filecoin技术架构分析五:filecoin源码分析之协议层心跳协议

我是先河系统CTO杨尉，欢迎大加关注的的Github: waynewyang，本文是filecoin技术架构分析系列文章第五章filecoin源码分析之协议层心跳协议。

源码信息

• version
  • master分支 619b0eb1（2019年３月２日）
• package
  • metrics
• location
  • metrics/heartbeat.go
  • node/node.go

源码分析

数据结构

• 定义心跳协议名称以及连接超时时间

// HeartbeatProtocol is the libp2p protocol used for the heartbeat service
const (
    HeartbeatProtocol = "fil/heartbeat/1.0.0"
    // Minutes to wait before logging connection failure at ERROR level
    connectionFailureErrorLogPeriodMinutes = 10 * time.Minute
)

• 定义心跳信息结构
  • 节点的区块头
  • 节点的区块高度
  • 节点的昵称
  • 是否在区块同步中（ＴＯＤＯ）
  • 矿工地址（如果没有挖矿，这里为零地址）

// Heartbeat contains the information required to determine the current state of a node.
// Heartbeats are used for aggregating information about nodes in a log aggregator
// to support alerting and devnet visualization.
type Heartbeat struct {
    // Head represents the heaviest tipset the nodes is mining on
    Head string
    // Height represents the current height of the Tipset
    Height uint64
    // Nickname is the nickname given to the filecoin node by the user
    Nickname string
    // TODO: add when implemented
    // Syncing is `true` iff the node is currently syncing its chain with the network.
    // Syncing bool

    // Address of this node's active miner. Can be empty - will return the zero address
    MinerAddress address.Address
}

• 心跳服务结构体
  • 主机结构体：对应libp2p主机
  • 心跳配置
  • 区块头获取
  • 挖矿地址获取
  • stream锁
  • stream

// HeartbeatService is responsible for sending heartbeats.
type HeartbeatService struct {
    Host   host.Host
    Config *config.HeartbeatConfig

    // A function that returns the heaviest tipset
    HeadGetter func() types.TipSet

    // A function that returns the miner's address
    MinerAddressGetter func() address.Address

    streamMu sync.Mutex
    stream   net.Stream
}

• 定义心跳服务Option函数
  • 函数入参为心跳服务结构体,主要用于对心跳服务结构体传参或者解析

    // HeartbeatServiceOption is the type of the heartbeat service's functional options.
    type HeartbeatServiceOption func(service *HeartbeatService)

方法

• 获取心跳服务的stream实例

// Stream returns the HeartbeatService stream. Safe for concurrent access.
// Stream is a libp2p connection that heartbeat messages are sent over to an aggregator.
func (hbs *HeartbeatService) Stream() net.Stream {
    hbs.streamMu.Lock()
    defer hbs.streamMu.Unlock()
    return hbs.stream
}

• 设置心跳服务的stream实例

// SetStream sets the stream on the HeartbeatService. Safe for concurrent access.
func (hbs *HeartbeatService) SetStream(s net.Stream) {
    hbs.streamMu.Lock()
    defer hbs.streamMu.Unlock()
    hbs.stream = s
}

• 定时确认连接性，并调用运行心跳服务

// Start starts the heartbeat service by, starting the connection loop. The connection
// loop will attempt to connected to the aggregator service, once a successful
// connection is made with the aggregator service hearbeats will be sent to it.
// If the connection is broken the heartbeat service will attempt to reconnect via
// the connection loop. Start will not return until context `ctx` is 'Done'.
func (hbs *HeartbeatService) Start(ctx context.Context) {
    log.Debug("starting heartbeat service")

    rd, err := time.ParseDuration(hbs.Config.ReconnectPeriod)
    if err != nil {
        log.Errorf("invalid heartbeat reconnectPeriod: %s", err)
        return
    }

