Run mempool benchmarks in a separate GHA job (#1237)

We can then mark the build+test job as required, while leaving the
benchmark job as non-required

Author: jorisdral

.github/workflows/ci.yml

@@ -146,10 +146,76 @@ jobs:
       if: matrix.test-set == 'no-thunks-safe'
       run: cabal test ouroboros-consensus:consensus-test ouroboros-consensus:doctest ouroboros-consensus:infra-test ouroboros-consensus:storage-test ouroboros-consensus-cardano:byron-test ouroboros-consensus-cardano:shelley-test ouroboros-consensus-diffusion:infra-test ouroboros-consensus-protocol:protocol-test -j --test-show-details=streaming
 
+    - name: Identify benchmark executables
+      run: |
+        cp $(cabal list-bin mempool-bench) mempool-bench
+
+    - name: Upload benchmark executables
+      uses: actions/upload-artifact@v4
+      with:
+        name: benchmark-exes-${{ runner.os }}-${{ matrix.ghc }}
+        path: mempool-bench
+        retention-days: 1
+
+    # NB: build the haddocks at the end to avoid unecessary recompilations.
+    # We build the haddocks only for one GHC version.
+    - name: Build Haddock documentation
+      if: |
+        github.event_name == 'push'
+        && github.ref == 'refs/heads/main'
+        && matrix.ghc=='9.6.6'
+      run: |
+        # need for latex, dvisvgm and standalone
+        sudo apt install texlive-latex-extra texlive-latex-base
+        # cabal-docspec doesn't work with XDG https://github.com/phadej/cabal-extras/issues/136
+        sed -i 's_-- store-dir:_store-dir: /home/runner/.local/state/cabal/store_g' ~/.config/cabal/config
+        export CABAL_CONFIG=~/.config/cabal/config
+
+        ./scripts/docs/haddocks.sh
+        tar vzcf haddocks.tgz ./docs/website/static/haddocks
+
+    - name: Upload haddocks as an artifact
+      if: |
+        github.event_name == 'push'
+        && github.ref == 'refs/heads/main'
+        && matrix.ghc=='9.6.6'
+      uses: actions/upload-artifact@v4
+      with:
+        name: haddocks
+        path: haddocks.tgz
+        retention-days: 1
+
+  benchmarks:
+    name: Run benchmarks
+    needs: build-test-bench-haddocks
+
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ghc: ["8.10.7", "9.6.6", "9.10.1"]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install base libraries
+      uses: input-output-hk/actions/base@latest
+      with:
+        use-sodium-vrf: false
+
+    - name: Download benchmark executables
+      uses: actions/download-artifact@v4
+      with:
+        name: benchmark-exes-${{ runner.os }}-${{ matrix.ghc }}
+
+    - name: Set permissions for benchmark executables
+      run: |
+        chmod u+x mempool-bench
+
     - name: Create baseline-benchmark
       if: github.event_name == 'push' && github.ref == 'refs/heads/main'
       run: |
-        cabal new-run ouroboros-consensus:mempool-bench -- \
+        ./mempool-bench \
         --timeout=60 --csv mempool-benchmarks.csv \
         +RTS -T
 
@@ -163,7 +229,6 @@ jobs:
     # then we will save the same results we just restored.
     - name: Cache benchmark baseline results
       uses: actions/cache@v4
-      if: matrix.variant == 'default'
       with:
         path: baseline-mempool-benchmarks.csv
         key:  baseline-mempool-benchmarks-${{ runner.os }}-${{ matrix.ghc }}-${{ github.run_id }}
@@ -188,7 +253,7 @@ jobs:
       if: ${{ github.event_name == 'pull_request' }}
       run: |
         if [ -f baseline-mempool-benchmarks.csv ]; then
-          cabal new-run ouroboros-consensus:mempool-bench -- \
+          ./mempool-bench \
           --timeout=60 --baseline baseline-mempool-benchmarks.csv \
           --fail-if-slower 100 \
           +RTS -T
@@ -197,34 +262,6 @@ jobs:
           echo "Benchmarks comparison skipped."
         fi
 
-    # NB: build the haddocks at the end to avoid unecessary recompilations.
-    # We build the haddocks only for one GHC version.
-    - name: Build Haddock documentation
-      if: |
-        github.event_name == 'push'
-        && github.ref == 'refs/heads/main'
-        && matrix.ghc=='9.6.6'
-      run: |
-        # need for latex, dvisvgm and standalone
-        sudo apt install texlive-latex-extra texlive-latex-base
-        # cabal-docspec doesn't work with XDG https://github.com/phadej/cabal-extras/issues/136
-        sed -i 's_-- store-dir:_store-dir: /home/runner/.local/state/cabal/store_g' ~/.config/cabal/config
-        export CABAL_CONFIG=~/.config/cabal/config
-
-        ./scripts/docs/haddocks.sh
-        tar vzcf haddocks.tgz ./docs/website/static/haddocks
-
-    - name: Upload haddocks as an artifact
-      if: |
-        github.event_name == 'push'
-        && github.ref == 'refs/heads/main'
-        && matrix.ghc=='9.6.6'
-      uses: actions/upload-artifact@v4
-      with:
-        name: haddocks
-        path: haddocks.tgz
-        retention-days: 1
-
   deploy-documentation:
     name: Deploy documentation to GitHub Pages
     if: github.event_name == 'push' && github.ref == 'refs/heads/main'