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[Interprocess] managed_shared_memory between 32 & 64bit
by leunm 17 Feb '13

17 Feb '13

Hi, I am new to Boost and am looking for a way to pass xyz coordinates from a 32-bit application to a 64-bit one. I see two recent posts on this same topic, but the explanation, as well as the Boost documentation (on offset_ptr) is a bit sparse. Below is a simple example I modified from the Boost documentations <http://www.boost.org/doc/libs/1_53_0/doc/html/interprocess/quick_guide.html…> , which works for either 32-bit or 64-bit but not when the parent is 32-bit and child is 64-bit, and vice versa. Can someone tell me what I need to do enable this function? Thank you in advance, Mike ----------------------------------------------------------------- #define BOOST_DATE_TIME_NO_LIB #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <string> #include <cstdlib> //std::system #include <conio.h> #include <iostream> #include <windows.h> using namespace boost::interprocess; //Define an STL compatible allocator of ints that allocates from the managed_shared_memory. //This allocator will allow placing containers in the segment typedef allocator<float, managed_shared_memory::segment_manager> ShmemAllocator; //Alias a vector that uses the previous STL-like allocator so that allocates //its values from the segment typedef vector<float, ShmemAllocator> MyVector; //Main function. For parent process argc == 1, for child process argc == 2 int main(int argc, char *argv[]) { if(argc == 1){ //Parent process //Remove shared memory on construction and destruction struct shm_remove { shm_remove() { shared_memory_object::remove("MySharedMemory"); } ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); } } remover; //Create a new segment with given name and size managed_shared_memory segment(create_only, "MySharedMemory", 65536); //Initialize shared memory STL-compatible allocator const ShmemAllocator alloc_inst (segment.get_segment_manager()); //Construct a vector named "MyVector" in shared memory with argument alloc_inst MyVector *myvector = segment.construct<MyVector>("MyVector")(alloc_inst); for(int i = 0; i < 100; ++i) //Insert data in the vector myvector->push_back(0.0); // Loop bool exitFlag = false; while (1) { // Store 3 values myvector->at(0) = rand() % 100; myvector->at(1) = rand() % 100; myvector->at(2) = rand() % 100; std::cout << "Parent: " << myvector->at(0) << ", " << myvector->at(1) << ", " << myvector->at(2) << std::endl; if (kbhit()) { switch (getch()) { default: exitFlag = true; break; } if (exitFlag) break; } Sleep(500); } //When done, destroy the vector from the segment segment.destroy<MyVector>("MyVector"); } else { //Child process //Open the managed segment managed_shared_memory segment(open_only, "MySharedMemory"); //Find the vector using the c-string name MyVector *myvector = segment.find<MyVector>("MyVector").first; //Loop bool exitFlag = false; while (1) { try { std::cout << "Child: " << myvector->at(0) << ", " << myvector->at(1) << ", " << myvector->at(2) << std::endl; } catch (...) { std::cout << "Error accessing vector, exiting..." << std::endl; exitFlag = true; } if (kbhit()) { switch (getch()) { default: exitFlag = true; break; } } if (exitFlag) break; Sleep(500); } } return 0; }; -- View this message in context: http://boost.2283326.n4.nabble.com/Interprocess-managed-shared-memory-betwe… Sent from the Boost - Users mailing list archive at Nabble.com.

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Behaviour of asio
by ustulation 17 Feb '13

