Why is this change being made?

Mentioned in #95, script execution time can be slow. For R packages, the utility included LinkingTo packages when resolving dependencies for binary packages. Consequentially, LinkingTo packages (i.e. BH and Rcpp where many header files exist) can have large files counts, which contribute to longer execution times. Longer because there many more files which need permissions applied when SQL Server uses the launchpad service to instantiate an external script session contained in an AppContainer.

• launchpad: Microsoft Docs
• App Container Isolation Process: Microsoft Docs

What does this change do?

When the utility calculates package dependencies, it gets type-specific URL paths (binary and source) to the configured CRAN repos and compiles a list of available packages to install. The available binary and source package lists are combined into one list and are now joined such that the binary package is kept when a package exists as an entry in both the binary and source lists.

• This is achieved by making binaryPackages the first argument in rbind(binaryPackages, sourcePackages) so that when the duplicated() function runs on the combined list, the first instance of a duplicate (top to bottom) is removed.
  • rbind() reference
  • duplicated() reference

The above change is sufficient in isolation if a user only asks for one package to be installed via sql_install.packages(). Now, the utility will iterate over each package requested and properly resolve dependencies (whether to include LinkingTo package dependencies) based on whether the desired package is available as binary, or only as source.

The function tools::package_dependencies() reference argument which includes the LinkingTo packages in the dependency calculation by default (RDocumentation). The utility now determines whether a package is available as source or binary, and populates the which argument accordingly.

• Binary: which = c("Depends", "Imports")
• Source: which = c("Depends", "Imports", "LinkingTo")

How is this change tested?

Two tests are added to validate only the appropriate packages are installed.

1. Binary Package install with LinkingTo dependency ensures no LinkingTo packages are installed if the package has an available binary.
2. Source Package install with LinkingTo dependency ensures the LinkingTo package dependencies are resolved and are made available for reference when a package is built from source.