[ci] Optimize clang-tidy for small PRs by avoiding unnecessary job splitting

.github/workflows/ci.yml

@@ -175,6 +175,7 @@ jobs:
       changed-components-with-tests: ${{ steps.determine.outputs.changed-components-with-tests }}
       directly-changed-components-with-tests: ${{ steps.determine.outputs.directly-changed-components-with-tests }}
       component-test-count: ${{ steps.determine.outputs.component-test-count }}
+      changed-cpp-file-count: ${{ steps.determine.outputs.changed-cpp-file-count }}
       memory_impact: ${{ steps.determine.outputs.memory-impact }}
     steps:
       - name: Check out code from GitHub
@@ -205,6 +206,7 @@ jobs:
           echo "changed-components-with-tests=$(echo "$output" | jq -c '.changed_components_with_tests')" >> $GITHUB_OUTPUT
           echo "directly-changed-components-with-tests=$(echo "$output" | jq -c '.directly_changed_components_with_tests')" >> $GITHUB_OUTPUT
           echo "component-test-count=$(echo "$output" | jq -r '.component_test_count')" >> $GITHUB_OUTPUT
+          echo "changed-cpp-file-count=$(echo "$output" | jq -r '.changed_cpp_file_count')" >> $GITHUB_OUTPUT
           echo "memory-impact=$(echo "$output" | jq -c '.memory_impact')" >> $GITHUB_OUTPUT
 
   integration-tests:
@@ -249,7 +251,15 @@ jobs:
     needs:
       - common
       - determine-jobs
-    if: needs.determine-jobs.outputs.clang-tidy == 'true'
+    # Skip split jobs for small PRs (< 30 files) - run single job instead for faster completion
+    # Skip unsplit job for large PRs (>= 30 files) - run split jobs instead for parallelization
+    # Jobs without split attribute (ESP8266, IDF, ZEPHYR) always run when clang-tidy is enabled
+    if: |
+      needs.determine-jobs.outputs.clang-tidy == 'true' &&
+      (matrix.split == null || (
+        !(matrix.split == true && fromJSON(needs.determine-jobs.outputs.changed-cpp-file-count) < 30) &&
+        !(matrix.split == false && fromJSON(needs.determine-jobs.outputs.changed-cpp-file-count) >= 30)
+      ))
     env:
       GH_TOKEN: ${{ github.token }}
     strategy:
@@ -261,22 +271,33 @@ jobs:
             name: Run script/clang-tidy for ESP8266
             options: --environment esp8266-arduino-tidy --grep USE_ESP8266
             pio_cache_key: tidyesp8266
+          # For small PRs (< 30 files), run ESP32 Arduino as a single job for faster completion
+          # For larger PRs, split into 4 parallel jobs to distribute the load
+          - id: clang-tidy
+            name: Run script/clang-tidy for ESP32 Arduino
+            options: --environment esp32-arduino-tidy
+            pio_cache_key: tidyesp32
+            split: false
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 Arduino 1/4
             options: --environment esp32-arduino-tidy --split-num 4 --split-at 1
             pio_cache_key: tidyesp32
+            split: true
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 Arduino 2/4
             options: --environment esp32-arduino-tidy --split-num 4 --split-at 2
             pio_cache_key: tidyesp32
+            split: true
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 Arduino 3/4
             options: --environment esp32-arduino-tidy --split-num 4 --split-at 3
             pio_cache_key: tidyesp32
+            split: true
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 Arduino 4/4
             options: --environment esp32-arduino-tidy --split-num 4 --split-at 4
             pio_cache_key: tidyesp32
+            split: true
           - id: clang-tidy
             name: Run script/clang-tidy for ESP32 IDF
             options: --environment esp32-idf-tidy --grep USE_ESP_IDF

script/determine-jobs.py

@@ -210,6 +210,22 @@ def should_run_clang_tidy(branch: str | None = None) -> bool:
     return _any_changed_file_endswith(branch, CPP_FILE_EXTENSIONS)
 
 
+def count_changed_cpp_files(branch: str | None = None) -> int:
+    """Count the number of changed C++ files.
+
+    This is used to determine whether to split clang-tidy jobs or run them as a single job.
+    For PRs with < 30 changed C++ files, running a single job is faster than splitting.
+
+    Args:
+        branch: Branch to compare against. If None, uses default.
+
+    Returns:
+        Number of changed C++ files.
+    """
+    files = changed_files(branch)
+    return sum(1 for file in files if file.endswith(CPP_FILE_EXTENSIONS))
+
+
 def should_run_clang_format(branch: str | None = None) -> bool:
     """Determine if clang-format should run based on changed files.
 
