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兄弟连区块链入门教程以太坊源码分析node源码分析，2018年下半年，区块链行业正逐渐褪去发展之初的浮躁、回归理性，表面上看相关人才需求与身价似乎正在回落。但事实上，正是初期泡沫的渐退，让人们更多的关注点放在了区块链真正的技术之上。
node在go ethereum中代表了一个节点。 可能是全节点，可能是轻量级节点。 node可以理解为一个进程，以太坊由运行在世界各地的很多中类型的node组成。
一个典型的node就是一个p2p的节点。 运行了p2p网络协议，同时根据节点类型不同，运行了不同的业务层协议(以区别网络层协议。 参考p2p peer中的Protocol接口)。
node的结构。
// Node is a container on which services can be registered.
type Node struct {
eventmux *event.TypeMux // Event multiplexer used between the services of a stack
config *Config
accman *accounts.Manager
ephemeralKeystore string // if non-empty, the key directory that will be removed by Stop
instanceDirLock flock.Releaser // prevents concurrent use of instance directory
serverConfig p2p.Config
server *p2p.Server // Currently running P2P networking layer
serviceFuncs []ServiceConstructor // Service constructors (in dependency order)
services map[reflect.Type]Service // Currently running services
rpcAPIs []rpc.API // List of APIs currently provided by the node
inprocHandler *rpc.Server // In-process RPC request handler to process the API requests
ipcEndpoint string // IPC endpoint to listen at (empty = IPC disabled)
ipcListener net.Listener // IPC RPC listener socket to serve API requests
ipcHandler *rpc.Server // IPC RPC request handler to process the API requests
httpEndpoint string // HTTP endpoint (interface + port) to listen at (empty = HTTP disabled)
httpWhitelist []string // HTTP RPC modules to allow through this endpoint
httpListener net.Listener // HTTP RPC listener socket to server API requests
httpHandler *rpc.Server // HTTP RPC request handler to process the API requests
wsEndpoint string // Websocket endpoint (interface + port) to listen at (empty = websocket disabled)
wsListener net.Listener // Websocket RPC listener socket to server API requests
wsHandler *rpc.Server // Websocket RPC request handler to process the API requests
stop chan struct{} // Channel to wait for termination notifications
lock sync.RWMutex
}
节点的初始化, 节点的初始化并不依赖其他的外部组件， 只依赖一个Config对象。
// New creates a new P2P node, ready for protocol registration.
func New(conf *Config) (*Node, error) {
// Copy config and resolve the datadir so future changes to the current
// working directory don't affect the node.
confCopy := *conf
conf = &confCopy
if conf.DataDir != "" { //转化为绝对路径。
absdatadir, err := filepath.Abs(conf.DataDir)
if err != nil {
return nil, err
}
conf.DataDir = absdatadir
}
// Ensure that the instance name doesn't cause weird conflicts with
// other files in the data directory.
if strings.ContainsAny(conf.Name, `/\`) {
return nil, errors.New(`Config.Name must not contain '/' or '\'`)
}
if conf.Name == datadirDefaultKeyStore {
return nil, errors.New(`Config.Name cannot be "` + datadirDefaultKeyStore + `"`)
}
if strings.HasSuffix(conf.Name, ".ipc") {
return nil, errors.New(`Config.Name cannot end in ".ipc"`)
}
// Ensure that the AccountManager method works before the node has started.
// We rely on this in cmd/geth.
am, ephemeralKeystore, err := makeAccountManager(conf)
if err != nil {
return nil, err
}
// Note: any interaction with Config that would create/touch files
// in the data directory or instance directory is delayed until Start.
return &Node{
accman: am,
ephemeralKeystore: ephemeralKeystore,
config: conf,
serviceFuncs: []ServiceConstructor{},
ipcEndpoint: conf.IPCEndpoint(),
httpEndpoint: conf.HTTPEndpoint(),
wsEndpoint: conf.WSEndpoint(),
eventmux: new(event.TypeMux),
}, nil
}
### node 服务和协议的注册
因为node并没有负责具体的业务逻辑。所以具体的业务逻辑是通过注册的方式来注册到node里面来的。
其他模块通过Register方法来注册了一个 服务构造函数。 使用这个服务构造函数可以生成服务。
// Register injects a new service into the node's stack. The service created by
// the passed constructor must be unique in its type with regard to sibling ones.
func (n *Node) Register(constructor ServiceConstructor) error {
n.lock.Lock()
defer n.lock.Unlock()
if n.server != nil {
return ErrNodeRunning
}
n.serviceFuncs = append(n.serviceFuncs, constructor)
return nil
}
服务是什么
type ServiceConstructor func(ctx *ServiceContext) (Service, error)
// Service is an individual protocol that can be registered into a node.
//
// Notes:
//
// • Service life-cycle management is delegated to the node. The service is allowed to
// initialize itself upon creation, but no goroutines should be spun up outside of the
// Start method.
//
// • Restart logic is not required as the node will create a fresh instance
// every time a service is started.
// 服务的生命周期管理已经代理给node管理。该服务允许在创建时自动初始化，但是在Start方法之外不应该启动goroutines。
// 重新启动逻辑不是必需的，因为节点将在每次启动服务时创建一个新的实例。
type Service interface {
// Protocols retrieves the P2P protocols the service wishes to start.
// 服务希望提供的p2p协议
Protocols() []p2p.Protocol
// APIs retrieves the list of RPC descriptors the service provides
// 服务希望提供的RPC方法的描述
APIs() []rpc.API
// Start is called after all services have been constructed and the networking
// layer was also initialized to spawn any goroutines required by the service.
// 所有服务已经构建完成后，调用开始，并且网络层也被初始化以产生服务所需的任何goroutine。
Start(server *p2p.Server) error
// Stop terminates all goroutines belonging to the service, blocking until they
// are all terminated.
