See if we improved anything

Author: alan-george-lk

.github/workflows/builds.yml

@@ -18,6 +18,10 @@ env:
   # transient cache backend failures fall back to uncached rustc instead of
   # failing the build.
   SCCACHE_GHA_ENABLED: "true"
+  # sccache cannot cache Cargo incremental artifacts; without this, sccache
+  # reports ~0% utilization even on cache misses. Disabling incremental lets
+  # sccache cache per-crate compilations whenever the cargo target cache misses.
+  CARGO_INCREMENTAL: "0"
   # Pinned commit for cpp-example-collection smoke build (https://github.com/livekit-examples/cpp-example-collection)
   CPP_EXAMPLE_COLLECTION_REF: 56815733a71c14692569e8adf2916a56a14d4882
   # vcpkg binary caching for Windows
@@ -133,7 +137,17 @@ jobs:
         run: |
           if sccache --start-server >/dev/null 2>&1; then
             echo "RUSTC_WRAPPER=sccache" >> "$GITHUB_ENV"
-            echo "::notice::sccache enabled (RUSTC_WRAPPER=sccache)"
+            # Wire sccache into the C++ build too (the dominant build cost),
+            # but only where the generator honors compiler launchers. The
+            # Windows preset uses the Visual Studio generator, which ignores
+            # CMAKE_<LANG>_COMPILER_LAUNCHER, so we skip it there.
+            if [[ "$RUNNER_OS" != "Windows" ]]; then
+              echo "CMAKE_C_COMPILER_LAUNCHER=sccache" >> "$GITHUB_ENV"
+              echo "CMAKE_CXX_COMPILER_LAUNCHER=sccache" >> "$GITHUB_ENV"
+              echo "::notice::sccache enabled for rustc + C/C++ (RUSTC_WRAPPER + CMAKE_*_COMPILER_LAUNCHER)"
+            else
+              echo "::notice::sccache enabled for rustc only (Windows VS generator ignores compiler launchers)"
+            fi
           else
             echo "::warning::sccache backend unreachable; building without compile cache this run"
           fi
@@ -180,6 +194,11 @@ jobs:
         shell: pwsh
         run: ${{ matrix.build_cmd }}
 
+      - name: sccache stats
+        if: always()
+        shell: bash
+        run: sccache --show-stats || true
+
       # ---------- Smoke test cpp-example-collection binaries ----------
       # Built under cpp-example-collection-build/ (not build-dir/bin). Visual Studio
       # multi-config places executables in per-target Release/ (or Debug/) subdirs.

.github/workflows/ci.yml

@@ -27,12 +27,6 @@ concurrency:
 
 permissions:
   contents: read
-  # Reusable child workflows (builds.yml, tests.yml) request actions:read
-  # (GHA cache) and packages:read (GHCR). GitHub clamps a child workflow's
-  # permissions to the MIN of (caller's permissions, child's request), so
-  # we must grant these at the caller level even though ci.yml itself
-  # doesn't use them. Without this, callers get
-  #   "actions: read, packages: read" but is only allowed "actions: none, packages: none"
   actions: read
   packages: read
 

.github/workflows/tests.yml

@@ -18,6 +18,10 @@ env:
   # transient cache backend failures fall back to uncached rustc instead of
   # failing the build.
   SCCACHE_GHA_ENABLED: "true"
+  # sccache cannot cache Cargo incremental artifacts; without this, sccache
+  # reports ~0% utilization even on cache misses. Disabling incremental lets
+  # sccache cache per-crate compilations whenever the cargo target cache misses.
+  CARGO_INCREMENTAL: "0"
   # vcpkg binary caching for Windows (mirrors builds.yml)
   VCPKG_DEFAULT_TRIPLET: x64-windows-static-md
   VCPKG_DEFAULT_HOST_TRIPLET: x64-windows-static-md
@@ -123,7 +127,17 @@ jobs:
         run: |
           if sccache --start-server >/dev/null 2>&1; then
             echo "RUSTC_WRAPPER=sccache" >> "$GITHUB_ENV"
-            echo "::notice::sccache enabled (RUSTC_WRAPPER=sccache)"
+            # Wire sccache into the C++ build too (the dominant build cost),
+            # but only where the generator honors compiler launchers. The
+            # Windows preset uses the Visual Studio generator, which ignores
+            # CMAKE_<LANG>_COMPILER_LAUNCHER, so we skip it there.
+            if [[ "$RUNNER_OS" != "Windows" ]]; then
+              echo "CMAKE_C_COMPILER_LAUNCHER=sccache" >> "$GITHUB_ENV"
+              echo "CMAKE_CXX_COMPILER_LAUNCHER=sccache" >> "$GITHUB_ENV"
+              echo "::notice::sccache enabled for rustc + C/C++ (RUSTC_WRAPPER + CMAKE_*_COMPILER_LAUNCHER)"
+            else
+              echo "::notice::sccache enabled for rustc only (Windows VS generator ignores compiler launchers)"
+            fi
           else
             echo "::warning::sccache backend unreachable; building without compile cache this run"
           fi
@@ -170,6 +184,11 @@ jobs:
         shell: pwsh
         run: ${{ matrix.build_cmd }}
 
