# Fabric 1.0源代码笔记 之 gossip（流言算法） #GossipServer（Gossip服务端）
## 1、GossipServer概述
GossipServer相关代码，分布在protos/gossip、gossip/comm目录下。目录结构如下：
* protos/gossip目录：
* message.pb.go，GossipClient接口定义及实现，GossipServer接口定义。
* gossip/comm目录：
* comm.go，Comm接口定义。
* conn.go，connFactory接口定义，以及connectionStore结构体及方法。
* comm_impl.go，commImpl结构体及方法（同时实现GossipServer接口/Comm接口/connFactory接口）。
* demux.go，ChannelDeMultiplexer结构体及方法。
## 2、GossipClient接口定义及实现
### 2.1、GossipClient接口定义
```go
type GossipClient interface {
// GossipStream is the gRPC stream used for sending and receiving messages
GossipStream(ctx context.Context, opts ...grpc.CallOption) (Gossip_GossipStreamClient, error)
// Ping is used to probe a remote peer's aliveness
Ping(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*Empty, error)
}
//代码在protos/gossip/message.pb.go
```
### 2.2、GossipClient接口实现
```go
type gossipClient struct {
cc *grpc.ClientConn
}
func NewGossipClient(cc *grpc.ClientConn) GossipClient {
return &gossipClient{cc}
}
func (c *gossipClient) GossipStream(ctx context.Context, opts ...grpc.CallOption) (Gossip_GossipStreamClient, error) {
stream, err := grpc.NewClientStream(ctx, &_Gossip_serviceDesc.Streams[0], c.cc, "/gossip.Gossip/GossipStream", opts...)
if err != nil {
return nil, err
}
x := &gossipGossipStreamClient{stream}
return x, nil
}
func (c *gossipClient) Ping(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*Empty, error) {
out := new(Empty)
err := grpc.Invoke(ctx, "/gossip.Gossip/Ping", in, out, c.cc, opts...)
if err != nil {
return nil, err
}
return out, nil
}
//代码在protos/gossip/message.pb.go
```
### 2.3、Gossip_GossipStreamClient接口定义及实现
```go
type Gossip_GossipStreamClient interface {
Send(*Envelope) error
Recv() (*Envelope, error)
grpc.ClientStream
}
type gossipGossipStreamClient struct {
grpc.ClientStream
}
func (x *gossipGossipStreamClient) Send(m *Envelope) error {
return x.ClientStream.SendMsg(m)
}
func (x *gossipGossipStreamClient) Recv() (*Envelope, error) {
m := new(Envelope)
if err := x.ClientStream.RecvMsg(m); err != nil {
return nil, err
}
return m, nil
}
//代码在protos/gossip/message.pb.go
```
## 3、GossipServer接口定义
### 3.1、GossipServer接口定义
```go
type GossipServer interface {
// GossipStream is the gRPC stream used for sending and receiving messages
GossipStream(Gossip_GossipStreamServer) error
// Ping is used to probe a remote peer's aliveness
Ping(context.Context, *Empty) (*Empty, error)
}
func RegisterGossipServer(s *grpc.Server, srv GossipServer) {
s.RegisterService(&_Gossip_serviceDesc, srv)
}
func _Gossip_GossipStream_Handler(srv interface{}, stream grpc.ServerStream) error {
return srv.(GossipServer).GossipStream(&gossipGossipStreamServer{stream})
}
func _Gossip_Ping_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
in := new(Empty)
if err := dec(in); err != nil {
return nil, err
}
if interceptor == nil {
return srv.(GossipServer).Ping(ctx, in)
}
info := &grpc.UnaryServerInfo{
Server: srv,
FullMethod: "/gossip.Gossip/Ping",
}
handler := func(ctx context.Context, req interface{}) (interface{}, error) {
return srv.(GossipServer).Ping(ctx, req.(*Empty))
}
return interceptor(ctx, in, info, handler)
}
var _Gossip_serviceDesc = grpc.ServiceDesc{
ServiceName: "gossip.Gossip",
HandlerType: (*GossipServer)(nil),
Methods: []grpc.MethodDesc{
{
MethodName: "Ping",
Handler: _Gossip_Ping_Handler,
