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server.go
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server.go
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package debug
import (
"io"
"io/ioutil"
"log"
"net"
"sync"
"time"
)
// Vars populated at init by godebugconfig pkg (generated at compile).
var AnnotatorFilesData []*AnnotatorFileData // all debug data
var ServerNetwork string
var ServerAddress string
var SyncSend bool // don't send in chunks (usefull to get msgs before crash)
//----------
//var logger = log.New(os.Stdout, "debug: ", 0)
var logger = log.New(ioutil.Discard, "debug: ", 0)
const chunkSendRate = 15 // per second
const chunkSendNowNMsgs = 2048 // don't wait for send rate, send now (memory)
const chunkSendQSize = 512 // msgs queueing to be sent
//----------
type Server struct {
ln net.Listener
lnwait sync.WaitGroup
client struct {
sync.RWMutex
cconn *CConn
}
sendReady sync.RWMutex
}
func NewServer() (*Server, error) {
// start listening
logger.Print("listen")
ln, err := net.Listen(ServerNetwork, ServerAddress)
if err != nil {
return nil, err
}
srv := &Server{ln: ln}
srv.sendReady.Lock() // not ready to send (no client yet)
// accept connections
srv.lnwait.Add(1)
go func() {
defer srv.lnwait.Done()
srv.acceptClientsLoop()
}()
return srv, nil
}
//----------
func (srv *Server) Close() {
// close listener
logger.Println("closing server")
_ = srv.ln.Close()
srv.lnwait.Wait()
// close client
logger.Println("closing client")
srv.client.Lock()
if srv.client.cconn != nil {
srv.client.cconn.Close()
srv.client.cconn = nil
}
srv.client.Unlock()
logger.Println("server closed")
}
//----------
func (srv *Server) acceptClientsLoop() {
for {
// accept client
logger.Println("waiting for client")
conn, err := srv.ln.Accept()
if err != nil {
logger.Printf("accept error: (%T) %v ", err, err)
// unable to accept (ex: server was closed)
if operr, ok := err.(*net.OpError); ok {
if operr.Op == "accept" {
logger.Println("end accept client loop")
return
}
}
continue
}
logger.Println("got client")
// start client
srv.client.Lock()
if srv.client.cconn != nil {
srv.client.cconn.Close() // close previous connection
}
srv.client.cconn = NewCCon(srv, conn)
srv.client.Unlock()
}
}
//----------
func (srv *Server) Send(v *LineMsg) {
// locks if client is not ready to send
srv.sendReady.RLock()
defer srv.sendReady.RUnlock()
srv.client.cconn.Send(v)
}
//----------
// Client connection.
type CConn struct {
srv *Server
conn net.Conn
rwait, swait sync.WaitGroup
sendch chan *LineMsg // sending loop channel
reqStart struct {
sync.Mutex
start chan struct{}
started bool
closed bool
}
}
func NewCCon(srv *Server, conn net.Conn) *CConn {
cconn := &CConn{srv: srv, conn: conn}
cconn.reqStart.start = make(chan struct{})
qsize := chunkSendQSize
if SyncSend {
qsize = 0
}
cconn.sendch = make(chan *LineMsg, qsize)
// receive messages
cconn.rwait.Add(1)
go func() {
defer cconn.rwait.Done()
cconn.receiveMsgsLoop()
}()
// send msgs
cconn.swait.Add(1)
go func() {
defer cconn.swait.Done()
cconn.sendMsgsLoop()
}()
return cconn
}
func (cconn *CConn) Close() {
cconn.reqStart.Lock()
if cconn.reqStart.started {
// not sendready anymore
cconn.srv.sendReady.Lock()
}
cconn.reqStart.closed = true
cconn.reqStart.Unlock()
// close send msgs: can't close receive msgs first (closes client)
close(cconn.reqStart.start) // ok even if it didn't start
close(cconn.sendch)
cconn.swait.Wait()
// close receive msgs
_ = cconn.conn.Close()
cconn.rwait.Wait()
}
//----------
func (cconn *CConn) receiveMsgsLoop() {
for {
msg, err := DecodeMessage(cconn.conn)
if err != nil {
// unable to read (server was probably closed)
if operr, ok := err.(*net.OpError); ok {
if operr.Op == "read" {
break
}
}
// connection ended gracefully by the client
if err == io.EOF {
break
}
// always print if the error reaches here
log.Print(err)
return
}
// handle msg
switch t := msg.(type) {
case *ReqFilesDataMsg:
logger.Print("sending files data")
msg := &FilesDataMsg{Data: AnnotatorFilesData}
if err := cconn.send2(msg); err != nil {
log.Println(err)
}
case *ReqStartMsg:
logger.Print("reqstart")
cconn.reqStart.Lock()
if !cconn.reqStart.started && !cconn.reqStart.closed {
cconn.reqStart.start <- struct{}{}
cconn.reqStart.started = true
cconn.srv.sendReady.Unlock()
}
cconn.reqStart.Unlock()
default:
// always print if there is a new msg type
log.Printf("todo: unexpected msg type: %T", t)
}
}
}
//----------
func (cconn *CConn) sendMsgsLoop() {
// wait for reqstart, or the client won't have the index data
_, ok := <-cconn.reqStart.start
if !ok {
return
}
if SyncSend {
cconn.syncSendLoop()
} else {
cconn.chunkSendLoop()
}
}
func (cconn *CConn) syncSendLoop() {
for {
v, ok := <-cconn.sendch
if !ok {
break
}
if err := cconn.send2(v); err != nil {
log.Println(err)
}
}
}
func (cconn *CConn) chunkSendLoop() {
scheduled := false
timeToSend := make(chan bool)
msgs := []*LineMsg{}
sendMsgs := func() {
if len(msgs) > 0 {
if err := cconn.send2(msgs); err != nil {
log.Println(err)
}
msgs = nil
}
}
loop1:
for {
select {
case v, ok := <-cconn.sendch:
if !ok {
break loop1
}
msgs = append(msgs, v)
if len(msgs) >= chunkSendNowNMsgs {
sendMsgs()
} else if !scheduled {
scheduled = true
go func() {
d := time.Second / time.Duration(chunkSendRate)
time.Sleep(d)
timeToSend <- true
}()
}
case <-timeToSend:
scheduled = false
sendMsgs()
}
}
// send last messages if any
sendMsgs()
}
func (cconn *CConn) send2(v interface{}) error {
encoded, err := EncodeMessage(v)
if err != nil {
panic(err)
}
n, err := cconn.conn.Write(encoded)
if err != nil {
return err
}
if n != len(encoded) {
logger.Printf("n!=len(encoded): %v %v\n", n, len(encoded))
}
return nil
}
//----------
func (cconn *CConn) Send(v *LineMsg) {
cconn.sendch <- v
}