.github: add and use ccache on cygwin build

.github/workflows/cygwin_build.yml

@@ -13,21 +13,65 @@ jobs:
       - uses: actions/checkout@v3
         with:
           submodules: 'recursive'
+      - name: Prepare ccache timestamp
+        id: ccache_cache_timestamp
+        shell: bash
+        run: |
+          NOW=$(date -u +"%F-%T")
+          echo "timestamp=${NOW}" >> $GITHUB_OUTPUT
+          WORKFLOWNAME="${{github.workflow}}"
+          NAME_DASHED=${WORKFLOWNAME//+( )/_}
+          echo "cache-key=${NAME_DASHED}" >> $GITHUB_OUTPUT
+
       - uses: cygwin/cygwin-install-action@master
         with:
-          packages: cygwin64 gcc-g++=10.2.0-1 python37 python37-future python37-lxml python37-pip python37-setuptools python37-wheel git procps gettext
+          packages: cygwin64 gcc-g++=10.2.0-1 ccache python37 python37-future python37-lxml python37-pip python37-setuptools python37-wheel git procps gettext
+          add-to-path: false
+      # Put ccache into github cache for faster build
+      - name: setup ccache
+        env:
+          PATH: /usr/bin:$(cygpath ${SYSTEMROOT})/system32
+        shell: C:\cygwin\bin\bash.exe -eo pipefail '{0}'
+        run: >-
+          mkdir -p /cygdrive/d/a/ardupilot/ardupilot/ccache &&
+          mkdir -p /usr/local/etc &&
+          echo "export CCACHE_SLOPPINESS=file_stat_matches" >> ~/ccache.conf &&
+          echo "export CCACHE_DIR=/cygdrive/d/a/ardupilot/ardupilot/ccache" >> ~/ccache.conf &&
+          echo "export CCACHE_BASEDIR=/cygdrive/d/a/ardupilot/ardupilot" >> ~/ccache.conf &&
+          echo "export CCACHE_COMPRESS=1" >> ~/ccache.conf &&
+          echo "export CCACHE_COMPRESSLEVEL=6" >> ~/ccache.conf &&
+          echo "export CCACHE_MAXSIZE=400M" >> ~/ccache.conf &&
+          source ~/ccache.conf &&
+          ccache -s
+      - name: ccache cache files
+        uses: actions/cache@v3
+        with:
+          path: D:/a/ardupilot/ardupilot/ccache
+          key: ${{ steps.ccache_cache_timestamp.outputs.cache-key }}-ccache-${{steps.ccache_cache_timestamp.outputs.timestamp}}
+          restore-keys: ${{ steps.ccache_cache_timestamp.outputs.cache-key }}-ccache-  # restore ccache from either previous build on this branch or on base branch
       - name: Prepare Python environment
         env:
-          HOME: ${{ runner.workspace }}/ardupilot
+          PATH: /usr/bin:$(cygpath ${SYSTEMROOT})/system32
-        run: |
+        shell: C:\cygwin\bin\bash.exe -eo pipefail '{0}'
-          bash --login -c "ln -sf /usr/bin/python3.7 /usr/bin/python && ln -sf /usr/bin/pip3.7 /usr/bin/pip"
+        run: >-
-          bash --login -c "python -m pip install --progress-bar off empy pexpect"
+          ln -sf /usr/bin/python3.7 /usr/bin/python && ln -sf /usr/bin/pip3.7 /usr/bin/pip &&
-          bash --login -c "python -m pip install --progress-bar off dronecan --upgrade"
+          python -m pip install --progress-bar off empy pexpect &&
+          python -m pip install --progress-bar off dronecan --upgrade &&
+          cp /usr/bin/ccache /usr/local/bin/ &&
+          cd /usr/local/bin && ln -s ccache /usr/local/bin/gcc &&
+          ln -s ccache /usr/local/bin/g++ &&
+          ln -s ccache /usr/local/bin/x86_64-pc-cygwin-gcc &&
+          ln -s ccache /usr/local/bin/x86_64-pc-cygwin-g++
+
       - name: Build SITL
         env:
-          HOME: ${{ runner.workspace }}/ardupilot
+          PATH: /usr/bin:$(cygpath ${SYSTEMROOT})/system32
-        run: |
+        shell: C:\cygwin\bin\bash.exe -eo pipefail '{0}'
-          bash --login -c "Tools/scripts/cygwin_build.sh"
+        run: >-
+          export PATH=/usr/local/bin:/usr/bin:$(cygpath ${SYSTEMROOT})/system32 &&
+          source ~/ccache.conf &&
+          Tools/scripts/cygwin_build.sh &&
+          ccache -s
 
       - name: Check build files
         id: check_files
@@ -39,6 +83,6 @@ jobs:
       - name: Archive build
         uses: actions/upload-artifact@v3
         with:
-           name: binaries
+          name: binaries
-           path: artifacts
+          path: artifacts
-           retention-days: 7
+          retention-days: 7