    //启动重连定时器
    reconTicker := time.NewTicker(rd)
    defer reconTicker.Stop()
    // Timestamp of the first connection failure since the last successful connection.
    // Zero initially and while connected.
    var failedAt time.Time
    // Timestamp of the last ERROR log (or of failure, before the first ERROR log).
    var erroredAt time.Time
    for {
        select {
        case <-ctx.Done():
            return
        case <-reconTicker.C:
            //重连定时周期到，重新连接
            if err := hbs.Connect(ctx); err != nil {
                // Logs once as a warning immediately on failure, then as error every 10 minutes.
                now := time.Now()
                logfn := log.Debugf
                if failedAt.IsZero() { // First failure since connection
                    failedAt = now
                    erroredAt = failedAt // Start the timer on raising to ERROR level
                    logfn = log.Warningf
                } else if now.Sub(erroredAt) > connectionFailureErrorLogPeriodMinutes {
                    logfn = log.Errorf
                    erroredAt = now // Reset the timer
                }
                failureDuration := now.Sub(failedAt)
                logfn("Heartbeat service failed to connect for %s: %s", failureDuration, err)
                // failed to connect, continue reconnect loop
                continue
            }
            failedAt = time.Time{}

            // we connected, send heartbeats!
            // Run will block until it fails to send a heartbeat.
            //如果连接成功，运行心跳服务
            if err := hbs.Run(ctx); err != nil {
                log.Warning("disconnecting from aggregator, failed to send heartbeat")
                continue
            }
        }
    }
}

• 运行心跳服务

// Run is called once the heartbeat service connects to the aggregator. Run
// send the actual heartbeat. Run will block until `ctx` is 'Done`. An error will
// be returned if Run encounters an error when sending the heartbeat and the connection
// to the aggregator will be closed.
func (hbs *HeartbeatService) Run(ctx context.Context) error {
    bd, err := time.ParseDuration(hbs.Config.BeatPeriod)
    if err != nil {
        log.Errorf("invalid heartbeat beatPeriod: %s", err)
        return err
    }

    //启动心跳定时器
    beatTicker := time.NewTicker(bd)
    defer beatTicker.Stop()

    //通过encoder进行流写入
    // TODO use cbor instead of json
    encoder := json.NewEncoder(hbs.stream)
    for {
        select {
        case <-ctx.Done():
            return nil
        case <-beatTicker.C:
        //心跳定时周期到，调用Beat方法获取心跳参数
            hb := hbs.Beat()
            //写入流，发起心跳
            if err := encoder.Encode(hb); err != nil {
                //发生错误会关闭流连接
                hbs.stream.Conn().Close() // nolint: errcheck
                return err
            }
        }
    }
}

• 获取心跳参数

// Beat will create a heartbeat.
func (hbs *HeartbeatService) Beat() Heartbeat {
    nick := hbs.Config.Nickname
    ts := hbs.HeadGetter()
    tipset := ts.ToSortedCidSet().String()
    height, err := ts.Height()
    if err != nil {
        log.Warningf("heartbeat service failed to get chain height: %s", err)
    }
    addr := hbs.MinerAddressGetter()
    return Heartbeat{
        Head:         tipset,
        Height:       height,
        Nickname:     nick,
        MinerAddress: addr,
    }
}

• 心跳流连接

  // Connect will connects to `hbs.Config.BeatTarget` or returns an error
  func (hbs *HeartbeatService) Connect(ctx context.Context) error {
  log.Debugf("Heartbeat service attempting to connect, targetAddress: %s", hbs.Config.BeatTarget)
  targetMaddr, err := ma.NewMultiaddr(hbs.Config.BeatTarget)
  if err != nil {
      return err
  }
  
  pid, err := targetMaddr.ValueForProtocol(ma.P_P2P)
  if err != nil {
      return err
  }
  
  peerid, err := peer.IDB58Decode(pid)
  if err != nil {
      return err
  }
  
  // Decapsulate the /p2p/<peerID> part from the target
  // /ip4/<a.b.c.d>/p2p/<peer> becomes /ip4/<a.b.c.d>
  targetPeerAddr, _ := ma.NewMultiaddr(
      fmt.Sprintf("/p2p/%s", peer.IDB58Encode(peerid)))
  targetAddr := targetMaddr.Decapsulate(targetPeerAddr)
  
  hbs.Host.Peerstore().AddAddr(peerid, targetAddr, pstore.PermanentAddrTTL)
  
