action: cache the compiler cache between invocations

Set up the compiler cache (ccache) and cache it between invocations,
speeding up incremental builds.

Caching of the compiler cache between invocations can be disabled by
setting "enable-ccache: false" when using the action. The ccache is
limited to 512MB by default.

Currently, ccache is only supported on Linux and macOS platforms.

Co-authored-by: Fabio Baltieri <fabiobaltieri@google.com>
Signed-off-by: Henrik Brix Andersen <henrik@brixandersen.dk>

Author: henrikbrixandersen

action.yml

@@ -19,6 +19,19 @@ inputs:
     required: false
     default: .
 
+  ccache-max-size:
+    description: |
+      Maximum size of the files stored in the compiler cache (ccache). Defaults to 512MB.
+    required: false
+    default: 512MB
+
+  enable-ccache:
+    description: |
+      Enable caching/restoring of compiler cache (ccache) files between invocations.
+      Defaults to 'true'.
+    required: false
+    default: true
+
   manifest-file-name:
     description: Name of the west workspace manifest file name in "app-path"
     required: false
@@ -121,16 +134,19 @@ runs:
 
         if [ "${{ runner.os }}" = "Linux" ]; then
           pip_cache_path="~/.cache/pip"
+          ccache_path="$HOME/.cache/ccache"
           sdk_ext="tar.xz"
           setup_file="./setup.sh"
           setup_opt="-"
         elif [ "${{ runner.os }}" = "macOS" ]; then
           pip_cache_path="~/Library/Caches/pip"
+          ccache_path="$HOME/Library/Caches/ccache"
           sdk_ext="tar.xz"
           setup_file="./setup.sh"
           setup_opt="-"
         elif [ "${{ runner.os }}" = "Windows" ]; then
           pip_cache_path="~/AppData/Local/pip/Cache"
+          ccache_path="$HOME/AppData/Local/ccache/Cache"
           sdk_ext="7z"
           setup_file="./setup.cmd"
           setup_opt="//"
@@ -156,6 +172,9 @@ runs:
         echo "SDK_VERSION=${sdk_version}" >> $GITHUB_ENV
         echo "SDK_FILE=zephyr-sdk-${sdk_version}_${sdk_variant}_minimal.${sdk_ext}" >> $GITHUB_ENV
         echo "PIP_CACHE_PATH=${pip_cache_path}" >> $GITHUB_ENV
+        echo "CCACHE_TIMESTAMP=$(date +%s)" >> $GITHUB_ENV
+        echo "CCACHE_DIR=${ccache_path}" >> $GITHUB_ENV
+        echo "CCACHE_IGNOREOPTIONS=-specs=* --specs=*" >> $GITHUB_ENV
         echo "SETUP_FILE=${setup_file}" >> $GITHUB_ENV
         echo "SETUP_OPT=${setup_opt}" >> $GITHUB_ENV
 
@@ -207,3 +226,20 @@ runs:
             ${SETUP_FILE} ${SETUP_OPT}h
         fi
         ${SETUP_FILE} ${SETUP_OPT}c
+
+    - name: Cache ccache data
+      if: inputs.enable-ccache == 'true' && runner.os != 'Windows'
+      uses: actions/cache@v4
+      with:
+        path: ${{ env.CCACHE_DIR }}
+        key: ccache-${{ matrix.os }}-${{ matrix.release }}-${{ env.CCACHE_TIMESTAMP }}
+        restore-keys: ccache-${{ matrix.os }}-${{ matrix.release }}-
+
+    - name: Set up ccache
+      if: inputs.enable-ccache == 'true' && runner.os != 'Windows'
+      shell: bash
+      run: |
+        mkdir -p ${{ env.CCACHE_DIR }}
+        ccache -M ${{ inputs.ccache-max-size }}
+        ccache -p
+        ccache -z -s -vv