ci: Use codspeed for benchmarking

.github/workflows/codspeed.yml

@@ -0,0 +1,103 @@
+name: CodSpeed Benchmarks
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["main"]
+  merge_group:
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: 1
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  bench-matrix:
+    name: Determine benchmark matrix
+    runs-on: ubuntu-24.04
+    outputs:
+      benches: ${{ steps.benches.outputs.benches }}
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
+      - id: benches
+        run: |
+          # Create a GitHub matrix where each entry is a bench with its
+          # associated crate and benchmarking mode taken from the Cargo
+          # metadata.
+          {
+            echo -n "["
+            first=true
+            while IFS=: read -r crate manifest_path; do
+              dir=$(dirname "$manifest_path")
+              if [ -e "$dir/benches" ]; then
+                for bench in "$dir/benches"/*.rs; do
+                  bench=$(basename -s .rs "$bench")
+                  # Set measurement mode from Cargo.toml metadata, default to "instrumentation".
+                  mode=$(cargo metadata --no-deps --format-version 1 | jq -r --arg crate "$crate" --arg bench "$bench" '.packages[] | select(.name == $crate) | .metadata.bench[$bench].codspeed.mode // "instrumentation"')
+                  if [ "$first" = true ]; then
+                    first=false
+                  else
+                    echo -n ","
+                  fi
+                  echo -n "{\"crate\":\"$crate\",\"bench\":\"$bench\",\"mode\":\"$mode\"}"
+                done
+              fi
+            done < <(cargo metadata --no-deps --format-version 1 | jq -r '.packages[] | .name + ":" + .manifest_path')
+            echo -n "]"
+          } > benches.json
+          cat benches.json
+          echo "benches=$(cat benches.json)" >> "${GITHUB_OUTPUT}"
+
+  benchmarks:
+    name: Run benchmarks
+    runs-on: ubuntu-24.04
+    strategy:
+      matrix:
+        bench: ${{ fromJson(needs.bench-matrix.outputs.benches) }}
+    needs: bench-matrix
+
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
+
+      - uses: ./.github/actions/rust
+        with:
+          version: stable
+          tools: cargo-codspeed
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - id: nss-version
+        run: echo "minimum=$(cat neqo-crypto/min_version.txt)" >> "$GITHUB_OUTPUT"
+
+      - uses: ./.github/actions/nss
+        with:
+          minimum-version: ${{ steps.nss-version.outputs.minimum }}
+
+      - env:
+          BENCH: ${{ matrix.bench.bench }}
+          CRATE: ${{ matrix.bench.crate }}
+          MODE: ${{ matrix.bench.mode }}
+        run: |
+          echo "Building benchmark '$BENCH' in crate '$CRATE' with measurement mode '$MODE'"
+          cargo codspeed build --package "$CRATE" --locked --features bench --bench "$BENCH" --measurement-mode "$MODE"
+
+      - name: Run the benchmarks
+        uses: CodSpeedHQ/action@4348f634fa7309fe23aac9502e88b999ec90a164 # v4.3.1
+        with:
+          mode: ${{ matrix.bench.mode }}
+          run: cargo codspeed run
+          token: ${{ secrets.CODSPEED_TOKEN }}