Stop leaking goroutines past Control.Stop, consolidate punching in Punchy (#1708)

scheduler_test.go

@@ -0,0 +1,79 @@
+package nebula
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestScheduler_PooledReuse(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	s := NewScheduler[int](16)
+	delivered := make(chan int, 256)
+	go s.Run(ctx, func(item int) { delivered <- item })
+
+	const N = 100
+	for i := 0; i < N; i++ {
+		s.Schedule(ctx, i, time.Millisecond)
+	}
+
+	deadline := time.After(2 * time.Second)
+	got := 0
+	for got < N {
+		select {
+		case <-delivered:
+			got++
+		case <-deadline:
+			t.Fatalf("only %d/%d items delivered", got, N)
+		}
+	}
+}
+
+// BenchmarkScheduler_Schedule reports allocations per Schedule call.
+// In steady state the Scheduler's sync.Pool means we should see zero allocs per op once the pool warms up.
+func BenchmarkScheduler_Schedule(b *testing.B) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	s := NewScheduler[int](b.N)
+	go s.Run(ctx, func(int) {})
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		s.Schedule(ctx, i, time.Microsecond)
+	}
+}
+
+// BenchmarkBareAfterFunc is the comparison baseline.
+// What we'd pay per Schedule if Punchy called time.AfterFunc directly without the pooled Scheduler.
+// Allocates a *time.Timer plus a closure each call.
+func BenchmarkBareAfterFunc(b *testing.B) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	queue := make(chan int, b.N)
+	go func() {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-queue:
+			}
+		}
+	}()
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		i := i
+		time.AfterFunc(time.Microsecond, func() {
+			select {
+			case queue <- i:
+			case <-ctx.Done():
+			}
+		})
+	}
+}