// Join a server to the cluster
func (c *JoinCommand) Apply(context raft.Context) (interface{}, error) {
ps, _ := context.Server().Context().(*PeerServer)
b := make([]byte, 8)
binary.PutUvarint(b, context.CommitIndex())
// Make sure we're not getting a cached value from the registry.
ps.registry.Invalidate(c.Name)
// Check if the join command is from a previous peer, who lost all its previous log.
if _, ok := ps.registry.ClientURL(c.Name); ok {
return b, nil
}
// Check peer number in the cluster
if ps.registry.Count() == ps.Config.MaxClusterSize {
log.Debug("Reject join request from ", c.Name)
return []byte{0}, etcdErr.NewError(etcdErr.EcodeNoMorePeer, "", context.CommitIndex())
}
// Add to shared peer registry.
ps.registry.Register(c.Name, c.RaftURL, c.EtcdURL)
// Add peer in raft
err := context.Server().AddPeer(c.Name, "")
// Add peer stats
if c.Name != ps.RaftServer().Name() {
ps.followersStats.Followers[c.Name] = &raftFollowerStats{}
ps.followersStats.Followers[c.Name].Latency.Minimum = 1 << 63
}
return b, err
}
// Remove a server from the cluster
func (c *RemoveCommand) Apply(context raft.Context) (interface{}, error) {
ps, _ := context.Server().Context().(*PeerServer)
// Remove node from the shared registry.
err := ps.registry.Unregister(c.Name)
// Delete from stats
delete(ps.followersStats.Followers, c.Name)
if err != nil {
log.Debugf("Error while unregistering: %s (%v)", c.Name, err)
return []byte{0}, err
}
// Remove peer in raft
err = context.Server().RemovePeer(c.Name)
if err != nil {
log.Debugf("Unable to remove peer: %s (%v)", c.Name, err)
return []byte{0}, err
}
if c.Name == context.Server().Name() {
// the removed node is this node
// if the node is not replaying the previous logs
// and the node has sent out a join request in this
// start. It is sure that this node received a new remove
// command and need to be removed
if context.CommitIndex() > ps.joinIndex && ps.joinIndex != 0 {
log.Debugf("server [%s] is removed", context.Server().Name())
os.Exit(0)
} else {
// else ignore remove
log.Debugf("ignore previous remove command.")
}
}
b := make([]byte, 8)
binary.PutUvarint(b, context.CommitIndex())
return b, err
}