這期內(nèi)容當(dāng)中小編將會(huì)給大家?guī)碛嘘P(guān)怎么進(jìn)行Go語言HTTP Server源碼分析，文章內(nèi)容豐富且以專業(yè)的角度為大家分析和敘述，閱讀完這篇文章希望大家可以有所收獲。
成都創(chuàng)新互聯(lián)是專業(yè)的富陽網(wǎng)站建設(shè)公司，富陽接單;提供網(wǎng)站設(shè)計(jì)制作、成都網(wǎng)站制作,網(wǎng)頁設(shè)計(jì),網(wǎng)站設(shè)計(jì),建網(wǎng)站,PHP網(wǎng)站建設(shè)等專業(yè)做網(wǎng)站服務(wù);采用PHP框架,可快速的進(jìn)行富陽網(wǎng)站開發(fā)網(wǎng)頁制作和功能擴(kuò)展;專業(yè)做搜索引擎喜愛的網(wǎng)站,專業(yè)的做網(wǎng)站團(tuán)隊(duì),希望更多企業(yè)前來合作!
Go語言中HTTP Server:
HTTP server，顧名思義，支持http協(xié)議的服務(wù)器，HTTP是一個(gè)簡(jiǎn)單的請(qǐng)求-響應(yīng)協(xié)議，通常運(yùn)行在TCP之上。通過客戶端發(fā)送請(qǐng)求給服務(wù)器得到對(duì)應(yīng)的響應(yīng)。
HTTP服務(wù)簡(jiǎn)單實(shí)現(xiàn)
重慶分公司
重慶分公司
package main import ( "fmt" "net/http" ) //③處理請(qǐng)求，返回結(jié)果 func Hello(w http.ResponseWriter, r *http.Request) { fmt.Fprintln(w, "hello world") } func main() { //①路由注冊(cè) http.HandleFunc("/", Hello) //②服務(wù)監(jiān)聽 http.ListenAndServe(":8080", nil) }
你以為這樣就結(jié)束了嗎，不才剛剛開始。
源碼分析
①路由注冊(cè)
func HandleFunc(pattern string, handler func(ResponseWriter, *Request)) { DefaultServeMux.HandleFunc(pattern, handler) }DefaultServeMux是什么?
DefaultServeMux是ServeMux的一個(gè)實(shí)例。
ServeMux又是什么?
// DefaultServeMux is the default ServeMux used by Serve. var DefaultServeMux = &defaultServeMux var defaultServeMux ServeMux type ServeMux struct { mu sync.RWMutex m map[string]muxEntry hosts bool } type muxEntry struct { explicit bool h Handler pattern string }ServeMux主要通過map[string]muxEntry，來存儲(chǔ)了具體的url模式和handler(此handler是實(shí)現(xiàn)Handler接口的類型)。通過實(shí)現(xiàn)Handler的ServeHTTP方法，來匹配路由(這一點(diǎn)下面源碼會(huì)講到)
很多地方都涉及到了Handler,那么Handler是什么?
type Handler interface { ServeHTTP(ResponseWriter, *Request) }此接口可以算是HTTP Server一個(gè)樞紐
func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Request)) { mux.Handle(pattern, HandlerFunc(handler)) } type HandlerFunc func(ResponseWriter, *Request) func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) { f(w, r) }從代碼中可以看出HandlerFunc是一個(gè)函數(shù)類型，并實(shí)現(xiàn)了Handler接口。當(dāng)通過調(diào)用HandleFunc()，把Hello強(qiáng)轉(zhuǎn)為HandlerFunc類型時(shí)，就意味著 Hello函數(shù)也實(shí)現(xiàn)ServeHTTP方法。
ServeMux的Handle方法:
func (mux *ServeMux) Handle(pattern string, handler Handler) { mux.mu.Lock() defer mux.mu.Unlock() if pattern == "" { panic("http: invalid pattern " + pattern) } if handler == nil { panic("http: nil handler") } if mux.m[pattern].explicit { panic("http: multiple registrations for " + pattern) } if mux.m == nil { mux.m = make(map[string]muxEntry) } //把handler和pattern模式綁定到 //map[string]muxEntry的map上 mux.m[pattern] = muxEntry{explicit: true, h: handler, pattern: pattern} if pattern[0] != '/' { mux.hosts = true } //這里是綁定靜態(tài)目錄，不作為本片重點(diǎn)。 n := len(pattern) if n > 0 && pattern[n-1] == '/' && !mux.m[pattern[0:n-1]].explicit { path := pattern if pattern[0] != '/' { path = pattern[strings.Index(pattern, "/"):] } url := &url.URL{Path: path} mux.m[pattern[0:n-1]] = muxEntry{h: RedirectHandler(url.String(), StatusMovedPermanently), pattern: pattern} } }上面的流程就完成了路由注冊(cè)。
②服務(wù)監(jiān)聽
type Server struct {
Addr string
Handler Handler
ReadTimeout time.Duration
WriteTimeout time.Duration
TLSConfig *tls.Config
MaxHeaderBytes int
TLSNextProto map[string]func(*Server, *tls.Conn, Handler)
ConnState func(net.Conn, ConnState)
ErrorLog *log.Logger
disableKeepAlives int32 nextProtoOnce sync.Once
nextProtoErr error
