define a quic.TokenStore interface and provide a LRU implementation

token_store_test.go

@@ -0,0 +1,108 @@
+package quic
+
+import (
+	"fmt"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Token Cache", func() {
+	var s TokenStore
+
+	BeforeEach(func() {
+		s = NewLRUTokenStore(3, 4)
+	})
+
+	mockToken := func(num int) *ClientToken {
+		return &ClientToken{data: []byte(fmt.Sprintf("%d", num))}
+	}
+
+	Context("for a single origin", func() {
+		const origin = "localhost"
+
+		It("adds and gets tokens", func() {
+			s.Put(origin, mockToken(1))
+			s.Put(origin, mockToken(2))
+			Expect(s.Pop(origin)).To(Equal(mockToken(2)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(1)))
+			Expect(s.Pop(origin)).To(BeNil())
+		})
+
+		It("overwrites old tokens", func() {
+			s.Put(origin, mockToken(1))
+			s.Put(origin, mockToken(2))
+			s.Put(origin, mockToken(3))
+			s.Put(origin, mockToken(4))
+			s.Put(origin, mockToken(5))
+			Expect(s.Pop(origin)).To(Equal(mockToken(5)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(4)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(3)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(2)))
+			Expect(s.Pop(origin)).To(BeNil())
+		})
+
+		It("continues after getting a token", func() {
+			s.Put(origin, mockToken(1))
+			s.Put(origin, mockToken(2))
+			s.Put(origin, mockToken(3))
+			Expect(s.Pop(origin)).To(Equal(mockToken(3)))
+			s.Put(origin, mockToken(4))
+			s.Put(origin, mockToken(5))
+			Expect(s.Pop(origin)).To(Equal(mockToken(5)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(4)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(2)))
+			Expect(s.Pop(origin)).To(Equal(mockToken(1)))
+			Expect(s.Pop(origin)).To(BeNil())
+		})
+	})
+
+	Context("for multiple origins", func() {
+		It("adds and gets tokens", func() {
+			s.Put("host1", mockToken(1))
+			s.Put("host2", mockToken(2))
+			Expect(s.Pop("host1")).To(Equal(mockToken(1)))
+			Expect(s.Pop("host1")).To(BeNil())
+			Expect(s.Pop("host2")).To(Equal(mockToken(2)))
+			Expect(s.Pop("host2")).To(BeNil())
+		})
+
+		It("evicts old entries", func() {
+			s.Put("host1", mockToken(1))
+			s.Put("host2", mockToken(2))
+			s.Put("host3", mockToken(3))
+			s.Put("host4", mockToken(4))
+			Expect(s.Pop("host1")).To(BeNil())
+			Expect(s.Pop("host2")).To(Equal(mockToken(2)))
+			Expect(s.Pop("host3")).To(Equal(mockToken(3)))
+			Expect(s.Pop("host4")).To(Equal(mockToken(4)))
+		})
+
+		It("moves old entries to the front, when new tokens are added", func() {
+			s.Put("host1", mockToken(1))
+			s.Put("host2", mockToken(2))
+			s.Put("host3", mockToken(3))
+			s.Put("host1", mockToken(11))
+			// make sure one is evicted
+			s.Put("host4", mockToken(4))
+			Expect(s.Pop("host2")).To(BeNil())
+			Expect(s.Pop("host1")).To(Equal(mockToken(11)))
+			Expect(s.Pop("host1")).To(Equal(mockToken(1)))
+			Expect(s.Pop("host3")).To(Equal(mockToken(3)))
+			Expect(s.Pop("host4")).To(Equal(mockToken(4)))
+		})
+
+		It("deletes hosts that are empty", func() {
+			s.Put("host1", mockToken(1))
+			s.Put("host2", mockToken(2))
+			s.Put("host3", mockToken(3))
+			Expect(s.Pop("host2")).To(Equal(mockToken(2)))
+			Expect(s.Pop("host2")).To(BeNil())
+			// host2 is now empty and should have been deleted, making space for host4
+			s.Put("host4", mockToken(4))
+			Expect(s.Pop("host1")).To(Equal(mockToken(1)))
+			Expect(s.Pop("host3")).To(Equal(mockToken(3)))
+			Expect(s.Pop("host4")).To(Equal(mockToken(4)))
+		})
+	})
+})