timeout.go

package middleware

import (
	"context"
	"github.com/gin-gonic/gin"
	"net/http"
	"time"
)

// timeout middleware wraps the request context with a timeout
func TimeoutMiddleware(timeout time.Duration) func(c *gin.Context) {

	return func(c *gin.Context) {

		//是否超时，都会执行，进行收尾
		// wrap the request context with a timeout
		ctx, cancel := context.WithTimeout(c.Request.Context(), timeout)

		defer func() {
			// check if context timeout was reached
			if ctx.Err() == context.DeadlineExceeded {
				//这里超时，才会执行

				// write response and abort the request
				c.JSON(http.StatusOK, gin.H{
					"code": 400,
					"msg":  "数据有误",
					"data": nil,
				})
				c.Abort()

			}
			c.JSON(http.StatusOK, "hello")

			//是否超时，都会执行，进行收尾
			//cancel to clear resources after finished
			cancel()
		}()

		//是否超时，都会执行
		// replace request with context wrapped request
		c.Request = c.Request.WithContext(ctx)
		c.Next()//实际调用具体的handler处理业务，实际还在这个方法中，所以业务执行结束会回到中间件中执行中间件中的defer函数
	}
}