March 2009 - Boost-users - lists.boost.org

[result_of] member function
by er 03 Mar '09

03 Mar '09

Hi All, Is this feasible? How? class Foo { template<typename Signature> struct result{}; template<typename F> struct result<(F::*f)(value_type)>{ typedef value0_type if f == foo, value1_type if f == bar type; }; value0_type foo(value_type); value1_type bar(value_type); }; How do I invoke result_of to get the result type of F::foo(value_type)?

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Re: [Boost-users] [asio] still weird crashes with asio using libpion on windows
by FantasyDR 03 Mar '09

03 Mar '09

I met the same issue. And finally I found it was caused by the sequence of object destruction. The asio needs an io_service object to handle all async call. The io_service implementation such as win_iocp_io_service hold a list of its service instance. These instances may be held by object such as tcp::acceptor from their constructor. If io_service was destroyed before the tcp::acceptor then the instance pointer will be released and cause a crash in tcp::acceptor's destructor. The solution is very simple: make sure the io_service was destroyed after all other object that may hold a reference to it. I hope I've described it clearly and can give you some help :-) Bugzilla from stephan.menzel(a)gmx.eu wrote: > > Hi all, > > I have been experiencing problems with weird crashes on Windows using > libpion (http://www.pion.org/projects/pion-network-library) and the > problem is still there with pion 1.0.10 but it changed a little and might > shed some new light on the > Let me just outline the situation. I have a simple project with an app and > two libs, both using boost 1.36 at this time. The app links against those > two libs, and one of the libs links against pion. So does the app of > course. I've built pion as debug dll with boost 1.36. This runs on Windows > and Linux. > Now on Linux everything is fine, no problem at all, no dangerous valgrind > output, nothing. > On Windows however, the application crashes as soon as I do something with > pion, and the callstack leads me to believe it's got something to do with > boost asio. > > Usually it happens within asio win_mutex and looks a lot like this: > http://trac.atomiclabs.com/ticket/32 > To me this looks like an uninitialized mutex is being used. > Not entirely however. I get this: > > First-chance exception at 0x7c91100b in myapp.exe: 0xC0000005: Access > violation reading location 0x00000028. > > it's in win_mutex.hpp > > int do_lock() > { > #if defined(__MINGW32__) > // Not sure if MinGW supports structured exception handling, so for > now > // we'll just call the Windows API and hope. > ::EnterCriticalSection(&crit_section_); > return 0; > #else > __try > { > -> ::EnterCriticalSection(&crit_section_); // CRASH > } > __except(GetExceptionCode() == STATUS_INVALID_HANDLE > || GetExceptionCode() == STATUS_NO_MEMORY > ? EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) > { > if (GetExceptionCode() == STATUS_NO_MEMORY) > return ERROR_OUTOFMEMORY; > return ERROR_INVALID_HANDLE; > } > > return 0; > #endif > } > > This exception repeats many times until eventually the app crashes because > 'this' is invalid, pointing somewhere it shouldn't. > The Bug occurs several seconds after the application has started, but I > don't have to actually access pion's http socket for that. I think it > might not be pion's fault at all. > > The whole thing only happens on Windows and renders both pion useless on > that system. I know, it's only Windows but I've been debugging around that > for some months now and I'd really like that solved at some point. > > Any ideas? > > Thanks a lot... > > Stephan > > > PS: > I can't go to boost 1.37 because of: > https://svn.boost.org/trac/boost/ticket/2541 > With Chris apparently not responding or posting about ASIO any more is > there any chance of this being fixed in the next release? Is ASIO > maintained at all? Cause nobody seems to care about that bug. Again, I > know it's only Windows but as long as Windows is officially a supported > system an imporant lib like ASIO should work on it. > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > -- View this message in context: http://www.nabble.com/-asio--still-weird-crashes-with-asio-using-libpion-on… Sent from the Boost - Users mailing list archive at Nabble.com.

