April 2010 - Boost-users - lists.preview.boost.org

Multi-threaded Debug DLL and boost 1.42
by V.V. 15 Apr '10

15 Apr '10

I have a simple code that uses the boost date/time library. I can compile it and run it with Multi-threaded Debug DLL (/MDd) switch and boost v 1.38. However, when I switch to boost v. 1.42, I cannot run it ("The system cannot execute"). The only way how I can run it with boost 1.42 is if I recompile it with /MTd switch (Multi-threaded Debug). I am probably doing something silly that has nothing to do with boost 1.38 vs 1.42 but I can't find out what it is. I am using VC++ 2005 and I installed both versions of boost from Boost Consulting. Thanks. -- View this message in context: http://old.nabble.com/Multi-threaded-Debug-DLL-and-boost-1.42-tp28259124p28… Sent from the Boost - Users mailing list archive at Nabble.com.

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Boost::Thread referenced to a MFC regular dll, assertion error occur while loading this dll
by DDGG 15 Apr '10

15 Apr '10

Hello everyone! I created a new VC2008 MFC regular dll project, do nothing but insert a line in stdafx.h: #include <boost/thread.hpp> Then I exported a do-nothing function at the dll's head file: extern "C" __declspec(dllexport) void DllFunc() { } After I compiled the proejct, I got a dll file and a lib file. I created a MFC dialog project, implicit call to the dll, that's: 1) #include the dll's head file 2) use #pragma comment(lib, "...") to import the dll's lib file 3) make a call to the DllFunc in dll I run the dialog project in the debug mode, and got an assertion error: void AFXAPI AfxCoreInitModule() { ASSERT(AfxGetModuleState() != AfxGetAppModuleState()); // assertion error // the return value of AfxGetModuleState() and AfxGetAppModuleState() are both not-empty, // but they are not the same. ... } Could anybody help me? thanks! My boost version is 1.38, 1.42 also tried. Compiler: Microsoft VC2008 (SP1)

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Boost 1.33.1 - 64bit static libraries with -fPIC (gcc)
by Nicholas Yue 15 Apr '10

15 Apr '10

Hi, I have a need to build Boost 1.33.1 [this is to match a legacy system which was supplied to us by an external party] as 64bit static libraries with the -fPIC option enabled. I know that the shared libraries are built with -fPIC but my linkage of the static libraries from 1.33.1 indicates that they are not build with -fPIC Does anyone have suggestion as to how best to enable PIC in Boost 1.33.1 static libraries? e.g. Jam files ? I tried modifying the Jam files but didn't work out for me. Regards

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[Accmulators][ConceptCheck]: Many warnings for constructing accumulator with density
by Roland Bock 15 Apr '10

15 Apr '10

Hi, the following line results in several kB of warnings: accumulator_set<double, stats<tag::density > > acc(tag::density::cache_size=10, tag::density::num_bins=5); include/boost/concept_check.hpp:335: warning: non-static reference 'const double& boost::UnaryFunction<boost::numeric::functional::as_min<const double, void>, double, const double&>::arg' in class without a constructor gcc-4.2.4, boost-1.41 Am I doing something wrong? Or is there a way to avoid these warnings (other than to turn off warnings)? Regards, Roland

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Boost.Asio thread pool - add/remove threads at runtime
by Vance Grkov 15 Apr '10

15 Apr '10

I am creating a simple task and timer thread pool using Boost.Asio. I am searching for the recommended way to dynamically add and remove threads to the thread pool. I don’t want to have to queue up tasks most of the time, only when the thread count gets very high (100s) queuing is ok, also I want for the thread count to go down to example 5 threads when there is no more work presented to the thread pool. This is because some of the tasks can take some time to complete and I don't want to hold off other tasks when computer resource are still available. Basically this is the solution I have in mind now. Given the following configuration values: gInitialThreadPoolSize = 4; gMaximumThreadPoolSize = 1024; gNumberOfThreadsDoingWork = 0; And 2 events: HANDLE moreWorkAvailable; HANDLE exit; Create a thread pool using this worker function: void ThreadWorkerFunction(boost::asio::io_service *io, boost::thread &thread) { for (;;) { HANDLE objects[] = { moreWorkAvailable, exit }; errorCode = WaitForMultipleObjects(objects) if (errorCode == WAIT_OBJECT_0) { // More work is available, lets start processing... gNumberOfThreadsDoingWork++; io->run(); gNumberOfThreadsDoingWork--; // When all work has been processed, go back to the original thread pool size if (threads.size() < gInitialThreadPoolSize ) { threads.remove(thread); break; } } else if (errorCode == WAIT_OBJECT_1) { threads.remove(thread); break; } } } This is now the thread pool is created: std::vector<boost::shared_ptr<boost::thread> > threads; for (std::size_t i = 0; i < gInitialThreadPoolSize; ++i) { boost::shared_ptr<boost::thread> thread(new boost::thread( boost::bind(&ThreadWorkerFunction, &io, thread) )); threads.push_back(thread); } Next every time a task is inserted into the queue we check if all worker threads are busy, and in case they are busy, create a new thread if (threadsDoingWork == threads.size()) { boost::shared_ptr<boost::thread> thread(new boost::thread( boost::bind(&worker, &io) )); threads.push_back(thread); } SetEvent(moreWorkAvailable); Also in the ThreadWorkerFunction(...) function, after io->run() returns, we can check if more than N threads are idle and keep exiting until we get at minimum. I would appreciate if you can let me know if there is some better and more simpler way to achieve this than implementing this myself. I am new to Asio so I might have overlooked something. _________________________________________________________________ Hotmail: Trusted email with powerful SPAM protection. https://signup.live.com/signup.aspx?id=60969

