Gin的启动流程

今天我们介绍Gin平滑停机。首先我们看一下，Gin在的启动流程，如下图。所有的处理逻辑在Run()函数中，里面还是调用底层的TCP连接的listen函数。

gin_default_run.png

Gin平滑停机流程

有时候我们服务器停机之前处理完之前接收的请求，这就是所谓优雅停机或者平滑停机。其流程见下图：

gin_shutdown_gracefu.png

Gin平滑停机示例代码

package main

import (
    "context"
    "github.com/gin-gonic/gin"
    "log"
    "net/http"
    "os"
    "os/signal"
    "syscall"
    "time"
)

func main() {
    router := gin.Default()

    router.GET("/testing", func(c *gin.Context) {
        time.Sleep(10 * time.Second)
        c.JSON(http.StatusOK, gin.H{
            "message":"Welcom Gin Srever",
        })
    })

    srv := &http.Server{
        Addr:    ":8080",
        Handler: router,
    }

    go func() {
        // service connections
        if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
            log.Fatalf("listen:%s\n", err)
        }
    }()

    // wait for interrupt signal to gracefully shutdown the server with
    // a timeout of 10 seconds.
    quit := make(chan os.Signal, 1)
    // kill (no param) default send syscall.SIGTERM
    // kill -2 is syscall.SIGINT
    // kill -9 is syscall.SIGKILL but can't be catch, so don't need add it
    signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
    <-quit
    log.Println("Shutdown Server ...")

    ctx, cancel := context.WithTimeout(context.Background(), 10 * time.Second)
    defer cancel()
    if err:= srv.Shutdown(ctx); err != nil {
        log.Fatal("Server Shutdown:", err)
    }
    log.Println("Server exiting")
}

测试

1. 启动服务
   [GIN-debug] GET /testing --> main.main.func1 (3 handlers)
2. 命令窗口：curl "localhost:8080/testing"
3. 停止服务
   2020/03/17 08:35:09 Shutdown Server ...
[GIN] 2020/03/17 - 08:35:17 | 200 | 10.002280953s | 127.0.0.1 | GET /testing
2020/03/17 08:35:18 Server exiting
4. 观察命令窗口

{"message":"Welcom Gin Srever"}