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reverseproxy: Ignore context cancel in stream mode (#4952)

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Matt Holt 2022-08-12 13:15:41 -06:00 committed by GitHub
parent 922d9f5c25
commit f5dce84a70
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@ -109,6 +109,11 @@ type Handler struct {
// response is recognized as a streaming response, or if its // response is recognized as a streaming response, or if its
// content length is -1; for such responses, writes are flushed // content length is -1; for such responses, writes are flushed
// to the client immediately. // to the client immediately.
//
// Normally, a request will be canceled if the client disconnects
// before the response is received from the backend. If explicitly
// set to -1, client disconnection will be ignored and the request
// will be completed to help facilitate low-latency streaming.
FlushInterval caddy.Duration `json:"flush_interval,omitempty"` FlushInterval caddy.Duration `json:"flush_interval,omitempty"`
// A list of IP ranges (supports CIDR notation) from which // A list of IP ranges (supports CIDR notation) from which
@ -757,6 +762,15 @@ func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, origRe
req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace)) req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
} }
// if FlushInterval is explicitly configured to -1 (i.e. flush continuously to achieve
// low-latency streaming), don't let the transport cancel the request if the client
// disconnects: user probably wants us to finish sending the data to the upstream
// regardless, and we should expect client disconnection in low-latency streaming
// scenarios (see issue #4922)
if h.FlushInterval == -1 {
req = req.WithContext(ignoreClientGoneContext{req.Context(), h.ctx.Done()})
}
// do the round-trip; emit debug log with values we know are // do the round-trip; emit debug log with values we know are
// safe, or if there is no error, emit fuller log entry // safe, or if there is no error, emit fuller log entry
start := time.Now() start := time.Now()
@ -1374,6 +1388,19 @@ type handleResponseContext struct {
isFinalized bool isFinalized bool
} }
// ignoreClientGoneContext is a special context.Context type
// intended for use when doing a RoundTrip where you don't
// want a client disconnection to cancel the request during
// the roundtrip. Set its done field to a Done() channel
// of a context that doesn't get canceled when the client
// disconnects, such as caddy.Context.Done() instead.
type ignoreClientGoneContext struct {
context.Context
done <-chan struct{}
}
func (c ignoreClientGoneContext) Done() <-chan struct{} { return c.done }
// proxyHandleResponseContextCtxKey is the context key for the active proxy handler // proxyHandleResponseContextCtxKey is the context key for the active proxy handler
// so that handle_response routes can inherit some config options // so that handle_response routes can inherit some config options
// from the proxy handler. // from the proxy handler.