ci.yml

name: MPI build and TSPLIB validation

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: read

jobs:
  build-and-validate:
    runs-on: ubuntu-latest

    steps:
      - name: Check out repository
        uses: actions/checkout@v4

      - name: Install OpenMPI
        run: |
          sudo apt-get update
          sudo apt-get install -y openmpi-bin libopenmpi-dev

      - name: Build production solver
        run: make

      - name: Verify the official Berlin52 optimal-tour weight
        run: |
          output=$(mpirun --oversubscribe -np 1 ./tsp_solver \
            data/berlin52.tsp \
            --evaluate-tour data/berlin52.opt.tour)
          printf '%s\n' "$output"
          test "$output" = "Tour weight (TSPLIB EUC_2D): 7542"

      - name: Build reduced smoke-test binary
        run: |
          python3 - <<'PY'
          from pathlib import Path

          source = Path('script/tsp_mpi.c').read_text(encoding='utf-8')
          production = '#define TOTAL_SWAP_ATTEMPTS 5000'
          smoke = '#define TOTAL_SWAP_ATTEMPTS 5'
          if production not in source:
              raise SystemExit('Could not locate the production swap-attempt setting.')
          Path('/tmp/tsp_mpi_smoke.c').write_text(
              source.replace(production, smoke, 1),
              encoding='utf-8',
          )
          PY
          mpicc -O2 -std=c99 -Wall -Wextra /tmp/tsp_mpi_smoke.c -o /tmp/tsp_solver_smoke -lm

      - name: Run deterministic two-rank MPI smoke case
        run: |
          timeout 60s mpirun --oversubscribe -np 2 \
            /tmp/tsp_solver_smoke data/berlin52.tsp --seed 20260720

      - name: Verify MPI outputs
        run: |
          test -x tsp_solver
          test -s solution.txt
          test -s my_route.txt
          python3 - <<'PY'
          from math import isfinite
          from pathlib import Path

          text = Path('solution.txt').read_text(encoding='utf-8').strip()
          distance = float(text)
          if not isfinite(distance) or distance <= 0.0 or not distance.is_integer():
              raise SystemExit(f'Invalid TSPLIB route length: {text}')

          route = [int(value) for value in Path('my_route.txt').read_text(encoding='utf-8').split()]
          expected = list(range(52))
          if len(route) != 52 or sorted(route) != expected:
              raise SystemExit('The MPI result is not a valid permutation of the 52 cities.')

          print(f'Verified deterministic two-rank MPI output with route length {distance:.0f}.')
          PY