ci: Use ccache to cache build objects for speeding up building (#6104)

Right now, each pipeline invocation builds the source code from scratch. Although compiled Conan dependencies are cached in a remote server, the source build objects are not. We are able to further speed up our builds by leveraging `ccache`. This change enables caching of build objects using `ccache` on Linux, macOS, and Windows.

.github/workflows/on-pr.yml

@@ -114,6 +114,9 @@ jobs:
       matrix:
         os: [linux, macos, windows]
     with:
+      # Enable ccache only for events targeting the XRPLF repository, since
+      # other accounts will not have access to our remote cache storage.
+      ccache_enabled: ${{ github.repository_owner == 'XRPLF' }}
       os: ${{ matrix.os }}
     secrets:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

.github/workflows/on-trigger.yml

@@ -66,6 +66,12 @@ jobs:
     strategy:
       fail-fast: ${{ github.event_name == 'merge_group' }}
       matrix:
+        # Enable ccache only for events targeting the XRPLF repository, since
+        # other accounts will not have access to our remote cache storage.
+        # However, we do not enable ccache for events targeting the master or a
+        # release branch, to protect against the rare case that the output
+        # produced by ccache is not identical to a regular compilation.
+        ccache_enabled: ${{ github.repository_owner == 'XRPLF' && !(github.base_ref == 'master' || startsWith(github.base_ref, 'release')) }}
         os: [linux, macos, windows]
     with:
       os: ${{ matrix.os }}

.github/workflows/reusable-build-test-config.yml

@@ -10,8 +10,14 @@ on:
 
       build_type:
         description: 'The build type to use ("Debug", "Release").'
-        type: string
         required: true
+        type: string
+
+      ccache_enabled:
+        description: "Whether to enable ccache."
+        required: false
+        type: boolean
+        default: false
 
       cmake_args:
         description: "Additional arguments to pass to CMake."
@@ -21,8 +27,8 @@ on:
 
       cmake_target:
         description: "The CMake target to build."
-        type: string
         required: true
+        type: string
 
       runs_on:
         description: Runner to run the job on as a JSON string
@@ -66,8 +72,25 @@ jobs:
     container: ${{ inputs.image != '' && inputs.image || null }}
     timeout-minutes: 60
     env:
-      ENABLED_VOIDSTAR: ${{ contains(inputs.cmake_args, '-Dvoidstar=ON') }}
-      ENABLED_COVERAGE: ${{ contains(inputs.cmake_args, '-Dcoverage=ON') }}
+      # Use a namespace to keep the objects separate for each configuration.
+      CCACHE_NAMESPACE: ${{ inputs.config_name }}
+      # Ccache supports both Redis and HTTP endpoints.
+      # * For Redis, use the following format: redis://ip:port, see
+      #   https://github.com/ccache/ccache/wiki/Redis-storage. Note that TLS is
+      #   not directly supported by ccache, and requires use of a proxy.
+      # * For HTTP use the following format: http://ip:port/cache when using
+      #   nginx as backend or http://ip:port|layout=bazel when using Bazel
+      #   Remote Cache, see https://github.com/ccache/ccache/wiki/HTTP-storage.
+      #   Note that HTTPS is not directly supported by ccache.
+      CCACHE_REMOTE_ONLY: true
+      CCACHE_REMOTE_STORAGE: http://cache.dev.ripplex.io:8080|layout=bazel
+      # Ignore the creation and modification timestamps on files, since the
+      # header files are copied into separate directories by CMake, which will
+      # otherwise result in cache misses.
+      CCACHE_SLOPPINESS: include_file_ctime,include_file_mtime
+      # Determine if coverage and voidstar should be enabled.
+      COVERAGE_ENABLED: ${{ contains(inputs.cmake_args, '-Dcoverage=ON') }}
+      VOIDSTAR_ENABLED: ${{ contains(inputs.cmake_args, '-Dvoidstar=ON') }}
     steps:
       - name: Cleanup workspace (macOS and Windows)
         if: ${{ runner.os == 'macOS' || runner.os == 'Windows' }}
@@ -79,7 +102,11 @@ jobs:
       - name: Prepare runner
         uses: XRPLF/actions/prepare-runner@2ece4ec6ab7de266859a6f053571425b2bd684b6
         with:
-          disable_ccache: false
+          disable_ccache: ${{ !inputs.ccache_enabled }}
+
+      - name: Set ccache log file
+        if: ${{ inputs.ccache_enabled && runner.debug == '1' }}
+        run: echo "CCACHE_LOGFILE=${{ runner.temp }}/ccache.log" >> "${GITHUB_ENV}"
 
