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Plans to add parameter parsing in Beast?
by David Demelier 30 May '18

30 May '18

Hello, I'm trying to use Beast, it works fine and looks promising. Unfortunately, it looks like (unless I'm wrong) that there is no facilities to parse URL parameters or POST data. Such as /foo&option1=1&option2=2 Or simply form data: option1=1&option2=2 Are there plans to add such things or is definitely a non-goal of Boost Beast? Regards, -- David

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Boost::Log memory allocation
by Olivier Tristan 29 May '18

29 May '18

Hi, I was wondering if it is possible to avoid allocation in the thread trying to log stuff ? I thought that using asynchronous_sink and bounded_fifo_queue with drop_on_overflow would be enough but it do not look like to be the case. Thanks ! -- Olivier Tristan Research & Development www.uvi.net

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boost-iostreams problem
by Theodore Papadopoulo 28 May '18

28 May '18

Hi, I'm trying to use boost_iostream in a way that is probably not intented. My use case is the following, I have a C++ stream. I want to read its first bytes to determine if its gzip or Bzip2 or none of those, putback the characters to the stream and then create the appropriate pipeline to read the stream. Ideally, I'd then restart the procedure, so that I can incrementally build a pipeline based on the successive magic numbers read at the begining of the stream after different level of decoding. Imagine a file that has been gzipped and uuencoded. Let's call its stream ifs. Reading the first bytes of ifs, I would detect that it's an uuencoded file, so I construct a pipeline ifs1 = ifs | uudecode. Reading the first bytes of ifs1, I would detect that it's a gzipped file, and will construct a new pipeline ifs2 = ifs | uuencode | gzip (the reverse ordering for reading pipelines does not help here, but I can manage that). And so on.... Unfortunately, this does not work as I'm expecting it. The attached code is a small example showing the problem. When, reading the stream after having pushed the gzip filter (line 23), I get an exception. boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::iostreams::gzip_error> > Digging a little with gdb seems to show that the putback buffer is somehow lost, so the gzip filter does not read the proper header and hence the exception. The raw in.read does not throw exceptions but returns random bytes after the first 1f.... What is strange is that if I do the sequence: in.push(file); read(in,buffer,1); putback(in,buffer[0]); in.pop(); in.push(file); read(in,buffer,1); std::cout << std::hex << static_cast<int>(static_cast<unsigned char>(buffer[0])) << std::endl; putback(in,buffer[0]); The second read correctly reads the character put back (1f), but the second putback triggers an exception (putback buffer full). If the first read/putback is done directly on file, everything works as expected. I'm really stuck at this point, so any help would be welcome.... I hope there is a way to use boost_iostreams to achieve what I want to do. Thank's in advance for any clue on how to solve this... Theo.

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[asio] continuous reads into streambuf
by Stephan Menzel 25 May '18

