add a sync.Pool of byte buffers with maximum packet size as cap

ref #217

buffer_pool_test.go

@@ -0,0 +1,26 @@
+package quic
+
+import (
+	"github.com/lucas-clemente/quic-go/protocol"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Buffer Pool", func() {
+	It("returns buffers of correct len and cap", func() {
+		buf := getPacketBuffer()
+		Expect(buf).To(HaveLen(0))
+		Expect(buf).To(HaveCap(int(protocol.MaxPacketSize)))
+	})
+
+	It("zeroes put buffers' length", func() {
+		for i := 0; i < 1000; i++ {
+			buf := getPacketBuffer()
+			putPacketBuffer(buf[0:10])
+			buf = getPacketBuffer()
+			Expect(buf).To(HaveLen(0))
+			Expect(buf).To(HaveCap(int(protocol.MaxPacketSize)))
+		}
+	})
+})