func TestSimultOpenMany(t *testing.T) {
	// t.Skip("very very slow")

	addrs := 20
	rounds := 10
	if ci.IsRunning() {
		addrs = 10
		rounds = 5
	}
	SubtestSwarm(t, addrs, rounds)
}

func TestSimultOpenMany(t *testing.T) {
	// t.Skip("very very slow")

	addrs := 20
	rounds := 10
	if ci.IsRunning() || runtime.GOOS == "darwin" {
		// osx has a limit of 256 file descriptors
		addrs = 10
		rounds = 5
	}
	SubtestSwarm(t, addrs, rounds)
}

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

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 1)
	s1 := swarms[0]
	defer s1.Close()

	s1.dialT = time.Millisecond * 300 // lower timeout for tests.
	if ci.IsRunning() {
		s1.dialT = time.Second
	}

	// dial to a non-existent peer.
	s2p, s2addr, s2l := newSilentPeer(t)
	go acceptAndHang(s2l)
	defer s2l.Close()
	s1.peers.AddAddr(s2p, s2addr, peer.PermanentAddrTTL)

	before := time.Now()
	if c, err := s1.Dial(ctx, s2p); err == nil {
		defer c.Close()
		t.Fatal("error swarm dialing to unknown peer worked...", err)
	} else {
		t.Log("correctly got error:", err)
	}
	duration := time.Now().Sub(before)

	dt := s1.dialT
	if duration < dt*dialAttempts {
		t.Error("< DialTimeout * dialAttempts not being respected", duration, dt*dialAttempts)
	}
	if duration > 2*dt*dialAttempts {
		t.Error("> 2*DialTimeout * dialAttempts not being respected", duration, 2*dt*dialAttempts)
	}

	if !s1.backf.Backoff(s2p) {
		t.Error("s2 should now be on backoff")
	}
}

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

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)
	s1 := swarms[0]
	s2 := swarms[1]
	defer s1.Close()
	defer s2.Close()
	s1.dialT = time.Millisecond * 300 // lower timeout for tests.
	s2.dialT = time.Millisecond * 300 // lower timeout for tests.
	if ci.IsRunning() {
		s1.dialT = 2 * time.Second
		s2.dialT = 2 * time.Second
	}

	// use another address first, that accept and hang on conns
	_, s2bad, s2l := newSilentPeer(t)
	go acceptAndHang(s2l)
	defer s2l.Close()

	// phase 1 -- dial to non-operational addresses
	s1.peers.AddAddr(s2.local, s2bad, peer.PermanentAddrTTL)

	before := time.Now()
	if c, err := s1.Dial(ctx, s2.local); err == nil {
		t.Fatal("dialing to broken addr worked...", err)
		defer c.Close()
	} else {
		t.Log("correctly got error:", err)
	}
	duration := time.Now().Sub(before)

	dt := s1.dialT
	if duration < dt*dialAttempts {
		t.Error("< DialTimeout * dialAttempts not being respected", duration, dt*dialAttempts)
	}
	if duration > 2*dt*dialAttempts {
		t.Error("> 2*DialTimeout * dialAttempts not being respected", duration, 2*dt*dialAttempts)
	}

	if !s1.backf.Backoff(s2.local) {
		t.Error("s2 should now be on backoff")
	} else {
		t.Log("correctly added to backoff")
	}

	// phase 2 -- add the working address. dial should succeed.
	ifaceAddrs1, err := swarms[1].InterfaceListenAddresses()
	if err != nil {
		t.Fatal(err)
	}
	s1.peers.AddAddrs(s2.local, ifaceAddrs1, peer.PermanentAddrTTL)

	before = time.Now()
	if c, err := s1.Dial(ctx, s2.local); err != nil {
		t.Fatal(err)
	} else {
		c.Close()
		t.Log("correctly connected")
	}
	duration = time.Now().Sub(before)

	if duration >= dt {
		// t.Error("took too long", duration, dt)
	}

	if s1.backf.Backoff(s2.local) {
		t.Error("s2 should no longer be on backoff")
	} else {
		t.Log("correctly cleared backoff")
	}
}

func TestDialBackoff(t *testing.T) {
	// t.Skip("skipping for another test")
	if ci.IsRunning() {
		t.Skip("travis and jenkins will never have fun with this test")
	}

	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)
	s1 := swarms[0]
	s2 := swarms[1]
	defer s1.Close()
	defer s2.Close()

	s1.dialT = time.Second // lower timeout for tests.
	s2.dialT = time.Second // lower timeout for tests.

	s2addrs, err := s2.InterfaceListenAddresses()
	if err != nil {
		t.Fatal(err)
	}
	s1.peers.AddAddrs(s2.local, s2addrs, peer.PermanentAddrTTL)

	// dial to a non-existent peer.
	s3p, s3addr, s3l := newSilentPeer(t)
	go acceptAndHang(s3l)
	defer s3l.Close()
	s1.peers.AddAddr(s3p, s3addr, peer.PermanentAddrTTL)

