inst/developeer-notes.md

In r-lib/crancache: Transparent Caching of Packages from CRAN-Like Repositories

Caching binaries

This is tricky:

• R CMD INSTALL has a --build argument, but that puts the output file in the current working directory, and we might overwrite something there, so we don't want this.
• Working out whether an installation (and a binary build) failed or not, is hard. utils::install.packages does not work us a lot in this respect, because it only gives warnings for failed installs.
• If we get a warning, then something has failed, but it is hard to work out what exactly.
• Even if an installation succeeeds, the user might have used --no-test-load, and then the actual binary might be broken.
• It is hard to work out the packages that were installed. E.g. if the source package is coming from the cache, then it will not be in downloaded_packages.

Even if we don't use --build, but create the binary package archive manually, we need to know which installs fails, because we don not want to package up those.

So here is a plan:

• If the --no-test-load argument is included in INSTALL_opts, then we do not deal with binary packages at all. (Possibly, some other arguments could be treated the same, e.g. --fake.)
• We catch warnings and errors from utils::install.packages. (We also re-throw them.)
• We work out the lib directory where the new packages were installed.
• If we installed from source, then in the library, the file modification dates should be updated. So we check all directories in the library, that have a more recent modification date, than the install_packages invocation, and these will be our candidates to package up.
• If we got warnings, and the name of a package matches the warning (simple matching, stupid, but we want to be conservative), then that package is ignored.
• The chosen packages are packaged up and added to the cache.

r-lib/crancache documentation built on July 27, 2023, 4:55 p.m.