Fabric 1.0源代码笔记 之 events（事件服务）
1、events概述
events代码分布在events/producer和events/consumer目录下，目录结构如下：
- events/producer目录：生产者，提供事件服务器。
- producer.go，EventsServer结构体及方法。
- events.go，eventProcessor结构体及方法，handlerList接口及实现。
- handler.go，handler结构体及方法。
- events/consumer目录：消费者，获取事件。
2、producer（生产者）
2.1、EventsServer结构体及方法
EventsServer结构体定义：（空）
type EventsServer struct {
}
//全局事件服务器globalEventsServer
var globalEventsServer *EventsServer
//代码在events/producer/producer.go
涉及方法如下：
//globalEventsServer创建并初始化
func NewEventsServer(bufferSize uint, timeout time.Duration) *EventsServer
//接收消息并处理
func (p *EventsServer) Chat(stream pb.Events_ChatServer) error
//代码在events/producer/producer.go
2.2、eventProcessor结构体及方法（事件处理器）
eventProcessor结构体定义：
type eventProcessor struct {
sync.RWMutex
eventConsumers map[pb.EventType]handlerList
eventChannel chan *pb.Event
timeout time.Duration //生产者发送事件的超时时间
}
//全局事件处理器gEventProcessor
var gEventProcessor *eventProcessor
//代码在events/producer/events.go
涉及方法如下：
func (ep *eventProcessor) start() //启动并处理事件，从ep.eventChannel通道接收消息并处理
//初始化gEventProcessor，并添加消息类型，并发启动start()
func initializeEvents(bufferSize uint, tout time.Duration)
//添加消息类型至gEventProcessor.eventConsumers，并初始化handlerList
func AddEventType(eventType pb.EventType) error
//绑定Interest和handler
func registerHandler(ie *pb.Interest, h *handler) error
//取消绑定Interest和handler
func deRegisterHandler(ie *pb.Interest, h *handler) error
func Send(e *pb.Event) error //Event发送至gEventProcessor.eventChannel
//代码在events/producer/events.go
2.3、handlerList接口及实现
2.3.1、handlerList接口定义（handler列表）
type handlerList interface {
add(ie *pb.Interest, h *handler) (bool, error) //添加
del(ie *pb.Interest, h *handler) (bool, error) //删除
foreach(ie *pb.Event, action func(h *handler)) //遍历
}
//代码在events/producer/events.go
2.3.2、handlerList接口实现
type genericHandlerList struct {
sync.RWMutex
handlers map[*handler]bool
}
type chaincodeHandlerList struct {
sync.RWMutex
handlers map[string]map[string]map[*handler]bool
}
//代码在events/producer/events.go
2.4、handler结构体及方法
handler结构体定义：
type handler struct {
ChatStream pb.Events_ChatServer
interestedEvents map[string]*pb.Interest
}
//代码在events/producer/handler.go
补充pb.Events_ChatServer和pb.Interest（关注）定义：
type Events_ChatServer interface {
Send(*Event) error
Recv() (*SignedEvent, error)
grpc.ServerStream //type ServerStream interface
}
Interest struct {
EventType EventType //type EventType int32
RegInfo isInterest_RegInfo //type isInterest_RegInfo interface
ChainID string
}
type EventType int32
const (
EventType_REGISTER EventType = 0
EventType_BLOCK EventType = 1
EventType_CHAINCODE EventType = 2
EventType_REJECTION EventType = 3
)
//代码在protos/peer/events.pb.go
handler结构体方法如下：
func newEventHandler(stream pb.Events_ChatServer) (*handler, error) //构造handler
func (d *handler) Stop() error //停止handler，取消所有handler注册
func getInterestKey(interest pb.Interest) string //获取interest.EventType
func (d *handler) register(iMsg []*pb.Interest) error //逐一绑定Interest和handler
func (d *handler) deregister(iMsg []*pb.Interest) error //逐一取消绑定Interest和handler
func (d *handler) deregisterAll() //取消所有handler绑定
func (d *handler) HandleMessage(msg *pb.SignedEvent) error //处理消息
func (d *handler) SendMessage(msg *pb.Event) error //通过流向远程PEER发送消息
func validateEventMessage(signedEvt *pb.SignedEvent) (*pb.Event, error) //验证事件消息
//代码在events/producer/handler.go
补充pb.Event和pb.SignedEvent：
type Event struct {
Event isEvent_Event //type isEvent_Event interface
Creator []byte //事件创建者
}
SignedEvent struct {
Signature []byte //在事件字节上的签名
EventBytes []byte //事件对象序列化，即type Event struct
}
//代码在protos/peer/events.pb.go