Add benchmark workflow.

.github/tools/extract_criterion.jq

@@ -0,0 +1,3 @@
+[.[2][] |
+.reportName as $bench_name |
+{ name: $bench_name, unit: "Nanoseconds", value: .reportAnalysis.anMean.estPoint, range: .reportAnalysis.anStdDev.estPoint }]

.github/workflows/bench.yml

@@ -0,0 +1,46 @@
+name: Ledger Benchmarks
+on:
+  push:
+    branches:
+      - master
+      - nc/bench-tx
+
+permissions:
+  contents: write
+  deployments: write
+
+jobs:
+  benchmark:
+    name: cardano-ledger benchmarks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: cachix/install-nix-action@v15
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+          extra_nix_config: |
+            trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+            substituters = https://hydra.iohk.io https://cache.nixos.org/
+      - name: Build benchmarks
+        run: nix-build -A haskellPackages.cardano-ledger-test.components.benchmarks
+      - name: Run benchmark
+        run: |
+          cd libs/cardano-ledger-test
+          ../../result/bin/bench "applyTxBenchmarks" --json bench.json
+      - name: Transform results
+        run: |
+          nix-env -i jq -f '<nixpkgs>'
+          jq -f .github/tools/extract_criterion.jq < libs/cardano-ledger-test/bench.json > output.json
+      - name: Store benchmark result
+        uses: benchmark-action/github-action-benchmark@v1
+        with:
+          name: Haskell Benchmark
+          tool: 'customSmallerIsBetter'
+          output-file-path: output.json
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          auto-push: true
+          # Show alert with commit comment on detecting possible performance regression
+          alert-threshold: '200%'
+          comment-on-alert: true
+          fail-on-alert: true
+          alert-comment-cc-users: '@nc6'