17 Feb '13

By going through the doc. i understand that async completion handlers will be called whenever io_service::run() reads posted events from the queue for which the corresponding handlers were registered by us. Now if i have a registered handler for some event (say async_wait() of deadline_timer) which does something time consuming, then event loop (io_service::run()) does not get a chance to read the event queue until the handler returns thus preventing calls to other handlers for which events are queued. I've tested this behaviour with timers and it works as expected. However i could not understand the behaviour of async_read_from() of udp::socket. void A::read() { udpSoc.async_receive_from( boost::asio::buffer(m_cRxData, 1024), m_endpoint, boost::bind(&A::readHandler, this, _1, _2) ); } ////////////////////////////// <1> /////////////////////////// void A::readHandler(......) { std::string szDatagram(m_cRxData, bytesReceived); std::cerr << "Rxd Datagram: " << szDatagram << std::endl; read(); //............ } ////////////////////////////// <2> /////////////////////////// void A::readHandler(......) { read(); std::string szDatagram(m_cRxData, bytesReceived); std::cerr << "Rxd Datagram: " << szDatagram << std::endl; //............ } in above when 2 datagrams arrive simultaneously, readHandler <1> works fine but <2> does not. In <1> std::cerr write 1st and 2nd Datagrams distinctly, but in <2> data gets corrupted and std::cerr writes a string that would be formed if the 1st datagram in it were overwritten by the 2nd datagram (ie., if 1st one was 12345 and 2nd one xyz then <2> above prints "xyz45".) This means that clearly m_cRxData (which is a private member) is getting overwritten. Why does this happen? async_read_from should return immediately without reading into m_cRxData, readHandler(..) should continue and complete, and control should reach event loop, and then finally async read should be done calling the completion handler. Is this explanation wrong? -- View this message in context: http://boost.2283326.n4.nabble.com/Behaviour-of-asio-tp4642911.html Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] Question about installing and using boost library.
by Giovanni 17 Feb '13

17 Feb '13

Greetings Pan, I am using Ubuntu 12.04 with one of my machines. I used the Ubuntu Software Center to install the Boost C++ Libraries, which makes things so much easier. You can enter "Boost" into the search box on the top-right corner, and find the Boost C++ Libraries to install. There are a number of them, including versions that conflict with each other. I chose the default version, and packages that don't conflict with that. I suggest that you install Boost C++ that way. After you have installed Boost C++ with Ubuntu Software Center, you should/"should" (it depends on how you set things up and if you have root access) see the following. The collection of header files for the Boost C++ Libraries in the location: /usr/lib. The collection of dynamic libraries (to be dynamically linked) for the Boost C++ Libraries in the location: /usr/include/boost. To test if you have installed the Boost C++ Libraries correctly, run a very simple C++ program that includes one of the Boost C++ Libraries and calls a function from that library. For example, you can try my attached toy program. To compile and run the program, try: g++ -o static2.out get_sys_info.cpp -lboost_filesystem -lboost_system ./static2.out As for your specific problem, I am guessing that it is a linking error that I also had. You need to include the Boost C++ Libraries at the end of the compilation command (for GCC/g++). Hence, I placed the filename (C++ source file) before including the libraries. I suggest that you post your compilation/linking commands, or makefile or script for build automation, so that people can help you. In addition, I would include the relevant source code (make it a simple C++ program, like my example) to test your Boost C++ installation. Furthermore, I would include the transcript from the Terminal. Just copy and paste what appears on the Terminal as you compile the program. Good luck, and have a great weekend! Regards On Fri, Feb 15, 2013 at 8:47 AM, pan yi <outlook_eye(a)yahoo.com.cn> wrote: > Hi all, > > I'm a beginner to use boost library for my c++ coding project. After I > include the <boost/algorithm/string.hpp> in my cpp file and compile the > code, the compiling error indicates that: > fatal error: boost/algorithm/string.hpp: No such file or directory > I search on internet and knows that I need to install some boost library. > But which library should I install? (I tried to install the whole library > with "sudo apt-get install libboost*", but it doesn't work.) > > Can any one help me? I'm compiling and executing c++ on ubuntu Version12.04 > environment > > Thank you so much. > > Best Regards > Pan

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Re: [Boost-users] [Chrono] Memory leak in Chrono?
by Don 16 Feb '13

16 Feb '13

On 2/16/2013 Vincent wrote: > Please, could you create a Trac ticket so this issue not lost? Submitted as ticket #8079 https://svn.boost.org/trac/boost/ticket/8079 Thanks, Don

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Re: [Boost-users] [Chrono] Memory leak in Chrono?
by Don 16 Feb '13

