sdf

book_with_bridge/chat/main.go

@@ -0,0 +1,133 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"net"
+	"time"
+)
+
+type client struct {
+	_chan chan <- string
+	name string
+}
+
+
+var (
+	entering = make(chan client)
+	leaving = make(chan client)
+	messages = make(chan string)
+	cancel = make(chan time.Time)
+)
+
+func handleConn(conn net.Conn) {
+	defer conn.Close()
+
+	ch := make(chan string)
+
+	go clientWriter(conn,ch)
+
+	who := conn.RemoteAddr().String()
+	client := client{
+		_chan: ch,
+		name: who,
+	}
+	ch <- "You " + who
+	messages <- who + " connected"
+	entering <- client
+
+	inputChan := make(chan string)
+	timeout := time.NewTimer(40*time.Second)
+	defer timeout.Stop()
+
+	input := bufio.NewScanner(conn)
+
+	go func() {
+		log.Println("inside of goroutine")
+		for input.Scan() {
+			log.Println("inside of Scan for loop")
+			inputChan <- client.name + ": " + input.Text()
+			}
+
+		if err := input.Err(); err != nil {
+			log.Printf("Scanner error: %v", err)
+		} else {
+			log.Println("Scanner reached EOF (connection closed)")
+		}
+		
+		log.Println("Closing input channel")
+		close(inputChan)
+	}()
+
+loop:	
+	for {
+		select {
+		case text,ok := <- inputChan:
+			if !ok {
+				leaving <- client
+				messages <- who + " disconnected"
+				break loop
+			}
+			if !timeout.Stop() {
+				<- timeout.C
+			}
+			timeout.Reset(40*time.Second)
+			messages <- text
+		case <- timeout.C:
+			ch <- "Connection timed out due to inactivity"
+			leaving <- client
+			messages <- who + " disconnected (timeout)"
+			break loop
+		}
+	}
+}
+
+func clientWriter(conn net.Conn, ch <- chan string) {
+	for msg := range ch {
+		fmt.Fprintln(conn,msg)
+	}
+}
+
+
+func broadcaster() {
+	clients := make(map[client]bool)
+	for {
+		select {
+		case msg := <- messages:
+			log.Println("Got a msg")
+			for cli := range clients {
+				cli._chan <- msg
+			}
+		case cli := <- entering:
+			cli._chan <- "List of connected clients"
+			for i := range clients {
+				cli._chan <- i.name
+			}
+			clients[cli] = true
+		case cli := <- leaving:
+			log.Printf("Deleting client %s")
+			delete(clients,cli)
+			close(cli._chan)
+		}
+	}
+
+}
+
+func main() {
+	listener,err := net.Listen("tcp",":9090")
+	if err != nil {
+		log.Fatalf("Error in Lister %v",err)
+	}
+
+	go broadcaster()
+
+	for {
+		conn,err := listener.Accept()
+		if err != nil {
+			log.Fatalf("Error in Accept %v",err)
+			continue
+		}
+		go handleConn(conn)
+	}
+}

book_with_bridge/du/main.go

@@ -5,8 +5,12 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"time"
 )
 
+
+var verbos = flag.Bool("v",false,"show verbose")
+
 func main() {
 	flag.Parse()
 	roots := flag.Args()
@@ -23,13 +27,25 @@ func main() {
 		close(fileSizes)
 	}()
 
+	var tick <- chan time.Time
+
+	if *verbos{
+		tick = time.Tick(500 * time.Millisecond)
+	}
 	var nfiles,nbytes int64
-	for size := range fileSizes {
+loop:
+	for {
+		select {
+		case size,ok := <- fileSizes:
+			if !ok {
+				break loop
+			}
 			nfiles++
 			nbytes += size
-	}
+		case <- tick:
 			printDU(nfiles,nbytes)
-
+		}
+	}
 }
 
 func printDU(nfiles, nbytes int64) {
@@ -50,7 +66,6 @@ func WalkDir(dir string, fileSizes chan <- int64) {
 
 func dirents(dir string) []os.DirEntry{
 	entries, err := os.ReadDir(dir)
-	fmt.Println(entries)
 	if err != nil {
 		fmt.Fprintf(os.Stderr,"du1: %v\n",err)
 		return  nil