MOSN 源码解析 - 启动流程

type Mosn struct {
	isFromUpgrade  bool // hot upgrade from old MOSN
	Upgrade        UpgradeData
	Clustermanager types.ClusterManager
	RouterManager  types.RouterManager
	Config         *v2.MOSNConfig
	// internal data
	servers   []server.Server
	xdsClient *istio.ADSClient
}

// stagemanagr/stage_manager.go
// StageManager is used to controls service life stages.
type StageManager struct {
	lock                    sync.Mutex
	state                   State
	exitCode                int
	stopAction              StopAction
	data                    Data  //保存了app不同生命周期阶段所使用的数据
	app                     Application // Application interface app其实就是MOSN
	wg                      sync.WaitGroup
    //以下是不同生命周期对应的处理函数 -- start
	paramsStages            []func(*cli.Context)  //参数准备阶段
	initStages              []func(*v2.MOSNConfig) //初始化场景
	preStartStages          []func(Application)  //启动之前
	startupStages           []func(Application)  //启动
	afterStartStages        []func(Application)  //启动之后
	beforeStopStages        []func(StopAction, Application) error //停止之前
	gracefulStopStages      []func(Application) error  //优雅停止
	afterStopStages         []func(Application) //停止之后处理
    //生命周期阶段 --- end  
	onStateChangedCallbacks []func(State)
	upgradeHandler          func() error // old server: send listener/config/old connections to new server
	newServerC              chan bool
}

// Data contains objects used in stages
type Data struct {
	// ctx contains the start parameters
	ctx *cli.Context
	// config path represents the config file path,
	// will create basic config from it and if auto config dump is set,
	// new config data will write into this path
	configPath string
	// basic config, created after parameters parsed stage
	config *v2.MOSNConfig
}

// Run until the application is started
func (stm *StageManager) Run() {
	// 1: parser params
	stm.runParamsParsedStage()
	// 2: init
	stm.runInitStage()
	// 3: pre start
	stm.runPreStartStage()
	// 4: run
	stm.runStartStage()
	// 5: after start
	stm.runAfterStartStage()

	stm.SetState(Running)
}

func (stm *StageManager) runParamsParsedStage() {
	st := time.Now()
    //设置场景状态
	stm.SetState(ParamsParsed) 
    //果然和猜测一样，遍历回调函数的数组并调用
	for _, f := range stm.paramsStages {
		f(stm.data.ctx)
	}
	// after all registered stages are completed
	stm.data.config = configmanager.Load(stm.data.configPath)

	log.StartLogger.Infof("parameters parsed stage cost: %v", time.Since(st))
}

// run all stages
func (stm *StageManager) RunAll() {
	// start to work
	stm.Run()
	// wait server finished
	stm.WaitFinish()
	// stop working
	stm.Stop()
}

159         Action: func(c *cli.Context) error {
	            // 创建Application
160             app := mosn.NewMosn()
                // 创建stagemanager场景管理器
161             stm := stagemanager.InitStageManager(c, c.String("config"), app)
162             // if needs featuregate init in parameter stage or init stage
163             // append a new stage and called featuregate.ExecuteInitFunc(keys...)
164             // parameter parsed registered
165             stm.AppendParamsParsedStage(ExtensionsRegister)
166             stm.AppendParamsParsedStage(DefaultParamsParsed)
167             // initial registered
168             stm.AppendInitStage(func(cfg *v2.MOSNConfig) {
169                 drainTime := c.Int("drain-time-s")
170                 server.SetDrainTime(time.Duration(drainTime) * time.Second)
171                 // istio parameters
172                 serviceCluster := c.String("service-cluster")
173                 serviceNode := c.String("service-node")
174                 serviceType := c.String("service-type")
175                 serviceMeta := c.StringSlice("service-meta")
176                 metaLabels := c.StringSlice("service-lables")
177                 clusterDomain := c.String("cluster-domain")
178                 podName := c.String("pod-name")
179                 podNamespace := c.String("pod-namespace")
180                 podIp := c.String("pod-ip")
181
182                 if serviceNode != "" {
183                     istio1106.InitXdsInfo(cfg, serviceCluster, serviceNode, serviceMeta, metaLabels)
184                 } else {
185                     if istio1106.IsApplicationNodeType(serviceType) {
186                         sn := podName + "." + podNamespace
187                         serviceNode = serviceType + "~" + podIp + "~" + sn + "~" + clusterDomain
188                         istio1106.InitXdsInfo(cfg, serviceCluster, serviceNode, serviceMeta, metaLabels)
189                     } else {
190                         log.StartLogger.Infof("[mosn] [start] xds service type is not router/sidecar, use config only")
191                         istio1106.InitXdsInfo(cfg, "", "", nil, nil)
192                     }
193                 }
194             })
195             stm.AppendInitStage(mosn.DefaultInitStage)
196             stm.AppendInitStage(func(_ *v2.MOSNConfig) {
197                 // set version and go version
198                 metrics.SetVersion(Version)
199                 metrics.SetGoVersion(runtime.Version())
200                 admin.SetVersion(Version)
201             })
202             stm.AppendInitStage(holmes.Register)
203             // pre-startup
204             stm.AppendPreStartStage(mosn.DefaultPreStartStage) // called finally stage by default
205             // startup
206             stm.AppendStartStage(mosn.DefaultStartStage)
207             // after-stop
208             stm.AppendAfterStopStage(holmes.Stop)
209             // execute all stages
                //执行所有场景
210             stm.RunAll()
211             return nil
212  },

func DefaultInitStage(c *v2.MOSNConfig) {
	InitDefaultPath(c) //初始化mosn需要的相关运行时的目录,比如：日志，存储mosn进程ID的文件等
	InitDebugServe(c)   //启动mosn的debug信息查看服务，可以查看pprof信息
	InitializePidFile(c)  //初始化mosn pid持久化的文件
	InitializeTracing(c)   //初始化mosn 链路追踪的组件，根据配置文件中链路相关的配置。在之前的分析ParamParsed阶段会维护一些mosn支持的链路追踪的驱动列表，然后在这个阶段里会选择一个具体的组件作为链路追踪的实现。
	InitializePlugin(c) //这个阶段是初始化一下插件，不过看了实现其实就是初始化log配置
	InitializeWasm(c) //初始化web assembly 环境
	InitializeThirdPartCodec(c)  //初始化第三方的编解码的配置，这块我也不太理解，需要后面继续研究一下。个人感觉是加载动态代码，目前支持wasm和goPlugin
}

// Default Pre-start Stage wrappers
func DefaultPreStartStage(mosn stagemanager.Application) {
	m := mosn.(*Mosn)

	// start xds client
	_ = m.StartXdsClient()
	featuregate.FinallyInitFunc()  //初始化配置中指定的Feature
	m.HandleExtendConfig()  //将配置中扩展配置信息转换成对象
}

// Default Start Stage wrappers
func DefaultStartStage(mosn stagemanager.Application) {
	m := mosn.(*Mosn)
	// register admin server
	// admin server should register after all prepares action ready
	srv := admin.Server{}
	srv.Start(m.Config)
}