25 May '18

Hello all, once again I find myself struggling with asio streambufs but wanted to ask here before chicken out to char buffers again. My problem is that I cannot read more than one protocol loop successfully. I got a TCP connection here that continuously receives messages on a simple protocol like that: header_size CRLF header (contains payload size) payload <repeat> I thought this is a prime use case for reading into a streambuf as I can easily deal with additional data being in there and the client pushing as fast as it can. Here is what I do (simplified quite a bit, sorry for copy and paste and simplify errors): (m_socket and m_streambuf are only used by one io_context, one thread, no races as far as I can tell) void read_header_size() { asio::async_read_until(m_socket, m_streambuf, "\r\n", [self](const boost::system::error_code, const std::size_t) { // < handle error skipped > std::string hsizestr; hsizestr.reserve(32); { std::istream is(&self->m_streambuf); std::getline(is, hsizestr); } std::size_t header_size = parse(hsizestr); self->read_header(header_size); }); } void read_header(const std::size_t n_header_size) { asio::async_read(m_socket, m_streambuf, boost::asio::transfer_exactly(n_header_size), [self, packet, n_header_size](const boost::system::error_code, const std::size_t) { // < handle error skipped > // Tried two versions of parsing the header (manual consume and istreams of various sorts) // manual consume: size_t payload_size = parse_header(n_streambuf.data().data(), n_header_size)) { n_streambuf.consume(n_header_size); self->read_payload(payload_size); }); } void read_payload(const std::size_t n_payload_size) { asio::async_read(m_socket, m_streambuf, boost::asio::transfer_exactly(payload_size), [self, n_packet, packet_size](const boost::system::error_code, const std::size_t) { // < handle error skipped > { std::istream is(&self->m_streambuf, std::ios::binary); is.read(target_buffer, target_buffer_size); // target buffer is elsewhere and well guarded } // read next message self->read_header_size(); }); } When I run this and make sure the client pushes at least 2 packets I can safely receive and process the first but after that the next asnc_read() in read_header never returns. As in never calls its handler. From debugging and looking at the streambuf I can reasonably assume the buffer contains all the data after the first async_read_until because the packages are very small (only about 60 bytes total). This leads me to believe the transfer_exactly don't return unless something is actually really transferred. But if such is the case, why does the first loop succeed? I am quite lost here. If anybody has some suggestion it is much appreciated. Thanks a bunch! Stephan

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Boost Process continuously read output
by Surya Kiran Gullapalli 16 May '18

16 May '18

Hi, I'm trying to read outputs/logs from different processes and display them in a GUI. The processes will be running for long time and produce huge output. I'm planning to stream the output from those processes and display them according to my needs. All the while allow my gui application to take user inputs and perform other actions. What I've done here is, from main thread launch two threads for each process. One for launching the process and another for reading output from the process. This is the solution I've come up thus far. // Process Class class MyProcess { namespace bp = boost::process; boost::asio::io_service mService; // member variable of the class bp::ipstream mStream // member variable of the class std::thread mProcessThread, mReaderThread // member variables of the class. public void launch(); }; void MyProcess::launch() { mReaderThread = std::thread([&](){ std::string line; while(getline(mStream, line)) { std::cout << line << std::endl; } }); mProcessThread = std::thread([&]() { auto c = boost::child ("/path/of/executable", bp::std_out > mStream, mService); mService.run(); mStream.pipe().close(); } } // Main Gui class class MyGui { MyProcess process; void launchProcess(); } MyGui::launchProcess() { process.launch(); doSomethingElse(); } The program is working as expected so far. But I'm not sure if this is the correct solution. Please let me know if there's any alternative/better/correct solution Thanks, Surya

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how to add comments to boost property tree while export in xml file
by neelam baliyan 16 May '18

16 May '18

Hi All, I have read and store my complete configuration file in to boost property tree, now I want to export it to a xml file which i can do via function write_xml(). I wanted to add some comments inside my exported xml file. Please help me to know, how to add comments inside xml file while exporting data from boost property tree. Thanks & Regards Neelam

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Boost and Intellisense
by Leo Cacciari 16 May '18

16 May '18

Hi, I'm developing a windows application using boost libraries. Unfurtunately, some parameters of it are totally out of my control, nor I have the leverage needed to change it. Namely, - the application *must* use Visual C++ 9.0 runtime - the IDE to be used is capped at Visual Studio 2013 - to avoid problems with other related projects, the boost release should be 1.54.0 (here I have a modicum of liberty, as far as the previous two conditions are satisfied) I may live whit all of the above, however Intellisense has some glitches that are annoying me. For one, it appears unable to recognize the boost::asio::ip namespace. If I define a variable as, for instance boost::asio::ip::udp::endpoint ep; Intellisense marks 'ip' in red and keeps saying that ep is undefined (and consequently doesn't offer completion for its methods). I have tried including directly boost/asio/ip/udp.hpp and also putting an "using boost::asio::ip::udp" before the above definition as in #include <boost/asio/ip/udp.hpp> using boost::asio::ip::udp; udp::endpoint ep; but nothing changes (I'll gladly post a screenshot if I knew which is the accepted way to post images to this list). It should be noted that, aside from this and some analogous problems, Intellisense works fine, making the above even more annoying. Does anyone have a solution to this problem that do not violate the aforementioned constraints? Thanks in avance lc -- Leo Cacciari Aliae nationes servitutem pati possunt. Populi Romani est propria libertas.

