func (chordNode *ChordNode) checkPredecessor() {
chordNode.Logger.Println("Chord : In checkPredecessor")
//RPC call to check predecessor
jsonMessage := "{\"method\":\"CheckPredecessor\",\"params\":[]}"
chordNode.Logger.Println("Predecessor:", chordNode.Predecessor)
chordNode.Logger.Println("Predecessor serverInfo:", chordNode.FtServerMapping[chordNode.Predecessor])
clientServerInfo := rpcclient.ServerInfo{}
clientServerInfo.ServerID = chordNode.FtServerMapping[chordNode.Predecessor].ServerID
clientServerInfo.Protocol = chordNode.FtServerMapping[chordNode.Predecessor].Protocol
clientServerInfo.IpAddress = chordNode.FtServerMapping[chordNode.Predecessor].IpAddress
clientServerInfo.Port = chordNode.FtServerMapping[chordNode.Predecessor].Port
chordNode.Logger.Println("RPC call to:", clientServerInfo)
client := &rpcclient.RPCClient{}
err, response := client.RpcCall(clientServerInfo, jsonMessage)
chordNode.Logger.Println("Response:", response)
if err != nil {
chordNode.Logger.Println(err)
return
}
chordNode.Logger.Println("response.Result=", response.(*(rpcclient.ResponseParameters)).Result)
// Set the predecessor to nil if empty response
if response.(*(rpcclient.ResponseParameters)).Result == nil {
chordNode.Logger.Println("SETTING PREDECESSOR TO NIL")
chordNode.SetPredecessor(true, 0)
}
}
// initially FingerTableIndex = 0
func (chordNode *ChordNode) fixFingers(FingerTableIndex int) {
chordNode.Logger.Println("Chord : In fixFingers")
//find the successor of (p+2^(i-1)) by initiaing the find_successor call from the current node
nextNodeId := chordNode.Id + uint32(math.Pow(2, float64(FingerTableIndex-1)))
jsonMessage := "{\"method\":\"findSuccessor\",\"params\":[" + fmt.Sprint(nextNodeId) + "]}"
clientServerInfo := rpcclient.ServerInfo{}
clientServerInfo.ServerID = chordNode.MyServerInfo.ServerID
clientServerInfo.Protocol = chordNode.MyServerInfo.Protocol
clientServerInfo.IpAddress = chordNode.MyServerInfo.IpAddress
clientServerInfo.Port = chordNode.MyServerInfo.Port
client := &rpcclient.RPCClient{}
err, response := client.RpcCall(clientServerInfo, jsonMessage)
if err != nil {
chordNode.Logger.Println(err)
return
}
// process only if response is present
if response.(*(rpcclient.ResponseParameters)).Result != nil {
chordNode.FingerTable[FingerTableIndex] = uint32((response.(*(rpcclient.ResponseParameters)).Result[0]).(float64))
resultServerInfo := rpcclient.ServerInfo{}
for key, value := range response.(*(rpcclient.ResponseParameters)).Result[1].(map[string]interface{}) {
switch key {
case "serverID":
resultServerInfo.ServerID = value.(string)
break
case "protocol":
resultServerInfo.Protocol = value.(string)
break
case "IpAddress":
resultServerInfo.IpAddress = value.(string)
break
case "Port":
resultServerInfo.Port = int(value.(float64))
}
}
chordNode.FtServerMapping[chordNode.FingerTable[FingerTableIndex]] = resultServerInfo
chordNode.Successor = chordNode.FingerTable[1]
}
chordNode.Logger.Println("FingerTable=", chordNode.FingerTable)
}
func getDefaultServerInfo() rpcclient.ServerInfo {
serverInfo := rpcclient.ServerInfo{}
serverInfo.ServerID = "mainserver"
serverInfo.Protocol = "tcp"
serverInfo.IpAddress = "127.0.0.1"
serverInfo.Port = 1234
return serverInfo
}
func (chordNode *ChordNode) join(serverInfo rpcclient.ServerInfo) {
chordNode.Logger.Println("Chord : In Join")
jsonMessage := "{\"method\":\"findSuccessor\",\"params\":[" + fmt.Sprint(chordNode.Id) + "]}"
clientServerInfo := rpcclient.ServerInfo{}
clientServerInfo.ServerID = serverInfo.ServerID
clientServerInfo.Protocol = serverInfo.Protocol
clientServerInfo.IpAddress = serverInfo.IpAddress
clientServerInfo.Port = serverInfo.Port
client := &rpcclient.RPCClient{}
err, response := client.RpcCall(clientServerInfo, jsonMessage)
if err != nil {
chordNode.Logger.Println(err)
return
}
chordNode.Predecessor = 0
