July 2013 - Boost-users - lists.preview.boost.org

Boost::thread instantiation and clean up
by Riskybiz 19 Jul '13

19 Jul '13

I have a C++ DLL written in Visual Studio for use on Windows 7 using Boost 1_53_0. The following two functions, CREATE & DESTROY, are called to launch and shutdown a simple ZeroMQ server (code below). The thread is launched and the server on that thread goes into a continuous listening loop (as intended). When it comes time to shut down the server then the thread is interrupted to cause thread termination (though I cannot tell if the interrupt is actually working as I get no output from the catch block). The boost::thread object is then deleted. Problem is that the 3rd party application which this DLL is designed for is prone to crashing after DESTROY is called and I think it's because either the boost::thread resources are not being freed/cleared up properly or the boost::thread is not interrupting. Have I properly handled thread instantiation, interruption and object destruction here? With thanks, Riskybiz. static bool createCalled = false;//initialise static variable static bool destroyCalled = false;//initialise static variable static boost::thread *serverThread = nullptr; int __stdcall CREATE() { if(createCalled == false) { createCalled = true; OutputDebugStringA("TestDataAccess: CREATE"); serverThread = new boost::thread(ListenOnReplySocket);//create instance of boost::thread object return 0; } return 1; } int __stdcall DESTROY() { if(createCalled == true && destroyCalled == false) { destroyCalled = true; OutputDebugStringA("TestDataAccess: DESTROY"); serverThread->interrupt();//set flag for interruption delete serverThread; return 0; } return 1; } Simple ZeroMQ server: #ifndef ZMQ_COMMUNICATIONS_H//if not defined already #define ZMQ_COMMUNICATIONS_H//then define it #define _WINSOCK2API_ //stops windows.h including winsock2.h #include <zmq.hpp> #include "boost\thread.hpp" int ListenOnReplySocket() { // Prepare our context and socket zmq::context_t context (1); zmq::socket_t socket (context, ZMQ_REP); socket.bind ("tcp://*:5555"); boost::this_thread::interruption_enabled(); try { while (true) { zmq::message_t request; // Wait for next request from client socket.recv (&request); char buffer[50]; int j; j = sprintf_s(buffer, 50, "TestDataAccess: ZMQComms: Hello"); OutputDebugStringA(buffer); // Do some 'work' Sleep (1000); // Send reply back to client zmq::message_t reply (5); memcpy ((void *) reply.data (), "World", 5); socket.send (reply); boost::this_thread::interruption_point();//check iterruption flag } } catch(boost::thread_interrupted) { char buffer[100]; int j; j = sprintf_s(buffer, 100, "TestDataAccess: ZMQComms: Server Thread Interrupted"); OutputDebugStringA(buffer); return 0; } } #endif

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[fusion] how to get the tuple of min values of 2 tuples whatever their length?
by Frédéric Bron 18 Jul '13

18 Jul '13

I have two tuples: typedef boost::tuple<double, int, std::string> Key; Key k1, k2; I would like to get the tuple of the min values for each corresponding value between k1 and k2: Key min=Key(std::min(k1.get<0>(), k2.get<0>()), std::min(k1.get<1>(), k2.get<1>()), std::min(k1.get<2>(), k2.get<2>())); but I do not know the length of the tuple so I am looking for a generic algorithm... Is this possible with boost::fusion or boost::mpl? I have tried with boost::fusion::accumulate but I need to now in the functor the index of the value that is currently accessed to compare to the right one in k1. Frédéric

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Named condition not behaving as expected
by rudasi 18 Jul '13

18 Jul '13

I have 2 processes (producer and consumer) sharing an int deque in shared memory, I have the producer process put 2 numbers in the deque and then it gets in a wait state losing its mutex lock. I then have the consumer process removing the numbers and printing them. It then does a notify on the condition which the producer is waiting on. The consumer then goes on its own wait on a second condition. After this case the producer does not wake up. I am using the same mutex between the processes. I have removed some of the code where i set up the shared memory and create the mutex and conditions. Producer process: int main() { scoped_lock<named_mutex> lock(mutex); while(1) { while (MyDeque->size() == 2) { full.wait(lock); std::cout << "unlocked producer" << std::endl; } if (MyDeque->size() == 0) { *a = 2; MyDeque->push_back(a); } if (MyDeque->size() == 1) { *b = 4; MyDeque->push_back(b); empty.notify_one(); } } } Consumer process: int main() { scoped_lock<named_mutex> lock(mutex); while(1) { //volatile int size = MyDeque->size(); while (MyDeque->size() == 0) { empty.wait(lock); } if (MyDeque->size() == 2) { std::cout << "Consumer: " << *MyDeque->front() << std::endl; MyDeque->pop_front(); } if (MyDeque->size() == 1) { std::cout << "Consumer: " << *MyDeque->front() << std::endl; MyDeque->pop_front(); full.notify_one(); } } } While debugging things seem to go ok for the first iteration, the producer puts numbers 2 and 4 on the deque then waits on the full condition. The Consumer then gets the lock, prints these numbers, does a notify_one on the full condition and then goes into a wait. After this the producer does not wake up. -- View this message in context: http://boost.2283326.n4.nabble.com/Named-condition-not-behaving-as-expected… Sent from the Boost - Users mailing list archive at Nabble.com.

