graceful相关逻辑处理

graceful.go

@@ -25,13 +25,13 @@ import (
 )
 
 const (
-	PRE_SIGNAL = iota
+	PreSignal = iota
-	POST_SIGNAL
+	PostSignal
 
-	STATE_INIT
+	StateInit
-	STATE_RUNNING
+	StateRunning
-	STATE_SHUTTING_DOWN
+	StateShuttingDown
-	STATE_TERMINATE
+	StateTerminate
 )
 
 var (
@@ -111,7 +111,7 @@ func NewServer(addr string, handler http.Handler) (srv *endlessServer) {
 		sigChan: make(chan os.Signal),
 		isChild: isChild,
 		SignalHooks: map[int]map[os.Signal][]func(){
-			PRE_SIGNAL: map[os.Signal][]func(){
+			PreSignal: map[os.Signal][]func(){
 				syscall.SIGHUP:  []func(){},
 				syscall.SIGUSR1: []func(){},
 				syscall.SIGUSR2: []func(){},
@@ -119,7 +119,7 @@ func NewServer(addr string, handler http.Handler) (srv *endlessServer) {
 				syscall.SIGTERM: []func(){},
 				syscall.SIGTSTP: []func(){},
 			},
-			POST_SIGNAL: map[os.Signal][]func(){
+			PostSignal: map[os.Signal][]func(){
 				syscall.SIGHUP:  []func(){},
 				syscall.SIGUSR1: []func(){},
 				syscall.SIGUSR2: []func(){},
@@ -128,7 +128,7 @@ func NewServer(addr string, handler http.Handler) (srv *endlessServer) {
 				syscall.SIGTSTP: []func(){},
 			},
 		},
-		state: STATE_INIT,
+		state: StateInit,
 		lock:  &sync.RWMutex{},
 	}
 
@@ -196,11 +196,11 @@ down the server.
 */
 func (srv *endlessServer) Serve() (err error) {
 	defer log.Println(syscall.Getpid(), "Serve() returning...")
-	srv.setState(STATE_RUNNING)
+	srv.setState(StateRunning)
 	err = srv.Server.Serve(srv.EndlessListener)
 	log.Println(syscall.Getpid(), "Waiting for connections to finish...")
 	srv.wg.Wait()
-	srv.setState(STATE_TERMINATE)
+	srv.setState(StateTerminate)
 	return
 }
 
@@ -318,10 +318,7 @@ func (srv *endlessServer) getListener(laddr string) (l net.Listener, err error)
 	return
 }
 
-/*
+// handleSignals 监听系统传递的信号量, 并根据不同的信号量进行不同的逻辑处理
-handleSignals listens for os Signals and calls any hooked in function that the
-user had registered with the signal.
-*/
 func (srv *endlessServer) handleSignals() {
 	var sig os.Signal
 
@@ -330,10 +327,13 @@ func (srv *endlessServer) handleSignals() {
 		hookableSignals...,
 	)
 
+	// 获取当前进程ID
 	pid := syscall.Getpid()
 	for {
+		// 无缓冲chan, 阻塞等待信号量
 		sig = <-srv.sigChan
-		srv.signalHooks(PRE_SIGNAL, sig)
+		// 触发信号量处理之前的逻辑
+		srv.signalHooks(PreSignal, sig)
 		switch sig {
 		case syscall.SIGHUP:
 			log.Println(pid, "Received SIGHUP. forking.")
@@ -357,7 +357,8 @@ func (srv *endlessServer) handleSignals() {
 		default:
 			log.Printf("Received %v: nothing i care about...\n", sig)
 		}
-		srv.signalHooks(POST_SIGNAL, sig)
+		// 触发信号量处理之后的逻辑
+		srv.signalHooks(PostSignal, sig)
 	}
 }
 
@@ -371,21 +372,24 @@ func (srv *endlessServer) signalHooks(ppFlag int, sig os.Signal) {
 	return
 }
 
-/*
+// shutdown 关闭服务(平滑)
-shutdown closes the listener so that no new connections are accepted. it also
+//
-starts a goroutine that will hammer (stop all running requests) the server
+// 1. 关闭监听器, 不再接受新的连接
-after DefaultHammerTime.
+//
-*/
+// 2. 等待所有连接处理完毕后, 退出服务
+//
+// 3. 如果设置了 DefaultHammerTime, 则在该时间后强制退出服务
 func (srv *endlessServer) shutdown() {
-	if srv.getState() != STATE_RUNNING {
+	if srv.getState() != StateRunning {
 		return
 	}
 
-	srv.setState(STATE_SHUTTING_DOWN)
+	// 将服务状态设置为 StateShuttingDown(关闭中)
+	srv.setState(StateShuttingDown)
 	if DefaultHammerTime >= 0 {
 		go srv.hammerTime(DefaultHammerTime)
 	}
-	// disable keep-alives on existing connections
+	// 已存在的连接禁用keep-alives
 	srv.SetKeepAlivesEnabled(false)
 	err := srv.EndlessListener.Close()
 	if err != nil {
@@ -413,13 +417,13 @@ func (srv *endlessServer) hammerTime(d time.Duration) {
 			log.Println("WaitGroup at 0", r)
 		}
 	}()
-	if srv.getState() != STATE_SHUTTING_DOWN {
+	if srv.getState() != StateShuttingDown {
 		return
 	}
 	time.Sleep(d)
 	log.Println("[STOP - Hammer Time] Forcefully shutting down parent")
 	for {
-		if srv.getState() == STATE_TERMINATE {
+		if srv.getState() == StateTerminate {
 			break
 		}
 		srv.wg.Done()
@@ -555,13 +559,10 @@ func (w endlessConn) Close() error {
 	return err
 }
 
-/*
+// RegisterSignalHook 注册各个信号前置/后置处理逻辑
-RegisterSignalHook registers a function to be run PRE_SIGNAL or POST_SIGNAL for
+// PreSignal 和 PostSignal 分别表示信号前置和后置处理逻辑
-a given signal. PRE or POST in this case means before or after the signal
-related code endless itself runs
-*/
 func (srv *endlessServer) RegisterSignalHook(prePost int, sig os.Signal, f func()) (err error) {
-	if prePost != PRE_SIGNAL && prePost != POST_SIGNAL {
+	if prePost != PreSignal && prePost != PostSignal {
 		err = fmt.Errorf("Cannot use %v for prePost arg. Must be endless.PRE_SIGNAL or endless.POST_SIGNAL.", sig)
 		return
 	}