Re: [Boost-bugs] [Boost C++ Libraries] #8967: Spurious zero bytes written and eof notifications highlight ASIO IOCP issues

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #8967: Spurious zero bytes written and eof notifications highlight ASIO IOCP issues
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-08-10 21:28:28

#8967: Spurious zero bytes written and eof notifications highlight ASIO IOCP
issues
-------------------------+-------------------------------------------------
  Reporter:              |      Owner:  chris_kohlhoff
  simoncperkins@…        |     Status:  new
      Type:  Bugs        |  Component:  asio
 Milestone:  To Be       |   Severity:  Problem
  Determined             |   Keywords:  eof GetQueuedCompletionStatus
   Version:  Boost       |  WSARecv WSASend overlapped
  1.54.0                 |
Resolution:              |
-------------------------+-------------------------------------------------

Comment (by Shane Powell <killerbee@…>):

 Looking at the asio code up util 1.53.0, the on_pending is used to delay
 the result of a early completion routine result until after the OS call
 (WSARecv/WSASend/...) has been completed.

 It works because the on_pending only calls PostQueuedCompletionStatus if
 op ready_ was already 1.  i.e. the completion routine has already fired.
 It doesn't post a PostQueuedCompletionStatus if the completion routine
 hasn't fired, it just sets the ready_ to 1 which allows the the callers
 completion handler to be fired in the completion routine.  So I don't
 think there is a problem with the on_pending code.

 So the change to 1.54.0 from 'overlapped_contains_result' to using '0' is
 what is causing all the problems.


 I can also see you may be correct is that it's not actually required in
 the case of WSARecv/WSASend/WSA* winsock functions to use the op
 ready_/overlapped_contains_result.  It's used in other places so you may
 not be able to get rid of the overlapped_contains_result and storing the
 results in the overlapped structure tho.

 Also you would have to check all the other places that use the on_pending
 to see if it's completely ok to remove the ready flag ok as well.  I see
 it's used with ReadFile/WriteFile/AcceptEx

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8967#comment:3>
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