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global instances for managed_shared_memory & message_queue
by bb.andersen 27 Jun '13

27 Jun '13

Dear Boost Grurus, First of all let me thank you for the huge effort that people like Mr. Gaztañaga has made to keep boost interprocess improved. It is a really time-saver API! I have a very basic question that, despite the large amount of documentation I've looked, I haven't clarified yet. I just want to create a global static variables (i.e. instances) for managed_shared_memory, message_queue, mutex and condition var. By now I have my app prototype (CGI) is running fine with auto vars, as appeared in the several examples: /main() { ... boost::interprocess::permissions perm; perm.set_unrestricted(); managed_shared_memory segment(create_only,"MonitorOEE_SharedMemory", 65536, 0, perm); ... message_queue mq(create_only, "MonitorOEE_MessageQueue", 256, sizeof(t_QRequest), perm); ... named_mutex mutex_waiting(create_only, namedMutex, perm); ... named_condition cdv_wakeup(create_only, namedConditionVar, perm); ... }/ All segment, mq, cdv_wakeup live in the context of the main function... Now I want them to be globally accessible from different functions. But I am not able to. I just partially succeeded creating global pointers to managed_shared_memory and message_queue. But when constructing object to the pointer segmentation faults appear... ///Global Declarations ... static boost::interprocess::message_queue *mq; static boost::interprocess::managed_shared_memory *segment; static boost::interprocess::interprocess_mutex mutex_waiting; static boost::interprocess::interprocess_condition cdv_wakeup; ... main() { .. std::auto_ptr<boost::interprocess::managed_shared_memory>ptr01(new boost::interprocess::managed_shared_memory(open_only,"MonitorOEE_SharedMemory")); segment = ptr01.get(); //this seems to work but fails when constructing objects: IPC_SOAPRequest *pSOAPRequest =segment->construct<IPC_SOAPRequest>(namedSOAPRequest)(); (the autovar counterpart works seamlessly) ... std::auto_ptr<boost::interprocess::message_queue>ptr02(new boost::interprocess::message_queue(open_only,MonitorOEE_MessageQueue")); mq = ptr02.get(); //Seems to work...(send and receive) .. //dunno how to instantiate to mutex and cond var global references } / I am sure it should be an easier and tidier way. Can you give me just the first steps to work this out? I've been sleepless a couple of nights. Eskerrik Asko! (Thanks in the basque language!) -- View this message in context: http://boost.2283326.n4.nabble.com/global-instances-for-managed-shared-memo… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] Mutex synchronised wrapper class for boost::interprocess
by Riskybiz 27 Jun '13

