September 2010 - Boost - lists.preview.boost.org

[iostreams] filtering_ostream does not flush std::cout.
by Duncan Smith 01 Sep '10

01 Sep '10

I'm using Boost 1.43.0, and I've found that filtering_ostream does not flush "std::cout". I found a relevant (and recent) ticket against Boost 1.44.0, but my issue is slightly different. https://svn.boost.org/trac/boost/ticket/4590 I'm using GCC 4.3.4 on Gentoo Linux. I'm hoping that I'm just doing something wrong, but if you think there's a bug, I'll add my testcase to the ticket. The basic recipe: filtering_ostream out; out.push(any_filter_at_all()); out.push(std::cout); out << "Hello World!" << std::flush; sleep(10); // Observe an empty console. std::cout << std::flush; sleep(10); // Observe printed text on console. This problem is quite bad for me when doing the following on the command-line (for a more complicated program): ./program 2>&1 | tee some-file.log Because stdout is not getting flushed, the stdout and stderr get intermingled strangely. However, disabling buffering on stdout works around the problem: stdbuf --output=0 ./program 2>&1 | tee some-file.log Please tell me if you think there's a bug in my code. If it's a bug in Boost.Iostreams (or I'm expecting the wrong behaviour), I would appreciate any ideas for workarounds (I tried cout.setf(unitbuf), and that doesn't seem to do the trick). Here's the full text of my code: ------------------ // Test case for flushing a filtering_ostream based on the // boost_iostreams_filtering_ostream.cpp attached to ticket #4950: // https://svn.boost.org/trac/boost/ticket/4590 // https://svn.boost.org/trac/boost/attachment/ticket/4590/boost_iostreams_fil… // changed to use "cout" as the sink. // // Flushing a filtering_ostream using the flush() global function does not work // in Boost 1.43. I suspect it also does not work in Boost 1.44. // // Using GCC-4.3.4 on Gentoo Linux. // #include <cassert> #include <string> #include <boost/iostreams/categories.hpp> #include <boost/iostreams/operations.hpp> #include <boost/iostreams/filtering_stream.hpp> #include <iostream> // Included for "sleep()" call below. #include <unistd.h> namespace io = boost::iostreams; // Simple output filter forwarding just forwarding the put chars to // the sink. struct transparent_output_filter { typedef char char_type; typedef io::output_filter_tag category; template <typename Sink> bool put(Sink& snk, char c) { return io::put(snk, c); } }; int main(int argc, char *argv[]) { using namespace std; io::filtering_stream<io::output> out; // Transparent filter just forward the characters to the sink. // // Note: I observe this behaviour with and without this line. out.push(transparent_output_filter()); // Sink appends characters to "cout". out.push(cout); // Write test string to filtering_ostream. out << "Hello World!"; // On my system, this will flush the buffer iff I'm on an // interactive console. "\n" and endl have the same effect. I believe // that my shell sets "stdout" to be line-buffered if it's interactive. // out << "\n"; bool wasFlushed = false; // The flush does *not* work in Boost 1.43. wasFlushed = io::flush(out); // This assertion does not go off, though. assert(wasFlushed); // This also doesn't work. wasFlushed = out.flush(); assert(wasFlushed); // This also doesn't work. out << std::flush; // Demonstrate that none of the above flush calls had any effect on "cout". sleep(10); // Now we finally get the characters on the console. cout << flush; // Demonstrate that the direct flush call works when called directly on // "cout". sleep(10); return 0; }

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[msm] on_entry must be implemented for every initial events for every states in substatemachines.
by Richard Szabo 01 Sep '10

01 Sep '10

Hi All In the following little example see attachment, I have a problem that in the RunningStateMachine::State2 the on_entry function must be implemented with event1 and with event3 as well but from the logic point of view there is no possibility to call on_entry in RunningStateMachine::State2 with event1. actually at runtime there is no call is happening to to the function : void on_entry(event1 const&,FSM& ) {std::cout << "entering: State2:Event1" << std::endl;} but it must be defined and even implemented ( if no implementation provided linker error occurs). Is it a restriction/bug or I'm missing something ? It is only happening with initial events for substatemachines ? Or is there a kind of pattern to know what events can enter exit a state in a top of the ones present in the transition tables ?. Br. Richie

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Re: [boost] [msm] Boost MPL vector limit size exceeded
by Michael.Herchel＠rohde-schwarz.com 01 Sep '10

01 Sep '10

Hi, thanks for the answers. >> I also tried the define "BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS" >> with and without specifying the define "FUSION_MAX_VECTOR_SIZE". > I used the #defines > BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS > BOOST_MPL_LIMIT_VECTOR_SIZE=60 Sorry, this was a mistake. Of course I used "BOOST_MPL_LIMIT_VECTOR_SIZE" instead of "FUSION_MAX_VECTOR_SIZE"

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[msm] Boost MPL vector limit size exceeded
by Michael.Herchel＠rohde-schwarz.com 01 Sep '10

01 Sep '10

Hi, while building a state machine that also includes submachines, we exceeded the possible max number of MPL vector entries (which is to 50 to my knowledge) for transition tables. Is there an easy way to solve that? How to increase the max possible number of MPL vector entries? Do I have to manually create vector60.hpp and vector60_c.hpp? Or is there something that generates all those files (also for larger vectors)? I also tried the define "BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS" with and without specifing the define "FUSION_MAX_VECTOR_SIZE". I tried the "favor_compile_time" vs "favor_runtime_speed" as well. In both cases the MPL vector size was to small. Does it actually mean, in case we use submachines, that MSM generates a flat transition table including everything in one MPL vector? Example: Main state machine consiting of 10 transitions + 1 submachine consiting of 5 transitions. Do we than have a transition table with around 15 entries that are stored somehow in an MPL vector of size 15? Thanks for your help, Michi

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