benchmarks.yml

name: Benchmarks

on:
  workflow_dispatch:
    inputs:
      filter:
        description: BenchmarkDotNet filter expression
        required: false
        default: '*'
        type: string
      compare_previous_commit:
        description: Run benchmarks on previous commit and compare
        required: false
        default: false
        type: boolean
      regression_threshold:
        description: Fail if mean regression exceeds this percentage (0 disables)
        required: false
        default: '0'
        type: string
  push:
    branches:
      - main
    paths:
      - src/**
      - benchmarks/**
      - LibSharp.sln
      - .github/workflows/benchmarks.yml
  schedule:
    - cron: '0 4 * * 1'

permissions:
  contents: read

concurrency:
  group: benchmarks-${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: false

jobs:
  benchmarks:
    runs-on: ubuntu-latest
    timeout-minutes: 120

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: 10.0.x

      - name: Resolve run labels and filter
        id: vars
        shell: bash
        run: |
          echo "before_label=before-${{ github.run_id }}-${{ github.run_attempt }}" >> "$GITHUB_OUTPUT"
          echo "after_label=after-${{ github.run_id }}-${{ github.run_attempt }}" >> "$GITHUB_OUTPUT"

          FILTER='*'
          if [ "${{ github.event_name }}" = "workflow_dispatch" ] && [ -n "${{ inputs.filter }}" ]; then
            FILTER='${{ inputs.filter }}'
          fi

          echo "filter=$FILTER" >> "$GITHUB_OUTPUT"

      - name: Restore dependencies
        run: dotnet restore LibSharp.sln

      - name: Run benchmarks (current commit)
        shell: pwsh
        run: |
          ./benchmarks/run-benchmarks.ps1 -Label "${{ steps.vars.outputs.after_label }}" -Filter "${{ steps.vars.outputs.filter }}"

      - name: Upload benchmark artifacts (current commit)
        uses: actions/upload-artifact@v4
        with:
          name: benchmark-results-${{ steps.vars.outputs.after_label }}
          path: benchmarks/results/${{ steps.vars.outputs.after_label }}
          if-no-files-found: error

      - name: Detect previous commit
        id: prev
        if: github.event_name == 'workflow_dispatch' && inputs.compare_previous_commit
        shell: bash
        run: |
          if git rev-parse --verify HEAD^ >/dev/null 2>&1; then
            echo "has_previous=true" >> "$GITHUB_OUTPUT"
            echo "previous_sha=$(git rev-parse HEAD^)" >> "$GITHUB_OUTPUT"
          else
            echo "has_previous=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Run benchmarks (previous commit)
        id: previous
        if: github.event_name == 'workflow_dispatch' && inputs.compare_previous_commit && steps.prev.outputs.has_previous == 'true'
        shell: bash
        run: |
          CURRENT_SHA="${{ github.sha }}"
          PREVIOUS_SHA="${{ steps.prev.outputs.previous_sha }}"

          echo "comparison_ready=false" >> "$GITHUB_OUTPUT"

          git checkout --detach "$PREVIOUS_SHA"

          if [ ! -f "benchmarks/run-benchmarks.ps1" ]; then
            echo "Skipping previous commit benchmark run: benchmarks script not found."
            git checkout --detach "$CURRENT_SHA"
            exit 0
          fi

          pwsh ./benchmarks/run-benchmarks.ps1 -Label "${{ steps.vars.outputs.before_label }}" -Filter "${{ steps.vars.outputs.filter }}"

          git checkout --detach "$CURRENT_SHA"
          echo "comparison_ready=true" >> "$GITHUB_OUTPUT"

      - name: Compare benchmark runs
        if: github.event_name == 'workflow_dispatch' && inputs.compare_previous_commit && steps.prev.outputs.has_previous == 'true' && steps.previous.outputs.comparison_ready == 'true'
        shell: pwsh
        run: |
          [double]$threshold = 0
          [double]::TryParse('${{ inputs.regression_threshold }}', [ref]$threshold) | Out-Null

          ./benchmarks/compare-benchmarks.ps1 `
            -Before "${{ steps.vars.outputs.before_label }}" `
            -After "${{ steps.vars.outputs.after_label }}" `
            -RegressionThreshold $threshold

      - name: Upload benchmark artifacts (comparison)
        if: github.event_name == 'workflow_dispatch' && inputs.compare_previous_commit && steps.prev.outputs.has_previous == 'true' && steps.previous.outputs.comparison_ready == 'true'
        uses: actions/upload-artifact@v4
        with:
          name: benchmark-comparison-${{ github.run_id }}-${{ github.run_attempt }}
          path: |
            benchmarks/results/${{ steps.vars.outputs.before_label }}
            benchmarks/results/comparison-${{ steps.vars.outputs.after_label }}-vs-${{ steps.vars.outputs.before_label }}.csv
          if-no-files-found: warn