chordNode.Successor = uint32((response.(*(rpcclient.ResponseParameters)).Result[0]).(float64))
resultServerInfo := rpcclient.ServerInfo{}
for key, value := range response.(*(rpcclient.ResponseParameters)).Result[1].(map[string]interface{}) {
switch key {
case "serverID":
resultServerInfo.ServerID = value.(string)
break
case "protocol":
resultServerInfo.Protocol = value.(string)
break
case "IpAddress":
resultServerInfo.IpAddress = value.(string)
break
case "Port":
resultServerInfo.Port = int(value.(float64))
}
}
chordNode.FtServerMapping[chordNode.Successor] = resultServerInfo
}
func (chordNode *ChordNode) updateFtServerMapping(id uint32, serverInfo rpcclient.ServerInfo) {
if _, ok := chordNode.FtServerMapping[id]; !ok {
clientServerInfo := rpcclient.ServerInfo{}
clientServerInfo.ServerID = serverInfo.ServerID
clientServerInfo.Protocol = serverInfo.Protocol
clientServerInfo.IpAddress = serverInfo.IpAddress
clientServerInfo.Port = serverInfo.Port
chordNode.FtServerMapping[id] = clientServerInfo
}
}
/*
Use this function to create server info to whom RPCcall is going to be made
Input: Chord Id of the server
*/
func (chordNode *ChordNode) PrepareClientServerInfo(chordID uint32) (rpcclient.ServerInfo, error) {
clientServerInfo := rpcclient.ServerInfo{}
if _, ok := chordNode.FtServerMapping[chordID]; ok {
clientServerInfo.ServerID = chordNode.FtServerMapping[chordID].ServerID
clientServerInfo.Protocol = chordNode.FtServerMapping[chordID].Protocol
clientServerInfo.IpAddress = chordNode.FtServerMapping[chordID].IpAddress
clientServerInfo.Port = chordNode.FtServerMapping[chordID].Port
return clientServerInfo, nil
} else {
customError := errors.New("Entry not found in FTServerMapping")
chordNode.Logger.Println(customError)
return rpcclient.ServerInfo{}, customError
}
}
/*
request <-"{"method":"Notify","params":[10,{"ServerID":"9999","Protocol":"tcp","IpAddress":"127.0.0.1","Port":1235}]}"
response <- "{"result":[],"id":,"error":null }"
*/
func (rpcMethod *RPCMethod) Notify(jsonInput RequestParameters, jsonOutput *ResponseParameters) error {
//Initialize rpcserver
var err error
err, rpcMethod.rpcServer = GetRPCServerInstance()
var customError error
if err != nil {
customError = errors.New("Getting Server Instance error :" + err.Error())
rpcMethod.rpcServer.logger.Println(customError)
return customError
}
rpcMethod.rpcServer.logger.Println("RPCCall: In Notify")
rpcMethod.rpcServer.logger.Println("Input=", jsonInput)
var probablePredecessorId uint32
probablePredecessorServerInfo := rpcclient.ServerInfo{}
var parameters []interface{}
parameters = jsonInput.Params
//get inputId from the []interface
for k, v := range parameters {
if k == 0 {
probablePredecessorId = uint32(v.(float64))
} else if k == 1 {
resultServerInfo := rpcclient.ServerInfo{}
for key, value := range v.(map[string]interface{}) {
switch key {
case "serverID":
resultServerInfo.ServerID = value.(string)
break
case "protocol":
resultServerInfo.Protocol = value.(string)
break
case "IpAddress":
resultServerInfo.IpAddress = value.(string)
break
case "Port":
resultServerInfo.Port = int(value.(float64))
}
}
probablePredecessorServerInfo = resultServerInfo
}
}
//probablePredecessor ∈ (predecessor, chordNode)
isPredecessorNil, predecessor := rpcMethod.rpcServer.chordNode.GetPredecessor()
//predecessor == chordNode.Id refers to the case where the ActualNodesInRing = 1 i.e. predecessor is the node itself
nodeId := rpcMethod.rpcServer.chordNode.Id
if isPredecessorNil ||
(probablePredecessorId > predecessor && probablePredecessorId < nodeId) ||
predecessor == nodeId ||
(probablePredecessorId < nodeId && predecessor > probablePredecessorId && predecessor > nodeId) ||
(probablePredecessorId > nodeId && predecessor < probablePredecessorId && predecessor > nodeId) {
rpcMethod.rpcServer.chordNode.SetPredecessor(false, probablePredecessorId)
