actions: clang: use ccache

Use ccache to speed up builds.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

.github/workflows/clang.yaml

@@ -57,6 +57,29 @@ jobs:
           ${CLANG_ROOT_DIR}/bin/clang --version
           gcc --version
           ls -la
+      - name: Prepare ccache timestamp/data
+        id: ccache_cache_timestamp
+        shell: cmake -P {0}
+        run: |
+          string(TIMESTAMP current_date "%Y-%m-%d-%H;%M;%S" UTC)
+          string(REPLACE "/" "_" repo ${{github.repository}})
+          string(REPLACE "-" "_" repo2 ${repo})
+          message("::set-output name=repo::${repo2}")
+      - name: use cache
+        id: cache-ccache
+        uses: nashif/action-s3-cache@master
+        with:
+          key: ${{ steps.ccache_cache_timestamp.outputs.repo }}-clang-${{ matrix.platform }}-ccache
+          path: /github/home/.ccache
+          aws-s3-bucket: ccache.zephyrproject.org
+          aws-access-key-id: ${{ secrets.CCACHE_S3_ACCESS_KEY_ID }}
+          aws-secret-access-key: ${{ secrets.CCACHE_S3_SECRET_ACCESS_KEY }}
+          aws-region: us-east-2
+
+      - name: ccache stats initial
+        run: |
+          test -d github/home/.ccache && mv github/home/.ccache /github/home/.ccache
+          ccache -M 10G -s
 
       - name: Run Tests with Twister
         id: twister
@@ -87,6 +110,10 @@ jobs:
             fi
           fi
 
+      - name: ccache stats post
+        run: |
+          ccache -s
+
       - name: Upload Unit Test Results
         if: always() && steps.twister.outputs.report_needed != 0
         uses: actions/upload-artifact@v2