  // 建立心跳服务流
  s, err := hbs.Host.NewStream(ctx, peerid, HeartbeatProtocol)
  if err != nil {
      log.Debugf("failed to open stream, peerID: %s, targetAddr: %s %s", peerid, targetAddr, err)
      return err
  }
  log.Infof("successfully to open stream, peerID: %s, targetAddr: %s", peerid, targetAddr)
  
  //设置流函数
  hbs.SetStream(s)
  return nil
  }

函数

• 向心跳服务结构体传参,用于设置获取矿工地址函数

// WithMinerAddressGetter returns an option that can be used to set the miner address getter.
func WithMinerAddressGetter(ag func() address.Address) HeartbeatServiceOption {
    return func(service *HeartbeatService) {
        service.MinerAddressGetter = ag
    }
}

• 获取默认的矿工地址

func defaultMinerAddressGetter() address.Address {
    return address.Address{}
}

• 实例化心跳服务,具体的实例化在node包中实现。

// NewHeartbeatService returns a HeartbeatService
func NewHeartbeatService(h host.Host, hbc *config.HeartbeatConfig, hg func() types.TipSet, options ...HeartbeatServiceOption) *HeartbeatService {
    srv := &HeartbeatService{
        Host:               h,
        Config:             hbc,
        HeadGetter:         hg,
        MinerAddressGetter: defaultMinerAddressGetter,
    }

    // 设置心跳服务的获取矿工属性,这会覆盖到上面设置的默认矿工地址
    for _, option := range options {
        option(srv)
    }

    return srv
}

实例化及业务逻辑

• 主要由node调用,location:node/node.go,主要逻辑如下

• 在node的启动方法中，调用node.setupHeartbeatServices方法，建立心跳服务

// Start boots up the node.
func (node *Node) Start(ctx context.Context) error {
    ......

    if err := node.setupHeartbeatServices(ctx); err != nil {
        return errors.Wrap(err, "failed to start heartbeat services")
    }

    return nil
}

• 建立心跳服务,具体见如下注释

func (node *Node) setupHeartbeatServices(ctx context.Context) error {
    // 设置“矿工地址获取函数”
    mag := func() address.Address {
        addr, err := node.miningAddress()
        // the only error miningAddress() returns is ErrNoMinerAddress.
        // if there is no configured miner address, simply send a zero
        // address across the wire.
        if err != nil {
            return address.Address{}
        }
        return addr
    }

    // 存在心跳目标的时候，实例化心跳服务实例
    // start the primary heartbeat service
    if len(node.Repo.Config().Heartbeat.BeatTarget) > 0 {
        //调用metrics包中的建立心跳服务实例、以及启动心跳服务实例方法
        hbs := metrics.NewHeartbeatService(node.Host(), node.Repo.Config().Heartbeat, node.ChainReader.Head, metrics.WithMinerAddressGetter(mag))
        go hbs.Start(ctx)
    }

    // 确认是否用户有通过环境变量配置额外的心跳告警服务（自定义指向其他节点），根据用户配置的数目，拉起对应的多线程心跳服务。
    // check if we want to connect to an alert service. An alerting service is a heartbeat
    // service that can trigger alerts based on the contents of heatbeats.
    if alertTarget := os.Getenv("FIL_HEARTBEAT_ALERTS"); len(alertTarget) > 0 {
        ahbs := metrics.NewHeartbeatService(node.Host(), &config.HeartbeatConfig{
            BeatTarget:      alertTarget,
            BeatPeriod:      "10s",
            ReconnectPeriod: "10s",
            Nickname:        node.Repo.Config().Heartbeat.Nickname,
        }, node.ChainReader.Head, metrics.WithMinerAddressGetter(mag))
        go ahbs.Start(ctx)
    }
    return nil
}

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