//A echo server with max-connections limit and interval connection show
package main
import (
"fmt"
"net"
"os"
"time"
)
const (
MAX_CONN_NUM = 5
)
//echo server Goroutine
func EchoFunc(conn net.Conn, conn_close_flag chan int) {
defer conn.Close()
defer func() {
conn_close_flag <- -1
}()
buf := make([]byte, 1024)
for {
_, err := conn.Read(buf)
if err != nil {
//println("Error reading:", err.Error())
return
}
//send reply
_, err = conn.Write(buf)
if err != nil {
//println("Error send reply:", err.Error())
return
}
}
}
//initial listener and run
func main() {
listener, err := net.Listen("tcp", "0.0.0.0:8088")
if err != nil {
println("error listening:", err.Error())
os.Exit(1)
}
defer listener.Close()
fmt.Printf("running ...\n")
var cur_conn_num float64 = 0
ch_conn_change := make(chan int, MAX_CONN_NUM)
tick := time.Tick(1e8)
for {
//read all close flags berfor accept new connection
//TODO: better code to handle batch close?
readmore := 1
for readmore > 0 {
select {
case conn_change := <-ch_conn_change:
cur_conn_num = cur_conn_num + float64(conn_change)
default:
readmore = 0
}
}
//FIXME: tick block by listener.Accept()
select {
case <-tick:
fmt.Printf("cur conn num: %f\n", cur_conn_num)
default:
}
if cur_conn_num >= MAX_CONN_NUM {
//reach MAX_CONN_NUM, waiting for exist connection close
time.Sleep(time.Second)
} else {
//accept new connetion
conn, err := listener.Accept()
if err != nil {
println("Error accept:", err.Error())
return
}
cur_conn_num++
go EchoFunc(conn, ch_conn_change)
}
}
}