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[serialization] platform independence (32 & 64bit windows)
by आशीष वर्मन् 18 Jul '13

18 Jul '13

Hi We are using boost serialization our product which was 32bit only till now. Now we have started building it on 64bit as well. On finding that boost::binary_archive is not platform independent, we seem to have 2 options: 1. Use text_archive - (but are worried about performance since the serialized data is approx 500MB even after gzip compression) 2. Use the eos portable archive - (but it is updated only till boost 1.49. We are using 1.53) So my questions are: 1. One (and only one) of our archives created by our 32 bit executable is successfully read in by the 64 bit executable while the rest throw exception on reading the archive signature. If the platform is encoded in the signature, why is that one archive being read in successfully. 2. Which of the above two approaches would be better and why. Thanks in advance. Yours Sincerely Ashish Varman

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Boost::Interprocess mutex with condition variable
by Riskybiz 17 Jul '13

17 Jul '13

I'm trying to get a working implementation of a boost::interprocess named_mutex with a named_condition_variable. I have created the following toy console applications to try and understand what's necessary. The console application 'Sleeper' is run first; it simply creates some resources and then goes to sleep. Then 'Waker' is run with the intention that it would cause the 'Sleeper' instance to resume execution and print out a further message. Ultimately the intention is to have one Waker process and several Sleeper processes. When each application is run in a separate terminal window then the Sleeper process sleeps and the Waker process tries to wake; but it is ineffective. Can anyone advise what is wrong here and how to get the notify_all() to take effect? Thanks Riskybiz. // Sleeper.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/sync/named_mutex.hpp> #include <boost/interprocess/sync/named_condition.hpp> #include <iostream> int _tmain(int argc, _TCHAR* argv[]) { using namespace boost::interprocess; //Clean up resources from any prior instances named_condition::remove("msm_named_condition"); named_mutex::remove("msm_named_mutex"); //shared_memory_object::remove("msm"); //Setup shared memory resources managed_shared_memory *msm = new managed_shared_memory(create_only, "msm", 10000); named_mutex *nm = new named_mutex(create_only, "msm_named_mutex"); named_condition *nc = new named_condition(create_only, "msm_named_condition"); try { scoped_lock<named_mutex> lock(*nm);//acquire scoped lock for mutex std::cout << "Going to sleep now...." << std::endl; nc->wait(lock);//induce wait std::cout << "Wide awake and back in the room" << std::endl;//print this out on waking up } catch(interprocess_exception &ipe) { std::cout << "Error in Sleeper process: interprocess_exception: "<< ipe.what() << std::endl; } //Clean up delete msm; delete nm; delete nc; return 0; } // Waker.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/sync/named_mutex.hpp> #include <boost/interprocess/sync/named_condition.hpp> #include <iostream> int _tmain(int argc, _TCHAR* argv[]) { using namespace boost::interprocess; //Setup shared memory resources managed_shared_memory *msm = new managed_shared_memory(open_only, "msm"); named_mutex *nm = new named_mutex(open_only, "msm_named_mutex"); named_condition *nc = new named_condition(open_only, "msm_named_condition"); try { scoped_lock<named_mutex> lock(*nm);//acquire scoped lock for mutex std::cout << "Going to Notify...." << std::endl; nc->notify_all();//notify to release the wait condition std::cout << "Wakey Wakey....Notified...." << std::endl; } catch(interprocess_exception &ipe) { std::cout << "Error in Waker process: interprocess_exception: "<< ipe.what() << std::endl; } //Clean up delete msm; delete nm; delete nc; return 0; }

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multi_index_container with protected constructor
by Horváth Imre 17 Jul '13

17 Jul '13

Hi, I want to use boost::multi_index_container with a class that have protected constructors, but the compile fails. I think I should make multi_index_container a friend of my class, but I don't know how. #include <iostream> #include <boost/shared_ptr.hpp> #include <boost/multi_index_container.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/composite_key.hpp> #include <boost/multi_index/mem_fun.hpp> class Item { public: typedef boost::shared_ptr<Item> P; static P create() { return P(new Item()); } static P create(P item) { return P(new Item(item)); } protected: Item() { } Item(P item) : source(item->get_source()) , target(item->get_target()) { } public: std::string source; std::string target; std::string get_source() const {return source;} std::string get_target() const {return target;} struct key : boost::multi_index::composite_key< P, boost::multi_index::const_mem_fun<Item, std::string, &Item::get_source>, boost::multi_index::const_mem_fun<Item, std::string, &Item::get_target> >{}; typedef boost::multi_index_container< P, boost::multi_index::indexed_by< boost::multi_index::ordered_non_unique< key, boost::multi_index::composite_key_result_less<key::result_type> > > > index_t; }; int main() { Item::index_t index; Item::P t1 = Item::create(); index.insert(t1); return 0; } Thanks in advance: Imre Horvath