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Formal Review: Boost.RangeEx
by Thorsten Ottosen 02 Mar '09

02 Mar '09

Dear Developers and Users, It's my pleasure to announce that the review of Neil Groves' RangeEx library starts today and lasts until March 3, 2009. What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

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[Review] Reminder: Boost.RangeEx review is going on
by Thorsten Ottosen 02 Mar '09

02 Mar '09

Dear Developers and Users, The review of Neil Groves' RangeEx library lasts until March 3, 2009. Please find the time to do a review if you are interested in this library. The discussion so far may be found here: http://archives.free.net.ph/message/20090220.122836.73bdbd04.en.html Below you will find a description of the library and information on how to write a review. best regards Thorsten, review manager What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

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IEC/SI Binary Prefix Formatter
by Rodrigo Madera 02 Mar '09

02 Mar '09

Hello guys, I'm wondering if in the Boost universe we already have something to format numbers according to IEC's "new" prefixes (such as MiB and GiB) or SI prefixes (such as MB and GB). What I'm looking for is something like: formatter << boost::iec_prefix << 5*1024*1024; // Will output "5 GiB" formatter << boost::si_prefix << 5*1024*1024; // Will output "5GB" Do you have anything like this? Thank you for your support, Rodrigo Madera

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[asio] SSL enabled http server3 example is blocking
by Jean-Pierre Bergamin 02 Mar '09

