ci: speedup CI

.github/workflows/ci.yml

@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ "main", "master" ]
 
+env:
+  BUILD_DEPS: cmake ninja-build libsdl2-dev protobuf-compiler
+
 jobs:
   build-and-test:
     runs-on: ubuntu-latest
@@ -17,17 +20,53 @@ jobs:
     - name: Install dependencies
       run: |
         sudo apt-get update
-        sudo apt-get install -y cmake clang-format clang-tidy-20 libsdl2-dev protobuf-compiler gcovr
+        sudo apt-get install -y $BUILD_DEPS clang-format gcovr
 
     - name: Check Code Formatting
       run: |
         find src include tests -type f \( -name "*.cpp" -o -name "*.hpp" -o -name "*.c" -o -name "*.h" \) | xargs clang-format --dry-run -Werror
 
     - name: Configure CMake
-      run: cmake -B build -DCMAKE_BUILD_TYPE=Release -DNEURON_IDE_ENABLE_COVERAGE=ON
+      run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DNEURON_IDE_ENABLE_COVERAGE=ON -DNEURON_IDE_ENABLE_CLANG_TIDY=OFF
 
     - name: Build
-      run: cmake --build build --config Release
+      run: cmake --build build --parallel
 
     - name: Run Tests & Check Coverage
       run: cmake --build build --target coverage
+
+  clang-tidy:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+      with:
+        # On pull requests HEAD is the merge commit and HEAD^1 the base branch, which the
+        # changed-file list below diffs against.
+        fetch-depth: 2
+
+    - name: Install dependencies
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y $BUILD_DEPS clang-tidy-20
+
+    - name: Configure CMake
+      run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DNEURON_IDE_ENABLE_CLANG_TIDY=OFF
+
+    - name: Generate protobuf headers
+      run: cmake --build build --target neuronide_proto
+
+    - name: Run clang-tidy
+      run: |
+        if [ "$GITHUB_EVENT_NAME" = "pull_request" ] && git diff --quiet HEAD^1 HEAD -- .clang-tidy; then
+          files=$(git diff --name-only --diff-filter=d HEAD^1 HEAD -- \
+            'src/*.cpp' 'src/*.hpp' 'include/*.hpp' 'tests/*.cpp' 'tests/*.hpp')
+        else
+          files=$(git ls-files 'src/*.cpp' 'tests/*.cpp')
+        fi
+        if [ -z "$files" ]; then
+          echo "No C++ files changed."
+          exit 0
+        fi
+        echo "$files" | xargs -P "$(nproc)" -n 1 clang-tidy-20 -p build --quiet

README.md

@@ -35,7 +35,7 @@ EEG samples and the stimulus markers must share a **common clock domain** so tha
 | Concern                  | Choice                                                                 |
 | ------------------------ | ---------------------------------------------------------------------- |
 | Language                 | C++20                                                                  |
-| Build system             | CMake (≥ 3.25), Ninja-friendly                                         |
+| Build system             | CMake (≥ 3.25), Ninja recommended                                      |
 | Experiment file format   | Protocol Buffers (proto3) — see `protoFiles/neuronide.proto`           |
 | Device config format     | JSON (`config.json`) parsed with [nlohmann/json](https://github.com/nlohmann/json) |
 | EEG acquisition          | [LSL — Lab Streaming Layer](https://github.com/sccn/liblsl) (`liblsl`) |
@@ -407,21 +407,50 @@ All commands are run from the `Neuron-IDE-runtime/` directory.
 
 ```bash
 sudo apt update
-sudo apt install cmake clang-format clang-tidy libsdl2-dev protobuf-compiler gcovr
-# GTest, LSL and concurrentqueue are fetched automatically by CMake.
+sudo apt install cmake ninja-build clang-format clang-tidy-20 libsdl2-dev protobuf-compiler gcovr
+# GTest, LSL, concurrentqueue and nlohmann/json are fetched automatically by CMake.
 ```
 
 ### Configure & build
 
+Use the [Ninja](https://ninja-build.org/) generator: it builds on all CPU cores by default and
+rebuilds only what changed.
+
 ```bash
-cmake -B build
+cmake -B build -G Ninja
 cmake --build build
 ./build/src/NeuronIDE config.json experiment.neuroz  # waits for the EEG stream, then records and runs the experiment
 ```
 
+`-G Ninja` is needed only the first time you configure a build directory; CMake remembers it.
+A `build/` already configured with the default generator (Make) can't be switched, so delete it
+first (`rm -rf build`). If you stay on Make, build with `cmake --build build --parallel`;
+without `--parallel`, Make compiles one file at a time.
+
 `NeuronIDE` takes the path to a device `config.json` (defaults to `config.json` in
 the working directory).
 
+#### Faster builds without clang-tidy
+
+By default clang-tidy runs on every file during the build and takes several times longer than
+compiling it. While iterating, turn it off. The setting is remembered in `build/`; configure
+with `=ON` to turn it back on.
+
+```bash
+cmake -B build -G Ninja -DNEURON_IDE_ENABLE_CLANG_TIDY=OFF -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+cmake --build build
+```
+
+CI still runs clang-tidy and fails on any warning, so run the same check before pushing. It
+reads the `compile_commands.json` that `CMAKE_EXPORT_COMPILE_COMMANDS` writes:
+
+```bash
+git ls-files 'src/*.cpp' 'tests/*.cpp' | xargs -P "$(nproc)" -n 1 clang-tidy-20 -p build --quiet
+```
+
+Lines like `43669 warnings generated.` count warnings in third-party headers, which
+`.clang-tidy` filters out; only `error:` lines are problems.
+
 ### Tests
 
 ```bash
@@ -444,11 +473,13 @@ ctest -L component --output-on-failure
   ```bash
   cmake --build build --target format
   ```
+- clang-tidy runs as part of the build; see
+  [Faster builds without clang-tidy](#faster-builds-without-clang-tidy) to turn it off.
 
 ### Coverage
 
 ```bash
-cmake -B build -DNEURON_IDE_ENABLE_COVERAGE=ON
+cmake -B build -G Ninja -DNEURON_IDE_ENABLE_COVERAGE=ON
 cmake --build build
 cmake --build build --target coverage     # runs tests + gcovr
 xdg-open build/coverage/index.html

cmake/StaticAnalysis.cmake

@@ -1,12 +1,18 @@
 # cmake/StaticAnalysis.cmake
 
 # --- Clang-Tidy Configuration ---
-find_program(CLANG_TIDY_EXE NAMES "clang-tidy-20")
-if(CLANG_TIDY_EXE)
-    message(STATUS "clang-tidy found: ${CLANG_TIDY_EXE}")
-    set(CMAKE_CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
-else()
-    message(WARNING "clang-tidy not found.")
+# Runs clang-tidy next to the compiler on every file, which costs several times more than the
+# compile itself. CI turns it off and runs clang-tidy in a separate job instead.
+option(NEURON_IDE_ENABLE_CLANG_TIDY "Run clang-tidy on every file as part of the build" ON)
+
+if(NEURON_IDE_ENABLE_CLANG_TIDY)
+    find_program(CLANG_TIDY_EXE NAMES "clang-tidy-20")
+    if(CLANG_TIDY_EXE)
+        message(STATUS "clang-tidy found: ${CLANG_TIDY_EXE}")
+        set(CMAKE_CXX_CLANG_TIDY "${CLANG_TIDY_EXE}")
+    else()
+        message(WARNING "clang-tidy not found.")
+    endif()
 endif()
 
 # --- Clang-Format Target ---