Golang context.Background函数代码示例

func ExampleEventLogger() {
	{
		log := EventLogger(nil)
		e := log.EventBegin(context.Background(), "dial")
		e.Done()
	}
	{
		log := EventLogger(nil)
		e := log.EventBegin(context.Background(), "dial")
		_ = e.Close() // implements io.Closer for convenience
	}
}

func TestSecureClose(t *testing.T) {
	// t.Skip("Skipping in favor of another test")

	ctx := context.Background()
	c1, c2, p1, p2 := setupSingleConn(t, ctx)

	done := make(chan error)
	go secureHandshake(t, ctx, p1.PrivKey, c1, done)
	go secureHandshake(t, ctx, p2.PrivKey, c2, done)

	for i := 0; i < 2; i++ {
		if err := <-done; err != nil {
			t.Fatal(err)
		}
	}

	testOneSendRecv(t, c1, c2)

	c1.Close()
	testNotOneSendRecv(t, c1, c2)

	c2.Close()
	testNotOneSendRecv(t, c1, c2)
	testNotOneSendRecv(t, c2, c1)

}

func TestFilterBounds(t *testing.T) {
	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)

	conns := make(chan struct{}, 8)
	swarms[0].SetConnHandler(func(conn *Conn) {
		conns <- struct{}{}
	})

	// Address that we wont be dialing from
	_, block, err := net.ParseCIDR("192.0.0.1/8")
	if err != nil {
		t.Fatal(err)
	}

	// set filter on both sides, shouldnt matter
	swarms[1].Filters.AddDialFilter(block)
	swarms[0].Filters.AddDialFilter(block)

	connectSwarms(t, ctx, swarms)

	select {
	case <-time.After(time.Second):
		t.Fatal("should have gotten connection")
	case <-conns:
		t.Log("got connect")
	}
}

func TestDialBadAddrs(t *testing.T) {

	m := func(s string) ma.Multiaddr {
		maddr, err := ma.NewMultiaddr(s)
		if err != nil {
			t.Fatal(err)
		}
		return maddr
	}

	ctx := context.Background()
	s := makeSwarms(ctx, t, 1)[0]

	test := func(a ma.Multiaddr) {
		p := testutil.RandPeerIDFatal(t)
		s.peers.AddAddr(p, a, peer.PermanentAddrTTL)
		if _, err := s.Dial(ctx, p); err == nil {
			t.Error("swarm should not dial: %s", m)
		}
	}

	test(m("/ip6/fe80::1"))                // link local
	test(m("/ip6/fe80::100"))              // link local
	test(m("/ip4/127.0.0.1/udp/1234/utp")) // utp
}

func TestAddrBlocking(t *testing.T) {
	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)

	swarms[0].SetConnHandler(func(conn *Conn) {
		t.Fatal("no connections should happen!")
	})

	_, block, err := net.ParseCIDR("127.0.0.1/8")
	if err != nil {
		t.Fatal(err)
	}

	swarms[1].Filters.AddDialFilter(block)

	swarms[1].peers.AddAddr(swarms[0].LocalPeer(), swarms[0].ListenAddresses()[0], peer.PermanentAddrTTL)
	_, err = swarms[1].Dial(ctx, swarms[0].LocalPeer())
	if err == nil {
		t.Fatal("dial should have failed")
	}

	swarms[0].peers.AddAddr(swarms[1].LocalPeer(), swarms[1].ListenAddresses()[0], peer.PermanentAddrTTL)
	_, err = swarms[0].Dial(ctx, swarms[1].LocalPeer())
	if err == nil {
		t.Fatal("dial should have failed")
	}
}

func TestConnHandler(t *testing.T) {
	// t.Skip("skipping for another test")
	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 5)

	gotconn := make(chan struct{}, 10)
	swarms[0].SetConnHandler(func(conn *Conn) {
		gotconn <- struct{}{}
	})

	connectSwarms(t, ctx, swarms)

	<-time.After(time.Millisecond)
	// should've gotten 5 by now.

