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membership.go
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/
membership.go
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package ring
import (
"net"
"github.com/hashicorp/serf/serf"
"go.uber.org/zap"
)
// membership Type wrapping Serf to provide discovery and cluster membership to our service.
type membership struct {
MembershipConfig
handler Handler
cluster *serf.Serf
events chan serf.Event
logger *zap.Logger
}
func newMemberShip(handler Handler, config MembershipConfig) (*membership, error) {
c := &membership{
MembershipConfig: config,
handler: handler,
logger: zap.L().Named("membership"),
}
if err := c.setupCluster(); err != nil {
return nil, err
}
return c, nil
}
func (m *membership) setupCluster() error {
addr, err := net.ResolveTCPAddr("tcp", m.BindAddr)
if err != nil {
return err
}
config := serf.DefaultConfig()
config.Init()
config.MemberlistConfig.BindAddr = addr.IP.String()
config.MemberlistConfig.BindPort = addr.Port
m.events = make(chan serf.Event)
config.EventCh = m.events
config.Tags = m.Tags
config.NodeName = m.NodeName
m.cluster, err = serf.Create(config)
if err != nil {
return err
}
go m.eventHandler()
if m.SeedAddresses != nil && len(m.SeedAddresses) > 0 {
_, err = m.cluster.Join(m.SeedAddresses, true)
if err != nil {
return err
}
}
return nil
}
// Runs in a loop reading events sent by Serf into the events channel, handling each incoming event according to the event’s type.
func (m *membership) eventHandler() {
for e := range m.events {
switch e.EventType() {
case serf.EventMemberJoin:
for _, member := range e.(serf.MemberEvent).Members {
m.handleJoin(member)
}
case serf.EventMemberLeave:
for _, member := range e.(serf.MemberEvent).Members {
m.handleLeave(member)
}
}
}
}
func (m *membership) handleJoin(member serf.Member) {
if err := m.handler.Join(
member.Name,
member.Tags,
); err != nil {
m.logError(err, "failed to join", member)
}
}
func (m *membership) handleLeave(member serf.Member) {
if err := m.handler.Leave(
member.Name,
member.Tags,
); err != nil {
m.logError(err, "failed to leave", member)
}
}
// Returns whether the given Serf member is the local member by checking the members’ names.
func (m *membership) isLocal(member serf.Member) bool {
return m.cluster.LocalMember().Name == member.Name
}
// Members Returns a point-in-time snapshot of the cluster’s Serf members.
func (m *membership) Members() []serf.Member {
return m.cluster.Members()
}
// Leave Tells this member to leave the Serf cluster.
func (m *membership) Leave() error {
return m.cluster.Leave()
}
// Logs the given error and message.
func (m *membership) logError(err error, msg string, member serf.Member) {
log := m.logger.Error
log(
msg,
zap.Error(err),
zap.String("name", member.Name),
zap.String("rpc_addr", member.Tags["rpc_addr"]),
)
}
type MembershipConfig struct {
NodeName string
BindAddr string
Tags map[string]string
SeedAddresses []string
virtualNodes int
}