[THRIFT-4591] lua client uses two write() calls per framed message send

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.11.0
• Fix Version/s: 0.12.0
• Component/s: Lua - Library
• Flags: Important
• Assignee: James E. King III
• Reporter: allen_lee
• Created: 24/Jun/18 08:35
• Updated: 27/Dec/18 15:24
• Resolved: 05/Jul/18 13:34

Description

1) realize thrift server with TNonblockingServer via c++;

2) realize thrift client via lua lib and choose frame transport.

3) call remote interface failed with "TTransportException:0: Default (unknown)" print, and the server show "TConnection::workSocket(): THRIFT_EAGAIN (unavailable resources)" error.

4)investigate this fault with tcpdump tool, attachment 9090.pcap show the frame msg doesnot contains frame size field, the rifht situation of attachment 9090_1.pcap show the frame msg contains 4 bytes (00 00 00 25) before protocol id field.

5) dig into the fault and tried to find root cause, then i found there is an fault in TFramedTransport:flush function in TFramedTransport.lua file. the original realization is:

---

function TFramedTransport:flush()
  if self.doWrite == false then
    return self.trans:flush()
  end

  – If the write fails we still want wBuf to be clear
  local tmp = self.wBuf
  self.wBuf = ''
  local frame_len_buf = libluabpack.bpack("i", string.len(tmp))
  self.trans:write(frame_len_buf)
  self.trans:write(tmp)
  self.trans:flush()
end

---

which send frame size file and reset msg content independently.

Issue Links

• is related to: THRIFT-3591 Add Lua cross test suite
• links to: GitHub Pull Request #1566