	swarms[0].SetConnHandler(nil)

	expect := 4
	for i := 0; i < expect; i++ {
		select {
		case <-time.After(time.Second):
			t.Fatal("failed to get connections")
		case <-gotconn:
		}
	}

	select {
	case <-gotconn:
		t.Fatalf("should have connected to %d swarms", expect)
	default:
	}
}

func TestSimultOpen(t *testing.T) {
	// t.Skip("skipping for another test")
	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)

	// connect everyone
	{
		var wg sync.WaitGroup
		connect := func(s *Swarm, dst peer.ID, addr ma.Multiaddr) {
			// copy for other peer
			log.Debugf("TestSimultOpen: connecting: %s --> %s (%s)", s.local, dst, addr)
			s.peers.AddAddr(dst, addr, peer.PermanentAddrTTL)
			if _, err := s.Dial(ctx, dst); err != nil {
				t.Fatal("error swarm dialing to peer", err)
			}
			wg.Done()
		}

		log.Info("Connecting swarms simultaneously.")
		wg.Add(2)
		go connect(swarms[0], swarms[1].local, swarms[1].ListenAddresses()[0])
		go connect(swarms[1], swarms[0].local, swarms[0].ListenAddresses()[0])
		wg.Wait()
	}

	for _, s := range swarms {
		s.Close()
	}
}

func TestNoTimeout(t *testing.T) {
	ctx := context.Background()
	resp, err := doRequest(ctx)

	if resp == nil || err != nil {
		t.Fatalf("error received from client: %v %v", err, resp)
	}
}

func TestLimitedStreams(t *testing.T) {
	mn, err := FullMeshConnected(context.Background(), 2)
	if err != nil {
		t.Fatal(err)
	}

	var wg sync.WaitGroup
	messages := 4
	messageSize := 500
	handler := func(s inet.Stream) {
		b := make([]byte, messageSize)
		for i := 0; i < messages; i++ {
			if _, err := io.ReadFull(s, b); err != nil {
				log.Fatal(err)
			}
			if !bytes.Equal(b[:4], []byte("ping")) {
				log.Fatal("bytes mismatch")
			}
			wg.Done()
		}
		s.Close()
	}

	hosts := mn.Hosts()
	for _, h := range mn.Hosts() {
		h.SetStreamHandler(protocol.TestingID, handler)
	}

	peers := mn.Peers()
	links := mn.LinksBetweenPeers(peers[0], peers[1])
	//  1000 byte per second bandwidth
	bps := float64(1000)
	opts := links[0].Options()
	opts.Bandwidth = bps
	for _, link := range links {
		link.SetOptions(opts)
	}

	s, err := hosts[0].NewStream(protocol.TestingID, hosts[1].ID())
	if err != nil {
		t.Fatal(err)
	}

	filler := make([]byte, messageSize-4)
	data := append([]byte("ping"), filler...)
	before := time.Now()
	for i := 0; i < messages; i++ {
		wg.Add(1)
		if _, err := s.Write(data); err != nil {
			panic(err)
		}
	}

	wg.Wait()
	if !within(time.Since(before), time.Duration(time.Second*2), time.Second/3) {
		t.Fatal("Expected 2ish seconds but got ", time.Since(before))
	}
}

func TestSimultDials(t *testing.T) {
	// t.Skip("skipping for another test")
	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)

	// connect everyone
	{
		var wg sync.WaitGroup
		connect := func(s *Swarm, dst peer.ID, addr ma.Multiaddr) {
			// copy for other peer
			log.Debugf("TestSimultOpen: connecting: %s --> %s (%s)", s.local, dst, addr)
			s.peers.AddAddr(dst, addr, peer.TempAddrTTL)
			if _, err := s.Dial(ctx, dst); err != nil {
				t.Fatal("error swarm dialing to peer", err)
			}
			wg.Done()
		}

		ifaceAddrs0, err := swarms[0].InterfaceListenAddresses()
		if err != nil {
			t.Fatal(err)
		}
		ifaceAddrs1, err := swarms[1].InterfaceListenAddresses()
		if err != nil {
			t.Fatal(err)
		}

		log.Info("Connecting swarms simultaneously.")
		for i := 0; i < 10; i++ { // connect 10x for each.
			wg.Add(2)
			go connect(swarms[0], swarms[1].local, ifaceAddrs1[0])
			go connect(swarms[1], swarms[0].local, ifaceAddrs0[0])
		}
		wg.Wait()
	}

