ace nonblock

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使用reactor, ACE_Sock_Stream进行收发数据。 nonblock模式下： [timeout参数均为NULL]

recv时，可能返回-1. errno可能是EWOULDBLOCK（要求下次继续读），或者其他系统错。

无需使用recv_n/send_n

ACE_Sock_Stream::recv  ---->ACE::recv():ssize_t ACE::recv (ACE_HANDLE handle,   void *buf, size_t len, int flags, const ACE_Time_Value *timeout){  if (timeout == 0)    <span style="color:#FF0000;">return ACE_OS::recv (handle, (char *) buf, len, flags);</span>  else    {      int val = 0;      if (ACE::enter_recv_timedwait (handle, timeout, val) ==-1)        return -1;      else        {          ssize_t bytes_transferred =            ACE_OS::recv (handle, (char *) buf, len, flags);          ACE::restore_non_blocking_mode (handle, val);          return bytes_transferred;        }    }}ACE::recv--->ACE_OS::recv():ACE_INLINE ssize_t  ACE_OS::recv (ACE_HANDLE handle, char *buf, size_t len, int flags){  ACE_OS_TRACE ("ACE_OS::recv");  // On UNIX, a non-blocking socket with no data to receive, this  // system call will return EWOULDBLOCK or EAGAIN, depending on the  // platform.  UNIX 98 allows either errno, and they may be the same  // numeric value.  So to make life easier for upper ACE layers as  // well as application programmers, always change EAGAIN to  // EWOULDBLOCK.  Rather than hack the ACE_OSCALL_RETURN macro, it's  // handled explicitly here.  If the ACE_OSCALL macro ever changes,  // this function needs to be reviewed.  On Win32, the regular macros  // can be used, as this is not an issue.#if defined (ACE_LACKS_RECV)  ACE_UNUSED_ARG (handle);  ACE_UNUSED_ARG (buf);  ACE_UNUSED_ARG (len);  ACE_UNUSED_ARG (flags);  ACE_NOTSUP_RETURN (-1);#elif defined (ACE_WIN32)  ACE_SOCKCALL_RETURN (::recv ((ACE_SOCKET) handle, buf,                               static_cast<int> (len), flags), ssize_t, -1);#else  <span style="color:#FF0000;">ssize_t ace_result_;  ace_result_ = ::recv ((ACE_SOCKET) handle, buf, len, flags);# if !(defined (EAGAIN) && defined (EWOULDBLOCK) && EAGAIN == EWOULDBLOCK)  // Optimize this code out if we can detect that EAGAIN ==  // EWOULDBLOCK at compile time.  If we cannot detect equality at  // compile-time (e.g. if EAGAIN or EWOULDBLOCK are not preprocessor  // macros) perform the check at run-time.  The goal is to avoid two  // TSS accesses in the _REENTRANT case when EAGAIN == EWOULDBLOCK.  if (ace_result_ == -1#  if !defined (EAGAIN) || !defined (EWOULDBLOCK)      && EAGAIN != EWOULDBLOCK#  endif  /* !EAGAIN || !EWOULDBLOCK */      && errno == EAGAIN)    {      errno = EWOULDBLOCK;    }# endif /* EAGAIN != EWOULDBLOCK*/  return ace_result_;</span>#endif /* ACE_LACKS_RECV */}

同样， ACE_Sock_Stream::send--->ACE_OS::write---->::write

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