Re: [boost] [fusion] sequence io manipulators

On 3/25/2013 9:33 PM, Joel de Guzman wrote:

On 3/26/13 3:12 AM, Jeff Flinn wrote:

...

When streaming unrelated fusion sets to unrelated ostringstreams from different threads, I get an invalid iterator error. This appears to be due to using a boost::fusion::detail::stream_data::attach's local static arena instance.

static void attach(Stream& stream, T const& data) { static arena ar; // our arena ar.data.push_back(new T(data)); stream.pword(get_xalloc_index<Tag>()) = ar.data.back(); }

I assume there are issues with using the unguarded stream_data::data std::vector from multiple threads. This implementation looks problematic in that the arena data does not get cleaned up until program exit as well.

Right. That code is quite old, IIRC inherited from Boost.Tuples. Would you care to provide a patch?

Joel, See Ticket# 8336 with it's attached patch. I've compiled/linked/ran on VS2012 32bit and gcc4.2 32bit on Mac OSX 10.7. My app tests concurrent streaming. I have not added any such tests to fusion as I assume you do not want dependencies on thread library. I have not addressed possible issues with "static int index = std::ios::xalloc();" thread safety. gcc at least appears to guard this initialization with a mutex. I'm not sure what the standard guarantees in this regard pre/post C++11. Comments would be appreciated. Thanks, Jeff