@@ -408,6 +424,7 @@ def main() -> None:
     run_clang_tidy = should_run_clang_tidy(args.branch)
     run_clang_format = should_run_clang_format(args.branch)
     run_python_linters = should_run_python_linters(args.branch)
+    changed_cpp_file_count = count_changed_cpp_files(args.branch)
 
     # Get both directly changed and all changed components (with dependencies) in one call
     script_path = Path(__file__).parent / "list-components.py"
@@ -458,6 +475,7 @@ def main() -> None:
         "component_test_count": len(changed_components_with_tests),
         "directly_changed_count": len(directly_changed_with_tests),
         "dependency_only_count": len(dependency_only_components),
+        "changed_cpp_file_count": changed_cpp_file_count,
         "memory_impact": memory_impact,
     }
 

tests/script/test_determine_jobs.py

@@ -117,6 +117,9 @@ def test_main_all_tests_should_run(
     assert output["component_test_count"] == len(
         output["changed_components_with_tests"]
     )
+    # changed_cpp_file_count should be present
+    assert "changed_cpp_file_count" in output
+    assert isinstance(output["changed_cpp_file_count"], int)
     # memory_impact should be present
     assert "memory_impact" in output
     assert output["memory_impact"]["should_run"] == "false"  # No files changed
@@ -161,6 +164,8 @@ def test_main_no_tests_should_run(
     assert output["changed_components"] == []
     assert output["changed_components_with_tests"] == []
     assert output["component_test_count"] == 0
+    # changed_cpp_file_count should be 0
+    assert output["changed_cpp_file_count"] == 0
     # memory_impact should be present
     assert "memory_impact" in output
     assert output["memory_impact"]["should_run"] == "false"
@@ -249,6 +254,9 @@ def test_main_with_branch_argument(
     assert output["component_test_count"] == len(
         output["changed_components_with_tests"]
     )
+    # changed_cpp_file_count should be present
+    assert "changed_cpp_file_count" in output
+    assert isinstance(output["changed_cpp_file_count"], int)
     # memory_impact should be present
     assert "memory_impact" in output
     assert output["memory_impact"]["should_run"] == "false"
@@ -433,6 +441,40 @@ def test_should_run_clang_format_with_branch() -> None:
         mock_changed.assert_called_once_with("release")
 
 
+@pytest.mark.parametrize(
+    ("changed_files", "expected_count"),
+    [
+        (["esphome/core.cpp"], 1),
+        (["esphome/core.h"], 1),
+        (["test.hpp"], 1),
+        (["test.cc"], 1),
+        (["test.cxx"], 1),
+        (["test.c"], 1),
+        (["test.tcc"], 1),
+        (["esphome/core.cpp", "esphome/core.h"], 2),
+        (["esphome/core.cpp", "esphome/core.h", "test.cc"], 3),
+        (["README.md"], 0),
+        (["esphome/config.py"], 0),
+        (["README.md", "esphome/config.py"], 0),
+        (["esphome/core.cpp", "README.md", "esphome/config.py"], 1),
+        ([], 0),
+    ],
+)
+def test_count_changed_cpp_files(changed_files: list[str], expected_count: int) -> None:
+    """Test count_changed_cpp_files function."""
+    with patch.object(determine_jobs, "changed_files", return_value=changed_files):
+        result = determine_jobs.count_changed_cpp_files()
+        assert result == expected_count
+
+
+def test_count_changed_cpp_files_with_branch() -> None:
+    """Test count_changed_cpp_files with branch argument."""
+    with patch.object(determine_jobs, "changed_files") as mock_changed:
+        mock_changed.return_value = []
+        determine_jobs.count_changed_cpp_files("release")
+        mock_changed.assert_called_once_with("release")
+
+
 def test_main_filters_components_without_tests(
     mock_should_run_integration_tests: Mock,
     mock_should_run_clang_tidy: Mock,
@@ -501,6 +543,9 @@ def test_main_filters_components_without_tests(
     assert set(output["changed_components_with_tests"]) == {"wifi", "sensor"}
     # component_test_count should be based on components with tests
     assert output["component_test_count"] == 2
+    # changed_cpp_file_count should be present
+    assert "changed_cpp_file_count" in output
+    assert isinstance(output["changed_cpp_file_count"], int)
     # memory_impact should be present
     assert "memory_impact" in output
     assert output["memory_impact"]["should_run"] == "false"