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[Boost::Interprocess] access violation when function returns a pointer to shared memory object
by BaDBuTz 22 Oct '09

22 Oct '09

hi, I want to synchronize multiple Processes with boost::Interprocess. For the start I implemented a simple Synchronisation Class (with some mutexes) in my test program that will be stored in the Shared Memory. The first call of print() (in function getSyncObject) returns the correct output. But why do I get an access violation, when I call the function again (the pointer is the same!) in main()? I am using WINXP, msvc 7-1 and mingw44 (with both compilers I get the same error) Thanks in advance Martin (compilable) Code: #include <iostream> #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/string.hpp> typedef unsigned long U32; class SyncObject { public: SyncObject(std::string aId) : id(aId), locAddrSp0Range(0), locAddrSp0Remap(0), locAddrSp1Range(0), locAddrSp1Remap(0), usbInterfaceOwner(0), useCounter(0) {}; ~SyncObject() {} ; void print() { std::cout << id << " locAddrSp0Range = " << locAddrSp0Range << " locAddrSp0Remap = " << locAddrSp0Remap << " locAddrSp1Range = " << locAddrSp1Range << " locAddrSp1Remap = " << locAddrSp1Remap << " usbInterfaceOwner = " << usbInterfaceOwner << " useCounter = " << useCounter << "\n"; }; std::string id; boost::interprocess::interprocess_mutex mtxReadWrite; boost::interprocess::interprocess_mutex mtxFunction; U32 locAddrSp0Range; U32 locAddrSp0Remap; U32 locAddrSp1Range; U32 locAddrSp1Remap; U32 usbInterfaceOwner; U32 useCounter; }; class SharedMemory { public: SharedMemory(); ~SharedMemory(); SyncObject* getSyncObject(std::string id); }; using namespace boost::interprocess; const char* MANAGED_SHARED_MEMORY_NAME = "sharedMemoryMapTest17"; SharedMemory::SharedMemory() {} SharedMemory::~SharedMemory() {} SyncObject* SharedMemory::getSyncObject(std::string id) { managed_shared_memory segment(open_or_create, MANAGED_SHARED_MEMORY_NAME, 65536); SyncObject* ptr = segment.construct<SyncObject>(anonymous_instance)(id); ptr->print(); //works! return ptr; } int main() { SharedMemory shm; SyncObject* ptr = shm.getSyncObject("idName"); ptr->print(); //Application crashes here with an access violation return 0; }

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multiple or single joins on asio socket
by Lee MacDonald 22 Oct '09

22 Oct '09

Guys, I have a application running on Linux using boost 1.35, that receives packets to several different multicast addresses, but on the same port and interface. For each different multicast address I perform the following: // create a new socket socket_(ioService) // set the listen end point to that of the multicast address and port boost::asio::ip::udp::endpoint listenEndPoint(multicastAddress.to_v4(), port); // we need to be able to reuse the underlyling socket created as more than one asio socket will share it. socket_.set_option(boost::asio::ip::udp::socket::reuse_address(true)); socket_.bind(listenEndPoint); // perform the actual join to the multicast group socket_.set_option(boost::asio::ip::multicast::join_group(destAddress.to _v4(), interfaceAddress.to_v4())); So I bind to a seperate asio socket instance for each multicast address and then perform a join to that address, hence each asio socket only has a single join associated with it. Is a better approach to have a single asio socket instance and perform a join for each multicast address that shares the port & interface? If so, how would I set listenEndPoint? Is there any performance differences between the two? Are there better approaches? Thanks. Lee MacDonald Schneider Trading 4th Floor, 25 Copthall Avenue London EC2R 7BP -------------------------------------------------------- Message from: lee.macdonald(a)schneidertrading.com Message to: boost-users(a)lists.boost.org Attached files: 0 This e-mail and any files transmitted with it are confidential, may be legally privileged, and are for the sole use of the intended recipient. Copyright in this e-mail and any accompanying document created by us is owned by us. If you are not the intended recipient of this e-mail or any part of it please telephone our IT Department at the number shown above or by e-mail at info(a)schneidertrading.com. You should not use or disclose to any other person the contents of this e-mail or its attachments (if any), nor take copies. This e-mail is not a representation or warranty and is not intended nor should it be taken to create any legal relations, contractual or otherwise. Schneider Trading Associates Ltd (Registration No. 3692131) is incorporated in England and Wales and the registered office is at 25 Copthall Avenue, London EC2R 7BP. The company is authorised and regulated by the Financial Services Authority

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[Thread] join_all and interrupt_all playing together
by Ryan McConnehey 22 Oct '09

