Method load_buffer_and_write

src/iocore/net/UnixNetVConnection.cc:856–941

This code was pulled out of write_to_net so I could overwrite it for the SSL implementation (SSL read does not support overlapped i/o) without duplicating all the code in write_to_net.

// (SSL read does not support overlapped i/o)
// without duplicating all the code in write_to_net.
int64_t
UnixNetVConnection::load_buffer_and_write(int64_t towrite, MIOBufferAccessor &buf, int64_t &total_written, int &needs)
{
  int64_t         r            = 0;
  int64_t         try_to_write = 0;
  IOBufferReader *tmp_reader   = buf.reader()->clone();

  do {
    IOVec    tiovec[NET_MAX_IOV];
    unsigned niov = 0;
    try_to_write  = 0;

    while (niov < NET_MAX_IOV) {
      int64_t wavail = towrite - total_written - try_to_write;
      int64_t len    = tmp_reader->block_read_avail();

      // Check if we have done this block.
      if (len <= 0) {
        break;
      }

      // Check if the amount to write exceeds that in this buffer.
      if (len > wavail) {
        len = wavail;
      }

      if (len == 0) {
        break;
      }

      // build an iov entry
      tiovec[niov].iov_len  = len;
      tiovec[niov].iov_base = tmp_reader->start();
      niov++;

      try_to_write += len;
      tmp_reader->consume(len);
    }

    ink_assert(niov > 0);
    ink_assert(niov <= countof(tiovec));

    // If the platform doesn't support TCP Fast Open, verify that we
    // correctly disabled support in the socket option configuration.
    ink_assert(MSG_FASTOPEN != 0 || this->options.f_tcp_fastopen == false);
    struct msghdr msg;

    ink_zero(msg);
    if (!ats_is_unix(this->get_local_addr())) {
      msg.msg_name    = const_cast<sockaddr *>(this->get_remote_addr());
      msg.msg_namelen = ats_ip_size(this->get_remote_addr());
    }
    msg.msg_iov    = &tiovec[0];
    msg.msg_iovlen = niov;
    int flags      = 0;

    if (!this->con.is_connected && this->options.f_tcp_fastopen) {
      Metrics::Counter::increment(net_rsb.fastopen_attempts);