Re: [boost] Serialization and disctintion between eof and end of archive

From: Maciej Sobczak (prog_at_[hidden])
Date: 2006-01-31 04:20:36

Robert Ramey wrote:

>>I have experimented a bit with this program and I've found that when
>>the sender (the server in this case) flushes the stream, it's enough
>>for the data to arrive at the destination, and it can be retrieved by
>>regular stream read (the data is then identical as if the same
>>archive was written to cout in the first place). But when the
>>text_iarchive object is used to read it, it blocks. The only way to
>>make it continue is to close the stream on the server side. So it
>>looks like the text_iarchive is really waiting for eof (or for
>>something else in the stream).
> 
> It may look that way, but that's not what's happening.  I recomend
> you investigate the management (or lack there of, flushing of the
> underlying stream.

OK, after further investigation it appears that the archive reader is in 
fact sensitive to one of these two:

- end of line
- end of stream

It is possible to reuse long-lived connection for sending many archives 
(and receiving them without unnecessary waits), provided one of these 
two happens. So, the sender might look like this:

?ostream outstream(...);

while (...)
{
     {
         boost::archive::text_oarchive ar(outstream);

         ar << myObject;
     }

     // this:
     outstream << std::endl;  // or '\n' followed by .flush()
}

With this additional newline+flush the receiver has no problems with 
de-serializing the data as soon as they arrive.

Thank you for helping solving this.
Regards,

-- 
Maciej Sobczak : http://www.msobczak.com/
Programming    : http://www.msobczak.com/prog/