02 Mar '09

Dear boost-users I changed the http server3 example (many thready run io_service::run()) to use SSL connections. I now face the problem that the async_accept handler is only called when no other connections are alive and not immediately by another thread as with the original non-ssl example. My modified request_handler simply sleeps for 10 seconds. Now when a request arrives while another one is being processed (sleeping), it is only handled after the other one finished. By setting a breakpoint in server::handle_accept() I can see that this handler for the second request is only called after the first connection has been destroyed/closed. This happens on Windows XP. Do you may have an idea why the accept handler is not called immediately or where the blocking could happen? I may help if you could test this on another platform then XP. To test this, apply the attached patch to the directory boost_1_38_0/libs/asio/example/http/server3 and copy the *.pem files from the asio ssl example to the working directory of the server3 example. Regards James PS: I already posted this question to the asio-users list without gettinga reply. I'm trying my luck now here on the boost list. diff -ru server3.orig/connection.cpp server3/connection.cpp --- server3.orig/connection.cpp 2008-03-12 10:12:08.000000000 +0100 +++ server3/connection.cpp 2009-02-17 15:52:12.867198900 +0100 @@ -17,20 +17,20 @@ namespace server3 { connection::connection(boost::asio::io_service& io_service, + boost::asio::ssl::context &context, request_handler& handler) : strand_(io_service), - socket_(io_service), + socket_(io_service, context), request_handler_(handler) { } -boost::asio::ip::tcp::socket& connection::socket() +connection::socket_type::lowest_layer_type& connection::socket() { - return socket_; + return socket_.lowest_layer(); } -void connection::start() -{ +void connection::handle_handshake(const boost::system::error_code& e) { socket_.async_read_some(boost::asio::buffer(buffer_), strand_.wrap( boost::bind(&connection::handle_read, shared_from_this(), @@ -38,6 +38,14 @@ boost::asio::placeholders::bytes_transferred))); } +void connection::start() +{ + socket_.async_handshake(boost::asio::ssl::stream_base::server, + boost::bind(&connection::handle_handshake, shared_from_this(), + boost::asio::placeholders::error) + ); +} + void connection::handle_read(const boost::system::error_code& e, std::size_t bytes_transferred) { @@ -85,7 +93,7 @@ { // Initiate graceful connection closure. boost::system::error_code ignored_ec; - socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ignored_ec); + socket_.shutdown(ignored_ec); } // No new asynchronous operations are started. This means that all shared_ptr diff -ru server3.orig/connection.hpp server3/connection.hpp --- server3.orig/connection.hpp 2008-03-12 10:12:08.000000000 +0100 +++ server3/connection.hpp 2009-02-26 08:51:42.187500000 +0100 @@ -12,6 +12,7 @@ #define HTTP_SERVER3_CONNECTION_HPP #include <boost/asio.hpp> +#include <boost/asio/ssl.hpp> #include <boost/array.hpp> #include <boost/noncopyable.hpp> #include <boost/shared_ptr.hpp> @@ -30,17 +31,20 @@ private boost::noncopyable { public: + typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> socket_type; /// Construct a connection with the given io_service. explicit connection(boost::asio::io_service& io_service, + boost::asio::ssl::context &context, request_handler& handler); /// Get the socket associated with the connection. - boost::asio::ip::tcp::socket& socket(); + socket_type::lowest_layer_type& socket(); /// Start the first asynchronous operation for the connection. void start(); - + ~connection() {} private: + void handle_handshake(const boost::system::error_code& e); /// Handle completion of a read operation. void handle_read(const boost::system::error_code& e, std::size_t bytes_transferred); @@ -52,7 +56,7 @@ boost::asio::io_service::strand strand_; /// Socket for the connection. - boost::asio::ip::tcp::socket socket_; + socket_type socket_; /// The handler used to process the incoming request. request_handler& request_handler_; diff -ru server3.orig/reply.cpp server3/reply.cpp --- server3.orig/reply.cpp 2008-03-12 10:12:08.000000000 +0100 +++ server3/reply.cpp 2009-02-17 15:52:20.804800500 +0100 @@ -119,7 +119,7 @@ namespace stock_replies { -const char ok[] = ""; +const char ok[] = "ok\r\n"; const char created[] = "<html>" "<head><title>Created</title></head>" diff -ru server3.orig/request_handler.cpp server3/request_handler.cpp --- server3.orig/request_handler.cpp 2008-03-12 10:12:08.000000000 +0100 +++ server3/request_handler.cpp 2009-02-26 08:23:56.250000000 +0100 @@ -8,6 +8,7 @@ // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // +#include <boost/thread.hpp> #include "request_handler.hpp" #include <fstream> #include <sstream> @@ -27,56 +28,9 @@ void request_handler::handle_request(const request& req, reply& rep) { - // Decode url to path. - std::string request_path; - if (!url_decode(req.uri, request_path)) - { - rep = reply::stock_reply(reply::bad_request); - return; - } - - // Request path must be absolute and not contain "..". - if (request_path.empty() || request_path[0] != '/' - || request_path.find("..") != std::string::npos) - { - rep = reply::stock_reply(reply::bad_request); - return; - } - - // If path ends in slash (i.e. is a directory) then add "index.html". - if (request_path[request_path.size() - 1] == '/') - { - request_path += "index.html"; - } - - // Determine the file extension. - std::size_t last_slash_pos = request_path.find_last_of("/"); - std::size_t last_dot_pos = request_path.find_last_of("."); - std::string extension; - if (last_dot_pos != std::string::npos && last_dot_pos > last_slash_pos) - { - extension = request_path.substr(last_dot_pos + 1); - } - - // Open the file to send back. - std::string full_path = doc_root_ + request_path; - std::ifstream is(full_path.c_str(), std::ios::in | std::ios::binary); - if (!is) - { - rep = reply::stock_reply(reply::not_found); - return; - } - - // Fill out the reply to be sent to the client. - rep.status = reply::ok; - char buf[512]; - while (is.read(buf, sizeof(buf)).gcount() > 0) - rep.content.append(buf, is.gcount()); - rep.headers.resize(2); - rep.headers[0].name = "Content-Length"; - rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size()); - rep.headers[1].name = "Content-Type"; - rep.headers[1].value = mime_types::extension_to_type(extension); + using namespace boost; + this_thread::sleep(posix_time::seconds(10)); + rep = reply::stock_reply(reply::ok); } bool request_handler::url_decode(const std::string& in, std::string& out) diff -ru server3.orig/server.cpp server3/server.cpp --- server3.orig/server.cpp 2008-03-12 10:12:08.000000000 +0100 +++ server3/server.cpp 2009-02-17 16:24:16.173066900 +0100 @@ -21,9 +21,23 @@ const std::string& doc_root, std::size_t thread_pool_size) : thread_pool_size_(thread_pool_size), acceptor_(io_service_), - new_connection_(new connection(io_service_, request_handler_)), + context_(io_service_, boost::asio::ssl::context::sslv23), + new_connection_(new connection(io_service_, context_, request_handler_)), request_handler_(doc_root) { + + context_.set_options( + boost::asio::ssl::context::default_workarounds + | boost::asio::ssl::context::no_sslv2 + | boost::asio::ssl::context::single_dh_use); + context_.set_password_callback(boost::bind<const char*>(&server::get_password, this)); + + context_.use_certificate_chain_file("server.pem"); + context_.use_private_key_file("server.pem", boost::asio::ssl::context::pem); + context_.use_tmp_dh_file("dh512.pem"); + context_.set_verify_mode(boost::asio::ssl::context::verify_none); + + // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR). boost::asio::ip::tcp::resolver resolver(io_service_); boost::asio::ip::tcp::resolver::query query(address, port); @@ -63,7 +77,7 @@ if (!e) { new_connection_->start(); - new_connection_.reset(new connection(io_service_, request_handler_)); + new_connection_.reset(new connection(io_service_, context_, request_handler_)); acceptor_.async_accept(new_connection_->socket(), boost::bind(&server::handle_accept, this, boost::asio::placeholders::error)); diff -ru server3.orig/server.hpp server3/server.hpp --- server3.orig/server.hpp 2008-03-12 10:12:08.000000000 +0100 +++ server3/server.hpp 2009-02-17 16:02:27.187562100 +0100 @@ -39,6 +39,10 @@ void stop(); private: + const char * get_password() const { + return "test"; + } + /// Handle completion of an asynchronous accept operation. void handle_accept(const boost::system::error_code& e); @@ -51,6 +55,8 @@ /// Acceptor used to listen for incoming connections. boost::asio::ip::tcp::acceptor acceptor_; + boost::asio::ssl::context context_; + /// The next connection to be accepted. connection_ptr new_connection_;

