---
# Throwaway diagnostic: why does master's ccache serve only ~14% of calls when a
# whole pull-request cache is restored?
#
# Result so far (run 41818008344): one Arch configuration costs 1.2 GB with the
# default flags, and a cache bigger than that serves 1058 of 1059 calls. The 700M
# bound therefore cannot hold one build, and a cache just under the working set
# evicts exactly what the next build asks for.
#
# This run measures the only lever that can make one configuration fit a bound:
# less debug info. Every leg's objects carry full DWARF (Debug uses -ggdb, and
# CrashReporting adds -g to Release whenever the SDK is on), and debug info
# dominates the compressed object.
#
# Two jobs, two cold builds each, no Actions cache, so the repository quota is
# untouched:
#   -g0  no debug info at all: the lower bound of what a cache could cost
#   -g1  file and line only: what a backtrace needs, and the candidate default
# `du` of each cache dir is the number to compare against 1.2 GB.
name: ccache probe

on:
  push:
    branches:
      - ci/ccache-probe
  pull_request:
    branches:
      - master

concurrency:
  group: ${{ github.workflow }} @ ${{ github.ref_name }}
  cancel-in-progress: true

jobs:
  probe:
    name: ${{ matrix.label }} debug info
    runs-on: ubuntu-latest
    timeout-minutes: 150
    strategy:
      fail-fast: false
      matrix:
        include:
          # The debug leg: -ggdb on every object.
          - label: Arch
            name: Arch
            leg: --server --debug --test --cmake-generator Ninja
            run_env: ''
          # The release leg that packages: CrashReporting adds -g on top of -O2.
          - label: Debian 13
            name: Debian13
            leg: --server --release --test --cmake-generator Ninja
            run_env: '-e WITH_CRASH_REPORTING=ON'
    env:
      NAME: ${{ matrix.name }}
      CACHE: ${{ github.workspace }}/.cache/${{ matrix.name }}
      # Far above any candidate working set: a cache that evicts cannot be measured.
      CCACHE_BOUND: 6G

    steps:
      - name: "Checkout"
        uses: actions/checkout@v7

      - name: "Build image and record the compiler's identity"
        shell: bash
        run: |
          source .ci/docker.sh --build
          docker image inspect --format 'image id: {{.Id}}' "$IMAGE_NAME"
          echo "=== compiler as ccache sees it (compiler_check = mtime hashes mtime and size)"
          docker run --rm "$IMAGE_NAME" bash -c 'for c in c++ cc gcc g++; do p="$(command -v $c)"; [ -n "$p" ] && stat -c "%n size=%s mtime=%Y" "$p"; done; c++ --version | head -1'

      - name: "Cold build with -g0"
        shell: bash
        run: |
          rm -rf build
          source .ci/docker.sh
          export RUN_ARGS="$RUN_ARGS ${{ matrix.run_env }}"
          # One cache directory per measurement: a shared one would mix the two results.
          export CCACHE_DIR="$CACHE/.ccache-g0"
          export RUN_ARGS="$RUN_ARGS -e PROBE_CMAKE_ARGS=-DCOCKATRICE_DEBUG_INFO_LEVEL=0"
          RUN ${{ matrix.leg }} --ccache "$CCACHE_BOUND"
          echo "=== cache for -g0"
          du -sh "$CCACHE_DIR"

      - name: "Cold build with -g1"
        shell: bash
        run: |
          rm -rf build
          source .ci/docker.sh
          export RUN_ARGS="$RUN_ARGS ${{ matrix.run_env }}"
          export CCACHE_DIR="$CACHE/.ccache-g1"
          export RUN_ARGS="$RUN_ARGS -e PROBE_CMAKE_ARGS=-DCOCKATRICE_DEBUG_INFO_LEVEL=1"
          RUN ${{ matrix.leg }} --ccache "$CCACHE_BOUND"
          echo "=== cache for -g1"
          du -sh "$CCACHE_DIR"

      - name: "Both measurements"
        shell: bash
        run: |
          du -sh "$CACHE"/.ccache-* | sed 's/^/  /'