Daily Go Language Bible-Example: concurrent clock service exercises

Exercise 8.1: Modify Clock2 to support incoming parameters as port numbers, and then write a clockwall program that can communicate with multiple clock servers simultaneously, read time from multiple servers, and display the results of all services at once in a single table. Similar to the clock wall you see in some offices. If you have a geographically distributed server that can be used to run on different machines, or run multiple instances on the same machine, listen to different ports and pretend to be in a different time zone. Like this:

$ TZ=US/Eastern    ./clock2 -port 8010 &$ TZ=Asia/Tokyo    ./clock2 -port 8020 &$ TZ=Europe/London ./clock2 -port 8030 &$ clockwall NewYork=localhost:8010 Tokyo=localhost:8020 London=localhost:8030

Clock2.go

Package Mainimport (        "flag"        "IO" "        log"        "NET"        "Time")//support incoming parameter as port number var port = flag. String ("Port", "8000", "Please enter Port") Func main () {        flag. Parse ()        listener, err: = Net. Listen ("tcp", "localhost:" +*port)        if err! = Nil {                log. Fatal (Err)        }           for {                conn, err: = Listener. Accept ()                if err! = Nil {                        log. Print (ERR)//e.g., connection aborted                        continue                }                   go handleconn (conn)//New Goroutines processing connection        }   }func Handleconn (c net. Conn) {        defer c.close ()        for {                _, err: = Io. WriteString (c, time. Now (). Format ("15:04:05\n"))                if err! = Nil {                        return//e.g., client disconnected                } time                   . Sleep (1 * time. Second)        }   }

Clockwall.go

NETCAT1 is a read-only TCP client.package mainimport (        "io"        "log"        "NET" "        OS"        "Strings"        " Time ") Func main () {        for _, V: = Range os. Args[1:] {                KeyValue: = Strings. Split (V, "=")                go conntcp (keyvalue[1])        } for           {time                . Sleep (1 * time. Second)        }   }func conntcp (URI string) {        conn, err: = Net. Dial ("TCP", URI)        if err! = Nil {                log. Fatal (Err)        }           defer conn. Close ()        mustcopy (OS. STDOUT, conn)}func mustcopy (DST io. Writer, src io. Reader) {        If _, err: = Io. Copy (DST, SRC); Err! = Nil {                log. Fatal (Err)        }   }

　　

　　

Daily Go Language Bible-Example: concurrent clock service exercises