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phoenix: BOOST_PHOENIX_NO_VARIADIC_EXPRESSION purpose
by MM 10 May '18

10 May '18

Hello (Thomas Heller, Joel de Guzman :-) ) In /usr/include/boost/phoenix/object/construct.hpp, there appears this preprocessor test on this macro BOOST_PHOENIX_NO_VARIADIC_EXPRESSION whereby the code either: 1. includes boost/phoenix/object/detail/cpp03/construct_expr.hpp , or 2. defines a expression inline Is that macro used to workaround some compiler limitations (and/or c++ std version) back in the day? I work with g++7 and std=c++14, and boost 1.64, and yet somehow boost/phoenix/object/detail/cpp03/construct_expr.hpp is included, and somewhere down the line a compilation error happens. The cpp03 is unnerving. Rds, MM

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Boost Graph Library(biconnected_components) issue
by Meghana.M Reddy 07 May '18

07 May '18

Hi, I am working on the Boost Graph Library, currently trying to create an interface of the biconnected_components method to a Python code. I used the example code available here <https://www.boost.org/doc/libs/1_67_0/libs/graph/example/biconnected_compon…> for the method and modified it for my purpose. The template of the method is here <https://www.boost.org/doc/libs/1_67_0/libs/graph/doc/biconnected_components…>. The final code seems fine but I get an error while compiling it. And the errors are related to adjacency.hpp which I have not changed so I'm confused as to what the exact problem is. Hoping someone can help me out. My code: class BoostGraph { private: typedef typename boost::adjacency_list< OutEdgeListS, VertexListS, DirectedS, boost::property<boost::vertex_index_t, v_index>, EdgeProperty, boost::no_property, EdgeListS> adjacency_list; typedef typename boost::property_map<adjacency_list, boost::edge_index_t>::type components; public: adjacency_list graph; std::vector<v_index> bc_tree() { components components_bc = get(boost::edge_index, graph); std::size_t num_comps = biconnected_components(graph, components_bc); std::cerr << "Found " << num_comps << " biconnected components.\n"; std::vector<vertex_descriptor> art_points; articulation_points(graph, std::back_inserter(art_points)); std::cerr << "Found " << art_points.size() << " articulation points.\n"; std::vector<v_index> to_return; return to_return; } The error I'm getting: build/cythonized/sage/graphs/base/boost_graph.cpp:3730:26: required from here /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2696:29: error: forming reference to void typedef value_type& reference; ^ /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2697:35: error: forming reference to void typedef const value_type& const_reference; ^ /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2701:61: error: forming reference to void typename Graph::vertex_descriptor,Property,Tag> type; ^ /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2704:68: error: forming reference to void typename Graph::vertex_descriptor,const Property, Tag> const_type; ^ error: command 'gcc' failed with exit status 1 Makefile:33: recipe for target 'sage' failed make: *** [sage] Error 1 Thank you, Meghana

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Installing pre-built binaries on Windows with Docker
by Matthew Berry 04 May '18

04 May '18

Hi, I tried installing pre-built 1.67 binaries from https://dl.bintray.com/boostorg/release/1.67.0/binaries/ in a Windows Server Docker container but am running into an issue where the installation does not complete. I ran the installer exe in silent mode. A lot of the files including headers are installed, but not the lib directory with the binaries. The Inno Setup log does not indicate an error, it just stops writing in the middle of the installation. Does anyone know why installation does not complete? Has anyone been able to install pre-built libraries in a Windows Docker container? Any help would be appreciated. Thanks, Matt

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