memberlist库gossip集群

package main
import (
	"fmt"
	"github.com/hashicorp/memberlist"
	"time"
)
func main() {
	/* Create the initial memberlist from a safe configuration.
	   Please reference the godoc for other default config types.
	   http://godoc.org/github.com/hashicorp/memberlist#Config
	*/
	list, err := memberlist.Create(memberlist.DefaultLocalConfig())
	if err != nil {
		panic("Failed to create memberlist: " + err.Error())
	}
	t := time.NewTicker(time.Second * 5)
	for {
		select {
		case <-t.C:
			// Join an existing cluster by specifying at least one known member.
			n, err := list.Join([]string{"192.168.80.129"})
			if err != nil {
				fmt.Println("Failed to join cluster: " + err.Error())
				continue
			}
			fmt.Println("member number is:", n)
			goto END
		}
	}
END:
	for {
		select {
		case <-t.C:
			// Ask for members of the cluster
			for _, member := range list.Members() {
				fmt.Printf("Member: %s %s\n", member.Name, member.Addr)
			}
		}
	}
	// Continue doing whatever you need, memberlist will maintain membership
	// information in the background. Delegates can be used for receiving
	// events when members join or leave.
}

type Config struct {
	// ...
	// Delegate and Events are delegates for receiving and providing
	// data to memberlist via callback mechanisms. For Delegate, see
	// the Delegate interface. For Events, see the EventDelegate interface.
	//
	// The DelegateProtocolMin/Max are used to guarantee protocol-compatibility
	// for any custom messages that the delegate might do (broadcasts,
	// local/remote state, etc.). If you don't set these, then the protocol
	// versions will just be zero, and version compliance won't be done.
	Delegate                Delegate
	Events                  EventDelegate
	Conflict                ConflictDelegate
	Merge                   MergeDelegate
	Ping                    PingDelegate
	Alive                   AliveDelegate
	//...
}

const (
	pingMsg messageType = iota
	indirectPingMsg
	ackRespMsg
	suspectMsg
	aliveMsg
	deadMsg
	pushPullMsg
	compoundMsg
	userMsg // User mesg, not handled by us
	compressMsg
	encryptMsg
	nackRespMsg
	hasCrcMsg
	errMsg
)

type Delegate interface {
	// NodeMeta is used to retrieve meta-data about the current node
	// when broadcasting an alive message. It's length is limited to
	// the given byte size. This metadata is available in the Node structure.
	NodeMeta(limit int) []byte

	// NotifyMsg is called when a user-data message is received.
	// Care should be taken that this method does not block, since doing
	// so would block the entire UDP packet receive loop. Additionally, the byte
	// slice may be modified after the call returns, so it should be copied if needed
	NotifyMsg([]byte)

	// GetBroadcasts is called when user data messages can be broadcast.
	// It can return a list of buffers to send. Each buffer should assume an
	// overhead as provided with a limit on the total byte size allowed.
	// The total byte size of the resulting data to send must not exceed
	// the limit. Care should be taken that this method does not block,
	// since doing so would block the entire UDP packet receive loop.
	GetBroadcasts(overhead, limit int) [][]byte

	// LocalState is used for a TCP Push/Pull. This is sent to
	// the remote side in addition to the membership information. Any
	// data can be sent here. See MergeRemoteState as well. The `join`
	// boolean indicates this is for a join instead of a push/pull.
	LocalState(join bool) []byte

	// MergeRemoteState is invoked after a TCP Push/Pull. This is the
	// state received from the remote side and is the result of the
	// remote side's LocalState call. The 'join'
	// boolean indicates this is for a join instead of a push/pull.
	MergeRemoteState(buf []byte, join bool)
}

type EventDelegate interface {
	// NotifyJoin is invoked when a node is detected to have joined.
	// The Node argument must not be modified.
	NotifyJoin(*Node)

	// NotifyLeave is invoked when a node is detected to have left.
	// The Node argument must not be modified.
	NotifyLeave(*Node)