},
},
Streams: []grpc.StreamDesc{
{
StreamName: "GossipStream",
Handler: _Gossip_GossipStream_Handler,
ServerStreams: true,
ClientStreams: true,
},
},
Metadata: "gossip/message.proto",
}
//代码在protos/gossip/message.pb.go
```
### 3.2、Gossip_GossipStreamServer接口定义及实现
```go
type Gossip_GossipStreamServer interface {
Send(*Envelope) error
Recv() (*Envelope, error)
grpc.ServerStream
}
type gossipGossipStreamServer struct {
grpc.ServerStream
}
func (x *gossipGossipStreamServer) Send(m *Envelope) error {
return x.ServerStream.SendMsg(m)
}
func (x *gossipGossipStreamServer) Recv() (*Envelope, error) {
m := new(Envelope)
if err := x.ServerStream.RecvMsg(m); err != nil {
return nil, err
}
return m, nil
}
//代码在protos/gossip/message.pb.go
```
## 4、Comm接口/connFactory接口定义
### 4.1、Comm接口定义
```go
type Comm interface {
//返回此实例的 PKI id
GetPKIid() common.PKIidType
//向节点发送消息
Send(msg *proto.SignedGossipMessage, peers ...*RemotePeer)
//探测远程节点是否有响应
Probe(peer *RemotePeer) error
//握手验证远程节点
Handshake(peer *RemotePeer) (api.PeerIdentityType, error)
Accept(common.MessageAcceptor) <-chan proto.ReceivedMessage
//获取怀疑脱机节点的只读通道
PresumedDead() <-chan common.PKIidType
//关闭到某个节点的连接
CloseConn(peer *RemotePeer)
//关闭
Stop()
}
//代码在gossip/comm/comm.go
```
### 4.2、connFactory接口定义
```go
type connFactory interface {
createConnection(endpoint string, pkiID common.PKIidType) (*connection, error)
}
//代码在gossip/comm/conn.go
```
## 5、commImpl结构体及方法（同时实现GossipServer接口/Comm接口/connFactory接口）
### 5.1、commImpl结构体定义
```go
type commImpl struct {
selfCertHash []byte
peerIdentity api.PeerIdentityType
idMapper identity.Mapper
logger *logging.Logger
opts []grpc.DialOption
secureDialOpts func() []grpc.DialOption
connStore *connectionStore
PKIID []byte
deadEndpoints chan common.PKIidType
msgPublisher *ChannelDeMultiplexer
lock *sync.RWMutex
lsnr net.Listener
gSrv *grpc.Server
exitChan chan struct{}
stopWG sync.WaitGroup
subscriptions []chan proto.ReceivedMessage
port int
stopping int32
}
//代码在gossip/comm/comm_impl.go
```
### 5.2、commImpl结构体方法
```go
//conn.serviceConnection()，启动连接服务
func (c *commImpl) GossipStream(stream proto.Gossip_GossipStreamServer) error
//return &proto.Empty{}
func (c *commImpl) Ping(context.Context, *proto.Empty) (*proto.Empty, error)
func (c *commImpl) GetPKIid() common.PKIidType
//向指定节点发送消息
func (c *commImpl) Send(msg *proto.SignedGossipMessage, peers ...*RemotePeer)
//探测远程节点是否有响应，_, err = cl.Ping(context.Background(), &proto.Empty{})
func (c *commImpl) Probe(remotePeer *RemotePeer) error
//握手验证远程节点，_, err = cl.Ping(context.Background(), &proto.Empty{})
func (c *commImpl) Handshake(remotePeer *RemotePeer) (api.PeerIdentityType, error)
func (c *commImpl) Accept(acceptor common.MessageAcceptor) <-chan proto.ReceivedMessage
func (c *commImpl) PresumedDead() <-chan common.PKIidType
func (c *commImpl) CloseConn(peer *RemotePeer)
func (c *commImpl) Stop()
//创建并启动gRPC Server，以及注册GossipServer实例
func NewCommInstanceWithServer(port int, idMapper identity.Mapper, peerIdentity api.PeerIdentityType,
//将GossipServer实例注册至peerServer
func NewCommInstance(s *grpc.Server, cert *tls.Certificate, idStore identity.Mapper,
func extractRemoteAddress(stream stream) string
func readWithTimeout(stream interface{}, timeout time.Duration, address string) (*proto.SignedGossipMessage, error)
//创建gRPC Server，grpc.NewServer(serverOpts...)