rpcMethod.rpcServer.chordNode.FtServerMapping[rpcMethod.rpcServer.chordNode.Predecessor] = probablePredecessorServerInfo
//transfer keys to predecessor whose hash is less than predecessor chord ID
rpcMethod.rpcServer.transferKeysToPredecessor()
}
return nil
}
func (rpcMethod *RPCMethod) FindSuccessor(jsonInput RequestParameters, jsonOutput *ResponseParameters) error {
//Initialize rpcserver
var err error
err, rpcMethod.rpcServer = GetRPCServerInstance()
var customError error
if err != nil {
customError = errors.New("Getting Server Instance error :" + err.Error())
rpcMethod.rpcServer.logger.Println(customError)
return customError
}
rpcMethod.rpcServer.logger.Println("RPCCall: In FindSuccessor ")
rpcMethod.rpcServer.logger.Println("Input=", jsonInput)
defer rpcMethod.rpcServer.logger.Println("Exited FindSuccssor=")
var inputId uint32
var succId uint32
var interId uint32
succServerInfo := rpcclient.ServerInfo{}
var parameters []interface{}
parameters = jsonInput.Params
//get inputId from the []interface
for k, v := range parameters {
if k == 0 {
inputId = uint32(v.(float64))
}
}
/*
if (id ∈ (n, successor])
return successor;
*/
rpcMethod.rpcServer.logger.Println("Find Successor of (id)" + fmt.Sprint(inputId))
rpcMethod.rpcServer.logger.Println("Current Node (n):" + fmt.Sprint(rpcMethod.rpcServer.chordNode.Id))
rpcMethod.rpcServer.logger.Println("Current Node Successor (successor):" + fmt.Sprint(rpcMethod.rpcServer.chordNode.Successor))
//case when only 1 node in chord ring - that node will be the successor
if rpcMethod.rpcServer.chordNode.Id == rpcMethod.rpcServer.chordNode.Successor {
succId = rpcMethod.rpcServer.chordNode.Id
//basic condition
} else if rpcMethod.rpcServer.chordNode.Id < inputId && inputId <= rpcMethod.rpcServer.chordNode.Successor {
succId = rpcMethod.rpcServer.chordNode.Successor
//successor id is less than node id - check whether inputId falls between (n,sucessor + 2^m)
} else if rpcMethod.rpcServer.chordNode.Successor < rpcMethod.rpcServer.chordNode.Id && (inputId > rpcMethod.rpcServer.chordNode.Id || inputId < rpcMethod.rpcServer.chordNode.Successor) {
succId = rpcMethod.rpcServer.chordNode.Successor
} else {
interId = rpcMethod.rpcServer.chordNode.ClosestPrecedingNode(inputId)
// if call is being forwarded to the current node itself, that means current node itself is the successor
if interId == rpcMethod.rpcServer.chordNode.Id {
succId = rpcMethod.rpcServer.chordNode.Id
} else {
//create rpc call "{"method":"findSuccessor","params":[inputId]}"
jsonMessage := "{\"method\":\"findSuccessor\",\"params\":[" + fmt.Sprint(inputId) + "]}"
clientServerInfo := rpcclient.ServerInfo{}
clientServerInfo.ServerID = rpcMethod.rpcServer.chordNode.FtServerMapping[interId].ServerID
clientServerInfo.Protocol = rpcMethod.rpcServer.chordNode.FtServerMapping[interId].Protocol
clientServerInfo.IpAddress = rpcMethod.rpcServer.chordNode.FtServerMapping[interId].IpAddress
clientServerInfo.Port = rpcMethod.rpcServer.chordNode.FtServerMapping[interId].Port
client := &rpcclient.RPCClient{}
err, response := client.RpcCall(clientServerInfo, jsonMessage)
if err != nil {
fmt.Println(err)
return nil
}
jsonOutput.Result = make([]interface{}, 2)
// process only if response is present
if response.(*(rpcclient.ResponseParameters)).Result != nil {
succId = uint32(response.(*(rpcclient.ResponseParameters)).Result[0].(float64))
resultServerInfo := rpcclient.ServerInfo{}
for key, value := range response.(*(rpcclient.ResponseParameters)).Result[1].(map[string]interface{}) {
switch key {
case "serverID":
resultServerInfo.ServerID = value.(string)
break
case "protocol":
resultServerInfo.Protocol = value.(string)
break
case "IpAddress":
resultServerInfo.IpAddress = value.(string)
break
case "Port":
resultServerInfo.Port = int(value.(float64))
}
}
succServerInfo = resultServerInfo
//insert successor ID into jsonOutput
