Method SendError

library/cpp/neh/http2.cpp:1681–1757

called non thread-safe (from outside thread)

            //called non thread-safe (from outside thread)
            void SendError(TAtomicBase requestId, unsigned httpCode, const TString& descr, const THttpVersion& ver, const TString& headers) {
                if (Canceled_) {
                    return;
                }

                class THttpErrorResponseFormatter {
                public:
                    THttpErrorResponseFormatter(unsigned theHttpCode, const TString& theDescr, const THttpVersion& theVer, bool closeConnection, const TString& headers) {
                        PrintHttpVersion(Answer, theVer);
                        Answer << TStringBuf(" ") << theHttpCode << TStringBuf(" ");
                        if (theDescr.size() && !THttp2Options::ErrorDetailsAsResponseBody) {
                            // Reason-Phrase  = *<TEXT, excluding CR, LF>
                            // replace bad chars to '.'
                            TString reasonPhrase = theDescr;
                            for (TString::iterator it = reasonPhrase.begin(); it != reasonPhrase.end(); ++it) {
                                char& ch = *it;
                                if (ch == ' ') {
                                    continue;
                                }
                                if (((ch & 31) == ch) || static_cast<unsigned>(ch) == 127 || (static_cast<unsigned>(ch) & 0x80)) {
                                    //CTLs || DEL(127) || non ascii
                                    // (ch <= 32) || (ch >= 127)
                                    ch = '.';
                                }
                            }
                            Answer << reasonPhrase;
                        } else {
                            Answer << HttpCodeStr(static_cast<int>(theHttpCode));
                        }

                        if (closeConnection) {
                            Answer << TStringBuf("\r\nConnection: close");
                        }

                        if (headers) {
                            Answer << "\r\n" << headers;
                        }

                        if (THttp2Options::ErrorDetailsAsResponseBody) {
                            Answer << TStringBuf("\r\nContent-Length:") << theDescr.size() << "\r\n\r\n" << theDescr;
                        } else {
                            Answer << "\r\n"
                                      "Content-Length:0\r\n\r\n"sv;
                        }

                        Parts[0].buf = Answer.Data();
                        Parts[0].len = Answer.Size();
                    }

                    TStringStream Answer;
                    IOutputStream::TPart Parts[1];
                };

                class TBuffers: public THttpErrorResponseFormatter, public TTcpSocket::IBuffers {
                public:
                    TBuffers(
                        unsigned theHttpCode,
                        const TString& theDescr,