/
message.go
147 lines (129 loc) · 2.7 KB
/
message.go
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package cluster
import (
"bytes"
"encoding/gob"
"fmt"
"net"
"time"
)
type discriminant int
const (
msgJoin discriminant = iota
msgJoinReply
msgRemove
msgUnknown
msgWhoDoYouKnow
msgIKnow
msgHealthy
msgKeepAlive
msgUser
)
func (d discriminant) String() string {
switch d {
case msgUser:
return "USER"
case msgJoin:
return "JOIN"
case msgJoinReply:
return "JOIN REPLY"
case msgWhoDoYouKnow:
return "WHO DO YOU KNOW"
case msgIKnow:
return "I KNOW"
case msgHealthy:
return "HEALTHY"
}
panic("bug")
}
// Message represents data sent to your node from another node.
// They can be retrieved via the Inbox channel of the corresponding node.
type Message struct {
// The remote address of the sender.
From Remote
// The content of the message.
Payload []byte
}
type message struct {
D discriminant
Payload []byte
From Remote
To Remote
}
func (n *Node) destination(r Remote) Remote {
n.remlock.RLock()
defer n.remlock.RUnlock()
if bywayof, ok := n.bywayof[r.String()]; ok {
return bywayof
}
return r
}
func (n *Node) send(to Remote, d discriminant, data []byte) error {
if d > msgUnknown && !n.knows(to) {
return fmt.Errorf("I do not know about remote '%s'.", to)
}
dest := n.destination(to)
conn, err := net.DialTimeout("tcp", dest.String(), n.getNetworkTimeout())
if err != nil {
go n.unlearn(to, false)
return err
}
defer conn.Close()
m := &message{d, data, remote(n.Addr()), to}
enc := gob.NewEncoder(conn)
deadline := time.Now().Add(n.getNetworkTimeout())
if err := conn.SetWriteDeadline(deadline); err != nil {
go n.unlearn(to, false)
return err
}
if err := enc.Encode(&m); err != nil {
if isNetError(err) {
go n.unlearn(to, false)
}
return err
}
return nil
}
func isNetError(err error) bool {
if _, ok := err.(net.Error); ok {
return true
}
return false
}
func (n *Node) receive(conn *net.TCPConn) (*message, error) {
dec := gob.NewDecoder(conn)
m := new(message)
deadline := time.Now().Add(n.getNetworkTimeout())
if err := conn.SetReadDeadline(deadline); err != nil {
return nil, err
}
if err := dec.Decode(&m); err != nil {
return nil, err
}
return m, nil
}
func payload(data interface{}) ([]byte, error) {
// Special case the data to avoid unnecessary encoding/decoding.
var payload []byte
switch d := data.(type) {
case []byte:
payload = d
case string:
payload = []byte(d)
default:
b := new(bytes.Buffer)
w := gob.NewEncoder(b)
if err := w.Encode(data); err != nil {
return nil, err
}
payload = b.Bytes()
}
return payload, nil
}
func (m *message) decodePayload(v interface{}) error {
b := bytes.NewReader(m.Payload)
r := gob.NewDecoder(b)
if err := r.Decode(v); err != nil {
return err
}
return nil
}