}
func ListenAndServe(addr string, handler Handler) error {
server := &Server{Addr: addr, Handler: handler}
return server.ListenAndServe()
}
//初始化監(jiān)聽地址Addr，同時(shí)調(diào)用Listen方法設(shè)置監(jiān)聽。
//***將監(jiān)聽的TCP對(duì)象傳入Serve方法：
func (srv *Server) ListenAndServe() error {
addr := srv.Addr
if addr == "" {
addr = ":http"
}
ln, err := net.Listen("tcp", addr)
if err != nil {
return err
}
return srv.Serve(tcpKeepAliveListener{ln.(*net.TCPListener)})
}
Serve(l net.Listener)為每個(gè)請(qǐng)求開啟goroutine的設(shè)計(jì)，保證了go的高并發(fā)。
func (srv *Server) Serve(l net.Listener) error { defer l.Close() if fn := testHookServerServe; fn != nil { fn(srv, l) } var tempDelay time.Duration // how long to sleep on accept failure if err := srv.setupHTTP2_Serve(); err != nil { return err } srv.trackListener(l, true) defer srv.trackListener(l, false) baseCtx := context.Background() // base is always background, per Issue 16220 ctx := context.WithValue(baseCtx, ServerContextKey, srv) ctx = context.WithValue(ctx, LocalAddrContextKey, l.Addr()) //開啟循環(huán)進(jìn)行監(jiān)聽 for { //通過Listener的Accept方法用來獲取連接數(shù)據(jù) rw, e := l.Accept() if e != nil { select { case <-srv.getDoneChan(): return ErrServerClosed default: } if ne, ok := e.(net.Error); ok && ne.Temporary() { if tempDelay == 0 { tempDelay = 5 * time.Millisecond } else { tempDelay *= 2 } if max := 1 * time.Second; tempDelay > max { tempDelay = max } srv.logf("http: Accept error: %v; retrying in %v", e, tempDelay) time.Sleep(tempDelay) continue } return e } tempDelay = 0 //通過獲得的連接數(shù)據(jù)，創(chuàng)建newConn連接對(duì)象 c := srv.newConn(rw) c.setState(c.rwc, StateNew) // before Serve can return //開啟goroutine發(fā)送連接請(qǐng)求 go c.serve(ctx) } }serve()為核心,讀取對(duì)應(yīng)的連接數(shù)據(jù)進(jìn)行分配
func (c *conn) serve(ctx context.Context) { c.remoteAddr = c.rwc.RemoteAddr().String() //連接關(guān)閉相關(guān)的處理 defer func() { if err := recover(); err != nil && err != ErrAbortHandler { const size = 64 << 10 buf := make([]byte, size) buf = buf[:runtime.Stack(buf, false)] c.server.logf("http: panic serving %v: %v\n%s", c.remoteAddr, err, buf) } if !c.hijacked() { c.close() c.setState(c.rwc, StateClosed) } }() ..... ctx, cancelCtx := context.WithCancel(ctx) c.cancelCtx = cancelCtx defer cancelCtx() c.r = &connReader{conn: c} c.bufr = newBufioReader(c.r) c.bufw = newBufioWriterSize(checkConnErrorWriter{c}, 4<<10) for { //讀取客戶端的請(qǐng)求 w, err := c.readRequest(ctx) if c.r.remain != c.server.initialReadLimitSize() { // If we read any bytes off the wire, we're active. c.setState(c.rwc, StateActive) } ................. //處理網(wǎng)絡(luò)數(shù)據(jù)的狀態(tài) // Expect 100 Continue support req := w.req if req.expectsContinue() { if req.ProtoAtLeast(1, 1) && req.ContentLength != 0 { // Wrap the Body reader with one that replies on the connection req.Body = &expectContinueReader{readCloser: req.Body, resp: w} } } else if req.Header.get("Expect") != "" { w.sendExpectationFailed() return } c.curReq.Store(w) if requestBodyRemains(req.Body) { registerOnHitEOF(req.Body, w.conn.r.startBackgroundRead) } else { if w.conn.bufr.Buffered() > 0 { w.conn.r.closeNotifyFromPipelinedRequest() } w.conn.r.startBackgroundRead() } //調(diào)用serverHandler{c.server}.ServeHTTP(w, w.req) //方法處理請(qǐng)求 serverHandler{c.server}.ServeHTTP(w, w.req) w.cancelCtx() if c.hijacked() { return } w.finishRequest() if !w.shouldReuseConnection() { if w.requestBodyLimitHit || w.closedRequestBodyEarly() { c.closeWriteAndWait() } return } c.setState(c.rwc, StateIdle) c.curReq.Store((*response)(nil)) if !w.conn.server.doKeepAlives() { return } if d := c.server.idleTimeout(); d != 0 { c.rwc.SetReadDeadline(time.Now().Add(d)) if _, err := c.bufr.Peek(4); err != nil { return } } c.rwc.SetReadDeadline(time.Time{}) } }③處理請(qǐng)求，返回結(jié)果