	// should still just have 1, at most 2 connections :)
	c01l := len(swarms[0].ConnectionsToPeer(swarms[1].local))
	if c01l > 2 {
		t.Error("0->1 has", c01l)
	}
	c10l := len(swarms[1].ConnectionsToPeer(swarms[0].local))
	if c10l > 2 {
		t.Error("1->0 has", c10l)
	}

	for _, s := range swarms {
		s.Close()
	}
}

func ExampleWithTimeout() {
	// Pass a context with a timeout to tell a blocking function that it
	// should abandon its work after the timeout elapses.
	ctx, _ := context.WithTimeout(context.Background(), 100*time.Millisecond)
	select {
	case <-time.After(200 * time.Millisecond):
		fmt.Println("overslept")
	case <-ctx.Done():
		fmt.Println(ctx.Err()) // prints "context deadline exceeded"
	}
	// Output:
	// context deadline exceeded
}

func TestCancelAfterRequest(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())

	resp, err := doRequest(ctx)

	// Cancel before reading the body.
	// Request.Body should still be readable after the context is canceled.
	cancel()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil || string(b) != requestBody {
		t.Fatalf("could not read body: %q %v", b, err)
	}
}

func TestHostSimple(t *testing.T) {

	ctx := context.Background()
	h1 := testutil.GenHostSwarm(t, ctx)
	h2 := testutil.GenHostSwarm(t, ctx)
	defer h1.Close()
	defer h2.Close()

	h2pi := h2.Peerstore().PeerInfo(h2.ID())
	if err := h1.Connect(ctx, h2pi); err != nil {
		t.Fatal(err)
	}

	piper, pipew := io.Pipe()
	h2.SetStreamHandler(protocol.TestingID, func(s inet.Stream) {
		defer s.Close()
		w := io.MultiWriter(s, pipew)
		io.Copy(w, s) // mirror everything
	})

	s, err := h1.NewStream(protocol.TestingID, h2pi.ID)
	if err != nil {
		t.Fatal(err)
	}

	// write to the stream
	buf1 := []byte("abcdefghijkl")
	if _, err := s.Write(buf1); err != nil {
		t.Fatal(err)
	}

	// get it from the stream (echoed)
	buf2 := make([]byte, len(buf1))
	if _, err := io.ReadFull(s, buf2); err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(buf1, buf2) {
		t.Fatal("buf1 != buf2 -- %x != %x", buf1, buf2)
	}

	// get it from the pipe (tee)
	buf3 := make([]byte, len(buf1))
	if _, err := io.ReadFull(piper, buf3); err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(buf1, buf3) {
		t.Fatal("buf1 != buf3 -- %x != %x", buf1, buf3)
	}
}

func TestContextContainsMetadata(t *testing.T) {
	t.Parallel()

	m := Metadata{"foo": "bar"}
	ctx := ContextWithLoggable(context.Background(), m)
	got, err := MetadataFromContext(ctx)
	if err != nil {
		t.Fatal(err)
	}

	_, exists := got["foo"]
	if !exists {
		t.Fail()
	}
}

func TestCancel(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	go func() {
		time.Sleep(requestDuration / 2)
		cancel()
	}()

	resp, err := doRequest(ctx)

	if resp != nil || err == nil {
		t.Fatalf("expected error, didn't get one. resp: %v", resp)
	}
	if err != ctx.Err() {
		t.Fatalf("expected error from context but got: %v", err)
	}
}