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[serialization] Archive reload
by Ferllings 02 Mar '09

02 Mar '09

Hello, I have a Class A with string attributes that I serialize in XML format: Class A { public: string _nom; string _prenom; template<class Archive> void serialize(Archive& ar, const unsigned in version){ ar & boost::serialization::make_nvp("Nom", _nom); ar & boost::serialization::make_nvp("Prenom", _prenom); } } The object is correctly saved using this code: A _a; void save() const { ... oTextArchive::xml_oarchive oTextArchive(ofile); oTextArchive << make_nvp("A", _a); ... } But I want to reload the object, the A attributes aren't updated and keep the previous values: void load() { ... iTextArchive::xml_oarchive iTextArchive(ifile); iTextArchive >> make_nvp("A", _a); ... } The only way I found to reload my object is to use an temporary object: void load() { ... A _tmp; iTextArchive::xml_oarchive iTextArchive(ifile); iTextArchive >> make_nvp("A", _tmp); _a = _tmp; ... } Why can't I update the object directly? Thanks for your help.

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[accumulators] Any was to reset an accumulator_set object?
by dhruva 02 Mar '09

02 Mar '09

Hello, I am using boost::accumulator_set to compute mean. After every 100 samples, I need to start afresh. Since I am using accumulator_set as a member variable in a class (I get samples one at a time and need to preserve accumulator_set object across function calls), I need some mechanism to reset it to its initial state. I am not doing anything fancy like using droppable functionality. As a real crude work around, I am keeping 2 objects. The first is not used for any computing and hence its state is same throughout. The computing is done using the second object. After 100 samples, I just copy the first onto the second hoping the state of second object will be same as first which is the initial state. Is there a better way to achieve the above requirement? -dhruva Download prohibited? No problem. CHAT from any browser, without download. Go to http://in.webmessenger.yahoo.com/

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[lexical_cast] Locales.
by Emre Turkay 02 Mar '09

02 Mar '09

Hi folks, I wonder if there is a downside of adding an optional std::locale argument to lexical_cast? Thanks, Emre Turkay

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[Interprocess] Trying to include unistd.h on Windows?
by Derek Kivi 02 Mar '09

02 Mar '09

We are using the Interprocess library to make use of shared memory within our code. We are experiencing the following problem when building on Windows. Some of our projects are trying to include unistd.h from workaround.hpp. It looks like this happens if BOOST_WINDOWS is not defined. Tracing back through the header files I pieced together that BOOST_WINDOWS is not defined if BOOST_DISABLE_WIN32 is defined (win32.hpp). And BOOST_DISABLE_WIN32 gets defined if _MSC_EXTENSIONS is not defined (visualc.hpp). >From the MSDN documentation, _MSC_EXTENSIONS is not defined if the Visual C++ Language Extensions are turned off, which in fact they are for these projects. Has anyone else seen this and is there a workaround for getting Boost Interprocess to work on Windows in cases where the Visual C++ Language Extensions are turned off? Thanks, Derek -- Derek Kivi Senior Software Developer QuIC Financial Technologies Inc. Office: +1 403 210 8282 Mobile: +1 403 863 5204 derek.kivi(a)quic.com Risk. Managed. www.quic.com Confidentiality Notice: The information transmitted is intended only for the person(s) or entity(ies) to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this email in error, please contact the sender and delete the email and any related material from any computer. ver. QuIC 0707

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