add Go tick server

main.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"bufio"
+	"io"
+	"log"
+	"net"
+	"time"
+)
+
+// read all messages from client.
+func read(rc io.ReadCloser, id int, msg chan<- string, done chan<- int) {
+	defer rc.Close()
+
+	scanner := bufio.NewScanner(rc)
+	for scanner.Scan() {
+		msg <- scanner.Text()
+	}
+
+	done <- id
+}
+
+// write 'tick' message to all clients.
+func write(conns []net.Conn) {
+	for _, c := range conns {
+		if c != nil {
+			io.WriteString(c, "tick\n")
+		}
+	}
+}
+
+// add a client and read messages if there is room.
+func addClient(conns []net.Conn, conn net.Conn, msg chan<- string, done chan<- int) []net.Conn {
+	for i, c := range conns {
+		if c == nil {
+			go read(conn, i, msg, done)
+			conns[i] = conn
+			return conns
+		}
+	}
+
+	// reject the client if we are full
+	conn.Close()
+	return conns
+}
+
+func main() {
+	conns := make([]net.Conn, 15)
+
+	connC := make(chan net.Conn, 0)
+	msgC := make(chan string, 0)
+	doneC := make(chan int, 0)
+
+	listener, err := net.Listen("tcp", ":8080")
+	if err != nil {
+		log.Fatalf("listening on :8080: %s", err.Error())
+	}
+
+	go func() {
+		for {
+			c, err := listener.Accept()
+			if err == nil {
+				connC <- c
+			}
+		}
+	}()
+
+	ticker := time.NewTicker(time.Second)
+
+	for {
+		select {
+
+		case conn := <-connC:
+			conns = addClient(conns, conn, msgC, doneC)
+
+		case id := <-doneC:
+			conns[id] = nil
+
+		case msg := <-msgC:
+			log.Printf("client said: %s", msg)
+
+		case <-ticker.C:
+			write(conns)
+		}
+	}
+}