# Copyright 2024 RustFS Team
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Warp A/B budget gate for the hotpath series (rustfs/backlog#935 HP-14, item 4).
#
# Two entry points, honestly scoped:
#   * schedule (nightly, on main): post-merge detection — catches a regression
#     within 24h of landing, not before merge.
#   * pull_request labeled `perf-ab`: opt-in pre-merge gate for a specific PR.
# The `perf-deliberate-tradeoff` label runs the gate with --allow-regression so
# a deliberate correctness cost (e.g. the #4221 fsync durability fix) is
# recorded but does not block (rustfs/backlog#935 correction 1).

name: Performance A/B

on:
  schedule:
    - cron: "0 6 * * *" # 06:00 UTC nightly, against main
  workflow_dispatch:
    inputs:
      duration:
        description: "warp duration per round"
        required: false
        default: "30s"
        type: string
      allow_regression:
        description: "Pass the gate despite a FAIL (deliberate tradeoff)"
        required: false
        default: false
        type: boolean
  pull_request:
    types: [labeled, synchronize, reopened]

permissions:
  contents: read
  pull-requests: write

env:
  CARGO_TERM_COLOR: always
  RUST_BACKTRACE: 1

jobs:
  warp-ab:
    name: Warp A/B budget gate
    # Opt-in on PRs: only run when the `perf-ab` label is present. Always run on
    # schedule / manual dispatch.
    if: >-
      github.event_name != 'pull_request' ||
      contains(github.event.pull_request.labels.*.name, 'perf-ab')
    runs-on: sm-standard-2
    timeout-minutes: 90
    steps:
      - name: Checkout repository
        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
        with:
          fetch-depth: 0 # baseline is built from origin/main

      - name: Setup Rust environment
        uses: ./.github/actions/setup
        with:
          rust-version: stable
          cache-shared-key: warp-ab-${{ hashFiles('**/Cargo.lock') }}
          cache-save-if: ${{ github.ref == 'refs/heads/main' }}
          github-token: ${{ secrets.GITHUB_TOKEN }}

      - name: Install warp
        run: |
          set -euo pipefail
          WARP_VERSION="1.0.0"
          curl -fsSL "https://github.com/minio/warp/releases/download/v${WARP_VERSION}/warp_Linux_x86_64.tar.gz" \
            | sudo tar -xz -C /usr/local/bin warp
          warp --version

      - name: Decide exemption
        id: exempt
        run: |
          allow="false"
          if [[ "${{ github.event_name }}" == "pull_request" ]] \
            && ${{ contains(github.event.pull_request.labels.*.name, 'perf-deliberate-tradeoff') }}; then
            allow="true"
          fi
          if [[ "${{ github.event.inputs.allow_regression }}" == "true" ]]; then
            allow="true"
          fi
          echo "allow_regression=$allow" >> "$GITHUB_OUTPUT"

      - name: Run warp A/B and gate
        id: ab
        run: |
          set -euo pipefail
          args=(--baseline-ref origin/main --duration "${{ github.event.inputs.duration || '30s' }}")
          if [[ "${{ steps.exempt.outputs.allow_regression }}" == "true" ]]; then
            args+=(--allow-regression --exemption-reason "labeled perf-deliberate-tradeoff / dispatch override")
          fi
          # Do not let a gate FAIL abort the job here; capture status and surface
          # it after the PR comment is posted.
          set +e
          bash scripts/run_hotpath_warp_ab.sh "${args[@]}"
          echo "status=$?" >> "$GITHUB_OUTPUT"
          set -e
          # Locate the newest gate.md for the comment/artifact steps.
          gate_md="$(ls -t target/hotpath-ab/*/gate.md 2>/dev/null | head -n1 || true)"
          echo "gate_md=$gate_md" >> "$GITHUB_OUTPUT"

      - name: Upload A/B results
        if: always()
        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
        with:
          name: hotpath-warp-ab-${{ github.run_number }}
          path: target/hotpath-ab/
          if-no-files-found: warn

      - name: Comment gate result on PR
        if: always() && github.event_name == 'pull_request' && steps.ab.outputs.gate_md != ''
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          gh pr comment "${{ github.event.pull_request.number }}" --body-file "${{ steps.ab.outputs.gate_md }}"

      - name: Enforce gate
        if: always()
        run: |
          status="${{ steps.ab.outputs.status }}"
          if [[ "$status" != "0" ]]; then
            echo "::error::warp A/B budget gate failed (exit $status). See the PR comment / gate.md artifact." >&2
            exit "$status"
          fi
          echo "warp A/B budget gate passed."