22 Oct '09

I'm trying to set several threads running and have the main thread signal an interrupt. I've included an example that shows what I'm trying to accomplish. The threads that are created are associated with thread_group and then a join_all is called. I would expect the main thread to be able to call interrupt_all on the thread_group. Since this wasn't working I looked at what the join_all and interrupt_all function were actually doing. It turns out that thread_group has a mutex that is being called for each function and since the mutex for join_all is in use, the lock in interrupt_all is blocking. I understand why the mutex is there but am unclear how interrupt_all is suppose to work with join_all. To accomplish the functionality I need I have to use create_thread and store the return pointer in a list of my own. Then call interrupt on each pointer I stored. Which is basically duplicating the storage of thread_group. This seem like a waste. I would appreciate any advice. Ryan class Converter { public: Converter(void) { m_Threads.reset(new boost::thread_group); } void run(void) { m_Threads->add_thread(new boost::thread(boost::bind(&Converter::processSureTrakMessage, this))); //m_Threads_v.push_back(m_Threads->create_thread(boost::bind(&Converter::processSureTrakMessage, this))); m_Threads->join_all(); m_Threads.reset(new boost::thread_group); } void stop(void) { //for (std::vector<boost::thread *>::iterator iter = m_Threads_v.begin(); iter != m_Threads_v.end(); ++iter) { // (*iter)->interrupt(); //} m_Threads->interrupt_all(); } void processMessage(void) { try { for (;;) { boost::this_thread::interruption_point(); } } catch (...) { int bob = 1; } int bobo = 2; } private: boost::scoped_ptr<boost::thread_group> m_Threads; boost::scoped_ptr<boost::thread> m_IO_Service_Thread; std::vector<boost::thread *> m_Threads_v; }; boost::function<void ()> console_ctrl_function; BOOL WINAPI console_ctrl_handler(DWORD ctrl_type) { switch (ctrl_type) { case CTRL_C_EVENT: case CTRL_BREAK_EVENT: case CTRL_CLOSE_EVENT: case CTRL_SHUTDOWN_EVENT: console_ctrl_function(); return TRUE; default: return FALSE; } } int main(int argc, char * argv[]) { Converter convert; console_ctrl_function = boost::bind(&Converter::stop, &convert); SetConsoleCtrlHandler(console_ctrl_handler, TRUE); convert.run(); return 0; }

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Warnings in hash_table_impl.hpp with GCC 4.4.x
by Marco Alanen 22 Oct '09

22 Oct '09

Greetings I'm trying to compile our code in an environment where we treat warnings as errors. This worked fine when we used GCC 4.1.2 which is fairly forgiving when compared to newer versions. However, after upgrading to GCC 4.4.1 (and 4.4.2) we ran into a warning in hash_table_impl.hpp in Boost 1.40.0: .../include/boost/unordered/detail/hash_table_impl.hpp: In member function 'void boost::unordered_detail::hash_table_data_equivalent_keys<Alloc>:: node_constructor::construct_preamble() [with Alloc = std::allocator<std::pair <const unsigned int, GFL::refcounted_value<const std::basic_string<char, std:: char_traits<char>, std::allocator<char> > > > >]': .../include/boost/unordered/detail/hash_table_impl.hpp:101: error: '<anonymous>' may be used uninitialized in this function Is this problem patchable, or will it manifest itself throughout the code? One way would of course be to turn that particular warning off but I'd prefer to have all warnings enabled if possible. I also tried to compile with Boost 1.39.0 with the same results. Thank you /Marco

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[function] generalization of std::plus and std::multiplies with more than one argument type
by alfC 22 Oct '09

22 Oct '09

Does Boost have a generalization of std::plus and std::multiplies (std_function.hpp)? The standard defines this with only one template parameter template <class _Tp> struct multiplies : public binary_function<_Tp, _Tp, _Tp> { _Tp operator()(const _Tp& __x, const _Tp& __y) const { return __x * __y; } }; but I need something more general, where the types are different multiplies<type1, type2, type2> (assuming that the result has the type of the rhs. of course I could just define template <class _Tp1, class _Tp2, class Tp3> struct multiplies : public binary_function<_Tp1, _Tp2, _Tp3> { _Tp3 operator()(const _Tp1& __x, const _Tp2& __y) const { return __x * __y; } }; but I don't want to clutter my code with these pieces of basic code, specially if something like this is already part of other facilities in Boost. (Or even better, it would be nice if multiples<type3(type1, type2)> were defined, maybe I am asking to much sugar). I need this specific kind of multiply<3 args> in order to provide a default multiplication in the template parameters of vector space class, i.e. unless something is explicitly defined it tries to use * to implement scalar (pre)multiplication. (multiply<3 args> is the only reasonable default I can think of). Thanks, Alfredo

