序
本文主要研究一下dubbo-go-proxy的timeoutFilter
timeoutFilter
dubbo-go-proxy/pkg/filter/timeout/timeout.go
func Init() {
extension.SetFilterFunc(constant.TimeoutFilter, timeoutFilterFunc(0))
}
func timeoutFilterFunc(duration time.Duration) fc.FilterFunc {
return New(duration).Do()
}
// timeoutFilter is a filter for control request time out.
type timeoutFilter struct {
// global timeout
waitTime time.Duration
}
// New create timeout filter.
func New(t time.Duration) filter.Filter {
if t <= 0 {
t = constant.DefaultTimeout
}
return &timeoutFilter{
waitTime: t,
}
}timeoutFilter往extension设置了名为`dgp.filters.timeout的timeoutFilterFunc，默认的timeout为1s；timeoutFilterFunc执行的是timeoutFilter的Do方法
Do
dubbo-go-proxy/pkg/filter/timeout/timeout.go
// Do execute timeoutFilter filter logic.
func (f timeoutFilter) Do() fc.FilterFunc {
return func(c fc.Context) {
hc := c.(*contexthttp.HttpContext)
ctx, cancel := context.WithTimeout(hc.Ctx, f.getTimeout(hc.Timeout))
defer cancel()
// Channel capacity must be greater than 0.
// Otherwise, if the parent coroutine quit due to timeout,
// the child coroutine may never be able to quit.
finishChan := make(chan struct{}, 1)
go func() {
// panic by recovery
c.Next()
finishChan <- struct{}{}
}()
select {
// timeout do.
case <-ctx.Done():
logger.Warnf("api:%s request timeout", hc.GetAPI().URLPattern)
bt, _ := json.Marshal(filter.ErrResponse{Message: http.ErrHandlerTimeout.Error()})
hc.SourceResp = bt
hc.TargetResp = &client.Response{Data: bt}
hc.WriteJSONWithStatus(http.StatusGatewayTimeout, bt)
c.Abort()
case <-finishChan:
// finish call do something.
}
}
}
func (f timeoutFilter) getTimeout(t time.Duration) time.Duration {
if t <= 0 {
return f.waitTime
}
return t
}Do方法会通过context.WithTimeout创建ctx及cancel，然后注册defer这个cancel func；之后创建finishChan，异步执行c.Next()，之后往finishChan写入数据；最后select判断ctx.Done()或者是finishChan；如果是ctx.Done()则表示timeout了，返回http.StatusGatewayTimeout
小结
dubbo-go-proxy的timeoutFilter默认设置了1s超时，它通过context.WithTimeout创建ctx及cancel，并异步执行c.Next()，若ctx.Done()则表示timeout了，返回http.StatusGatewayTimeout；若是读取到了finishChan则表示请求正常响应。
doc
- dubbo-go-proxy
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