func createGRPCLayer(port int) (*grpc.Server, net.Listener, api.PeerSecureDialOpts, []byte)
//创建与服务端连接
func (c *commImpl) createConnection(endpoint string, expectedPKIID common.PKIidType) (*connection, error)
//向指定节点发送消息
func (c *commImpl) sendToEndpoint(peer *RemotePeer, msg *proto.SignedGossipMessage)
//return atomic.LoadInt32(&c.stopping) == int32(1)
func (c *commImpl) isStopping() bool
func (c *commImpl) emptySubscriptions()
func (c *commImpl) authenticateRemotePeer(stream stream) (*proto.ConnectionInfo, error)
func (c *commImpl) disconnect(pkiID common.PKIidType)
func (c *commImpl) createConnectionMsg(pkiID common.PKIidType, certHash []byte, cert api.PeerIdentityType, signer proto.Signer) (*proto.SignedGossipMessage, error)
//代码在gossip/comm/comm_impl.go
```
#### 5.2.1、func NewCommInstanceWithServer(port int, idMapper identity.Mapper, peerIdentity api.PeerIdentityType,secureDialOpts api.PeerSecureDialOpts, dialOpts ...grpc.DialOption) (Comm, error)
创建并启动gRPC Server，以及注册GossipServer实例
```go
func NewCommInstanceWithServer(port int, idMapper identity.Mapper, peerIdentity api.PeerIdentityType,
secureDialOpts api.PeerSecureDialOpts, dialOpts ...grpc.DialOption) (Comm, error) {
var ll net.Listener
var s *grpc.Server
var certHash []byte
if len(dialOpts) == 0 {
//peer.gossip.dialTimeout，gRPC连接拨号的超时
dialOpts = []grpc.DialOption{grpc.WithTimeout(util.GetDurationOrDefault("peer.gossip.dialTimeout", defDialTimeout))}
}
if port > 0 {
//创建gRPC Server，grpc.NewServer(serverOpts...)
s, ll, secureDialOpts, certHash = createGRPCLayer(port)
}
commInst := &commImpl{
selfCertHash: certHash,
PKIID: idMapper.GetPKIidOfCert(peerIdentity),
idMapper: idMapper,
logger: util.GetLogger(util.LoggingCommModule, fmt.Sprintf("%d", port)),
peerIdentity: peerIdentity,
opts: dialOpts,
secureDialOpts: secureDialOpts,
port: port,
lsnr: ll,
gSrv: s,
msgPublisher: NewChannelDemultiplexer(),
lock: &sync.RWMutex{},
deadEndpoints: make(chan common.PKIidType, 100),
stopping: int32(0),
exitChan: make(chan struct{}, 1),
subscriptions: make([]chan proto.ReceivedMessage, 0),
}
commInst.connStore = newConnStore(commInst, commInst.logger)
if port > 0 {
commInst.stopWG.Add(1)
go func() {
defer commInst.stopWG.Done()
s.Serve(ll) //启动gRPC Server
}()
//commInst注册到gRPC Server
proto.RegisterGossipServer(s, commInst)
}
return commInst, nil
}
//代码在gossip/comm/comm_impl.go
```
#### 5.2.2、func NewCommInstance(s *grpc.Server, cert *tls.Certificate, idStore identity.Mapper,peerIdentity api.PeerIdentityType, secureDialOpts api.PeerSecureDialOpts,dialOpts ...grpc.DialOption) (Comm, error)
将GossipServer实例注册至peerServer
```go
func NewCommInstance(s *grpc.Server, cert *tls.Certificate, idStore identity.Mapper,
peerIdentity api.PeerIdentityType, secureDialOpts api.PeerSecureDialOpts,
dialOpts ...grpc.DialOption) (Comm, error) {
dialOpts = append(dialOpts, grpc.WithTimeout(util.GetDurationOrDefault("peer.gossip.dialTimeout", defDialTimeout)))
//构造commImpl
commInst, err := NewCommInstanceWithServer(-1, idStore, peerIdentity, secureDialOpts, dialOpts...)