27 Jun '13

Ion; thank you!! I found the errors in my prior code thanks to your tip and used the improvements you suggested. I had unwittingly declared variables with very similar names and different types, leading to confused behavior. Anyway that is solved and I now have a working implementation of a mutex synchronised interprocess vector of strings. Have included it below in case it's of use to anyone else trying the same... A further question if I may? What is the best approach to extend a managed_shared_memory_segment? I can dynamically add (via write() function) shared vector elements until such time as an interprocess_exception boost_interprocess::bad_alloc is thrown; when the memory allocated to the shared segment is filled. Is there a way to handle this exception so that the segment can be extended with more memory and then resume adding data elements to the vector? Or perhaps some other way to detect the segment memory is running short and take action to extend it? Thanks again, Riskybiz. Code: Class Definition: #ifndef SHARED_MEMORY_WRAPPER_H//if not defined already #define SHARED_MEMORY_WRAPPER_H//then define it #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/sync/named_mutex.hpp> #include <iostream> #include <stdexcept> using namespace boost::interprocess; class SharedMemoryWrapper { public: SharedMemoryWrapper(const std::string &name, bool server) : m_name(name), m_server(server) { if (server) { //Clean up resources from any prior instances named_mutex::remove("named_mutex"); shared_memory_object::remove(m_name.c_str()); //Create shared memory m_segment = new managed_shared_memory(create_only, m_name.c_str(), 1000000); //Create allocators CharAllocator charallocator(m_segment->get_segment_manager()); StringAllocator stringallocator(m_segment->get_segment_manager()); //This vector is fully constructed in shared memory. All pointers //buffers are constructed in the same shared memory segment //This vector can be safely accessed from other processes. sharedSegmentVector = m_segment->construct<MyShmStringVector>("sharedSegmentVector")(stringallocat or); } else { try { //Open the shared segment m_segment = new managed_shared_memory(open_only, name.c_str()); //Find the vector using the c-string name and open it sharedSegmentVector = m_segment->find<MyShmStringVector>("sharedSegmentVector").first; } catch(interprocess_exception ipe) { std::cout << "Error: Interprocess Exception: " << ipe.what() << std::endl; } catch(...) { std::cout << "Error: Unknown Exception: " << std::endl; } } m_mutex = new named_mutex(open_or_create, "named_mutex"); } ~SharedMemoryWrapper() { /* //Destructor: Will remove the shared memory resources if (m_server) { named_mutex::remove("named_mutex"); //Destroy the vector from the managed_shared_memory //m_segment->destroy_ptr(sharedSegmentVector);//This will free all strings that the vector contains m_segment->destroy<MyShmStringVector>("sharedSegmentVector");//Destroy the vector //Is it necessary to destroy the allocators here? //Remove the managed_shared_memory; this may fail if the memory does not exist or is mapped or opened by another process shared_memory_object::remove(m_name.c_str()); } */ //Delete instance members delete m_mutex; delete m_segment; } //Writer void write(const std::string &inStr) { try { CharAllocator charallocator(m_segment->get_segment_manager()); scoped_lock<named_mutex> lock(*m_mutex); MyShmString shmStr(inStr.c_str(), charallocator); sharedSegmentVector->push_back(shmStr); } catch(interprocess_exception ipe) { std::cout << "Error in SharedMemoryWrapper::write(): interprocess_exception: "<< ipe.what() << std::endl; } catch(...) { std::cout << "Error in SharedMemoryWrapper::write(): unknown error" << std::endl; } } //Reader std::string read(size_t &index) { try { scoped_lock<named_mutex> lock(*m_mutex); const MyShmString &shmStr = (*sharedSegmentVector)[index]; std::string stdStr(shmStr.begin(), shmStr.end()); return stdStr; } catch(interprocess_exception ipe) { std::cout << "Error in SharedMemoryWrapper::read(): interprocess_exception: "<< ipe.what() << std::endl; } catch(std::range_error re) { std::cout << "Error in SharedMemoryWrapper::read(): range_error: " << re.what() << std::endl; } catch(...) { std::cout << "Error in SharedMemoryWrapper::read(): unknown error "<< std::endl; } return "Error in SharedMemoryWrapper::read()"; } //Vector Size size_t getSize() const { return this->sharedSegmentVector->size(); } private: //Typedefs typedef boost::interprocess::allocator<char, managed_shared_memory::segment_manager> CharAllocator; typedef boost::interprocess::basic_string<char, std::char_traits<char>, CharAllocator> MyShmString; typedef boost::interprocess::allocator<MyShmString, managed_shared_memory::segment_manager> StringAllocator; typedef boost::interprocess::vector<MyShmString, StringAllocator> MyShmStringVector; bool m_server; std::string m_name; managed_shared_memory *m_segment; MyShmStringVector *sharedSegmentVector; named_mutex *m_mutex; };//class #endif//header guard Test Programmes: // PrepareSharedMemoryVectorOfStrings.cpp : Defines the entry point for the console application. // #include "SharedMemoryWrapper.h" #include <iostream> #include <string> #include <sstream> int main(int argc, char *argv[]) { SharedMemoryWrapper *smw = new SharedMemoryWrapper("SharedMemoryTest", true); size_t cnt(0); while(cnt < 100) { //Convert number to string representation std::string cntStr = static_cast<std::ostringstream*>( &(std::ostringstream() << cnt) )->str(); //Write to shared memory vector smw->write("Iteration: " + cntStr); cnt++; } size_t vecSize = smw->getSize(); std::cout << "Elements Present: "<< vecSize << std::endl; delete smw; return 0; } // AccessSharedMemoryVectorOfStrings.cpp : Defines the entry point for the console application. // #include "SharedMemoryWrapper.h" #include <iostream> #include <string> int main(int argc, char *argv[]) { SharedMemoryWrapper *smw = new SharedMemoryWrapper("SharedMemoryTest", false); std::string outStr; for(size_t index = 0; index < 100; index++) { outStr = smw->read(index); std::cout << outStr << std::endl; } delete smw; return 0; }