	// in this test we will:
	//   1) dial 10x to each node.
	//   2) all dials should hang
	//   3) s1->s2 should succeed.
	//   4) s1->s3 should not (and should place s3 on backoff)
	//   5) disconnect entirely
	//   6) dial 10x to each node again
	//   7) s3 dials should all return immediately (except 1)
	//   8) s2 dials should all hang, and succeed
	//   9) last s3 dial ends, unsuccessful

	dialOnlineNode := func(dst peer.ID, times int) <-chan bool {
		ch := make(chan bool)
		for i := 0; i < times; i++ {
			go func() {
				if _, err := s1.Dial(ctx, dst); err != nil {
					t.Error("error dialing", dst, err)
					ch <- false
				} else {
					ch <- true
				}
			}()
		}
		return ch
	}

	dialOfflineNode := func(dst peer.ID, times int) <-chan bool {
		ch := make(chan bool)
		for i := 0; i < times; i++ {
			go func() {
				if c, err := s1.Dial(ctx, dst); err != nil {
					ch <- false
				} else {
					t.Error("succeeded in dialing", dst)
					ch <- true
					c.Close()
				}
			}()
		}
		return ch
	}

	{
		// 1) dial 10x to each node.
		N := 10
		s2done := dialOnlineNode(s2.local, N)
		s3done := dialOfflineNode(s3p, N)

		// when all dials should be done by:
		dialTimeout1x := time.After(s1.dialT)
		// dialTimeout1Ax := time.After(s1.dialT * 2)       // dialAttempts)
		dialTimeout10Ax := time.After(s1.dialT * 2 * 10) // dialAttempts * 10)

		// 2) all dials should hang
		select {
		case <-s2done:
			t.Error("s2 should not happen immediately")
		case <-s3done:
			t.Error("s3 should not happen yet")
		case <-time.After(time.Millisecond):
			// s2 may finish very quickly, so let's get out.
		}

		// 3) s1->s2 should succeed.
		for i := 0; i < N; i++ {
			select {
			case r := <-s2done:
				if !r {
					t.Error("s2 should not fail")
				}
//.........这里部分代码省略.........

func TestPeriodicBootstrap(t *testing.T) {
	// t.Skip("skipping test to debug another")
	if ci.IsRunning() {
		t.Skip("skipping on CI. highly timing dependent")
	}
	if testing.Short() {
		t.SkipNow()
	}

	ctx := context.Background()

	nDHTs := 30
	_, _, dhts := setupDHTS(ctx, nDHTs, t)
	defer func() {
		for i := 0; i < nDHTs; i++ {
			dhts[i].Close()
			defer dhts[i].host.Close()
		}
	}()

	// signal amplifier
	amplify := func(signal chan time.Time, other []chan time.Time) {
		for t := range signal {
			for _, s := range other {
				s <- t
			}
		}
		for _, s := range other {
			close(s)
		}
	}

	signal := make(chan time.Time)
	allSignals := []chan time.Time{}

	var cfg BootstrapConfig
	cfg = DefaultBootstrapConfig
	cfg.Queries = 5

	// kick off periodic bootstrappers with instrumented signals.
	for _, dht := range dhts {
		s := make(chan time.Time)
		allSignals = append(allSignals, s)
		dht.BootstrapOnSignal(cfg, s)
	}
	go amplify(signal, allSignals)

	t.Logf("dhts are not connected.", nDHTs)
	for _, dht := range dhts {
		rtlen := dht.routingTable.Size()
		if rtlen > 0 {
			t.Errorf("routing table for %s should have 0 peers. has %d", dht.self, rtlen)
		}
	}

	for i := 0; i < nDHTs; i++ {
		connect(t, ctx, dhts[i], dhts[(i+1)%len(dhts)])
	}

	t.Logf("dhts are now connected to 1-2 others.", nDHTs)
	for _, dht := range dhts {
		rtlen := dht.routingTable.Size()
		if rtlen > 2 {
			t.Errorf("routing table for %s should have at most 2 peers. has %d", dht.self, rtlen)
		}
	}

	if u.Debug {
		printRoutingTables(dhts)
	}

	t.Logf("bootstrapping them so they find each other", nDHTs)
	signal <- time.Now()

	// this is async, and we dont know when it's finished with one cycle, so keep checking
	// until the routing tables look better, or some long timeout for the failure case.
	waitForWellFormedTables(t, dhts, 7, 10, 20*time.Second)

	if u.Debug {
		printRoutingTables(dhts)
	}
}

func TestRepublisher(t *testing.T) {
	if ci.IsRunning() {
		t.Skip("dont run timing tests in CI")
	}

	ctx := context.TODO()

	pub := make(chan struct{})

	pf := func(ctx context.Context, k key.Key) error {
		pub <- struct{}{}
		return nil
	}

	tshort := time.Millisecond * 50
	tlong := time.Second / 2

	rp := NewRepublisher(ctx, pf, tshort, tlong)
	go rp.Run()

	rp.Update("test")

	// should hit short timeout
	select {
	case <-time.After(tshort * 2):
		t.Fatal("publish didnt happen in time")
	case <-pub:
	}

	cctx, cancel := context.WithCancel(context.Background())

	go func() {
		for {
			rp.Update("a")
			time.Sleep(time.Millisecond * 10)
			select {
			case <-cctx.Done():
				return
			default:
			}
		}
	}()

	select {
	case <-pub:
		t.Fatal("shouldnt have received publish yet!")
	case <-time.After((tlong * 9) / 10):
	}
	select {
	case <-pub:
	case <-time.After(tlong / 2):
		t.Fatal("waited too long for pub!")
	}

	cancel()

	go func() {
		err := rp.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()

	// final pub from closing
	<-pub
}