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|
package p2p
import (
"fmt"
"sync"
"time"
)
const (
handlerTimeout = 1000
)
type Handlers map[string](func(p *Peer) Protocol)
type Messenger struct {
conn *Connection
peer *Peer
handlers Handlers
protocolLock sync.RWMutex
protocols []Protocol
offsets []MsgCode // offsets for adaptive message idss
protocolTable map[string]int
quit chan chan bool
err chan *PeerError
pulse chan bool
}
func NewMessenger(peer *Peer, conn *Connection, errchan chan *PeerError, handlers Handlers) *Messenger {
baseProtocol := NewBaseProtocol(peer)
return &Messenger{
conn: conn,
peer: peer,
offsets: []MsgCode{baseProtocol.Offset()},
handlers: handlers,
protocols: []Protocol{baseProtocol},
protocolTable: make(map[string]int),
err: errchan,
pulse: make(chan bool, 1),
quit: make(chan chan bool, 1),
}
}
func (self *Messenger) Start() {
self.conn.Open()
go self.messenger()
self.protocolLock.RLock()
defer self.protocolLock.RUnlock()
self.protocols[0].Start()
}
func (self *Messenger) Stop() {
// close pulse to stop ping pong monitoring
close(self.pulse)
self.protocolLock.RLock()
defer self.protocolLock.RUnlock()
for _, protocol := range self.protocols {
protocol.Stop() // could be parallel
}
q := make(chan bool)
self.quit <- q
<-q
self.conn.Close()
}
func (self *Messenger) messenger() {
in := self.conn.Read()
for {
select {
case payload, ok := <-in:
//dispatches message to the protocol asynchronously
if ok {
go self.handle(payload)
} else {
return
}
case q := <-self.quit:
q <- true
return
}
}
}
// handles each message by dispatching to the appropriate protocol
// using adaptive message codes
// this function is started as a separate go routine for each message
// it waits for the protocol response
// then encodes and sends outgoing messages to the connection's write channel
func (self *Messenger) handle(payload []byte) {
// send ping to heartbeat channel signalling time of last message
// select {
// case self.pulse <- true:
// default:
// }
self.pulse <- true
// initialise message from payload
msg, err := NewMsgFromBytes(payload)
if err != nil {
self.err <- NewPeerError(MiscError, " %v", err)
return
}
// retrieves protocol based on message Code
protocol, offset, peerErr := self.getProtocol(msg.Code())
if err != nil {
self.err <- peerErr
return
}
// reset message code based on adaptive offset
msg.Decode(offset)
// dispatches
response := make(chan *Msg)
go protocol.HandleIn(msg, response)
// protocol reponse timeout to prevent leaks
timer := time.After(handlerTimeout * time.Millisecond)
for {
select {
case outgoing, ok := <-response:
// we check if response channel is not closed
if ok {
self.conn.Write() <- outgoing.Encode(offset)
} else {
return
}
case <-timer:
return
}
}
}
// negotiated protocols
// stores offsets needed for adaptive message id scheme
// based on offsets set at handshake
// get the right protocol to handle the message
func (self *Messenger) getProtocol(code MsgCode) (Protocol, MsgCode, *PeerError) {
self.protocolLock.RLock()
defer self.protocolLock.RUnlock()
base := MsgCode(0)
for index, offset := range self.offsets {
if code < offset {
return self.protocols[index], base, nil
}
base = offset
}
return nil, MsgCode(0), NewPeerError(InvalidMsgCode, " %v", code)
}
func (self *Messenger) PingPong(timeout time.Duration, gracePeriod time.Duration, pingCallback func(), timeoutCallback func()) {
fmt.Printf("pingpong keepalive started at %v", time.Now())
timer := time.After(timeout)
pinged := false
for {
select {
case _, ok := <-self.pulse:
if ok {
pinged = false
timer = time.After(timeout)
} else {
// pulse is closed, stop monitoring
return
}
case <-timer:
if pinged {
fmt.Printf("timeout at %v", time.Now())
timeoutCallback()
return
} else {
fmt.Printf("pinged at %v", time.Now())
pingCallback()
timer = time.After(gracePeriod)
pinged = true
}
}
}
}
func (self *Messenger) AddProtocols(protocols []string) {
self.protocolLock.Lock()
defer self.protocolLock.Unlock()
i := len(self.offsets)
offset := self.offsets[i-1]
for _, name := range protocols {
protocolFunc, ok := self.handlers[name]
if ok {
protocol := protocolFunc(self.peer)
self.protocolTable[name] = i
i++
offset += protocol.Offset()
fmt.Println("offset ", name, offset)
self.offsets = append(self.offsets, offset)
self.protocols = append(self.protocols, protocol)
protocol.Start()
} else {
fmt.Println("no ", name)
// protocol not handled
}
}
}
func (self *Messenger) Write(protocol string, msg *Msg) error {
self.protocolLock.RLock()
defer self.protocolLock.RUnlock()
i := 0
offset := MsgCode(0)
if len(protocol) > 0 {
var ok bool
i, ok = self.protocolTable[protocol]
if !ok {
return fmt.Errorf("protocol %v not handled by peer", protocol)
}
offset = self.offsets[i-1]
}
handler := self.protocols[i]
// checking if protocol status/caps allows the message to be sent out
if handler.HandleOut(msg) {
self.conn.Write() <- msg.Encode(offset)
}
return nil
}
|