+      - name: sccache stats
+        if: always()
+        shell: bash
+        run: sccache --show-stats || true
+
       # ---------- Run unit tests ----------
       - name: Run unit tests (Unix)
         if: runner.os != 'Windows'
@@ -280,6 +299,10 @@ jobs:
   coverage:
     name: Code Coverage
     runs-on: ubuntu-latest
+    # A debug build instrumented with --coverage is far heavier (RAM + disk)
+    # than the release builds. Cap the wall-clock so a stuck/OOM build fails
+    # fast and visibly instead of hanging toward the 6h default.
+    timeout-minutes: 45
 
     steps:
       - name: Checkout (with submodules)
@@ -291,6 +314,19 @@ jobs:
       - name: Pull LFS files
         run: git lfs pull
 
+      # Reclaim ~30GB on the runner. The debug+coverage object tree plus gcov
+      # data is large; prior runs died mid-build from disk/memory pressure.
+      - name: Free disk space
+        uses: jlumbroso/free-disk-space@54081f138730dfa15788a46383842cd2f914a1be # v1.3.1
+        with:
+          tool-cache: false
+          android: true
+          dotnet: true
+          haskell: true
+          large-packages: true
+          docker-images: true
+          swap-storage: false
+
       # ---------- OS deps ----------
       - name: Install deps
         run: |
@@ -366,8 +402,13 @@ jobs:
             -DCMAKE_EXE_LINKER_FLAGS="--coverage" \
             -DCMAKE_SHARED_LINKER_FLAGS="--coverage"
 
+      # Cap parallelism: a debug build with --coverage instrumentation has a
+      # much larger per-TU memory footprint, and unbounded --parallel (one job
+      # per core) is what OOM-killed prior runs (failure surfaced only as an
+      # abandoned "Build" step). 2 keeps peak RAM in check on the standard
+      # runner; bump if/when this moves to a larger runner.
       - name: Build
-        run: cmake --build build-debug --parallel
+        run: cmake --build build-debug --parallel 2
 
       # ---------- Run unit tests ----------
       - name: Run unit tests
@@ -376,6 +417,16 @@ jobs:
           build-debug/bin/livekit_unit_tests \
             --gtest_output=xml:build-debug/unit-test-results.xml
 
+      # Make resource-exhaustion failures visible instead of silent. Runs only
+      # if an earlier step failed (e.g. OOM during Build).
+      - name: Diagnostics on failure
+        if: failure()
+        run: |
+          echo "===== disk ====="; df -h || true
+          echo "===== memory ====="; free -h || true
+          echo "===== dmesg (OOM killer) ====="
+          sudo dmesg 2>/dev/null | grep -iE 'killed process|out of memory|oom' | tail -20 || true
+
       # ---------- Generate coverage reports ----------
       - name: Generate coverage reports
         run: |
@@ -415,7 +466,3 @@ jobs:
           path: coverage-html/
           retention-days: 14
 
-      - name: Upload coverage to Codecov
-        uses: getsentry/codecov-action@03112cc3b486a3397dc8d17a58680008721fc86f # v0.3.7
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}

build.sh

@@ -144,6 +144,19 @@ configure() {
     echo "==> Setting CMAKE_OSX_ARCHITECTURES=${MACOS_ARCH}"
     extra_args+=("-DCMAKE_OSX_ARCHITECTURES=${MACOS_ARCH}")
   fi
+  # Bridge compiler-launcher env vars (e.g. sccache/ccache) into the CMake
+  # cache. CMake does NOT read CMAKE_<LANG>_COMPILER_LAUNCHER from the
+  # environment, so CI exports these and we forward them explicitly. Only the
+  # Ninja/Makefile generators honor launchers; the Visual Studio generator
+  # ignores them, so Windows builds simply leave these unset.
+  if [[ -n "${CMAKE_C_COMPILER_LAUNCHER:-}" ]]; then
+    echo "==> Using C compiler launcher: ${CMAKE_C_COMPILER_LAUNCHER}"
+    extra_args+=("-DCMAKE_C_COMPILER_LAUNCHER=${CMAKE_C_COMPILER_LAUNCHER}")
+  fi
+  if [[ -n "${CMAKE_CXX_COMPILER_LAUNCHER:-}" ]]; then
+    echo "==> Using C++ compiler launcher: ${CMAKE_CXX_COMPILER_LAUNCHER}"
+    extra_args+=("-DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER}")
+  fi
   if ((${#extra_args[@]})); then
     if ! cmake --preset "${PRESET}" "${extra_args[@]}"; then
       echo "Warning: CMake preset '${PRESET}' failed. Falling back to traditional configure..."