1 files changed, 103 insertions, 0 deletions
diff --git a/internal/clock/concurrent_test.go b/internal/clock/concurrent_test.go
new file mode 100644
index 00000000..86283a9b
--- /dev/null
+++ b/internal/clock/concurrent_test.go
@@ -0,0 +1,103 @@
+package clock //nolint:testpackage
+
+import (
+	"sync"
+	"testing"
+)
+
+func keyValue(key int) int {
+	return key*1000003 + 7
+}
+
+func TestConcurrentStress(t *testing.T) {
+	t.Parallel()
+
+	const (
+		maxWeight = 512
+		keys      = 400
+		workers   = 8
+		rounds    = 5000
+	)
+
+	cache := New(maxWeight, func(_ int, _ int) uint64 { return 1 })
+
+	var wg sync.WaitGroup
+
+	for worker := range workers {
+		wg.Go(func() {
+			for i := range rounds {
+				key := (worker*7 + i) % keys
+
+				switch i % 4 {
+				case 0, 1:
+					cache.Add(key, keyValue(key))
+				case 2:
+					if got, ok := cache.Get(key); ok && got != keyValue(key) {
+						t.Errorf("Get(%d) = %d, want %d", key, got, keyValue(key))
+					}
+				case 3:
+					if got, ok := cache.Peek(key); ok && got != keyValue(key) {
+						t.Errorf("Peek(%d) = %d, want %d", key, got, keyValue(key))
+					}
+				}
+			}
+		})
+	}
+
+	wg.Wait()
+
+	checkCache(t, cache)
+
+	if got := cache.Weight(); got > maxWeight {
+		t.Fatalf("weight %d exceeds max %d", got, maxWeight)
+	}
+}
+
+func TestReadDuringEviction(t *testing.T) {
+	t.Parallel()
+
+	const (
+		maxWeight = 8
+		hot       = 64
+		writers   = 2
+		readers   = 6
+		rounds    = 20000
+	)
+
+	cache := New(maxWeight, func(_ int, _ int) uint64 { return 1 })
+
+	var wg sync.WaitGroup
+
+	for range writers {
+		wg.Go(func() {
+			for i := range rounds {
+				key := i % hot
+				cache.Add(key, keyValue(key))
+			}
+		})
+	}
+
+	for range readers {
+		wg.Go(func() {
+			for i := range rounds {
+				key := i % hot
+
+				if got, ok := cache.Get(key); ok && got != keyValue(key) {
+					t.Errorf("Get(%d) = %d, want %d", key, got, keyValue(key))
+				}
+
+				if got, ok := cache.Peek(key); ok && got != keyValue(key) {
+					t.Errorf("Peek(%d) = %d, want %d", key, got, keyValue(key))
+				}
+			}
+		})
+	}
+
+	wg.Wait()
+
+	checkCache(t, cache)
+
+	if got := cache.Weight(); got > maxWeight {
+		t.Fatalf("weight %d exceeds max %d", got, maxWeight)
+	}
+}