serverHandler 主要初始化路由多路復(fù)用器。如果server對(duì)象沒有指定Handler，則使用默認(rèn)的DefaultServeMux作為路由多路復(fù)用器。并調(diào)用初始化Handler的ServeHTTP方法。
type serverHandler struct { srv *Server } func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) { handler := sh.srv.Handler if handler == nil { handler = DefaultServeMux } if req.RequestURI == "*" && req.Method == "OPTIONS" { handler = globalOptionsHandler{} } handler.ServeHTTP(rw, req) }這里就是之前提到的匹配路由的具體代碼
func (mux *ServeMux) ServeHTTP (w ResponseWriter, r *Request) {
if r.RequestURI == "*" {
if r.ProtoAtLeast(1, 1) {
w.Header().Set("Connection", "close")
}
w.WriteHeader(StatusBadRequest)
return
}
//匹配注冊(cè)到路由上的handler函數(shù)
h, _ := mux.Handler(r)
//調(diào)用handler函數(shù)的ServeHTTP方法
//即Hello函數(shù)，然后把數(shù)據(jù)寫到http.ResponseWriter
//對(duì)象中返回給客戶端。
h.ServeHTTP(w, r)
}
func (mux *ServeMux) Handler(r *Request) (h Handler, pattern string) {
if r.Method != "CONNECT" {
if p := cleanPath(r.URL.Path); p != r.URL.Path {
_, pattern = mux.handler(r.Host, p)
url := *r.URL
url.Path = p
return RedirectHandler(url.String(), StatusMovedPermanently), pattern
}
}
return mux.handler(r.Host, r.URL.Path)
}
func (mux *ServeMux) handler(host, path string) (h Handler, pattern string) {
mux.mu.RLock()
defer mux.mu.RUnlock()
// Host-specific pattern takes precedence over generic ones
if mux.hosts {
//如 127.0.0.1/hello
h, pattern = mux.match(host + path)
}
if h == nil {
// 如 /hello
h, pattern = mux.match(path)
}
if h == nil {
h, pattern = NotFoundHandler(), ""
}
return
}
func (mux *ServeMux) match(path string) (h Handler, pattern string) {
var n = 0
for k, v := range mux.m {
if !pathMatch(k, path) {
continue
}
//通過迭代m尋找出注冊(cè)路由的patten模式
//與實(shí)際url匹配的handler函數(shù)并返回。
if h == nil || len(k) > n {
n = len(k)
h = v.h
pattern = v.pattern
}
}
return
}
func pathMatch(pattern, path string) bool {
if len(pattern) == 0 {
// should not happen
return false
}
n := len(pattern)
//如果注冊(cè)模式與請(qǐng)求uri一樣返回true，否則false
if pattern[n-1] != '/' {
return pattern == path
}
//靜態(tài)文件匹配
return len(path) >= n && path[0:n] == pattern
}
將數(shù)據(jù)寫給客戶端
//主要代碼，通過層層封裝才走到這一步 func (w checkConnErrorWriter) Write(p []byte) (n int, err error) { n, err = w.c.rwc.Write(p) if err != nil && w.c.werr == nil { w.c.werr = err w.c.cancelCtx() } return }serverHandler{c.server}.ServeHTTP(w, w.req)當(dāng)請(qǐng)求結(jié)束后，就開始執(zhí)行連接斷開的相關(guān)邏輯。
總結(jié)
Go語言通過一個(gè)ServeMux實(shí)現(xiàn)了的路由多路復(fù)用器來管理路由。同時(shí)提供一個(gè)Handler接口提供ServeHTTP方法，實(shí)現(xiàn)handler接口的函數(shù)，可以處理實(shí)際request并返回response。
ServeMux和handler函數(shù)的連接橋梁就是Handler接口。ServeMux的ServeHTTP方法實(shí)現(xiàn)了尋找注冊(cè)路由的handler的函數(shù)，并調(diào)用該handler的ServeHTTP方法。
所以說Handler接口是一個(gè)重要樞紐。
簡(jiǎn)單梳理下整個(gè)請(qǐng)求響應(yīng)過程，如下圖
上述就是小編為大家分享的怎么進(jìn)行Go語言HTTP Server源碼分析了，如果剛好有類似的疑惑，不妨參照上述分析進(jìn)行理解。如果想知道更多相關(guān)知識(shí)，歡迎關(guān)注創(chuàng)新互聯(lián)行業(yè)資訊頻道。
