Golang HTTP服务超时控制实现原理分析

// Context's methods may be called by multiple goroutines simultaneously.
type Context interface {
  // 当Context被取消或者到了deadline,返回一个被关闭的channel
  Done() <-chan struct{}
}
// 函数句柄
type CancelFunc func()

//创建退出Context
func WithCancel(parent Context)(ctx Context,cancel CancelFunc){}
//创建有超时时间的Context
func WithTimeout(parent Context,timeout time.Duration)(Context,CancelFunc){}
//创建有截止时间的Context
func WithDeadline(parent Context,d time.Time)(Context,CancelFunc){}

package framework
import (
	"context"
	"encoding/json"
	"net/http"
	"sync"
)
type Context struct {
	Request        *http.Request
	ResponseWriter http.ResponseWriter
	hasTimeOut     bool // 是否超时标记位
	writerMux      *sync.Mutex
}
func NewContext()*Context{
	return &Context{}
}
func (ctx *Context) BaseContext() context.Context {
	return ctx.Request.Context()
}
func (ctx *Context) Done() <-chan struct{} {
	return ctx.BaseContext().Done()
}
func (ctx *Context)SetHasTimeOut(){
	ctx.hasTimeOut=true
}
func (ctx *Context)HasTimeOut()bool{
	return ctx.hasTimeOut
}
// 自行封装一个Json的方法
func (ctx *Context) Json(status int, obj interface{}) (err error) {
	if ctx.HasTimeOut(){
		return nil
	}
	bytes, err := json.Marshal(obj)
	ctx.ResponseWriter.WriteHeader(status)
	_, err = ctx.ResponseWriter.Write(bytes)
	return
}
// 对外暴露锁
func (ctx *Context) WriterMux() *sync.Mutex {
	return ctx.writerMux
}
// 统一处理器Controller方法
type ControllerHandler func(c *Context) error

package main
import (
	"context"
	"fmt"
	"testdemo1/coredemo/framework"
	"time"
)
func FooController(ctx *framework.Context) error {
	durationCtx, cancel := context.WithTimeout(ctx.BaseContext(), time.Second)
	defer cancel()
	finish := make(chan struct{}, 1)
	panicChan := make(chan interface{}, 1)
	go func() {
		defer func() {
			if p := recover(); p != nil {
				panicChan <- p
			}
		}()
		time.Sleep(time.Second * 10)
		finish <- struct{}{}
	}()
	select {
	case p := <-panicChan: // panic
	fmt.Println("panic:",p)
	    ctx.WriterMux().Lock()  // 防止多个协程之前writer的消息乱序
		defer ctx.WriterMux().Unlock()
		ctx.Json(500, "panic")
	case <-finish: // 正常退出
		ctx.Json(200, "ok")
		fmt.Println("finish")
	case <-durationCtx.Done(): // 超时事件
		ctx.WriterMux().Lock()
		defer ctx.WriterMux().Unlock()
		ctx.Json(500, "timed out")
		ctx.SetHasTimeOut()  // 防止多次协程重复写入超时日志
	}
	return nil
}

package framework
import (
	"net/http"
)
type Core struct {
	RouterMap map[string]ControllerHandler
}
func (c Core) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
	http.DefaultServeMux.ServeHTTP(writer, request)
}
func NewCore() *Core {
	return &Core{
		RouterMap:make(map[string]ControllerHandler,0),
	}
}
// 注册Get方法
func (c *Core) Get(pattern string, handler ControllerHandler) {
	c.RouterMap["get"+"-"+pattern]=handler
}
// 注册Post方法
func (c *Core) Post(pattern string, handler ControllerHandler) {
	c.RouterMap["post"+"-"+pattern]=handler
}

package main
import "testdemo1/coredemo/framework"
func registerRouter(core *framework.Core){
	// 设置控制器
	core.Get("foo",FooController)
}

package main
import (
	"log"
	"net/http"
	"testdemo1/coredemo/framework"
)
func main() {
	server:=&http.Server{Addr: ":8080",Handler: framework.NewCore()}
	// 注册router
	registerRouter(framework.NewCore())
	err := server.ListenAndServe()
    if err!=nil{
    	log.Fatal(err)
	}
}