优雅地关闭Gorilla服务器

Question

我正在使用https://github.com/gorilla/mux中的大猩猩复用器库在go中构建一个服务器。问题是，当我使用Ctrl+C时，或者当有一个特定的API调用时，例如"/shutdown“时，我希望它能够优雅地关闭。

我已经知道，在Go 1.8中，优雅的关闭已经实现了。但如何与大猩猩复用器相结合呢？另外，如何将它与SIGINT信号相结合？

有人能教我怎么做吗？

Answer 1

通道可以通过API调用(/shutdown)或中断信号(Ctrl+C)捕获关闭请求。

1. 将http.Server嵌入自定义结构中，以便稍后调用http Server.Shutdown
2. 添加通道字段(shutdownReq)，用于从API调用/shutdown传递关闭请求
3. 在gorilla/mux的路由器中注册http处理程序，包括gorilla/mux，然后将路由器分配给http.Server.Handler
4. 寄存器os.Interrupt/syscall.SIGINT, syscall.SIGTERM处理程序
5. 使用select通过API调用或interrupt信号捕获关闭请求
6. 通过调用Server.Shutdown执行干净关闭

下面是示例代码：

package main

import (
    "context"
    "log"
    "net/http"
    "sync/atomic"
    "syscall"
    "time"

    "os"
    "os/signal"

    "github.com/gorilla/mux"
)

type myServer struct {
    http.Server
    shutdownReq chan bool
    reqCount    uint32
}

func NewServer() *myServer {
    //create server
    s := &myServer{
        Server: http.Server{
            Addr:         ":8080",
            ReadTimeout:  10 * time.Second,
            WriteTimeout: 10 * time.Second,
        },
        shutdownReq: make(chan bool),
    }

    router := mux.NewRouter()

    //register handlers
    router.HandleFunc("/", s.RootHandler)
    router.HandleFunc("/shutdown", s.ShutdownHandler)

    //set http server handler
    s.Handler = router

    return s
}

func (s *myServer) WaitShutdown() {
    irqSig := make(chan os.Signal, 1)
    signal.Notify(irqSig, syscall.SIGINT, syscall.SIGTERM)

    //Wait interrupt or shutdown request through /shutdown
    select {
    case sig := <-irqSig:
        log.Printf("Shutdown request (signal: %v)", sig)
    case sig := <-s.shutdownReq:
        log.Printf("Shutdown request (/shutdown %v)", sig)
    }

    log.Printf("Stoping http server ...")

    //Create shutdown context with 10 second timeout
    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()

    //shutdown the server
    err := s.Shutdown(ctx)
    if err != nil {
        log.Printf("Shutdown request error: %v", err)
    }
}

func (s *myServer) RootHandler(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("Hello Gorilla MUX!\n"))
}

func (s *myServer) ShutdownHandler(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("Shutdown server"))

    //Do nothing if shutdown request already issued
    //if s.reqCount == 0 then set to 1, return true otherwise false
    if !atomic.CompareAndSwapUint32(&s.reqCount, 0, 1) {
        log.Printf("Shutdown through API call in progress...")
        return
    }

    go func() {
        s.shutdownReq <- true
    }()
}

func main() {
    //Start the server
    server := NewServer()

    done := make(chan bool)
    go func() {
        err := server.ListenAndServe()
        if err != nil {
            log.Printf("Listen and serve: %v", err)
        }
        done <- true
    }()

    //wait shutdown
    server.WaitShutdown()

    <-done
    log.Printf("DONE!")
}

备注：请注意与优雅关闭相关的本期。