       - name: Print build environment
         uses: ./.github/actions/print-env
@@ -128,6 +155,15 @@ jobs:
             --parallel "${BUILD_NPROC}" \
             --target "${CMAKE_TARGET}"
 
+      - name: Show ccache statistics
+        if: ${{ inputs.ccache_enabled }}
+        run: |
+          ccache --show-stats -vv
+          if [ '${{ runner.debug }}' = '1' ]; then
+            cat "${CCACHE_LOGFILE}"
+            curl ${CCACHE_REMOTE_STORAGE%|*}/status || true
+          fi
+
       - name: Upload the binary (Linux)
         if: ${{ github.repository_owner == 'XRPLF' && runner.os == 'Linux' }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
@@ -150,7 +186,7 @@ jobs:
           fi
 
       - name: Verify presence of instrumentation (Linux)
-        if: ${{ runner.os == 'Linux' && env.ENABLED_VOIDSTAR == 'true' }}
+        if: ${{ runner.os == 'Linux' && env.VOIDSTAR_ENABLED == 'true' }}
         working-directory: ${{ env.BUILD_DIR }}
         run: |
           ./xrpld --version | grep libvoidstar
@@ -185,7 +221,7 @@ jobs:
           netstat -an
 
       - name: Prepare coverage report
-        if: ${{ !inputs.build_only && env.ENABLED_COVERAGE == 'true' }}
+        if: ${{ !inputs.build_only && env.COVERAGE_ENABLED == 'true' }}
         working-directory: ${{ env.BUILD_DIR }}
         env:
           BUILD_NPROC: ${{ steps.nproc.outputs.nproc }}
@@ -198,7 +234,7 @@ jobs:
             --target coverage
 
       - name: Upload coverage report
-        if: ${{ github.repository_owner == 'XRPLF' && !inputs.build_only && env.ENABLED_COVERAGE == 'true' }}
+        if: ${{ github.repository_owner == 'XRPLF' && !inputs.build_only && env.COVERAGE_ENABLED == 'true' }}
         uses: codecov/codecov-action@18283e04ce6e62d37312384ff67231eb8fd56d24 # v5.4.3
         with:
           disable_search: true

.github/workflows/reusable-build-test.yml

@@ -8,16 +8,24 @@ name: Build and test
 on:
   workflow_call:
     inputs:
+      ccache_enabled:
+        description: "Whether to enable ccache."
+        required: false
+        type: boolean
+        default: false
+
       os:
         description: 'The operating system to use for the build ("linux", "macos", "windows").'
         required: true
         type: string
+
       strategy_matrix:
         # TODO: Support additional strategies, e.g. "ubuntu" for generating all Ubuntu configurations.
         description: 'The strategy matrix to use for generating the configurations ("minimal", "all").'
         required: false
         type: string
         default: "minimal"
+
     secrets:
       CODECOV_TOKEN:
         description: "The Codecov token to use for uploading coverage reports."
@@ -43,6 +51,7 @@ jobs:
     with:
       build_only: ${{ matrix.build_only }}
       build_type: ${{ matrix.build_type }}
+      ccache_enabled: ${{ inputs.ccache_enabled }}
       cmake_args: ${{ matrix.cmake_args }}
       cmake_target: ${{ matrix.cmake_target }}
       runs_on: ${{ toJSON(matrix.architecture.runner) }}

.github/workflows/upload-conan-deps.yml

@@ -72,7 +72,7 @@ jobs:
       - name: Prepare runner
         uses: XRPLF/actions/prepare-runner@2ece4ec6ab7de266859a6f053571425b2bd684b6
         with:
-          disable_ccache: false
+          disable_ccache: true
 
       - name: Print build environment
         uses: ./.github/actions/print-env