Proposal: Support offline build

[takumin]

Proposal: Support offline build

[takumin]

It's trivial, but I think you need to mention in the README that you also need to get the git submodule.
(Mainly for beginners)

[masnagam]

OK. I can create a PR for this issue, but it may take some time to complete. Currently, I'm focusing on another project.

If you have a time, you can try to create a PR.

[takumin]

OK! I will create a PR.
Please give me a little time 🙏

[masnagam]

Updating third party modules is automated:
https://github.com/mirakc/mirakc-arib/blob/main/.github/workflows/daily.yml

I'll modify related scripts and settings after I merge your PR. So, you don't need to take care about that. Of course, you can try to modify them if you have a time.

[masnagam]

No problem. Thank you so much for your help!

[takumin]

@masnagam
I have created a PR for offline builds.
The daily GitHub Actions have also changed.
Thank you for your review!

[takumin]

I'm sorry, I forgot some important changes, so I fixed the issue.

[masnagam]

Thank you for your proposal.

We selected the git download method instead of the url download method so that we can easily make a patch for an external project when we need to modify it. So, we'd like to keep using the git download method even if we support the url download method.

Solution 1

One of simple solutions is using two ExternalProject_Adds like below:

if(MIRAKC_ARIB_USE_URL_DOWNLOAD)
  ExternalProject_Add(vendor-docopt
    URL ...
  )
else()
  ExternalProject_Add(vendor-docopt
    GIT_REPOSITORY ...
  )
endif()

This solution makes code clones, but works properly.

Solution 2

We may be able to solve your issue with Git submodule + the SOURCE_DIR property of ExternalProject_Add. However, I've never used this property. So, I'm not sure if this works properly.

Solution 3

If you want to download source files of external projects before building, you can run the following command:

cmake -S . -B build -G Ninja -D CMAKE_BUILD_TYPE=Release

# download docopt with the git download method
ninja -C build vendor/src/vendor-docopt-stamp/vendor-docopt-download

We use Ninja in the example above, but similar targets are probably defined in other project files like Makefiles.

There seems be no description about xxx-download targets in the cmake document. So, naming rules of such targets may change in the future.

[masnagam]

I think the solution 2 is better than the others. WDYT?

[masnagam]

Of course, you can propose other solutions.

[takumin]

Thank you for your quick reply!

I think Solution 2 is good!

For reference, the grpc sample project seems to recommend the git submodule.

https://github.com/grpc/grpc/blob/bb1c7fce6c49ccd1df47b4a39a86a856843e42a9/examples/cpp/helloworld/cmake_externalproject/CMakeLists.txt#L30-L32

[takumin]

great!!!
If possible, I would like to modify GitHub Actions, but since the amount of modification of CMakeLists.txt is larger than I expected, please concentrate on the support of Git submodule first. sorry 🙏