if cert != nil {
inst := commInst.(*commImpl)
inst.selfCertHash = certHashFromRawCert(cert.Certificate[0])
}
proto.RegisterGossipServer(s, commInst.(*commImpl))
return commInst, nil
}
//代码在gossip/comm/comm_impl.go
```
//创建与服务端连接
#### 5.2.3、func (c *commImpl) createConnection(endpoint string, expectedPKIID common.PKIidType) (*connection, error)
```go
func (c *commImpl) createConnection(endpoint string, expectedPKIID common.PKIidType) (*connection, error) {
var err error
var cc *grpc.ClientConn
var stream proto.Gossip_GossipStreamClient
var pkiID common.PKIidType
var connInfo *proto.ConnectionInfo
var dialOpts []grpc.DialOption
dialOpts = append(dialOpts, c.secureDialOpts()...)
dialOpts = append(dialOpts, grpc.WithBlock())
dialOpts = append(dialOpts, c.opts...)
cc, err = grpc.Dial(endpoint, dialOpts...)
cl := proto.NewGossipClient(cc)
if _, err = cl.Ping(context.Background(), &proto.Empty{}); err != nil {
cc.Close()
return nil, err
}
ctx, cf := context.WithCancel(context.Background())
stream, err = cl.GossipStream(ctx)
connInfo, err = c.authenticateRemotePeer(stream)
pkiID = connInfo.ID
conn := newConnection(cl, cc, stream, nil)
conn.pkiID = pkiID
conn.info = connInfo
conn.logger = c.logger
conn.cancel = cf
h := func(m *proto.SignedGossipMessage) {
c.msgPublisher.DeMultiplex(&ReceivedMessageImpl{
conn: conn,
lock: conn,
SignedGossipMessage: m,
connInfo: connInfo,
})
}
conn.handler = h
return conn, nil
}
//代码在gossip/comm/comm_impl.go
```
## 6、connectionStore和connection结构体及方法
### 6.1、connection结构体及方法
```go
type connection struct {
cancel context.CancelFunc
info *proto.ConnectionInfo
outBuff chan *msgSending
logger *logging.Logger // logger
pkiID common.PKIidType // pkiID of the remote endpoint
handler handler // function to invoke upon a message reception
conn *grpc.ClientConn // gRPC connection to remote endpoint
cl proto.GossipClient // gRPC stub of remote endpoint
clientStream proto.Gossip_GossipStreamClient // client-side stream to remote endpoint
serverStream proto.Gossip_GossipStreamServer // server-side stream to remote endpoint
stopFlag int32 // indicates whether this connection is in process of stopping
stopChan chan struct{} // a method to stop the server-side gRPC call from a different go-routine
sync.RWMutex // synchronizes access to shared variables
}
//构造connection
func newConnection(cl proto.GossipClient, c *grpc.ClientConn, cs proto.Gossip_GossipStreamClient, ss proto.Gossip_GossipStreamServer) *connection
//关闭connection
func (conn *connection) close()
//atomic.LoadInt32(&(conn.stopFlag)) == int32(1)
func (conn *connection) toDie() bool
//conn.outBuff <- m，其中m为msgSending{envelope: msg.Envelope,onErr: onErr,}
func (conn *connection) send(msg *proto.SignedGossipMessage, onErr func(error))
//go conn.readFromStream(errChan, msgChan)、go conn.writeToStream()，同时msg := <-msgChan，conn.handler(msg)
func (conn *connection) serviceConnection() error
//循环不间断从conn.outBuff取数据，然后stream.Send(m.envelope)
func (conn *connection) writeToStream()
//循环不间断envelope, err := stream.Recv()、msg, err := envelope.ToGossipMessage()、msgChan <- msg
