func()

in http2/transport.go [1196:1339]

• 111 lines of code
• 34 McCabe index (conditional complexity)

func (cs *clientStream) writeRequest(req *http.Request) (err error) {
	cc := cs.cc
	ctx := cs.ctx

	if err := checkConnHeaders(req); err != nil {
		return err
	}

	// Acquire the new-request lock by writing to reqHeaderMu.
	// This lock guards the critical section covering allocating a new stream ID
	// (requires mu) and creating the stream (requires wmu).
	if cc.reqHeaderMu == nil {
		panic("RoundTrip on uninitialized ClientConn") // for tests
	}
	select {
	case cc.reqHeaderMu <- struct{}{}:
	case <-cs.reqCancel:
		return errRequestCanceled
	case <-ctx.Done():
		return ctx.Err()
	}

	cc.mu.Lock()
	if cc.idleTimer != nil {
		cc.idleTimer.Stop()
	}
	cc.decrStreamReservationsLocked()
	if err := cc.awaitOpenSlotForStreamLocked(cs); err != nil {
		cc.mu.Unlock()
		<-cc.reqHeaderMu
		return err
	}
	cc.addStreamLocked(cs) // assigns stream ID
	if isConnectionCloseRequest(req) {
		cc.doNotReuse = true
	}
	cc.mu.Unlock()

	// TODO(bradfitz): this is a copy of the logic in net/http. Unify somewhere?
	if !cc.t.disableCompression() &&
		req.Header.Get("Accept-Encoding") == "" &&
		req.Header.Get("Range") == "" &&
		!cs.isHead {
		// Request gzip only, not deflate. Deflate is ambiguous and
		// not as universally supported anyway.
		// See: https://zlib.net/zlib_faq.html#faq39
		//
		// Note that we don't request this for HEAD requests,
		// due to a bug in nginx:
		//   http://trac.nginx.org/nginx/ticket/358
		//   https://golang.org/issue/5522
		//
		// We don't request gzip if the request is for a range, since
		// auto-decoding a portion of a gzipped document will just fail
		// anyway. See https://golang.org/issue/8923
		cs.requestedGzip = true
	}

	continueTimeout := cc.t.expectContinueTimeout()
	if continueTimeout != 0 {
		if !httpguts.HeaderValuesContainsToken(req.Header["Expect"], "100-continue") {
			continueTimeout = 0
		} else {
			cs.on100 = make(chan struct{}, 1)
		}
	}

	// Past this point (where we send request headers), it is possible for
	// RoundTrip to return successfully. Since the RoundTrip contract permits
	// the caller to "mutate or reuse" the Request after closing the Response's Body,
	// we must take care when referencing the Request from here on.
	err = cs.encodeAndWriteHeaders(req)
	<-cc.reqHeaderMu
	if err != nil {
		return err
	}

	hasBody := cs.reqBodyContentLength != 0
	if !hasBody {
		cs.sentEndStream = true
	} else {
		if continueTimeout != 0 {
			traceWait100Continue(cs.trace)
			timer := time.NewTimer(continueTimeout)
			select {
			case <-timer.C:
				err = nil
			case <-cs.on100:
				err = nil
			case <-cs.abort:
				err = cs.abortErr
			case <-ctx.Done():
				err = ctx.Err()
			case <-cs.reqCancel:
				err = errRequestCanceled
			}
			timer.Stop()
			if err != nil {
				traceWroteRequest(cs.trace, err)
				return err
			}
		}

		if err = cs.writeRequestBody(req); err != nil {
			if err != errStopReqBodyWrite {
				traceWroteRequest(cs.trace, err)
				return err
			}
		} else {
			cs.sentEndStream = true
		}
	}

	traceWroteRequest(cs.trace, err)

	var respHeaderTimer <-chan time.Time
	var respHeaderRecv chan struct{}
	if d := cc.responseHeaderTimeout(); d != 0 {
		timer := time.NewTimer(d)
		defer timer.Stop()
		respHeaderTimer = timer.C
		respHeaderRecv = cs.respHeaderRecv
	}
	// Wait until the peer half-closes its end of the stream,
	// or until the request is aborted (via context, error, or otherwise),
	// whichever comes first.
	for {
		select {
		case <-cs.peerClosed:
			return nil
		case <-respHeaderTimer:
			return errTimeout
		case <-respHeaderRecv:
			respHeaderRecv = nil
			respHeaderTimer = nil // keep waiting for END_STREAM
		case <-cs.abort:
			return cs.abortErr
		case <-ctx.Done():
			return ctx.Err()
		case <-cs.reqCancel:
			return errRequestCanceled
		}
	}
}