CCache

ccache is useful for Packaging large packages with Incremental builds

with ccache, recompile time can be reduced from many hours to a few minutes

derivation ccache

to enable ccache only for one derivation

add to /etc/nixos/configuration.nix

          nix.extraOptions = ''
            sandbox = false
          '';

run sudo nixos-rebuild switch

now /etc/nix/nix.conf should have sandbox = false

patch the default.nix file

{ stdenv
, ccacheStdenv
# ...
}:

#stdenv.mkDerivation {
ccacheStdenv.mkDerivation {

  preConfigure = ''
    export CCACHE_DIR=/var/cache/ccache
    export CCACHE_UMASK=007
  ''

# ...

add ccacheStdenv to dependencies

run nix-build

system ccache

todo

monitor ccache status

# watch ccache size
sudo watch du -sh /var/cache/ccache

# watch ccache stats
sudo watch ccache --dir /var/cache/ccache --show-stats --verbose