github.com/yinchengtsinghua/golang-Eos-dpos-Ethereum@v0.0.0-20190121132951-92cc4225ed8e/p2p/dial_test.go

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//版权所有2015 Go Ethereum作者
//此文件是Go以太坊库的一部分。
//
//Go-Ethereum库是免费软件：您可以重新分发它和/或修改
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//自由软件基金会，或者许可证的第3版，或者
//（由您选择）任何更高版本。
//
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//但没有任何保证；甚至没有
//适销性或特定用途的适用性。见
//GNU较低的通用公共许可证，了解更多详细信息。
//
//你应该收到一份GNU较低级别的公共许可证副本
//以及Go以太坊图书馆。如果没有，请参见<http://www.gnu.org/licenses/>。

package p2p

import (
	"encoding/binary"
	"net"
	"reflect"
	"testing"
	"time"

	"github.com/davecgh/go-spew/spew"
	"github.com/ethereum/go-ethereum/p2p/discover"
	"github.com/ethereum/go-ethereum/p2p/netutil"
)

func init() {
	spew.Config.Indent = "\t"
}

type dialtest struct {
init   *dialstate //测试前后的状态。
	rounds []round
}

type round struct {
peers []*Peer //当前对等集
done  []task  //这一轮完成的任务
new   []task  //结果必须与此匹配
}

func runDialTest(t *testing.T, test dialtest) {
	var (
		vtime   time.Time
		running int
	)
	pm := func(ps []*Peer) map[discover.NodeID]*Peer {
		m := make(map[discover.NodeID]*Peer)
		for _, p := range ps {
			m[p.rw.id] = p
		}
		return m
	}
	for i, round := range test.rounds {
		for _, task := range round.done {
			running--
			if running < 0 {
				panic("running task counter underflow")
			}
			test.init.taskDone(task, vtime)
		}

		new := test.init.newTasks(running, pm(round.peers), vtime)
		if !sametasks(new, round.new) {
			t.Errorf("round %d: new tasks mismatch:\ngot %v\nwant %v\nstate: %v\nrunning: %v\n",
				i, spew.Sdump(new), spew.Sdump(round.new), spew.Sdump(test.init), spew.Sdump(running))
		}

//每轮时间提前16秒。
		vtime = vtime.Add(16 * time.Second)
		running += len(new)
	}
}

type fakeTable []*discover.Node

func (t fakeTable) Self() *discover.Node                     { return new(discover.Node) }
func (t fakeTable) Close()                                   {}
func (t fakeTable) Lookup(discover.NodeID) []*discover.Node  { return nil }
func (t fakeTable) Resolve(discover.NodeID) *discover.Node   { return nil }
func (t fakeTable) ReadRandomNodes(buf []*discover.Node) int { return copy(buf, t) }

//此测试检查是否从发现结果启动动态拨号。
func TestDialStateDynDial(t *testing.T) {
	runDialTest(t, dialtest{
		init: newDialState(nil, nil, fakeTable{}, 5, nil),
		rounds: []round{
//将启动发现查询。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
				new: []task{&discoverTask{}},
			},
//动态拨号完成后启动。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
				done: []task{
					&discoverTask{results: []*discover.Node{
{ID: uintID(2)}, //这个已经连接，没有拨号。
						{ID: uintID(3)},
						{ID: uintID(4)},
						{ID: uintID(5)},
{ID: uintID(6)}, //因为最大动态拨号是5，所以不尝试使用。
{ID: uintID(7)}, //…
					}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(3)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
			},
//有些拨号盘已完成，但尚未启动新的拨号盘，因为
//活动拨号计数和动态对等计数之和=MaxDynDials。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(3)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(3)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
				},
			},
//此轮中没有启动新的拨号任务，因为
//已达到MaxDynDials。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(3)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
				new: []task{
					&waitExpireTask{Duration: 14 * time.Second},
				},
			},
//在这一轮中，ID为2的对等机将关闭。查询
//重新使用上次发现查找的结果。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(3)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(6)}},
				},
			},
//更多的对等端（3，4）停止并拨出ID 6完成。
//重新使用发现查找的最后一个查询结果
//因为需要更多的候选人，所以产生了一个新的候选人。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(6)}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(7)}},
					&discoverTask{},
				},
			},
//对等7已连接，但仍然没有足够的动态对等
//（5个中有4个）。但是，发现已经在运行，因此请确保
//没有新的开始。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(7)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(7)}},
				},
			},
//使用空集完成正在运行的节点发现。一种新的查找
//应立即请求。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(7)}},
				},
				done: []task{
					&discoverTask{},
				},
				new: []task{
					&discoverTask{},
				},
			},
		},
	})
}

