[#4] limiting/semaphore: Add benchmark for semaphore

Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>

limiting/semaphore/semaphore_bench_test.go

@@ -0,0 +1,95 @@
+package semaphore_test
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+	"time"
+
+	semaphores "git.frostfs.info/TrueCloudLab/frostfs-qos/limiting/semaphore"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
+)
+
+const maxWorkers = 10_000_000
+
+type benchmarkSemaphoreMetrics struct {
+	mu sync.Mutex
+
+	acquireDuration,
+	releaseDuration time.Duration
+
+	acquireCount,
+	releaseCount uint64
+}
+
+func (c *benchmarkSemaphoreMetrics) reportAcquire(duration time.Duration) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.acquireDuration += duration
+	c.acquireCount += 1
+}
+
+func (c *benchmarkSemaphoreMetrics) reportRelease(duration time.Duration) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.releaseDuration += duration
+	c.releaseCount += 1
+}
+
+func (c *benchmarkSemaphoreMetrics) getResults() (timePerAcquire, timePerRelease, successRate float64) {
+	timePerAcquire = float64(c.acquireDuration) / float64(c.acquireCount)
+	timePerRelease = float64(c.releaseDuration) / float64(c.releaseCount)
+	successRate = float64(c.releaseCount) / float64(c.acquireCount)
+	return
+}
+
+func BenchmarkSemaphore(b *testing.B) {
+	sizes := []int64{1, 10, 100, 1000, 10000}
+	lockDurations := []time.Duration{0, time.Microsecond, 10 * time.Microsecond, 100 * time.Microsecond}
+
+	for _, size := range sizes {
+		for _, lockDuration := range lockDurations {
+			name := fmt.Sprintf("semaphore_size=%d/lock_duration=%v", size, lockDuration)
+			b.Run(name, func(b *testing.B) {
+				benchmarkSemaphore(b, semaphores.NewSemaphore(size), lockDuration)
+			})
+		}
+	}
+}
+
+func benchmarkSemaphore(b *testing.B, sem *semaphores.Semaphore, lockDuration time.Duration) {
+	var m benchmarkSemaphoreMetrics
+	var g errgroup.Group
+	g.SetLimit(maxWorkers)
+
+	for range b.N {
+		g.Go(func() error {
+			now := time.Now()
+			ok := sem.Acquire()
+			m.reportAcquire(time.Since(now))
+
+			if !ok {
+				return nil
+			}
+
+			time.Sleep(lockDuration)
+
+			now = time.Now()
+			sem.Release()
+			m.reportRelease(time.Since(now))
+
+			return nil
+		})
+	}
+	require.NoError(b, g.Wait())
+
+	require.Equal(b, uint64(b.N), m.acquireCount)
+	require.LessOrEqual(b, m.releaseCount, m.acquireCount)
+
+	timePerAcquire, timePerRelease, successRate := m.getResults()
+
+	b.ReportMetric(timePerAcquire, "acquire-ns/op")
+	b.ReportMetric(timePerRelease, "release-ns/op")
+	b.ReportMetric(successRate, "success-rate")
+}