go codelet

菲葑不弃，敝帚自珍

接口

package main
import(
    "fmt"
)
type SendAlgorithm interface{
    OnDataAvailable(byte uint32)
    GetCongestionWindow() uint64
    OnPacketLost()
}
const MinimalWindow uint64=1
const InitialWindow uint64=12
const SSthresh uint64 =30
const Mss uint64 =1500
type CubicSender struct{
    CongestionWindow uint64
    CwndCnt uint64
    total uint64
    alpha float32
    beta float32
}
func NewCubicSender(a float32,b float32) SendAlgorithm{
    return &CubicSender{
    CongestionWindow:InitialWindow,
    alpha:a,
    beta:b,
    }
}
func (c*CubicSender)OnDataAvailable(byte uint32){
    c.total+=uint64(byte)
    c.CwndCnt=uint64(c.total/Mss)
    if c.CwndCnt>=c.CongestionWindow{
    c.total=0;
    c.CongestionWindow++
    }
    fmt.Printf("%f,%f\n",c.alpha,c.beta)
}
func (c*CubicSender) GetCongestionWindow() uint64{
    return c.CongestionWindow
}
func (c*CubicSender) OnPacketLost(){
    var cwnd float32 =float32(c.CongestionWindow)*c.beta
    c.CongestionWindow=uint64(cwnd)
    c.total=0
}
// just some simulation  with different a ,b
func NewRenoSender(a float32,b float32) SendAlgorithm{
    return &CubicSender{
    CongestionWindow:InitialWindow,
    alpha:a,
    beta:b,
    }
}
type State int
const (
    TCP_RENO State = iota // value --> 0
    TCP_CUBIC              // value --> 1
)
type PathManager struct{
    senders map[uint32]interface{}
}
func (pm*PathManager) SetUp(id uint32,tcp State,p*Path){
    var cong SendAlgorithm
    switch(tcp){
    case TCP_RENO:
    cong=NewRenoSender(1,0.5)
    case TCP_CUBIC:
    cong=NewRenoSender(1,0.7)
    default:
    cong=NewRenoSender(1,0.5)   
    }
    p.sendAlgorithm=cong
    pm.senders[id]=cong
    p.SetUp(pm.senders);
}
type Path struct{
    senders map[uint32]interface{}
    sendAlgorithm SendAlgorithm
}
func (p*Path)SetUp(senders map[uint32]interface{}){
    p.senders=senders
}
func (p*Path) OndataAvailble(byte uint32){
    p.sendAlgorithm.OnDataAvailable(byte)
}
func (p*Path) OnPacketLost(){
    p.sendAlgorithm.OnPacketLost()
}
func (p*Path) GetTotalCwnd() uint64{
    var totalcwnd uint64 
    for _,s:=range p.senders{
    var cubicSender SendAlgorithm=s.(*CubicSender)//this is ok
    //var cubicSender SendAlgorithm=s.(SendAlgorithm)//this is ok
    //var cubicSender SendAlgorithm=SendAlgorithm(s) this is not work
    //cwnd:=s.(SendAlgorithm).GetCongestionWindow()   this is ok
    cwnd:=cubicSender.GetCongestionWindow()
    totalcwnd+=cwnd
    }
    return totalcwnd
}
func (p*Path) GetPathCwnd() uint64{
    return p.sendAlgorithm.GetCongestionWindow()
}
func main(){
    pm:=new(PathManager)
    pm.senders=make(map[uint32]interface{})
    p1:=new(Path)
    p2:=new(Path)
    pm.SetUp(1,TCP_CUBIC,p1)
    pm.SetUp(2,TCP_RENO,p2)
    total1:=p1.GetTotalCwnd()
    total2:=p2.GetTotalCwnd()
    fmt.Printf("%d,%d\n",total1,total2)
    pathcwnd:=p1.GetPathCwnd()
    fmt.Printf("%d\n",pathcwnd)
}

获取系统时间(毫秒)

package main

import 
(
    "fmt"
    "flag"
    "time"
)
type Config struct{
    CreatePath *bool
}
func Test(config *Config){
    fmt.Println(*config.CreatePath);
}
func GetMilliSeconds() int64{
    now := time.Now()
    nanos := now.UnixNano()
    millis := nanos / 1000000
    return millis
}
func main(){
    var millis  int64=GetMilliSeconds()
    verbose := flag.Bool("v", false, "verbose")
    multipath := flag.Bool("m", false, "multipath")
    output := flag.String("o", "out.txt", "logging output")
    flag.Parse()
    fmt.Println(*verbose)
    fmt.Println(*multipath)
    fmt.Println(*output)
    var config *Config=new(Config)
    config.CreatePath=multipath;
    Test(config)
    var delta int64=GetMilliSeconds()-millis;
    fmt.Println(delta);
}

thus not work.
var config Config=new Config{
CreatePath:multipath,
})

multi value in single value context

package main

import 
(
    "fmt"
    "github.com/emirpasic/gods/lists/arraylist"
    "github.com/emirpasic/gods/utils"
)

func first(args ...interface{})interface{} {
    return args[0]
}
func main(){

    list := arraylist.New()
    list.Add("abc")                         // ["a"]
    list.Add("c", "b")                    // ["a","c","b"]
    list.Sort(utils.StringComparator)     // ["a","b","c"]
    var ele string
    ele=first(list.Get(0)).(string)
    fmt.Println(ele);
}

ele,=list.Get(0), error, since the first return value is a interface.
but ele,=list.Get(0) would be ok.
interface{} 即为引用

interface cast

import(
"fmt"
"unsafe"
)
    var  a int32
    a=123
    var b int64
    b=123
    var c *int64
    c=&b;
    var d interface{}
    d=&b
    var e *int64;
    e=d.(*int64)
    fmt.Println("size a in main",unsafe.Sizeof(a))
    fmt.Println("size b in main",unsafe.Sizeof(b))
    fmt.Println("size c in main",unsafe.Sizeof(c))
    fmt.Println("size d in main",unsafe.Sizeof(d))
    fmt.Println("value e in main",*e)

interface function

package main
 
import (
    "fmt"
)
type StreamSender  interface{
    onDataAvailable(int32)
}
func Test(sender StreamSender){
    sender.onDataAvailable(32);
}
type Session struct{
    id int32
}
func (s *Session)onDataAvailable(len int32){
    fmt.Printf("sesion %d data len %d\n",s.id,len)
}

func main(){
    s:=new(Session);
    s.id=1;
    Test(s)
}

interface{} to string

package main 
import(
    "fmt"
    "strings"
)
func GetString(value interface{}) int{
    return strings.Count(value.(string),"")-1
}
func main(){
    s:="hello world"
    fmt.Printf("length %d\n",GetString(s))
}

回调

package main
import(
    "fmt"
)
type stream struct{
    id int
    OnIncomingData func(len int)
}

func newStream(id int, cb func(len int)) *stream{
    return &stream{
        id:id,
        OnIncomingData:cb,
    }
}

func OnIncomingData(len int){
    fmt.Printf("incoming data len %d\n",len)
}

func main(){
    stream:=newStream(1,OnIncomingData)
    stream.OnIncomingData(1400)
}