	// NotifyUpdate is invoked when a node is detected to have
	// updated, usually involving the meta data. The Node argument
	// must not be modified.
	NotifyUpdate(*Node)
}

type ChannelEventDelegate struct {
  Ch chan<- NodeEvent
}

type ConflictDelegate interface {
	// NotifyConflict is invoked when a name conflict is detected
	NotifyConflict(existing, other *Node)
}

type MergeDelegate interface {
	// NotifyMerge is invoked when a merge could take place.
	// Provides a list of the nodes known by the peer. If
	// the return value is non-nil, the merge is canceled.
	NotifyMerge(peers []*Node) error
}

type PingDelegate interface {
	// AckPayload is invoked when an ack is being sent; the returned bytes will be appended to the ack
	AckPayload() []byte
	// NotifyPing is invoked when an ack for a ping is received
	NotifyPingComplete(other *Node, rtt time.Duration, payload []byte)
}

type AliveDelegate interface {
	// NotifyAlive is invoked when a message about a live
	// node is received from the network.  Returning a non-nil
	// error prevents the node from being considered a peer.
	NotifyAlive(peer *Node) error
}

// Broadcast is something that can be broadcasted via gossip to
// the memberlist cluster.
type Broadcast interface {
	// Invalidates checks if enqueuing the current broadcast
	// invalidates a previous broadcast
	Invalidates(b Broadcast) bool

	// Returns a byte form of the message
	Message() []byte

	// Finished is invoked when the message will no longer
	// be broadcast, either due to invalidation or to the
	// transmit limit being reached
	Finished()
}

func (q *TransmitLimitedQueue) QueueBroadcast(b Broadcast) {
	q.queueBroadcast(b, 0)
}

type simpleBroadcast []byte

func (b simpleBroadcast) Message() []byte                       { return []byte(b) }
func (b simpleBroadcast) Invalidates(memberlist.Broadcast) bool { return false }
func (b simpleBroadcast) Finished()

// TransmitLimitedQueue is used to queue messages to broadcast to
// the cluster (via gossip) but limits the number of transmits per
// message. It also prioritizes messages with lower transmit counts
// (hence newer messages).
type TransmitLimitedQueue struct {
	// NumNodes returns the number of nodes in the cluster. This is
	// used to determine the retransmit count, which is calculated
	// based on the log of this.
	NumNodes func() int

	// RetransmitMult is the multiplier used to determine the maximum
	// number of retransmissions attempted.
	RetransmitMult int

	mu    sync.Mutex
	tq    *btree.BTree // stores *limitedBroadcast as btree.Item
	tm    map[string]*limitedBroadcast
	idGen int64
}

// GossipInterval and GossipNodes are used to configure the gossip
	// behavior of memberlist.
	//
	// GossipInterval is the interval between sending messages that need
	// to be gossiped that haven't been able to piggyback on probing messages.
	// If this is set to zero, non-piggyback gossip is disabled. By lowering
	// this value (more frequent) gossip messages are propagated across
	// the cluster more quickly at the expense of increased bandwidth.
	//
	// GossipNodes is the number of random nodes to send gossip messages to
	// per GossipInterval. Increasing this number causes the gossip messages
	// to propagate across the cluster more quickly at the expense of
	// increased bandwidth.
	//
	// GossipToTheDeadTime is the interval after which a node has died that
	// we will still try to gossip to it. This gives it a chance to refute.
	GossipInterval      time.Duration
	GossipNodes         int
	GossipToTheDeadTime time.Duration

func (c *Channel) Broadcast(b []byte) {
	b, err := proto.Marshal(&clusterpb.Part{Key: c.key, Data: b})
	if err != nil {
		return
	}

	if OversizedMessage(b) {
		select {
		case c.msgc <- b: //从c.msgc 接收数据，并使用SendReliable发送
		default:
			level.Debug(c.logger).Log("msg", "oversized gossip channel full")
			c.oversizeGossipMessageDroppedTotal.Inc()
		}
	} else {
		c.send(b)
	}
}

func OversizedMessage(b []byte) bool {
	return len(b) > MaxGossipPacketSize/2
}