id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4807	"Sink devices ""leacks"" exception out of the stream"	artyomtnk@…	Jonathan Turkanis	"I implement the sink device that sometimes may fail on writes.
When Sink is implemented it should throw an exception on fault
to notify the stream on error.

However it is not always works this way.
I've got the exception to ""leak"" to the
main program when I combine in the
filter gzip_comressor() filter that writes
to output device that its Sink is full. 
When I call reset on the filter
the exception in leaking to the 
program instead of being caught.

On the other hand, if I don't throw but rather return 0,
I get into infinite loop
in the boost::iostreams::non_blocking_adapter::write 
when I call filter.reset().

In following example the exception is caught
when filter.reset() is called, when it shouldn't.


{{{
    #include <boost/iostreams/stream.hpp>
    #include <boost/iostreams/filtering_stream.hpp>
    #include <boost/iostreams/filter/gzip.hpp>
    #include <boost/iostreams/tee.hpp>
    #include <iostream>

    class my_small_device : public boost::iostreams::sink
    {
        int count;
    public:
        my_small_device() : count(1000) {}
        std::streamsize write(char const *d,std::streamsize n)
        {
            if(count < n)
                throw std::runtime_error(""Device is full"");
            count-=n;
            return n;
        }
    };

    int main()
    {
        try {
            using namespace boost::iostreams;
            boost::iostreams::stream<my_small_device> output(my_small_device(),10);
            {
                boost::iostreams::filtering_ostream filter;
                filter.push(gzip_compressor());
                filter.push(output);
                for(int i=0;i<10000000;i++) {
                    if(!(filter << i << '\n')) {
                        std::cerr << ""Fail!"" << std::endl;
                        break;
                    }
                }
                std::cout << ""Closing filter"" << std::endl;
                filter.reset();
            }

            std::cout << ""ok"" << std::endl;
            return 0;
        }catch(std::exception const &e) {
            std::cerr << ""Catched "" << e.what() << std::endl;
            return 1;
        }
    }
}}}
"	Bugs	new	To Be Determined	iostreams	Boost 1.44.0	Problem