//测试在没有连接对等机的情况下是否拨号引导节点，否则不拨号。
func TestDialStateDynDialBootnode(t *testing.T) {
	bootnodes := []*discover.Node{
		{ID: uintID(1)},
		{ID: uintID(2)},
		{ID: uintID(3)},
	}
	table := fakeTable{
		{ID: uintID(4)},
		{ID: uintID(5)},
		{ID: uintID(6)},
		{ID: uintID(7)},
		{ID: uintID(8)},
	}
	runDialTest(t, dialtest{
		init: newDialState(nil, bootnodes, table, 5, nil),
		rounds: []round{
//已尝试2个动态拨号，启动节点挂起回退间隔
			{
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
					&discoverTask{},
				},
			},
//没有拨号成功，引导节点仍挂起回退间隔
			{
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
			},
//没有拨号成功，引导节点仍挂起回退间隔
			{},
//没有成功的拨号，尝试了2个动态拨号，同时达到了回退间隔，还尝试了1个引导节点。
			{
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
			},
//没有拨号成功，尝试第二个bootnode
			{
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(2)}},
				},
			},
//没有拨号成功，尝试第三个启动节点
			{
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(2)}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(3)}},
				},
			},
//没有拨号成功，再次尝试第一个bootnode，重试过期的随机节点
			{
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(3)}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
			},
//随机拨号成功，不再尝试启动节点
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
			},
		},
	})
}

func TestDialStateDynDialFromTable(t *testing.T) {
//此表始终返回相同的随机节点
//按照下面给出的顺序。
	table := fakeTable{
		{ID: uintID(1)},
		{ID: uintID(2)},
		{ID: uintID(3)},
		{ID: uintID(4)},
		{ID: uintID(5)},
		{ID: uintID(6)},
		{ID: uintID(7)},
		{ID: uintID(8)},
	}

	runDialTest(t, dialtest{
		init: newDialState(nil, nil, table, 10, nil),
		rounds: []round{
//readrandomnodes返回的8个节点中有5个被拨号。
			{
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(2)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(3)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
					&discoverTask{},
				},
			},
//拨号节点1、2成功。启动查找中的拨号。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(2)}},
					&discoverTask{results: []*discover.Node{
						{ID: uintID(10)},
						{ID: uintID(11)},
						{ID: uintID(12)},
					}},
				},
				new: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(10)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(11)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(12)}},
					&discoverTask{},
				},
			},
//拨号节点3、4、5失败。查找中的拨号成功。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(10)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(11)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(12)}},
				},
				done: []task{
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(3)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(5)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(10)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(11)}},
					&dialTask{flags: dynDialedConn, dest: &discover.Node{ID: uintID(12)}},
				},
			},
//正在等待到期。没有启动waitexpiretask，因为
//发现查询仍在运行。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(10)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(11)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(12)}},
				},
			},
//节点3,4不会再次尝试，因为只有前两个
//返回的随机节点（节点1,2）将被尝试
//已经连接。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(10)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(11)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(12)}},
				},
			},
		},
	})
}

//此测试检查是否未拨出与NetRestrict列表不匹配的候选人。
func TestDialStateNetRestrict(t *testing.T) {
//此表始终返回相同的随机节点
//按照下面给出的顺序。
	table := fakeTable{
		{ID: uintID(1), IP: net.ParseIP("127.0.0.1")},
		{ID: uintID(2), IP: net.ParseIP("127.0.0.2")},
		{ID: uintID(3), IP: net.ParseIP("127.0.0.3")},
		{ID: uintID(4), IP: net.ParseIP("127.0.0.4")},
		{ID: uintID(5), IP: net.ParseIP("127.0.2.5")},
		{ID: uintID(6), IP: net.ParseIP("127.0.2.6")},
		{ID: uintID(7), IP: net.ParseIP("127.0.2.7")},
		{ID: uintID(8), IP: net.ParseIP("127.0.2.8")},
	}
	restrict := new(netutil.Netlist)
	restrict.Add("127.0.2.0/24")

	runDialTest(t, dialtest{
		init: newDialState(nil, nil, table, 10, restrict),
		rounds: []round{
			{
				new: []task{
					&dialTask{flags: dynDialedConn, dest: table[4]},
					&discoverTask{},
				},
			},
		},
	})
}

//此测试检查是否启动了静态拨号。
func TestDialStateStaticDial(t *testing.T) {
	wantStatic := []*discover.Node{
		{ID: uintID(1)},
		{ID: uintID(2)},
		{ID: uintID(3)},
		{ID: uintID(4)},
		{ID: uintID(5)},
	}

	runDialTest(t, dialtest{
		init: newDialState(wantStatic, nil, fakeTable{}, 0, nil),
		rounds: []round{
//为以下节点启动静态拨号：
//尚未连接。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
				new: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(3)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
			},
//由于所有静态任务
//节点已连接或仍在拨号。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
				},
				done: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(3)}},
				},
			},
//没有启动新的拨号任务，因为所有的拨号任务都是静态的
//节点现在已连接。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(4)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(5)}},
				},
				done: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(4)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(5)}},
				},
				new: []task{
					&waitExpireTask{Duration: 14 * time.Second},
				},
			},
//等待一轮拨号历史记录过期，不应生成新任务。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(4)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(5)}},
				},
			},
//如果一个静态节点被删除，它应该立即被重新拨号，
//不管它最初是静态的还是动态的。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(5)}},
				},
				new: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(2)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(4)}},
				},
			},
		},
	})
}