16 Feb '13

-------- Original Message -------- Subject: Boost-users Digest, Vol 3358, Issue 4 From: boost-users-request(a)lists.boost.org To: boost-users(a)lists.boost.org Date: 2/13/2013 1:33 PM > Subject: Re: [Boost-users] [Chrono] Memory leak in Chrono? > From: "Vicente J. Botet Escriba" <vicente.botet(a)wanadoo.fr> > Date: 2/13/2013 1:11 PM > > Le 13/02/13 14:30, Don a écrit : >>> Subject: Re: [Boost-users] [Chrono] Memory leak in Chrono? >>> From: "Vicente J. Botet Escriba" <vicente.botet(a)wanadoo.fr> >>> Date: 2/12/2013 1:17 PM >>> >>> Le 12/02/13 18:13, gast128 a écrit : >>>> we use Boost.Chrono too. MFC applications incorrectly report memory leaks, which can easily be solved. >>> Hi, >>> >>> if you have some patches to propose to avoids this incorrect reports I would try to include them. >> >> Vincente, >> >> I am using MFC, but I don't believe this is a MFC false-leak report. >> >> I added a destructor for duration_units_default_initializer_t, like this (near the end of chrono/io/duration_units.hpp): >> >> ~duration_units_default_initializer_t() >> { >> if (duration_units_default_holder<CharT>::initialized_) >> { >> delete[] duration_units_default_holder<CharT>::n_d_valid_units_; >> duration_units_default_holder<CharT>::n_d_valid_units_ = 0; >> delete[] duration_units_default_holder<CharT>::valid_units_; >> duration_units_default_holder<CharT>::valid_units_ = 0; >> duration_units_default_holder<CharT>::initialized_ = false; >> } >> } >> >> This solves the memory leak, and seems to work fine for my simple test program. > I could add this is this helps on the MFC report. Thanks, that would be useful. It would probably help with other memory leak detectors, as well. Since you are allocating heap that you are never freeing, most leak detectors are going to report this. >> But n_d_valid_units_, valid_units_, and initialized_ are static >> variables, so I assume you want to only create these variables >> once. > > Right. > >> When run with my test program and step through it in the debugger, >> only one instantiation of duration_units_default_initializer_t >> occurs. (That is, once for each char type, single-byte and wide.) > This is the goal of the type (implement a singleton). This technique > is used in some Boost libraries already > >> This occurs when the duration_units_default_initializer is >> instantiated (at the very end of duration_units.hpp). Since this is >> a global variable, this occurs during application startup and the >> destructor runs during application shuttdown. > > Right, this was the reason the destructor didn't do anything. >> >> But presumably this can occur in some other situations, otherwise >> why would you have all the logic of making valid_units_ etc. >> class-static variables.> > On which other situation do you think this could occur? I have no idea, that's what confused me. If duration_units_default_initializer_t is only instantiated as a global (static) variable), then I don't see any reason for making n_d_valid_units_, valid_units_, and initialized_ static variables -- they could be regular member variables. Making them static doesn't hurt, but it's confusing (to me at least) because it looks like you want to share those variables among multiple instantiations, and there is only ever one instantiation. If one can somehow instantiate multiple duration_units_default_initializer_t objects, then making the member variables static does make this behave as a singleton. In that case the simple destructor I wrote will not work, since it will delete the member variables when the first object destructs, not the last. In that case I would use a reference count or smart pointers to only delete when the final object destructs. Thanks for your help, I appreciate your spending the time to answer my questions. Don

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[Asio] How to implement my own TCP?
by Chengu Wang 16 Feb '13

16 Feb '13

Hi all, I'd like to implement the TCP over UDP, because I want to change TCP a little. The implementation includes the three-way handshake, retransmission, etc. My TCP must have the basic interfaces as the original TCP does, i.e. a my_tcp::acceptor class supporting bind, listen, accept, async_accept and close, and a my_tcp::socket supporting bind, connect, async_connect, send, async_send, receive, async_receive and close. Of course I can write these two classes from scratch, but can I do it in the framework of asio and reuse some codes of asio? What classes should I implement and what do the inherit from? Any help would be appreciated. -- Best, Chengu Wang

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Ideas for UT needed
by Olaf Peter 15 Feb '13

