httpflv使用问题

[zxs943023403]

使用httpflv进行播放的时候，通过<-request.Context().Done()方法获取到客户端在播放结束前关闭了当前链接，此时http处理方法返回会导致panic
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x1110196]

goroutine 12 [running]:
bufio.(*Writer).Flush(0xc00007ea40)
/sdk/go1.17/src/bufio/bufio.go:607 +0x56
bufio.(*Writer).Write(0xc00007ea40, {0xc00025e000, 0xc00025e000, 0xc000028d75})
/sdk/go1.17/src/bufio/bufio.go:643 +0xd8
net/http.(*response).write(0xc000152380, 0x90a, {0xc00025e000, 0x90a, 0xa80}, {0x0, 0x0})
/sdk/go1.17/src/net/http/server.go:1592 +0x21e
net/http.(*response).Write(0x0, {0xc00025e000, 0x1052306, 0x1064be0})
/sdk/go1.17/src/net/http/server.go:1550 +0x30
github.com/yapingcat/gomedia/go-flv.(*FlvWriter).writeVideo(0xc00000ec18, {0xc000233b00, 0xc000257d80, 0x10601ce}, 0x87b20a44, 0xc7c)
/Desktop/gopath/pkg/mod/github.com/yapingcat/[email protected]/go-flv/flv-file.go:373 +0x9f
github.com/yapingcat/gomedia/go-flv.(*FlvWriter).WriteH264(0x989680, {0xc000233b00, 0xc000544230, 0x0}, 0x4bfb, 0x4bfb)
/Desktop/gopath/pkg/mod/github.com/yapingcat/[email protected]/go-flv/flv-file.go:354 +0x155
是否可以在flvwriter增加一个writer是否已关闭的判断，或者手动关闭的方法？

[yapingcat]

目前gomedia不管理网络连接，连接交由调用方来管理

针对这个问题，可以把http.ResponseWriter封装一下，在封装的接口里面实现上述的逻辑判断
类似下面这个简单实现

type HttpWriterWrapper struct {
	closed    chan struct{}
	w         http.ResponseWriter
	sendChan  chan []byte
	die       chan struct{}
	lastError error
	once      sync.Once
}

func NewHttpWriterWrapper(w http.ResponseWriter, closed chan struct{}) *HttpWriterWrapper {
	return &HttpWriterWrapper{
		closed:   closed,
		w:        w,
		sendChan: make(chan []byte, 100),
		die:      make(chan struct{}),
	}
}

func (w *HttpWriterWrapper) Start() {
	go w.writeImpl()
}

func (w *HttpWriterWrapper) Stop() {
	w.once.Do(func() {
		close(w.closed)
	})
}

func (w *HttpWriterWrapper) Write(b []byte) (int, error) {
	if w.lastError != nil {
		return 0, w.lastError
	}
	w.sendChan <- b
	return len(b), nil
}

func (w *HttpWriterWrapper) writeImpl() {
	for {
		select {
		case <-w.closed:
			// reset connection by client
			// stop send
			// release some resource
			w.lastError = io.EOF
			return
		case b := <-w.sendChan:
			_, w.lastError = w.w.Write(b)
		case <-w.die:
			w.lastError = errors.New("closed by custom")
			return
		}
	}
}

//使用的时候
write_wrapper := NewHttpWriterWrapper(w,r.Context().Done())
writer := flv.CreateFlvWriter(write_wrapper)