Using ccache when compiling

The ccache application can speed up compilation by caching object file info. Even if you use make clean, and build again, it will pull in already compiled code (assuming no changes).

However, ccache cannot be used reliably with configure. Also, care must be taken when compiling using sudo or su since ccache will cache files under the user account directory, but with the root account permissions. This type of conflict causes unpredictable results!

Set up Environment variables

Export the following:

Variable Name and Value	Meaning
USE_CCACHE=1	1=yes, 0=no
CCACHE_COMPRESS=1	optional, but will compress cached output. 1=yes, 0=no
CCACHE_DIR=cache dir	optional cache directory per user. Default is ~/.ccache. Useful in group projects e.g. /var/cache/ .
CCACHE_UMASK=mask	optional cache read/write mask settings. 022=user read/write, group, other read. 000 Global read/write

Set up the cache using a ccache.conf file in the CCACHE_DIR directory (see ccache manpage). Start ccache with ccache -M size where size specifies the maximum cache size. 0 means unlimited. This value will be stored in ccache.conf. Only has to be run once or if you wish to enlarge or reduce the max cache size.

Do not embed ccache compiler command in the environment variables CC= or CXX= as that will affect configure.

Using ccache with lrzip-next

Once autogen.sh has run and configure has run, the make command can be amended slightly as follows in order to cache output.
make CC='ccache gcc' CXX='ccache g++' [make options, such as -j#]

Then next time you compile lrzip-next it may go faster, especially with the library files, such as zpaq which are slower to build because of the -O3 compile time option.