15 Feb '13

Hello, for my project I use the ideas used on spirit's conjure2 example. Now I like to do some test with the lexer/grammar using boost::test. The example uses sequentially initializing all iterators, lexer and grammar. I like to put this into the fixture but I run into the problem that the error_handler requires begin/end of iterator. ---8<--- original from conjure2 main typedef std::string::const_iterator base_iterator_type; typedef client::lexer::conjure_tokens<base_iterator_type> lexer_type; typedef lexer_type::iterator_type iterator_type; lexer_type lexer; // Our lexer base_iterator_type first = source_code.begin(); base_iterator_type last = source_code.end(); iterator_type iter = lexer.begin(first, last); iterator_type end = lexer.end(); client::error_handler<base_iterator_type, iterator_type> error_handler(first, last); // Our error handler client::parser::function<iterator_type, lexer_type> function(error_handler, lexer); // Our parser --->8--- My fixture looks so far: ---8<--- typedef std::string::const_iterator base_iterator_type; typedef my_tokens<base_iterator_type> lexer_type; typedef lexer_type::iterator_type iterator_type; typedef error_handler<base_iterator_type, iterator_type> error_handler_type; struct fixture : private boost::base_from_member<error_handler_type>, private boost::base_from_member<lexer_type>, my_grammar<iterator_type, lexer_type> { typedef boost::base_from_member<lexer_type> lexer_base; typedef boost::base_from_member<error_handler_type> error_handler_base; typedef my_grammar<iterator_type, lexer_type> grammar_base; fixture() : grammar_base(error_handler_base::member, lexer_base::member) { } }; --->8--- error_handler_base::member requires therefore the iterators first/last. How to give them? In the UT I have further a "test" function object so I can use e.g. it like here: ---8<--- BOOST_FIXTURE_TEST_SUITE(parameter_test, fixture) BOOST_AUTO_TEST_CASE(my_test) { BOOST_CHECK(test(rule_to_test, "input to parse", "expected output")); } --->8--- The next problem is related to the original use case. conjure2 is design as a compiler: initialize, analyse, generate and exit - no reuse of the grammar. I like to instance the grammar once (static) and use it several times using the qi::parse function. Since the iterators are fixed, they can't be changed later to point to other sources, isn't it? Is this the right approach for my problem? Thanks, Olaf

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Re: [Boost-users] [LockFree] a queue of std::shared_ptr?
by chris 15 Feb '13

15 Feb '13

Hello All, If we can't use shared_ptr in a lockfree queue, how can I share data between different queue ? I have some data that I have to be put in different queues and I want to avoid that I have to copy this data for each queue. -- View this message in context: http://boost.2283326.n4.nabble.com/LockFree-a-queue-of-std-shared-ptr-tp464… Sent from the Boost - Users mailing list archive at Nabble.com.

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Question about installing and using boost library.
by pan yi 15 Feb '13

15 Feb '13

Hi all, I'm a beginner to use boost library for my c++ coding project. After I include the <boost/algorithm/string.hpp> in my cpp file and compile the code, the compiling error indicates that: fatal error: boost/algorithm/string.hpp: No such file or directory I search on internet and knows that I need to install some boost library. But which library should I install? (I tried to install the whole library with "sudo apt-get install libboost*", but it doesn't work.) Can any one help me? I'm compiling and executing c++ on ubuntu Version12.04 environment Thank you so much. Best Regards Pan

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Re: [Boost-users] Boost-users Digest, Vol 3359, Issue 1
by John M. Dlugosz 14 Feb '13

14 Feb '13

On 2/14/2013 2:26 AM, boost-users-request-at-lists.boost.org |Boost/Allow to home| wrote: > Message: 5 > Date: Wed, 13 Feb 2013 19:20:40 -0500 > From: Edward Diener<eldiener(a)tropicsoft.com> > To:boost-users@lists.boost.org > Subject: Re: [Boost-users] [Preprocessor] Generate #include directive > with preprocessor > Message-ID:<kfhaku$ikt$1(a)ger.gmane.org> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 2/13/2013 6:43 AM, Adam Badura wrote: >> >Is it possible to use preprocessor to generate #include directives (or >> >in any other way include the files)? > No it is not possible. You cannot define a macro which expands to other > another macro definition or any other basic preprocessor construct, > including the #include. > > It is possible to use a macro as the name of the file to include. So you can choose the file via preprocessing logic, but not alter the fact that some file is to be included. So... given an empty file and a file with #include M1 #include M2 you can use recursion to include an arbitrary number of different files based on preprocessor logic. --John

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