//此测试检查静态对等点如果被重新添加到静态列表中，是否会立即重新启用。
func TestDialStaticAfterReset(t *testing.T) {
	wantStatic := []*discover.Node{
		{ID: uintID(1)},
		{ID: uintID(2)},
	}

	rounds := []round{
//为尚未连接的节点启动静态拨号。
		{
			peers: nil,
			new: []task{
				&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(1)}},
				&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(2)}},
			},
		},
//没有新的拨号任务，所有对等端都已连接。
		{
			peers: []*Peer{
				{rw: &conn{flags: staticDialedConn, id: uintID(1)}},
				{rw: &conn{flags: staticDialedConn, id: uintID(2)}},
			},
			done: []task{
				&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(1)}},
				&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(2)}},
			},
			new: []task{
				&waitExpireTask{Duration: 30 * time.Second},
			},
		},
	}
	dTest := dialtest{
		init:   newDialState(wantStatic, nil, fakeTable{}, 0, nil),
		rounds: rounds,
	}
	runDialTest(t, dTest)
	for _, n := range wantStatic {
		dTest.init.removeStatic(n)
		dTest.init.addStatic(n)
	}
//如果不删除同龄人，他们将被视为最近拨打过电话。
	runDialTest(t, dTest)
}

//此测试检查过去的拨号是否有一段时间没有重试。
func TestDialStateCache(t *testing.T) {
	wantStatic := []*discover.Node{
		{ID: uintID(1)},
		{ID: uintID(2)},
		{ID: uintID(3)},
	}

	runDialTest(t, dialtest{
		init: newDialState(wantStatic, nil, fakeTable{}, 0, nil),
		rounds: []round{
//为以下节点启动静态拨号：
//尚未连接。
			{
				peers: nil,
				new: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(2)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(3)}},
				},
			},
//由于所有静态任务
//节点已连接或仍在拨号。
			{
				peers: []*Peer{
					{rw: &conn{flags: staticDialedConn, id: uintID(1)}},
					{rw: &conn{flags: staticDialedConn, id: uintID(2)}},
				},
				done: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(1)}},
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(2)}},
				},
			},
//启动补救任务以等待节点3的历史记录
//条目将过期。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
				done: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(3)}},
				},
				new: []task{
					&waitExpireTask{Duration: 14 * time.Second},
				},
			},
//仍在等待节点3的条目在缓存中过期。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
			},
//节点3的缓存项已过期并重试。
			{
				peers: []*Peer{
					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
				},
				new: []task{
					&dialTask{flags: staticDialedConn, dest: &discover.Node{ID: uintID(3)}},
				},
			},
		},
	})
}

func TestDialResolve(t *testing.T) {
	resolved := discover.NewNode(uintID(1), net.IP{127, 0, 55, 234}, 3333, 4444)
	table := &resolveMock{answer: resolved}
	state := newDialState(nil, nil, table, 0, nil)

//检查是否使用不完整的ID生成任务。
	dest := discover.NewNode(uintID(1), nil, 0, 0)
	state.addStatic(dest)
	tasks := state.newTasks(0, nil, time.Time{})
	if !reflect.DeepEqual(tasks, []task{&dialTask{flags: staticDialedConn, dest: dest}}) {
		t.Fatalf("expected dial task, got %#v", tasks)
	}

//现在运行任务，它应该解析一次ID。
	config := Config{Dialer: TCPDialer{&net.Dialer{Deadline: time.Now().Add(-5 * time.Minute)}}}
	srv := &Server{ntab: table, Config: config}
	tasks[0].Do(srv)
	if !reflect.DeepEqual(table.resolveCalls, []discover.NodeID{dest.ID}) {
		t.Fatalf("wrong resolve calls, got %v", table.resolveCalls)
	}

//向拨号程序报告完成情况，拨号程序应更新静态节点记录。
	state.taskDone(tasks[0], time.Now())
	if state.static[uintID(1)].dest != resolved {
		t.Fatalf("state.dest not updated")
	}
}

//比较任务列表，但不关心顺序。
func sametasks(a, b []task) bool {
	if len(a) != len(b) {
		return false
	}
next:
	for _, ta := range a {
		for _, tb := range b {
			if reflect.DeepEqual(ta, tb) {
				continue next
			}
		}
		return false
	}
	return true
}

func uintID(i uint32) discover.NodeID {
	var id discover.NodeID
	binary.BigEndian.PutUint32(id[:], i)
	return id
}

//实现TestDialResolve的discovertable
type resolveMock struct {
	resolveCalls []discover.NodeID
	answer       *discover.Node
}

func (t *resolveMock) Resolve(id discover.NodeID) *discover.Node {
	t.resolveCalls = append(t.resolveCalls, id)
	return t.answer
}

func (t *resolveMock) Self() *discover.Node                     { return new(discover.Node) }
func (t *resolveMock) Close()                                   {}
func (t *resolveMock) Bootstrap([]*discover.Node)               {}
func (t *resolveMock) Lookup(discover.NodeID) []*discover.Node  { return nil }
func (t *resolveMock) ReadRandomNodes(buf []*discover.Node) int { return 0 }