> > CMake notices the downloaded tarball is up-to-date and > doesn't download it again, but it still extracts it again
>From what I can tell, the 'check|download tarball' and 'extract tarball' commands are independent parts of the "download step": as long as the download step runs at all, it will re-extract the tarball, even if it skipped re-downloading. So the issue (design questions aside) is what triggers the download step. The minimal dependency for that step looks like "LIBNAME-gitinfo.txt" file somewhere in the stamp directory, so you could check the mtime preservation there. I don't know if there are other dependencies added for the download target added separately. On Wed, Sep 5, 2018 at 8:06 AM Antoine Pitrou <anto...@python.org> wrote: > > Hello, > > On our project (Apache Arrow - https://arrow.apache.org/) we're using > CMake for the C++ source tree and have many external dependencies > fetched using ExternalProject. In turn building those dependencies can > make up a significant portion of build times on CI services, especially > AppVeyor. So I've been looking for a solution to cache those > third-party builds from one CI run to the other. > > Right now, what I'm trying to do is to set EP_BASE to a well-known base > directory and ask AppVeyor to cache and restore that directory in each > new build. The AppVeyor caching seems to work fine (the EP_BASE > directory is saved and restored). However, it seems that nevertheless > CMake will rebuild all those projects again, despite the cached build > results. > > This is with CMake 3.12.1 on Windows. > > Here is the log for an example build step, here the zstd library: > > https://ci.appveyor.com/project/pitrou/arrow/build/1.0.700/job/i4tj6tifp4xq1mjn?fullLog=true#L803 > > As you can see, CMake notices the downloaded tarball is up-to-date and > doesn't download it again, but it still extracts it again (why?) and > builds the source code anew. Yet the entire EP_BASE directory (here > "C:/Users/appveyor/arrow-externals") is cached and restored by AppVeyor. > > Did someone manage to make this work, and/or is there another solution? > > Thank you > > Regards > > Antoine. > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > https://cmake.org/mailman/listinfo/cmake >
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