (but may still be tracked so that they may be used).

The basic steps to import a project diy based on the tag v2.0 looks like this:

$ git clone https://github.com/diatomic/diy.git
$ cd diy/
$ git remote add kitware git@gitlab.kitware.com:third-party/diy.git
$ git push -u kitware
$ git push -u kitware --tags
$ git checkout v2.0
$ git checkout -b for/vtk-m
$ git push --set-upstream kitware for/vtk-m

Making the initial import involves filling out the project's update.sh script in its directory. The update-common.sh script describes what is necessary, but in a nutshell, it is basically metadata such as the name of the project and where it goes in the importing project.

The most important bit is the extract_source function which should subset the repository. If all that needs to be done is to extract the files given in the paths variable (described in the update-common.sh script), the git_archive function may be used if the git archive tool generates a suitable subset.

Make sure update.sh is executable before commit. On Unix, run:

  $ chmod u+x update.sh && git add -u update.sh

On Windows, run:

  $ git update-index --chmod=+x update.sh

Process

The basic process involves a second branch where the third party project's changes are tracked. This branch has a commit for each time it has been updated and is stripped to only contain the relevant parts (no unit tests, documentation, etc.). This branch is then merged into the main branch as a subdirectory using the subtree merge strategy.

Initial conversions will require a manual push by the maintainers since the conversion involves a root commit which is not allowed under normal circumstances. Please send an email to the mailing list asking for assistance if necessary.