jsonOutput.Result[0] = succId
//insert succId's serverInfo into jsonOutput
jsonOutput.Result[1] = succServerInfo
}
rpcMethod.rpcServer.logger.Println("Result from findSucc=", jsonOutput.Result)
return nil
} // END-ELSE
}
jsonOutput.Result = make([]interface{}, 2)
//insert successor ID into jsonOutput
jsonOutput.Result[0] = succId
//insert succId's serverInfo into jsonOutput
if rpcMethod.rpcServer.chordNode.Id == succId {
jsonOutput.Result[1] = rpcMethod.rpcServer.chordNode.MyServerInfo
} else {
jsonOutput.Result[1] = rpcMethod.rpcServer.chordNode.FtServerMapping[succId]
}
return nil
}
func (chordNode *ChordNode) stabilize() {
chordNode.Logger.Println("Chord : In Stabilize")
//RPC call to get predecessor of successor
jsonMessage := "{\"method\":\"GetPredecessor\",\"params\":[]}"
clientServerInfo := rpcclient.ServerInfo{}
clientServerInfo.ServerID = chordNode.FtServerMapping[chordNode.FingerTable[1]].ServerID
clientServerInfo.Protocol = chordNode.FtServerMapping[chordNode.FingerTable[1]].Protocol
clientServerInfo.IpAddress = chordNode.FtServerMapping[chordNode.FingerTable[1]].IpAddress
clientServerInfo.Port = chordNode.FtServerMapping[chordNode.FingerTable[1]].Port
client := &rpcclient.RPCClient{}
err, response := client.RpcCall(clientServerInfo, jsonMessage)
if err != nil {
chordNode.Logger.Println(err)
return
}
// process only if response is present -- CASE WHERE SUCCESSOR LEAVES ABRUPTLY
if response.(*(rpcclient.ResponseParameters)).Result != nil {
isPredecessorOfSuccessorNil := (response.(*(rpcclient.ResponseParameters)).Result[0]).(bool)
predecessorOfSuccessor := uint32((response.(*(rpcclient.ResponseParameters)).Result[1]).(float64))
resultServerInfo := rpcclient.ServerInfo{}
for key, value := range response.(*(rpcclient.ResponseParameters)).Result[2].(map[string]interface{}) {
switch key {
case "serverID":
resultServerInfo.ServerID = value.(string)
break
case "protocol":
resultServerInfo.Protocol = value.(string)
break
case "IpAddress":
resultServerInfo.IpAddress = value.(string)
break
case "Port":
resultServerInfo.Port = int(value.(float64))
}
}
predecessorOfSuccessorServerInfo := resultServerInfo
//update the successor
if !isPredecessorOfSuccessorNil {
isPredecessorNil, _ := chordNode.GetPredecessor()
//predecessor == chordNode.Id refers to the case where the ActualNodesInRing = 1 i.e. predecessor is the node itself
if (predecessorOfSuccessor > chordNode.Id && predecessorOfSuccessor < chordNode.Successor) ||
(!isPredecessorNil && chordNode.Successor == chordNode.Id) ||
(chordNode.Successor < chordNode.Id && predecessorOfSuccessor < chordNode.Successor) ||
(chordNode.Successor < chordNode.Id && predecessorOfSuccessor > chordNode.Successor && predecessorOfSuccessor > chordNode.Id) {
chordNode.Successor = predecessorOfSuccessor
chordNode.FtServerMapping[chordNode.Successor] = predecessorOfSuccessorServerInfo
}
}
}
chordNode.Logger.Println("About to make RPC call: Notify")
//RPC call to notify the successor about the predecessor(i.e. current node)
jsonMessage = "{\"method\":\"Notify\",\"params\":[" + fmt.Sprint(chordNode.Id) + ", {\"serverID\":\"" + chordNode.MyServerInfo.ServerID + "\", \"protocol\":\"" + chordNode.MyServerInfo.Protocol + "\",\"IpAddress\":\"" + chordNode.MyServerInfo.IpAddress + "\",\"Port\":" + fmt.Sprint(chordNode.MyServerInfo.Port) + "}]}"
clientServerInfo = rpcclient.ServerInfo{}
clientServerInfo.ServerID = chordNode.FtServerMapping[chordNode.FingerTable[1]].ServerID
clientServerInfo.Protocol = chordNode.FtServerMapping[chordNode.FingerTable[1]].Protocol
clientServerInfo.IpAddress = chordNode.FtServerMapping[chordNode.FingerTable[1]].IpAddress
clientServerInfo.Port = chordNode.FtServerMapping[chordNode.FingerTable[1]].Port
client = &rpcclient.RPCClient{}
err, _ = client.RpcCall(clientServerInfo, jsonMessage)
if err != nil {
chordNode.Logger.Println(err)
return
}
}