GitHub Actions CI 中缓存的命中率为 0.00 %

问题描述

我有一个 dummy C++ project，我有以下 github 操作配置：

name: CI

on: [push,pull_request] # on all pushes and PRs

jobs:
  dummy:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        distro: ["ros:foxy-ros-base-focal"]
    container:
      image: ${{ matrix.distro }}
    env:
      CCACHE_DIR: "${{ github.workspace }}/.ccache"
    steps:
      - uses: actions/checkout@v2
      - name: install ccache
        run: |
          sudo apt-get update -y
          sudo apt-get -qq install ccache
      - name: ccache cache
        uses: actions/cache@v2
        with:
          path: ${{ env.CCACHE_DIR }}
          key: ccache-${{ matrix.distro }}-${{github.run_id}}
          restore-keys: |
            ccache-${{ matrix.distro }}
      - name: ccache stats
        run: ccache -s
      - name: Build workspace
        run: |
          bash ./build_bridge.sh

我正在通过在 ccache 中添加/删除库来测试 CMakeLists.txt，但是 each time ccache 命中率为 0%

cache directory                     /__w/action_test/action_test/.ccache
primary config                      /__w/action_test/action_test/.ccache/ccache.conf
secondary config      (readonly)    /etc/ccache.conf
cache hit (direct)                     0
cache hit (preprocessed)               0
cache miss                             0
cache hit rate                      0.00 %
cleanups performed                     0
files in cache                         0
cache size                           0.0 kB
max cache size                       5.0 GB

从中恢复缓存的 previous job 有一个输出：

Post job cleanup.
/usr/bin/docker exec  b170bb77ebaac32aed0561984bb959d515d8a025b9329b6309b986f6b676c6c4 sh -c "cat /etc/*release | grep ^ID"
/usr/bin/tar --posix -z -cf cache.tgz -P -C /__w/action_test/action_test --files-from manifest.txt
Cache saved successfully

我需要做任何特定的事情来保存 cmake 特定的缓存吗？

解决方法

CMake 应该使用 ccache 的编译器包装器 Reference: "Enabling ccache in your project"。我将构建步骤修改为：

      - name: Build workspace
        run: |
          sudo /usr/sbin/update-ccache-symlinks
          export PATH="/usr/lib/ccache:$PATH"
          bash ./build_bridge.sh

CMake 输出：

-- Check for working C compiler: /usr/lib/ccache/cc -- works
-- Check for working CXX compiler: /usr/lib/ccache/c++ -- works

现在 ccache 统计数据看起来不错

stats updated                       Wed Mar 31 17:30:50 2021
cache hit (direct)                     1
cache hit (preprocessed)               0
cache miss                            48
cache hit rate                      2.04 %
called for link                       41
cleanups performed                     0
files in cache                        94
cache size                          42.8 MB
max cache size                       5.0 GB

构建时间从 1 分钟 ~20 秒减少到 24 秒。