/
cluster.go
executable file
·271 lines (228 loc) · 5.92 KB
/
cluster.go
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/*
* Written by: Sagar Sontakke
* Description: This is a clustering library that provide some abstractions for the setting up clusters.
* It provides functions related to parsing input config file, setting up a server, input/output message
* channels for the server, send/receive message functions, structure for server/mesage objects
*/
package cluster
import (
"bufio"
"fmt"
zmq "github.com/pebbe/zmq4"
"os"
"strconv"
"strings"
"sync/atomic"
)
var Peers []int
var PeerAddress = make(map[int]string)
var peerIdIndex = make(map[int]int)
const (
BROADCAST = -1
)
/*
* The structure to encapsulate the message, contains:
* 1. Node is of receipient 2. Unique ID for the message 3. Actual message
*/
type Envelope struct {
Pid int
MsgId int64
Msg string
}
/*
* Structure for server object. Contains the server specific info like ID of that server,
* server ip/port address, IDs and address of peer servers, message input/output channels
* message ID counts, server's own socket and sockets for all its peers.
*/
type servernode struct {
ServerId int
ServerAddress string
PeersId []int
PeerServers map[int]string
Serveroutchannel chan *Envelope
Serverinchannel chan *Envelope
MessageId int64
Serversocket *zmq.Socket
Peersockets []*zmq.Socket
}
/*
* The server object impliments the Server interface
*/
type Server interface {
GetPid() int
GetPeers() []int
Outbox() chan *Envelope
Inbox() chan *Envelope
}
/* Get PID of the server
*/
func (s servernode) GetPid() int {
return s.ServerId
}
/* Get IDs of the peer nodes
*/
func (s servernode) GetPeers() []int {
return s.PeersId
}
/* Set up a new cluster and retuern an array of object for the nodes
*/
func NewCluster(configFile string) []servernode {
parsedConfig := false
if !parsedConfig {
if ParseConfig(configFile) != 0 {
fmt.Println(": Error while parsing the config file")
os.Exit(1)
} else {
parsedConfig = true
}
}
var s servernode
var serv []servernode
var err error
for i := 0; i < len(Peers); i++ {
nodeid := Peers[i]
s.ServerId = nodeid
s.ServerAddress = PeerAddress[nodeid]
s.PeersId = Peers
s.PeerServers = PeerAddress
s.Serveroutchannel = make(chan *Envelope)
s.Serverinchannel = make(chan *Envelope)
s.MessageId = int64(nodeid * 1000)
s.Serversocket, err = zmq.NewSocket(zmq.PULL)
check_err(err)
s.Serversocket.Bind(s.ServerAddress)
serv = append(serv, s)
}
//time.Sleep(1 * time.Second)
for i := 0; i < len(serv); i++ {
for j := 0; j < len(serv); j++ {
sock, err := zmq.NewSocket(zmq.PUSH)
check_err(err)
serv[i].Peersockets = append(serv[i].Peersockets, sock)
serv[i].Peersockets[j].Connect(serv[i].PeerServers[serv[j].ServerId])
}
}
return serv
}
/* Queue the Inbox channel for a server
*/
func QueueInbox(s servernode, e Envelope, in chan *Envelope) {
in <- &e
}
/* Return the Inbox channel for a server
*/
func (s servernode) Inbox() chan *Envelope {
return s.Serverinchannel
}
/* Return the Outbox channel for a server
*/
func (s servernode) Outbox() chan *Envelope {
return s.Serveroutchannel
}
/* Send messages that are queued in the outbox channel to the correspnding servers
*/
func SendMessages(s servernode) {
for {
select {
case msg, valid := <-s.Outbox():
if !valid {
return
} else {
targetID := msg.Pid
if targetID == BROADCAST {
for i := 0; i < len(Peers); i++ {
msg.Pid = Peers[i]
msg.MsgId = s.MessageId
atomic.AddInt64(&s.MessageId, 1)
_, err := s.Peersockets[peerIdIndex[msg.Pid]].SendMessage(msg)
check_err(err)
//fmt.Println(n, "and", len(msg.Msg))
//fmt.Println("SENDING: (Src,Dst) --> (",s.ServerId,",",msg.Pid,") (Message:",*msg,")")
}
} else {
targetID = peerIdIndex[msg.Pid]
msg.MsgId = s.MessageId
atomic.AddInt64(&s.MessageId, 1)
_, err := s.Peersockets[targetID].SendMessage(msg)
//fmt.Println(n, "and", msg)
check_err(err)
//fmt.Println("SENDING: (Src,Dst) --> (",s.ServerId,",",msg.Pid,") (Message:",*msg,")")
}
}
}
}
}
/* Receive the messages that come from the peer servers and queue them to the inbox channel
*/
func ReceiveMessages(ser servernode) {
var e Envelope
for {
msg, err := ser.Serversocket.RecvMessage(0)
check_err(err)
a1 := strings.Split(msg[0], "&{")
a2 := strings.Split(a1[1], " ")
pid, err := strconv.Atoi(a2[0])
check_err(err)
mid, err := strconv.Atoi(a2[1])
check_err(err)
msgid := int64(mid)
text := ""
for b := 2; b < len(a2); b++ {
text = text + " " + a2[b]
}
text1 := text[1:]
msgtext := strings.Split(text1, "}")[0]
e.Pid = pid
e.MsgId = msgid
e.Msg = msgtext
go QueueInbox(ser, e, ser.Inbox())
}
}
/* Check for errors and panic out
*/
func check_err(e error) {
if e != nil {
panic(e)
}
}
/* Parse the given input cluster config file and collect all teh data for the cluster formation
*/
func ParseConfig(filename string) int {
fconf, err := os.OpenFile(filename, os.O_RDONLY, 0600)
check_err(err)
rdconf := bufio.NewReader(fconf)
nline, err := rdconf.ReadString('\n')
index := 0
for {
if err != nil {
break
}
line := strings.Split(nline, "\n")
if !strings.Contains(nline, "#") && line[0] != "" {
text := string(line[0])
pair := strings.Split(text, ",")
id := strings.TrimSpace(string(pair[0]))
address := strings.TrimSpace(string(pair[1]))
nodeid, err := strconv.Atoi(id)
check_err(err)
for k := 0; k < len(Peers); k++ {
if Peers[k] == nodeid {
fmt.Printf(strconv.Itoa(nodeid) + ": duplicate node IDs. Node IDs should be unique")
return 1
}
for _, value := range PeerAddress {
if value == address {
fmt.Printf(address + ": duplicate IP:port number. IP:port should be unique for nodes")
return 2
}
}
}
Peers = append(Peers, nodeid)
peerIdIndex[nodeid] = index
PeerAddress[nodeid] = address
index = index + 1
}
nline, err = rdconf.ReadString('\n')
}
return 0
}