Summary:
See https://github.com/facebook/flipper/issues/230 for a longer
explanation.
It turns out that many of the tasks in `native.gradle` (at least
`prepareGlog` which modifies files inside the source directory, but also
others) cause the cmake cache to invalidate.
Because we run those tasks unconditionally, we need to recompile all our
C++ code even when unmodified.
I fix this by adding a manual cache key to this which simply skips all
the tasks unless an up-to-date `external_cache_revision.txt` is found.
This is a bit hacky, but the alternatives are a) convincing cmake that
these modifications are not recompile-worthy which I have no idea how to
do and which might be impossible to do `mtime` on the files touches, or
b) having fine-grained `onlyIf` rules for every task which can easily
break. This seems the most straight-forward option.
Fixes#230.
Pull Request resolved: https://github.com/facebook/flipper/pull/242
Reviewed By: jknoxville
Differential Revision: D9381340
Pulled By: passy
fbshipit-source-id: a7db55aacac4a29076c29298d6c5b97d8bc91f66
02cf3a90a2