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[Boost.Log] Example tutorial_fmt_stream.cpp does not compile
by Mario Knezović 17 Jul '13

17 Jul '13

I am trying to change date formatting exactly in the way as described in the tutorial, sub-section "Specialized formatters": http://www.boost.org/doc/libs/1_54_0/libs/log/doc/html/log/tutorial/formatt… What I want to achieve is pretty simple, change month output from the default "Abbreviated month name" (%b): [2013-Jul-08 10:51:00.989235] to "Month name as a decimal 01 to 12" (%m): [2013-07-08 10:51:00.989235] Unfortunately this does not compile, nor does the example from which the snipped is taken: "tutorial_fmt_stream.cpp". The interesting part in the example source is commented out by default. (But this was the case with other examples too.) The part I'm interested in is in line 60 (from current Boost 1.54.0): expr::format_date_time< boost::posix_time::ptime >("TimeStamp", "%Y-%m-%d %H:%M:%S") The errors I get (Win7, 64-bit, MS VC++ 2010): error C2027: use of undefined type "boost::log::v2s_mt_nt5::expressions::aux::date_time_formatter_generator_traits<T,CharT>" d:\boost\boost_1_54_0\boost\log\expressions\formatters\date_time.hpp 94 error C3861: "parse": Identifier not found. d:\boost\boost_1_54_0\boost\log\expressions\formatters\date_time.hpp 94 I hope somebody can help or point me in the right direction. Thank you! Mario Knezović

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[log, spirit] phoenix version conflict
by Yi Ding 17 Jul '13

17 Jul '13

It looks like Boost.Log conflicts with Boost.Spirit because they're using different version of Boost Phoenix? Take this example file: #include <boost/log/common.hpp> #include <boost/log/sinks.hpp> #include <boost/spirit/include/karma.hpp> int main() { } We get this warning: In file included from /opt/boost_1_54_0/include/boost/log/detail/custom_terminal_spec.hpp:21, /opt/boost_1_54_0/include/boost/spirit/include/phoenix_core.hpp:13:1: warning: "BOOST_PHOENIX_DEFINE_CUSTOM_TERMINAL" redefined /opt/boost_1_54_0/include/boost/phoenix/core/terminal.hpp:22:1: warning: this is the location of the previous definition There are a bunch of errors that result as well.

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How to build libboost_filesystem-vc110-mt-sgd-1_54.lib with VS2012 x64?
by Amann, Julian 17 Jul '13

17 Jul '13

I have some trouble building the boost filesystem lib using VS2012 x64. I use the following instructions to build it: 1. Download boost 1.54.0 from http://www.boost.org/ 2. Extract files (e.g. "C:\thirdparty\vs2013\x64\boost_1_54_0") 3. Start Visual Studio 2012 x64 command prompt 4. Change to boost directory (e.g. "cd C:\thirdparty\vs2010\x64\boost_1_54_0") 5. Execute .\bootstrap.bat 6. Execute b2 address-model=64 toolset=msvc-11.0 --build-type=complete stage --with-filesystem --with-signals --with-system Unfortunately the file "libboost_filesystem-vc110-mt-sgd-1_54.lib" is not build Previously I used boost 1.51.0, 1.52.0 and 1.53.0. In this releases the libboost_filesystem-vc110-mt-sgd-1_5x.lib was always build without any problems. Did anybody mange to build this lib using VS2012? Which instructions do you use to build it? Best regards, Julian

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[log] operator<< best practices
by Yi Ding 16 Jul '13

16 Jul '13

I noticed boost log has a helper function for operator<< template< typename CharT, typename TraitsT, typename AllocatorT, typename T > inline basic_formatting_ostream< CharT, TraitsT, AllocatorT >& operator<< (basic_formatting_ostream< CharT, TraitsT, AllocatorT >& strm, T const& value) { strm.stream() << value; return strm; } which is useful because a lot of code has operator<< overloads specifically for std::ostream. Recently we've moved our code to use a generic template <class stream, int N> inline stream& operator<<(stream& os, const BlahClass& value) which conflicts with the boost log helper function, but is useful for our own ostream-like classes. What's the best practice here? Can we make the two mesh by using traits of some sort? Should we do all of our type to string conversions ahead of time using something like folly::to? Cheers, Yi

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