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[1.54.0] Release candidates available
by Marshall Clow 27 Jun '13

27 Jun '13

Release candidate files for 1.54.0 are available at http://boost.cowic.de/rc/ As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: efbfbff5a85a9330951f243d0a46e4b9 *boost_1_54_0_rc1.tar.gz 15cb8c0803064faef0c4ddf5bc5ca279 *boost_1_54_0_rc1.tar.bz2 78a35834c45220a6164310e280abe675 *boost_1_54_0_rc1.zip 89e734ffd2afe0982b2d9fc21d033dba *boost_1_54_0_rc1.7z Thanks! -- The release managers

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ASIO: Problem with building boost 1.53 ASIO examples under cygwin
by mschulze＠ivs.cs.ovgu.de 27 Jun '13

27 Jun '13

Hi all, I tried building boost 1.53 ASIO examples under cygwin and it didn't worked with bjam or b2 respectively. Then I used "bjam -n" to get the invoked commands in order to further track down the issue. I end up with the following command to compile an example "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -g -mthreads -DBOOST_ALL_NO_LIB=1 -DBOOST_CHRONO_DYN_LINK=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_POSIX -DBOOST_THREAD_USE_DLL=1 -I"../../../.." -o "blocking_udp_echo_server" "blocking_udp_echo_server.cpp" -D__USE_W32_SOCKETS -D_WIN32_WINNT=0x0501 ../../../../bin.v2/libs/thread/build/gcc-4.5.3/release/link-static/threading-multi/libboost_thread.a ../../../../bin.v2/libs/system/build/gcc-4.5.3/release/link-static/threading-multi/libboost_system.a -lws2_32 -lmswsock and I got the following errors: In file included from ../../../../boost/asio/detail/impl/posix_tss_ptr.ipp:24:0, from ../../../../boost/asio/detail/posix_tss_ptr.hpp:77, from ../../../../boost/asio/detail/tss_ptr.hpp:27, from ../../../../boost/asio/detail/call_stack.hpp:20, from ../../../../boost/asio/impl/handler_alloc_hook.ipp:19, from ../../../../boost/asio/handler_alloc_hook.hpp:80, from ../../../../boost/asio/detail/handler_alloc_helpers.hpp:22, from ../../../../boost/asio/detail/bind_handler.hpp:19, from ../../../../boost/asio/detail/wrapped_handler.hpp:18, from ../../../../boost/asio/io_service.hpp:24, from ../../../../boost/asio/basic_io_object.hpp:19, from ../../../../boost/asio/basic_socket.hpp:19, from ../../../../boost/asio/basic_datagram_socket.hpp:20, from ../../../../boost/asio.hpp:20, from blocking_udp_echo_server.cpp:13: ../../../../boost/asio/error.hpp:77:17: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:130:15: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:135:19: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:149:23: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:163:15: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:244:45: warning: boost::asio::error::system_category defined but not used ../../../../boost/asio/error.hpp:246:45: warning: boost::asio::error::netdb_category defined but not used ../../../../boost/asio/error.hpp:248:45: warning: boost::asio::error::addrinfo_category defined but not used ../../../../boost/asio/error.hpp:250:45: warning: boost::asio::error::misc_category defined but not used ../../../../boost/asio/detail/winsock_init.hpp:78:30: warning: boost::asio::detail::winsock_init_instance defined but not used The error messages boils down to the use of "__MSABI_LONG(x)" within an enumeration definition. __MSABI_LONG is a macro that has to be resolved during the cpp run but isn't but it seems not to be known at this point. I also tested the boost version 1.52 and there are none of these issues and it worked like it is intended. Best regards, Michael

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Accessing memory in shared segments
by Andy Falanga (afalanga) 27 Jun '13

