Re: [boost] boost::asio::streambuf problem

Subject: Re: [boost] boost::asio::streambuf problem
From: rod haxton (rehaxton_at_[hidden])
Date: 2008-10-18 14:48:48

I actually went back to the istream approach and I still can't get that to
work, after I pull the data out of the streambuf via the istream, "getline,"
and return to async_read_until, it immediately reads again and is grabbing
garbage.  Also, I can still see the previous data in the streambuf, and the
streambuf has grown.

On Sat, Oct 18, 2008 at 2:19 PM, rod haxton <rehaxton_at_[hidden]> wrote:

> Hello,
>
> "Long time listener, first time caller..."
>
> I'm struggling with the "boost::asio::streambuf," and the
> "boost::asio::async_read_until."
>
> I'm trying to wait on the async_read_until, which I can do after the first
> message is sent, but subsequent messages received cause the streambuf to
> continuously grow.  I am trying to use the streambuf via the .data() member.
>
>
>
> void TAsioSession::Start()
> {
>     boost::asio::async_read_until(m_Socket, m_szAsioData,
> boost::regex("\n"),
>             boost::bind(&TAsioSession::HandleRead,
>             this,
>             boost::asio::placeholders::error,
>             boost::asio::placeholders::bytes_transferred));
> }
>
> void TAsioSession::HandleRead(const boost::system::error_code& error,
> size_t bytes_transferred)
> {
>     if(!error)
>     {
>         boost::asio::streambuf::const_buffers_type bufs =
> m_szAsioData.data();
>
>         std::string szBuffer(
>             boost::asio::buffers_begin(bufs),
>             boost::asio::buffers_begin(bufs) + bytes_transferred);
>
>         LP_ICPACKET lpICPacket =
> reinterpret_cast<LP_ICPACKET>(const_cast<char*>(szBuffer.c_str()));
>
>      // reset streambuf for reading (how?)
>    .
>    .
>    .
>
>   Start();
> }
>
>  Once I grab the data that is in the buffer, I want to reset the streambuf
> and go back to "async_read_until," and wait for another message to come in.
>
> I try to do the following to reset the streambuf pointers...
>
>         // set the current put/get ptrs of streambuf to beginning of stream
>         m_szAsioData.commit(-m_szAsioData.size());
>         m_szAsioData.consume(-m_szAsioData.size());
>
>         // clear the streambuff
>         char szClear[512];
>         ZeroMemory(szClear, 512);
>         m_szAsioData.sputn(szClear, sizeof(szClear));
>         m_szAsioData.sgetn(szClear, sizeof(szClear));
>
>         // set the current ptrs of streambuf back to beginning
>         m_szAsioData.commit(-m_szAsioData.size());
>         m_szAsioData.consume(-m_szAsioData.size());
>
>  but the new message isn't at the head of the buffer, it is coming in at
> position 512 of the streambuf, and the streambuf grows.
>
> Any help would be appreciated.
>
> Thanks,
> Rod
>
>