map-tile-toolkit 0.3.2

name: Hotpath Profile

# Profiles the head and base of a PR with the `hotpath`-instrumented `profile` example, then uploads
# the two JSON reports. A separate, write-capable "Hotpath Comment" workflow (triggered on this one's
# completion) posts the timing + allocation diff back to the PR — the split keeps the profiling job
# read-only, so it is safe to run on fork PRs.

on:
  pull_request:
    paths:
      - 'src/**'
      - 'examples/**'
      - 'Cargo.toml'
      - '.github/workflows/hotpath.yml'

permissions:
  contents: read

defaults:
  run: { shell: bash }

env:
  # The `examples/profile.rs` case to profile and how many iterations to run it for. `big-all-multi`
  # is the primary `Slicer::line` path (many tiles); allocation counts are deterministic, timing is not.
  CASE: big-all-multi
  ITERS: '5000'

jobs:
  profile:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7
        with: { fetch-depth: 0 }

      - uses: dtolnay/rust-toolchain@stable
      - uses: Swatinem/rust-cache@v2
      - run: mkdir -p /tmp/metrics

      - name: Head profile (timing + alloc)
        env:
          HOTPATH_OUTPUT_FORMAT: json
          HOTPATH_OUTPUT_PATH: /tmp/metrics/head.json
        run: cargo run --release --example profile --features 'hotpath,hotpath-alloc' -- "$CASE" "$ITERS"

      - name: Checkout base
        run: git checkout ${{ github.event.pull_request.base.sha }}

      - name: Base profile (timing + alloc)
        env:
          HOTPATH_OUTPUT_FORMAT: json
          HOTPATH_OUTPUT_PATH: /tmp/metrics/base.json
        # The base may predate hotpath (e.g. the PR that introduces it); then there is nothing to
        # compare against and the comment falls back to a head-only note.
        run: cargo run --release --example profile --features 'hotpath,hotpath-alloc' -- "$CASE" "$ITERS" || echo "base has no hotpath profiling; skipping"

      - name: Save PR metadata
        env:
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          echo "$PR_NUMBER" > /tmp/metrics/pr_number.txt
          echo "$CASE" > /tmp/metrics/case.txt

      - uses: actions/upload-artifact@v7
        with:
          name: hotpath-metrics
          path: /tmp/metrics/
          retention-days: 1