add step to measure performance

Signed-off-by: Ying WANG <ying.wang@grafana.com>

Author: Ying WANG

.github/workflows/benchmark-check.yml

@@ -0,0 +1,45 @@
+name: Benchmark Regression Check
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  benchmark:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout PR branch
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # important to access main branch
+
+      - name: Set up Go
+        uses: actions/setup-go@v5.4.0
+        with:
+            go-version: '1.24'
+            check-latest: true
+            cache-dependency-path: go.sum
+
+      - name: Install benchstat
+        run: go install golang.org/x/perf/cmd/benchstat@latest
+
+      - name: Run benchmarks on PR branch
+        run: go test -bench=. -benchmem ./... > pr.txt
+
+      - name: Create worktree for origin/main
+        run: |
+          git fetch origin main
+          git worktree add ../main-worktree origin/main
+
+      - name: Run benchmark for origin/main
+        run: |
+          cd ../main-worktree
+          go test -bench=BenchmarkSamplesJsonSerialization -benchmem ./... > ../main.txt
+          cd -
+          rm -rf ../main-worktree
+
+      - name: Check for regressions
+        run: |
+          ls -l
+          bash .github/workflows/check-bench.sh ../main.txt pr.txt

.github/workflows/check-bench.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+set -euo pipefail
+
+main_file="$1"
+pr_file="$2"
+threshold=20
+
+echo "Comparing benchmark results..."
+
+benchstat "$main_file" "$pr_file" > result.txt
+cat result.txt
+
+# Fail if regression exceeds threshold
+fail=0
+awk -v threshold=$threshold '
+/±/ {
+  split($1, name, "-")
+  name = name[1]
+  old = $3
+  new = $6
+  delta = $7
+
+  if (match(delta, /\+([0-9.]+)%/, m)) {
+    change = m[1]
+    if (change > threshold) {
+      printf "❌ %s regressed by %s%%\n", name, change
+      exit 1
+    }
+  }
+}
+' result.txt || fail=1
+
+if [ "$fail" -eq 1 ]; then
+  echo "🚨 Performance regression > $threshold% detected!"
+  exit 1
+else
+  echo "✅ No significant regressions detected."
+fi