[core] Add CodSpeed C++ benchmarks for protobuf, main loop, and helpers (#14878)

.github/workflows/ci.yml

@@ -185,6 +185,7 @@ jobs:
       cpp-unit-tests-run-all: ${{ steps.determine.outputs.cpp-unit-tests-run-all }}
       cpp-unit-tests-components: ${{ steps.determine.outputs.cpp-unit-tests-components }}
       component-test-batches: ${{ steps.determine.outputs.component-test-batches }}
+      benchmarks: ${{ steps.determine.outputs.benchmarks }}
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -227,6 +228,7 @@ jobs:
           echo "cpp-unit-tests-run-all=$(echo "$output" | jq -r '.cpp_unit_tests_run_all')" >> $GITHUB_OUTPUT
           echo "cpp-unit-tests-components=$(echo "$output" | jq -c '.cpp_unit_tests_components')" >> $GITHUB_OUTPUT
           echo "component-test-batches=$(echo "$output" | jq -c '.component_test_batches')" >> $GITHUB_OUTPUT
+          echo "benchmarks=$(echo "$output" | jq -r '.benchmarks')" >> $GITHUB_OUTPUT
       - name: Save components graph cache
         if: github.ref == 'refs/heads/dev'
         uses: actions/cache/save@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
@@ -308,6 +310,38 @@ jobs:
             script/cpp_unit_test.py $ARGS
           fi
 
+  benchmarks:
+    name: Run CodSpeed benchmarks
+    runs-on: ubuntu-24.04
+    needs:
+      - common
+      - determine-jobs
+    if: github.event_name == 'pull_request' && needs.determine-jobs.outputs.benchmarks == 'true'
+    steps:
+      - name: Check out code from GitHub
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Restore Python
+        uses: ./.github/actions/restore-python
+        with:
+          python-version: ${{ env.DEFAULT_PYTHON }}
+          cache-key: ${{ needs.common.outputs.cache-key }}
+
+      - name: Build benchmarks
+        id: build
+        run: |
+          . venv/bin/activate
+          export BENCHMARK_LIB_CONFIG=$(python script/setup_codspeed_lib.py)
+          # --build-only prints BUILD_BINARY=<path> to stdout
+          BINARY=$(script/cpp_benchmark.py --all --build-only | grep '^BUILD_BINARY=' | tail -1 | cut -d= -f2-)
+          echo "binary=$BINARY" >> $GITHUB_OUTPUT
+
+      - name: Run CodSpeed benchmarks
+        uses: CodSpeedHQ/action@281164b0f014a4e7badd2c02cecad9b595b70537 # v4
+        with:
+          run: ${{ steps.build.outputs.binary }}
+          mode: simulation
+
   clang-tidy-single:
     name: ${{ matrix.name }}
     runs-on: ubuntu-24.04