WriteQuicDataResult writeCryptoAndAckDataToSocket()

in quic/api/QuicTransportFunctions.cpp [964:1043]
76 lines of code
6 McCabe index (conditional complexity)

WriteQuicDataResult writeCryptoAndAckDataToSocket(
    folly::AsyncUDPSocket& sock,
    QuicConnectionStateBase& connection,
    const ConnectionId& srcConnId,
    const ConnectionId& dstConnId,
    LongHeader::Types packetType,
    Aead& cleartextCipher,
    const PacketNumberCipher& headerCipher,
    QuicVersion version,
    uint64_t packetLimit,
    const std::string& token) {
  auto encryptionLevel = protectionTypeToEncryptionLevel(
      longHeaderTypeToProtectionType(packetType));
  FrameScheduler scheduler =
      std::move(FrameScheduler::Builder(
                    connection,
                    encryptionLevel,
                    LongHeader::typeToPacketNumberSpace(packetType),
                    "CryptoAndAcksScheduler")
                    .ackFrames()
                    .cryptoFrames())
          .build();
  auto builder = LongHeaderBuilder(packetType);
  WriteQuicDataResult result;
  auto& packetsWritten = result.packetsWritten;
  auto& bytesWritten = result.bytesWritten;
  auto& probesWritten = result.probesWritten;
  auto& cryptoStream =
      *getCryptoStream(*connection.cryptoState, encryptionLevel);
  auto& numProbePackets =
      connection.pendingEvents
          .numProbePackets[LongHeader::typeToPacketNumberSpace(packetType)];
  if (numProbePackets &&
      (cryptoStream.retransmissionBuffer.size() || scheduler.hasData())) {
    probesWritten = writeProbingDataToSocket(
        sock,
        connection,
        srcConnId,
        dstConnId,
        builder,
        encryptionLevel,
        LongHeader::typeToPacketNumberSpace(packetType),
        scheduler,
        numProbePackets, // This possibly bypasses the packetLimit.
        cleartextCipher,
        headerCipher,
        version,
        token);
  }
  packetLimit = probesWritten > packetLimit ? 0 : (packetLimit - probesWritten);
  // Only get one chance to write probes.
  numProbePackets = 0;
  // Crypto data is written without aead protection.
  auto writeResult = writeConnectionDataToSocket(
      sock,
      connection,
      srcConnId,
      dstConnId,
      std::move(builder),
      LongHeader::typeToPacketNumberSpace(packetType),
      scheduler,
      congestionControlWritableBytes,
      packetLimit - packetsWritten,
      cleartextCipher,
      headerCipher,
      version,
      Clock::now(),
      token);

  packetsWritten += writeResult.packetsWritten;
  bytesWritten += writeResult.bytesWritten;

  VLOG_IF(10, packetsWritten || probesWritten)
      << nodeToString(connection.nodeType)
      << " written crypto and acks data type=" << packetType
      << " packetsWritten=" << packetsWritten
      << " probesWritten=" << probesWritten << connection;
  CHECK_GE(packetLimit, packetsWritten);
  return result;
}