void QuicStreamAsyncTransport::handleRead()

in quic/api/QuicStreamAsyncTransport.cpp [371:436]
62 lines of code
21 McCabe index (conditional complexity)

void QuicStreamAsyncTransport::handleRead() {
  folly::DelayedDestruction::DestructorGuard dg(this);
  bool emptyRead = false;
  size_t numReads = 0;
  while (readCb_ && id_ && !ex_ && readEOF_ == EOFState::NOT_SEEN &&
         !emptyRead && ++numReads < 16 /* max reads per event */) {
    void* buf = nullptr;
    size_t len = 0;
    if (readCb_->isBufferMovable()) {
      len = readCb_->maxBufferSize();
    } else {
      readCb_->getReadBuffer(&buf, &len);
      if (buf == nullptr || len == 0) {
        ex_ = folly::AsyncSocketException(
            folly::AsyncSocketException::BAD_ARGS,
            "ReadCallback::getReadBuffer() returned empty buffer");
        break;
      }
    }
    auto readData = sock_->read(*id_, len);
    if (readData.hasError()) {
      ex_ = folly::AsyncSocketException(
          folly::AsyncSocketException::UNKNOWN,
          folly::to<std::string>("Quic read error: ", readData.error()));
    } else {
      if (!readData->first) {
        emptyRead = true;
      } else {
        if (readCb_->isBufferMovable()) {
          readCb_->readBufferAvailable(std::move(readData->first));
        } else {
          size_t readLen = readData->first->computeChainDataLength();
          folly::io::Cursor c(readData->first.get());
          CHECK_NOTNULL(buf);
          c.pull(buf, readLen);
          readCb_->readDataAvailable(readLen);
        }
      }
      if (readData->second && readEOF_ == EOFState::NOT_SEEN) {
        readEOF_ = EOFState::QUEUED;
      }
    }
  }

  // in case readCb_ got reset from read callbacks
  if (!readCb_) {
    return;
  }

  if (ex_) {
    auto cb = readCb_;
    readCb_ = nullptr;
    cb->readErr(*ex_);
  } else if (readEOF_ == EOFState::QUEUED) {
    auto cb = readCb_;
    readCb_ = nullptr;
    cb->readEOF();
    readEOF_ = EOFState::DELIVERED;
  }

  if (id_) {
    if (!readCb_ || readEOF_ != EOFState::NOT_SEEN) {
      sock_->setReadCallback(*id_, nullptr);
    }
  }
}