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building boost with python script
by Michał Nowotka 22 Oct '09

22 Oct '09

Hello, last time I didn't placed in my message an appropriate heading so I repeat it: I want to build boost library with python scrpt(s) (maybe SCons shuld be used). Or maybe someone has already done so - I don't want to reinvent the wheel. -- Regards Michał Nowotka

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asio stability and scalability
by Eric Twietmeyer 21 Oct '09

21 Oct '09

Hello, The project I am involved with required porting a Windows only networking application that was using the WSAAsynSelect mechanism to GNU/Linux, while remaining Windows compatible. We chose Boost asio as the framework to use. After spending time with asio and understanding it, the port was relatively straight forward. It basically works, both on Windows and on GNU/Linux. However, on both systems we are now running into stack corruptions. We have spent quite a few weeks now trying to track this down, mostly on Windows, as we have access to very many tools on that platform. We have verified that all underlying Win32 (and Winsock) function calls are valid (all parameters check), that our heap is not corrupt (all memory allocations and deallocations are clean), and we have eliminated all threading issues by restructuring the code to be runnable on a single io_service::run() thread (and Intel's Thread Checker found no issues either). We have done many other verifications as well, everything comes out clean. At this point we have to strongly consider the possibility that it is asio itself that is causing this error, though we are quite at a loss to explain how asio could result in this behavior. So we are wondering, are there known large production systems out there that use asio? Are there high volume web servers for instance written with asio? I came across this comment: http://dobbscodetalk.com/index.php?option=com_content&task=view&id=1700&Ite… which, if true, would also imply that asio is perhaps not appropriate for high throughput applications, at least on GNU/Linux systems. My basic question is: Do people have success stories using asio in production applications? Have people used other frameworks, for instance ACE, and can comment on how they compare? Have others ran into random crashes and given up on using asio? Thanks for any feedback, -Eric

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Question about Kolmogorov Max Flow function.
by Dev Ganesh 21 Oct '09

21 Oct '09

Hello, I am using the Kolmogorov Max Flow function from the BOOST Graph library to develop some software. I compared it with the Edmond Karps Max Flow function using some test cases. Each function gives the correct flow value, but the Kolomogorov function does not seem to give the correct set of vertices corresponding to the minimum cut. I would like to know if my input to the function is wrong or if I'm interpreting the vertex coloring wrongly. The Edmond Karps function seems to work fine, but the Kolomogorov function is faster and if possible, I would like to use it instead of the Edmond Karps function. Could someone please help me with this? Thanks, Dev Ganesh.

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[date_time] binary serialization / integer representation
by Rutger ter Borg 21 Oct '09

21 Oct '09

Hello, I would like to serialize date_time types to a binary archive, and/or convert them to, say, a integer types. I see the counted time system does use a 64 bit integer for ptime, but doesn't provide access to it. Is there something available for this use, or should I create a conversion function? Thanks in advance, Cheers, Rutger

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ASIO: sending QString (UTF-16)
by Rangel [LISTAS] 21 Oct '09

21 Oct '09

Hello, I am learning ASIO, and I need to send a QString (from QT) thru async_write. The "buffer" function does not supports QString, so I wrote my own, is it correct? "utf16()" returns a pointer to a ushort (16 bit values). namespace boost { namespace asio { inline const_buffers_1 buffer(const QString &data) { return const_buffers_1(const_buffer(data.utf16(), data.size()*sizeof(ushort))); } } }; As an example, I am trying to send HTTP header and data, using a simple HTTP server sample. As the header needs to be ASCII, I am sending a vector, with a std::string and a QString, is the way it is done right? (The "message_" had a Japanese string for effective test that was removed to put on this email) ba::ip::tcp::socket socket_; std::vector<ba::const_buffer> lbuf; static std::string header_; static QString message_; std::string connection::header_="HTTP/1.0 200 OK\r\nContent-Type: text/html; charset=utf-16\r\n\r\n"; QString connection::message_=QString::fromUtf16(L"<html><head><title>test</title>" L"</head><body><h1>Test</h1><p>This is a test!</p>" L"</body></html>"); void handle_read(const boost::system::error_code& error, size_t bytes_transferred) { lbuf.clear(); lbuf.push_back(ba::buffer(header_)); lbuf.push_back(ba::buffer(message_)); ba::async_write(socket_, lbuf, boost::bind(&connection::handle_write, shared_from_this(), ba::placeholders::error, ba::placeholders::bytes_transferred)); }

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