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[interprocess] ARM atomic operations problem.
by Ivan Dundek 15 Apr '10

15 Apr '10

Hi all. I've tried to test the boost IPC communication using: - boost::interprocess::shared_memory_object - boost::interprocess::mapped_region - boost::interprocess::interprocess_mutex - boost::interprocess::interprocess_condition So I created shared memory, and when the first process put the data into the shared memory, call the notify_one() method, to let the second process know, taht there are data in the shared memory. Everything is OK, when I'm using gcc 4.4.1 on linux. But when I tried to cross-compile the sources using arm-linux toolchain, which is based on gcc 3.3.2, I'm always geting error: "#error No atomic operations implemented for this platform, sorry!" I know, that if I will use gcc 4 and above, it will works. But is there any workaround or fix, how to compile boost::interprocess on gcc 3.3.2? Thank you for your advices. Dundee.

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[Spirit] questions about on_error and expectation points
by philip tucker 15 Apr '10

15 Apr '10

I have attached a code fragment (no driver) and a gcc error message. Please refer to the attached code. There, I ask three questions: - Why won't > compile where I expect it to? - Why are parentheses necessary in an expectation operator expression? - How can I detect and report an error in a particular case?

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[Chrono]
by Roland Bock 14 Apr '10

14 Apr '10

Hi, forgive me for asking the obvious, but I fail to see how to get timing information from the thread_clock? I can call thread_clock::now() to get time_point objects, e.g. boost::chrono::thread_clock threadClock; boost::chrono::thread_clock::time_point start = threadClock.now(); [...] boost::chrono::thread_clock::time_point end = threadClock.now(); But how do I get to the actual CPU milliseconds (or other units?) used by the current thread between end and start? Thanks and regards, Roland

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Please help with enable_if problem
by John Dlugosz 14 Apr '10

14 Apr '10

I'm getting tons of this from Microsoft's compiler: error C2893: Failed to specialize function template 'enable_if<boo... Reading the compiler docs, C2893 gives an example occurs because f's template parameter T is deduced to be std::map<int,int>, but std::map<int,int> has no member data_type (T::data_type can not be instantiated with T = std::map<int,int>.) but isn't that the whole point of using enable_if? I'm using it already in my project and understand the idea behind it. Here is the function in question: template <typename T, typename D> typename enable_if< boost::mpl::and_< std::tr1::is_base_of<generic_linear_time_ntbase, T>, boost::mpl::or_< is_dimensional_time<D>, std::tr1::is_same<duration,D>, std::tr1::is_same<linear_duration,D> > >, T>::type& operator+= (T& left, const D& right) { left.addop_ (right); // real implementation is in the generic base class return *this; // but I need this template to return the correct derived (actual) class. } Basically, I want to implement operator+= in a base class, but actual use is through derived classes of the common base. Rather than repeating a half dozen forms in each class that calls the common base and downcasts the return value, I made the real implementation in a named function, and this stand-alone function that calls it. enable_if is used to make this += present only for left arguments that are derived from the class of interest, and a right argument that is two specific classes or otherwise noted with the predicate. I've successfully used the predicate (derives from true_type or false_type) in other uses of enable_if. I've even mixed boost::mpl::or_ and and_ with the compiler-supplied TR1 before, with something quite similar. Here's one that does work: template <typename T, typename D> typename enable_if< boost::mpl::and_<is_Universal_time_API<T>, boost::mpl::or_<is_Universal_duration_API<D>,is_dimensional_time<D> > >, T>::type operator+ (const T& t1, const D& d1) { T temp (t1); temp += d1; return temp; } My predicates are based on the native TR1's true_type/false_type. Thanks, --John TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity 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 in error, please contact the sender and delete the material from any computer.

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Problem using boost::bind
by Iskandar Prins 14 Apr '10

14 Apr '10

Hi, Im trying to use boost::bind with 2 parameters on a member function, bind(&Foo::bar, this, _1, _1)); but somehow this fails compilation. Whats the proper syntaxis? Greets, Iskandar

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