func (conn *connection) readFromStream(errChan chan error, msgChan chan *proto.SignedGossipMessage)
//获取conn.serverStream
func (conn *connection) getStream() stream
//代码在gossip/comm/conn.go
```
### 6.2、connectionStore结构体及方法
```go
type connectionStore struct {
logger *logging.Logger // logger
isClosing bool // whether this connection store is shutting down
connFactory connFactory // creates a connection to remote peer
sync.RWMutex // synchronize access to shared variables
pki2Conn map[string]*connection //connection map, key为pkiID，value为connection
destinationLocks map[string]*sync.RWMutex //mapping between pkiIDs and locks,
// used to prevent concurrent connection establishment to the same remote endpoint
}
//构造connectionStore
func newConnStore(connFactory connFactory, logger *logging.Logger) *connectionStore
//从connection map中获取连接，如无则创建并启动连接，并写入connection map中
func (cs *connectionStore) getConnection(peer *RemotePeer) (*connection, error)
//连接数量
func (cs *connectionStore) connNum() int
//关闭指定连接
func (cs *connectionStore) closeConn(peer *RemotePeer)
//关闭所有连接
func (cs *connectionStore) shutdown()
func (cs *connectionStore) onConnected(serverStream proto.Gossip_GossipStreamServer, connInfo *proto.ConnectionInfo) *connection
//注册连接
func (cs *connectionStore) registerConn(connInfo *proto.ConnectionInfo, serverStream proto.Gossip_GossipStreamServer) *connection
//关闭指定连接
func (cs *connectionStore) closeByPKIid(pkiID common.PKIidType)
//代码在gossip/comm/conn.go
```
#### 6.2.1、func (cs *connectionStore) getConnection(peer *RemotePeer) (*connection, error)
```go
func (cs *connectionStore) getConnection(peer *RemotePeer) (*connection, error) {
cs.RLock()
isClosing := cs.isClosing
cs.RUnlock()
pkiID := peer.PKIID
endpoint := peer.Endpoint
cs.Lock()
destinationLock, hasConnected := cs.destinationLocks[string(pkiID)]
if !hasConnected {
destinationLock = &sync.RWMutex{}
cs.destinationLocks[string(pkiID)] = destinationLock
}
cs.Unlock()
destinationLock.Lock()
cs.RLock()
//从connection map中获取
conn, exists := cs.pki2Conn[string(pkiID)]
if exists {
cs.RUnlock()
destinationLock.Unlock()
return conn, nil
}
cs.RUnlock()
//创建连接
createdConnection, err := cs.connFactory.createConnection(endpoint, pkiID)
destinationLock.Unlock()
conn = createdConnection
cs.pki2Conn[string(createdConnection.pkiID)] = conn
go conn.serviceConnection() //启动连接的消息接收处理、以及向对方节点发送消息
return conn, nil
}
//代码在gossip/comm/conn.go
```
## 7、ChannelDeMultiplexer结构体及方法（多路复用器）
```go
type ChannelDeMultiplexer struct {
channels []*channel
lock *sync.RWMutex
closed int32
}
//构造ChannelDeMultiplexer
func NewChannelDemultiplexer() *ChannelDeMultiplexer
//atomic.LoadInt32(&m.closed) == int32(1)
func (m *ChannelDeMultiplexer) isClosed() bool
//关闭
func (m *ChannelDeMultiplexer) Close()
//添加通道
func (m *ChannelDeMultiplexer) AddChannel(predicate common.MessageAcceptor) chan interface{}
//挨个通道发送消息
func (m *ChannelDeMultiplexer) DeMultiplex(msg interface{})
//代码在
```
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