continue hybrid slow start implementation

congestion/hybrid_slow_start_test.go

@@ -1,6 +1,8 @@
 package congestion_test
 
 import (
+	"time"
+
 	"github.com/lucas-clemente/quic-go/congestion"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -44,4 +46,30 @@ var _ = Describe("Hybrid slow start", func() {
 		packet_number++
 		Expect(slowStart.IsEndOfRound(packet_number)).To(BeTrue())
 	})
+
+	It("works with delay", func() {
+		rtt := 60 * time.Millisecond
+		// We expect to detect the increase at +1/8 of the RTT; hence at a typical
+		// RTT of 60ms the detection will happen at 67.5 ms.
+		const kHybridStartMinSamples = 8 // Number of acks required to trigger.
+
+		end_packet_number := uint64(1)
+		end_packet_number++
+		slowStart.StartReceiveRound(end_packet_number)
+
+		// Will not trigger since our lowest RTT in our burst is the same as the long
+		// term RTT provided.
+		for n := 0; n < kHybridStartMinSamples; n++ {
+			Expect(slowStart.ShouldExitSlowStart(rtt+time.Duration(n)*time.Millisecond, rtt, 100)).To(BeFalse())
+		}
+		end_packet_number++
+		slowStart.StartReceiveRound(end_packet_number)
+		for n := 1; n < kHybridStartMinSamples; n++ {
+			Expect(slowStart.ShouldExitSlowStart(rtt+(time.Duration(n)+10)*time.Millisecond, rtt, 100)).To(BeFalse())
+		}
+		// Expect to trigger since all packets in this burst was above the long term
+		// RTT provided.
+		Expect(slowStart.ShouldExitSlowStart(rtt+10*time.Millisecond, rtt, 100)).To(BeTrue())
+	})
+
 })