// Stop方法会停止这个服务拥有的所有goroutine。 需要阻塞到所有的goroutine都已经终止
Stop() error
}
### node的启动
node的启动过程会创建和运行一个p2p的节点。
// Start create a live P2P node and starts running it.
func (n *Node) Start() error {
n.lock.Lock()
defer n.lock.Unlock()
// Short circuit if the node's already running
if n.server != nil {
return ErrNodeRunning
}
if err := n.openDataDir(); err != nil {
return err
}
// Initialize the p2p server. This creates the node key and
// discovery databases.
n.serverConfig = n.config.P2P
n.serverConfig.PrivateKey = n.config.NodeKey()
n.serverConfig.Name = n.config.NodeName()
if n.serverConfig.StaticNodes == nil {
// 处理配置文件static-nodes.json
n.serverConfig.StaticNodes = n.config.StaticNodes()
}
if n.serverConfig.TrustedNodes == nil {
// 处理配置文件trusted-nodes.json
n.serverConfig.TrustedNodes = n.config.TrustedNodes()
}
if n.serverConfig.NodeDatabase == "" {
n.serverConfig.NodeDatabase = n.config.NodeDB()
}
//创建了p2p服务器
running := &p2p.Server{Config: n.serverConfig}
log.Info("Starting peer-to-peer node", "instance", n.serverConfig.Name)
// Otherwise copy and specialize the P2P configuration
services := make(map[reflect.Type]Service)
for _, constructor := range n.serviceFuncs {
// Create a new context for the particular service
ctx := &ServiceContext{
config: n.config,
services: make(map[reflect.Type]Service),
EventMux: n.eventmux,
AccountManager: n.accman,
}
for kind, s := range services { // copy needed for threaded access
ctx.services[kind] = s
}
// Construct and save the service
// 创建所有注册的服务。
service, err := constructor(ctx)
if err != nil {
return err
}
kind := reflect.TypeOf(service)
if _, exists := services[kind]; exists {
return &DuplicateServiceError{Kind: kind}
}
services[kind] = service
}
// Gather the protocols and start the freshly assembled P2P server
// 收集所有的p2p的protocols并插入p2p.Rrotocols
for _, service := range services {
running.Protocols = append(running.Protocols, service.Protocols()...)
}
// 启动了p2p服务器
if err := running.Start(); err != nil {
return convertFileLockError(err)
}
// Start each of the services
// 启动每一个服务
started := []reflect.Type{}
for kind, service := range services {
// Start the next service, stopping all previous upon failure
if err := service.Start(running); err != nil {
for _, kind := range started {
services[kind].Stop()
}
running.Stop()
return err
}
// Mark the service started for potential cleanup
started = append(started, kind)
}
// Lastly start the configured RPC interfaces
// 最后启动RPC服务
if err := n.startRPC(services); err != nil {
for _, service := range services {
service.Stop()
}
running.Stop()
return err
}
// Finish initializing the startup
n.services = services
n.server = running
n.stop = make(chan struct{})
return nil
}
startRPC,这个方法收集所有的apis。 并依次调用启动各个RPC服务器， 默认是启动InProc和IPC。 如果指定也可以配置是否启动HTTP和websocket。
// startRPC is a helper method to start all the various RPC endpoint during node
// startup. It's not meant to be called at any time afterwards as it makes certain
// assumptions about the state of the node.
func (n *Node) startRPC(services map[reflect.Type]Service) error {
// Gather all the possible APIs to surface
apis := n.apis()
for _, service := range services {
apis = append(apis, service.APIs()...)
}
// Start the various API endpoints, terminating all in case of errors
if err := n.startInProc(apis); err != nil {
return err
}
if err := n.startIPC(apis); err != nil {
n.stopInProc()
return err
}
if err := n.startHTTP(n.httpEndpoint, apis, n.config.HTTPModules, n.config.HTTPCors); err != nil {
n.stopIPC()
n.stopInProc()
return err
}
if err := n.startWS(n.wsEndpoint, apis, n.config.WSModules, n.config.WSOrigins, n.config.WSExposeAll); err != nil {
n.stopHTTP()
n.stopIPC()
n.stopInProc()
return err
}
// All API endpoints started successfully
n.rpcAPIs = apis
return nil
}
startXXX 是具体的RPC的启动。 流程都是大同小异。 这里就只看startWS了
// startWS initializes and starts the websocket RPC endpoint.
func (n *Node) startWS(endpoint string, apis []rpc.API, modules []string, wsOrigins []string, exposeAll bool) error {
// Short circuit if the WS endpoint isn't being exposed
if endpoint == "" {
return nil
}
// Generate the whitelist based on the allowed modules
// 生成白名单
whitelist := make(map[string]bool)
for _, module := range modules {
whitelist[module] = true
}
// Register all the APIs exposed by the services
handler := rpc.NewServer()
for _, api := range apis {
if exposeAll || whitelist[api.Namespace] || (len(whitelist) == 0 && api.Public) {
// 只有这集中情况下才会把这个api进行注册。
if err := handler.RegisterName(api.Namespace, api.Service); err != nil {
return err
}
log.Debug(fmt.Sprintf("WebSocket registered %T under '%s'", api.Service, api.Namespace))
}
}
// All APIs registered, start the HTTP listener
var (
listener net.Listener
err error
)
if listener, err = net.Listen("tcp", endpoint); err != nil {
return err
}
go rpc.NewWSServer(wsOrigins, handler).Serve(listener)
log.Info(fmt.Sprintf("WebSocket endpoint opened: ws://%s", listener.Addr()))
// All listeners booted successfully
n.wsEndpoint = endpoint
n.wsListener = listener
n.wsHandler = handler
return nil
}
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