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[code]message ConfState {// The voters in the incoming config. (If the configuration is not joint,// then the outgoing config is empty).repeated uint64 voters = 1;// The learners in the incoming config.repeated uint64 learners = 2;// The voters in the outgoing config.repeated uint64 voters_outgoing = 3;// The nodes that will become learners when the outgoing config is removed.// These nodes are necessarily currently in nodes_joint (or they would have// been added to the incoming config right away).repeated uint64 learners_next = 4;// If set, the config is joint and Raft will automatically transition into// the final config (i.e. remove the outgoing config) when this is safe.optional bool auto_leave = 5 [(gogoproto.nullable) = false];}
这个是raftpd的proto文件中对于ConfState的结构定义，包括集群中的配置状态，voter、learner有多少个，移除了多少个voter等等。
在paxos中，Learners可以看做是所有被确认消息的执行器，一旦有Client的消息请求被Acceptors确认之后，Learners会做相应的处理（如：执行消息内容，发送回复给Client）。Learner可以有多个。Acceptor （Voters）可以看做是消息请求的存储器。一般来说Acceptors是由一定数量的服务组成的，当消息被发送给Acceptor， 只有大部分Acceptor确认接收此消息，该消息才会被存储，否则该消息将被丢弃。
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在confstate.go文件中只有如下一个函数，Equivalent函数，它是ConfState这个接口的一种方法，这个函数字面上理解就是相等，用于判断当前的confstate cs和传入的cs2这个confstate状态参数是否相等。相等就给error类型返回一个nil，表示没有错误；如果不相等就给error返回错误显示不同的地方在哪。其中用到了sort.Slice这个方法，就是一种排序的工具，这里i<j，就是从小到大的方式排序。
[code]// Equivalent returns a nil error if the inputs describe the same configuration.// On mismatch, returns a descriptive error showing the differences.func (cs ConfState) Equivalent(cs2 ConfState) error {cs1 := csorig1, orig2 := cs1, cs2s := func(sl *[]uint64) {*sl = append([]uint64(nil), *sl...)sort.Slice(*sl, func(i, j int) bool { return (*sl)[i] < (*sl)[j] })}for _, cs := range []*ConfState{&cs1, &cs2} {s(&cs.Voters)s(&cs.Learners)s(&cs.VotersOutgoing)s(&cs.LearnersNext)cs.XXX_unrecognized = nil}if !reflect.DeepEqual(cs1, cs2) {return fmt.Errorf(\"ConfStates not equivalent after sorting:\\n%+#v\\n%+#v\\nInputs were:\\n%+#v\\n%+#v\", cs1, cs2, orig1, orig2)}return nil}
下面我们来看看测试，首先定义一个测试案例的结构体， 包括两个参数，第一个是confstate状态参数，有2个state，第二个是是否相等的结果。
然后在测试案例中实例化一个testCases切片存储几种特殊的状态，看看那个Equivalent函数写的对不对，自己写了几种状态
case0：对于confstate中的值进行打乱顺序，但是值的相等的。
case1：对nil和empty的state不敏感
case2：不相等的voters
case3：不相等的learners
case4：对auto_leave 这个配置敏感
[code]func TestConfState_Equivalent(t *testing.T) {type testCase struct {cs, cs2 ConfStateok bool}testCases := []testCase{// Reordered voters and learners.{ConfState{Voters: []uint64{1, 2, 3},Learners: []uint64{5, 4, 6},VotersOutgoing: []uint64{9, 8, 7},LearnersNext: []uint64{10, 20, 15},}, ConfState{Voters: []uint64{1, 2, 3},Learners: []uint64{4, 5, 6},VotersOutgoing: []uint64{7, 9, 8},LearnersNext: []uint64{20, 10, 15},}, true},// Not sensitive to nil vs empty slice.{ConfState{Voters: []uint64{}}, ConfState{Voters: []uint64(nil)}, true},// Non-equivalent voters.{ConfState{Voters: []uint64{1, 2, 3, 4}}, ConfState{Voters: []uint64{2, 1, 3}}, false},{ConfState{Voters: []uint64{1, 4, 3}}, ConfState{Voters: []uint64{2, 1, 3}}, false},// Non-equivalent learners.{ConfState{Voters: []uint64{1, 2, 3, 4}}, ConfState{Voters: []uint64{2, 1, 3}}, false},// Sensitive to AutoLeave flag.{ConfState{AutoLeave: true}, ConfState{}, false},}for _, tc := range testCases {t.Run(\"\", func(t *testing.T) {if err := tc.cs.Equivalent(tc.cs2); (err == nil) != tc.ok {t.Fatalf(\"wanted error: %t, got:\\n%s\", tc.ok, err)}})}}
