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ctx_response.go
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/
ctx_response.go
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// Copyright 2020 GoFast Author(http://chende.ren). All rights reserved.
// Use of this source code is governed by a MIT license
package fst
import (
"bytes"
"github.com/qinchende/gofast/logx"
"github.com/qinchende/gofast/skill/lang"
"net/http"
"sync"
)
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// 对标准 http.ResponseWriter 的包裹,加入对响应的状态管理
const (
defaultStatus = 0
errAlreadyRendered = "ResWarp: already committed. "
)
type ResData struct {
dataBuf *bytes.Buffer // 记录响应的数据,用于框架统一封装之后的打印信息等场景
status int16 // HttpStatus
}
// 自定义 ResponseWriter, 对标准库的一层包裹处理,需要对返回的数据做缓存,做到更灵活的控制。
// 实现接口 ResponseWriter
type ResponseWrap struct {
http.ResponseWriter
respLock sync.Mutex
ResData
committed bool
isTimeout bool
// TODO: 如果isTimeout,主线程执行的返回结果将被放入这个对象中
// extRespData *ResData
}
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
func (w *ResponseWrap) HeaderValues() http.Header {
return w.ResponseWriter.Header()
}
func (w *ResponseWrap) Status() int {
return int(w.status)
}
// 数据长度
func (w *ResponseWrap) DataSize() int {
return w.dataBuf.Len()
}
// 当前已写的数据内容
func (w *ResponseWrap) WrittenData() []byte {
return w.dataBuf.Bytes()
}
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
func (w *ResponseWrap) Reset(res http.ResponseWriter) {
w.committed = false
w.isTimeout = false
w.ResponseWriter = res
w.status = defaultStatus
w.dataBuf = new(bytes.Buffer)
//w.extRespData = nil
}
// 重置返回结果(没有最终response的情况下,可以重置返回内容)
func (w *ResponseWrap) Flush() bool {
w.respLock.Lock()
defer w.respLock.Unlock()
if w.committed {
if !w.isTimeout {
logx.Warn(errAlreadyRendered + "Can't Flush.")
}
return false
}
w.status = defaultStatus
w.dataBuf.Reset()
return true
}
// Gin: 只会改变这里的w.status值,而不会改变response给客户端的状态了。(这没有多大意义,GoFast做出改变)
// GoFast: 没有提交之前可以无限次的改变,最终返回最后一次设置的值
func (w *ResponseWrap) WriteHeader(newStatus int) {
w.respLock.Lock()
defer w.respLock.Unlock()
if w.committed {
if !w.isTimeout {
logx.WarnF("%sCan't WriteHeader from %d to %d.", errAlreadyRendered, w.status, newStatus)
}
return
}
if w.status != int16(newStatus) && w.status != defaultStatus {
logx.WarnF("Response status already %d, but now change to %d.", w.status, newStatus)
}
w.status = int16(newStatus)
}
// 最后都要通过这个函数Render所有数据
// 问题1: 是否要避免 double render?
// 答:目前不需要管这个事,调用多少次Write,就往返回流写入多少数据。double render是前段业务逻辑的问题,开发应该主动避免。
func (w *ResponseWrap) Write(data []byte) (n int, err error) {
w.respLock.Lock()
defer w.respLock.Unlock()
if w.committed {
if !w.isTimeout {
logx.Warn(errAlreadyRendered + "Can't Write.")
}
return 0, nil
}
n, err = w.dataBuf.Write(data)
return
}
func (w *ResponseWrap) WriteString(s string) (n int, err error) {
w.respLock.Lock()
defer w.respLock.Unlock()
if w.committed {
if !w.isTimeout {
logx.Warn(errAlreadyRendered + "Can't WriteString.")
}
return 0, nil
}
n, err = w.dataBuf.WriteString(s)
return
}
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// Render才会真的往返回通道写数据,Render只执行一次
func (w *ResponseWrap) Send() (n int, err error) {
if w.tryToCommit("Can't Send.") == false {
return
}
if w.status == defaultStatus {
w.status = http.StatusOK
}
n, err = w.realFinalSend()
w.respLock.Unlock()
if err != nil {
logx.StackF("realSend error: %s", err)
}
return
}
// 这个主要用于严重错误的时候,特殊状态的返回
// 如果还没有render,强制返回服务器错误,中断其它返回。否则啥也不做。
func (w *ResponseWrap) SendHijack(resStatus int, data []byte) (n int) {
if w.tryToCommit("Can't Hijack.") == false {
return
}
w.resetResponse(resStatus, data)
n, err := w.realFinalSend()
w.respLock.Unlock()
if err != nil {
logx.StackF("realSend error: %s", err)
}
return
}
// 强制跳转
func (w *ResponseWrap) SendHijackRedirect(req *http.Request, resStatus int, redirectUrl string) {
if w.tryToCommit("Can't Hijack Redirect.") == false {
return
}
w.resetResponse(resStatus, lang.ToBytes(redirectUrl))
http.Redirect(w, req, redirectUrl, resStatus)
w.respLock.Unlock()
}
// 超时协程调用
func (w *ResponseWrap) sendByTimeoutGoroutine(resStatus int, data []byte) bool {
w.isTimeout = true
if w.tryToCommit("Can't Send by timeout goroutine.") == false {
return false
}
w.resetResponse(resStatus, data)
_, err := w.realFinalSend()
w.respLock.Unlock()
if err != nil {
logx.StackF("realSend error: %s", err)
}
return true
}
// 打劫成功,强制改写返回结果
func (w *ResponseWrap) resetResponse(resStatus int, data []byte) {
w.status = int16(resStatus)
w.dataBuf.Reset()
_, _ = w.dataBuf.Write(data)
}
func (w *ResponseWrap) realFinalSend() (n int, err error) {
w.ResponseWriter.WriteHeader(int(w.status))
n, err = w.ResponseWriter.Write(w.dataBuf.Bytes())
return
}
// NOTE: 要避免 double render。只执行第一次Render的结果,后面的Render直接丢弃
func (w *ResponseWrap) tryToCommit(tip string) bool {
w.respLock.Lock()
if w.committed {
w.respLock.Unlock()
if !w.isTimeout {
logx.Warn(errAlreadyRendered + tip)
}
return false
}
w.committed = true
return true // 此时没有解锁,需要在调用外部解锁
}