A Github action to speedup building using ccache for C/C++ projects.

- name: ccache
  uses: hendrikmuhs/ccache-action@v1

NB! This should always come after the actions/checkout step.

In order to use ccache in your other steps, point the compiler to it, e.g. with run-cmake:

- name: build with cmake
  uses: lukka/run-cmake@v3
  with:
    cmakeListsOrSettingsJson: CMakeListsTxtAdvanced
    cmakeAppendedArgs: '-DCMAKE_BUILD_TYPE=${{ matrix.type }} -D CMAKE_C_COMPILER_LAUNCHER=ccache -D CMAKE_CXX_COMPILER_LAUNCHER=ccache'
    ...

or by manipulating PATH:

- name: build
  run: |
    export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"

(works for both ubuntu and macos)

Ccache gets installed by this action, if its not installed yet.

If you have multiple targets(Debug, Release) and/or multiple OS's, it makes sense to cache them separately. An additional cache key can be specified. You can also specify the maximum cache size - default 500M (500 MB).

- name: ccache
  uses: hendrikmuhs/ccache-action@v1
  with:
    key: ${{ matrix.os }}-${{ matrix.type }}
    max-size: 100M

This action is based on https://cristianadam.eu/20200113/speeding-up-c-plus-plus-github-actions-using-ccache/

In a nutshell, the .ccache folder is configured in the runner path and the folder is persisted and reloaded using cache. For more details see: https://docs.github.com/en/free-pro-team@latest/actions/guides/caching-dependencies-to-speed-up-workflows.

Stats are provided as part of the post action, check the output to see if cache is effective.

You may also set verbose input to 1 to enable verbose output from this action or even to 2 to make it even more verbose.

• Keyvi