27 Jun '13

Hi, I have some code which shares data with shared memory. To that end, I'm using boost::interprocess:managed_shared_memory. Without respect to scope and functions, what I have is roughly: boost::interprocess::managed_shared_memory sharedMem(boost::interprocess::create_only, "SharedMemory", 4096); //later on u_int8_t* dataSegment = sharedMemory.construct<u_int8_t>("data")[5](0); char* string1 = sharedMemory.construct<char>("String 1")[50]('\0'); // other stuff // placing stuff in the data segment for(int i(0); i < 5; i++) dataSegment[i] = anEarlierArray[i]; // then, in other process read the data Segment char ary[5]; for(int i(0); i< 5; i++) ary[i] = dataSegment.first[i]; For whatever reason I couldn't simply access through dataSegment[n] notation. The weirdest thing is, the data is being read back to me in the reverse order that it should be. For example, if [0x2,0x4,0x7,0x1] is written I read it back as [0x1,0x7,0x4,x02] even though I'm writing and reading in the same order. Why is this? What is it I'm missing about using shared memory? Thanks, Andy

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[System] Getting error messages in English
by Igor R 27 Jun '13

27 Jun '13

I'd like to always get English error messages on Win7 with localized UI. As far as I can see, system_error_category::message() calls FormatMessageA passing it MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT). I tried to set locale, but it doesn't affect FormatMessageA for some reason. I'd appreciate any idea.

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[1.54.0] Beta 1 Available
by Marshall Clow 27 Jun '13

27 Jun '13

Boost release 1.54.0 beta 1 is now available from SourceForge See http://sourceforge.net/projects/boost/files/boost/1.54.0.beta.1/ This release contains 3 new libraries: • Log: Logging library, from Andrey Semashev. • TTI: Type Traits Introspection library, from Edward Diener. • Type Erasure: Runtime polymorphism based on concepts. and numerous enhancements and bug fixes for existing libraries. For details of what's in the release, see http://www.boost.org/users/history/version_1_54_0.html. Note that the links to files on this web page are for the final release - use the SourceForge link above to get the beta files. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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Re: [Boost-users] [boost] [thread] synchronized_value: value and move semantics
by Klaim - Joël Lamotte 26 Jun '13

26 Jun '13

On Wed, Jun 26, 2013 at 12:37 PM, Ben Pope <benpope81(a)gmail.com> wrote: > > I think this should just not exist in C++11 and instead be replaced by > something like monitor<T> described by Herb Sutter [1]: I'm using several variants of Monitor in my projects. It don't work well in cases where what you really want is syncrhonization, which happen sometime when the design suggests it. In this case you need a mutex, so synchronized_value helps with that. In my opinion, If the multiple access is a bottleneck in real application, it is very easy to spot with a profiler and modify the code as you pointed. Joel Lamotte

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Problem Iterating a directory
by Sarma Tangirala 26 Jun '13

26 Jun '13

Hello, I am using boost filesystem to iterate through my directory and have encountered a problem that I am unsure of how to debug. try { //for ( boostfs::directory_iterator dir(boostfs::path("/home/vtangira/Desktop/person_finder_v20130513/data/dummy1")), end_itr; for ( boostfs::directory_iterator dir(boostfs::path(paths_to_files.at(0).c_str())), end_itr; dir != end_itr; dir++ ) { std::cout << "File: " << dir->path() << std::endl; } } catch (boostfs::filesystem_error e) { cout << "Error Code: " << e.code() << endl << "Error Msg: " << e.code().message() << endl; } In this snippet, the line with the for loop that has been commented out works but the the one below it with the vector does not. The vector version represents the same string. Any advice is appreciated. Thanks -- 0 1 0 0 0 1 1 1 1

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Re: [Boost-users] [Asio] Does stop() cancel handlers post()ed to io_service?
by Marat Abrarov 26 Jun '13

26 Jun '13

> However, I'm still interested whether stop() should always cancel the > queued handlers, i.e. if this is a bug (on windows). The io_service > documentation says this regarding the use of a work object > (http://alturl.com/98rvq) > > "To effect a shutdown, the application will then need to call the > io_service > object's stop() member function. This will cause the io_service run() > call > to return as soon as possible, abandoning unfinished operations and > without > permitting ready handlers to be dispatched. > Alternatively, if the application requires that all operations and > handlers > be allowed to finish normally, the work object may be explicitly > destroyed." I think (I've just inspected the Asio code) this behavior is designed in such a way for performance reasons - to not check "stopped" flag too often. Even the "stopped" flag is just an atomic value - it's Windows IOCP where OS uses specific technics for scheduling IOCP-tied threads and, may be, the author of Asio thinks (or even knows/has experience) that even atomic-value-check degrades performance or brakes specific scheduling of IOCP-tied threads. Regards, Marat Abrarov.

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