如何实现Golang中的优雅停机机制

package main

import (
    "context"
    "fmt"
    "net/http"
    "os"
    "os/signal"
    "sync"
    "syscall"
    "time"
)

func main() {
    // 创建一个server
    server := &http.Server{
        Addr:    ":8080",
        Handler: http.HandlerFunc(handler),
    }

    // 创建一个channel来接收信号
    sigChan := make(chan os.Signal, 1)
    signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)

    // 创建一个context
    ctx, cancel := context.WithCancel(context.Background())

    // 创建一个WaitGroup来等待所有goroutine完成
    var wg sync.WaitGroup

    // 启动一个goroutine来监听信号
    go func() {
        sig := <-sigChan
        fmt.Println("Received signal:", sig)
        cancel() // 取消context
        shutdownServer(ctx, server, &wg)
    }()

    // 启动server
    wg.Add(1)
    go func() {
        defer wg.Done()
        fmt.Println("Server listening on :8080")
        if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
            fmt.Println("Server failed to start:", err)
        }
    }()

    // 等待所有goroutine完成
    wg.Wait()
    fmt.Println("Server gracefully stopped")
}

func handler(w http.ResponseWriter, r *http.Request) {
    // 模拟处理请求
    fmt.Println("Handling request...")
    time.Sleep(2 * time.Second)
    fmt.Fprintln(w, "Hello, World!")
}

func shutdownServer(ctx context.Context, server *http.Server, wg *sync.WaitGroup) {
    fmt.Println("Shutting down server...")

    // 创建一个带有超时的context
    shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer shutdownCancel()

    // 关闭server
    if err := server.Shutdown(shutdownCtx); err != nil {
        fmt.Println("Server shutdown error:", err)
    }

    fmt.Println("Server shutdown complete")
}