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How to suppress warnings from boost headers
by avib369 . 17 Apr '15

17 Apr '15

Is there any way using boost to suppress warning messages issued from the boost headers ? Is there a way to replace -I with -isystem ? Ta, Avi

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multiprecision -- eigen matrices using dynamically allocated variable-precision mpfr_float
by Daniel Brake 17 Apr '15

17 Apr '15

I'd like to use the variable-precision mpfr_float type offered by the Boost.Multiprecision library, with the templated Eigen linear algebra library. I observe that if I make an identity matrix created with dynamically-allocated variable-precision mpfr_floats, and multiply it against itself, every other row is populated with nan's. Here is some code: int main(){ int size = 9; typedef boost::multiprecision::mpfr_float_backend<0, boost::multiprecision::allocate_dynamic> mybackend; typedef boost::multiprecision::number<mybackend, boost::multiprecision::et_on> mynumtype; typedef Eigen::Matrix<mynumtype, Eigen::Dynamic, Eigen::Dynamic> mp_matrix; mp_matrix A = mp_matrix::Identity(size, size); mp_matrix B = A*A; std::cout << B << std::endl; return 0; } output: 1 0 0 0 0 0 0 0 0 nan nan nan nan nan nan nan nan nan 0 0 1 0 0 0 0 0 0 nan nan nan nan nan nan nan nan nan 0 0 0 0 1 0 0 0 0 nan nan nan nan nan nan nan nan nan 0 0 0 0 0 0 1 0 0 nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan I have been able to pin it down to the allocate_dynamic switch; if I select allocate_stack, the product computes correctly; allocate_dynamic reliably generates nans. Fixed-precision numbers work just fine, and expression templates on/off make no difference. I'd like to use the dynamic allocation, as I expect to use thousands of digits at times. I am using clang++, with c++11, on OSX, Boost 1.57.0, Eigen 3.2.4. Same behaviour in 1.56 / 3.2.3. It seems like maybe an offset issue, but I just can't get there by myself. I've also played with defining the NumTraits in Eigen various ways, but nothing affects the nan behaviour. Does anyone have any ideas? Daniel Brake Postdoctoral Research Scholar University of Notre Dame

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[boost][thread] thread_local vs boost::thread_specific vs ::pthread_key_t
by chilabot＠gmail.com 16 Apr '15

16 Apr '15

I have a program that dlopens some libraries (all C++), that use TLS for a variable (which passed to all libraries). With the keyword 'thread_local' and with 'boost::thread_specific', the storage of the variable is different for every thread AND for every shared library. With 'pthread_key_t' it's only different for every thread, it behaves as expected. I guess 'boost::thread_specific' uses 'thread_local' and that's why it behaves like it. Why does 'thread_local' behave like this? $ clang --version Ubuntu clang version 3.5.0-4ubuntu2~trusty2 (tags/RELEASE_350/final) (based on LLVM 3.5.0) Target: x86_64-pc-linux-gnu Thread model: posix $ uname -a Linux robert-y510p 3.13.0-49-generic #81-Ubuntu SMP Tue Mar 24 19:29:48 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux ref http://stackoverflow.com/questions/29656089/ thread-local-vs-boostthread-specific-vs-pthread-key-t

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[IPC Named Mutex]
by Lorenzo Trivelli 16 Apr '15

16 Apr '15

Hi to everyone, I'm experiencing a strange behaviour of named mutex on a windows 2008 machine. symptoms: when the system event log is empty, creation of named mutex fails with a boost::interprocess::interprocess:exception with msg boost::interprocess_exception::library_error. Now some data: 1) Boost 1.57.0 + stlport 5.2 2) VS 2005 3) Target Environment: Win 2008/32 3) after a night of code digging I managed to crete a small sample which raises the exception: #include <boost/shared_ptr.hpp> #include <boost/interprocess/sync/named_mutex.hpp> #include <boost/interprocess/sync/scoped_lock.hpp> #include <iostream> typedef boost::shared_ptr<boost::interprocess::named_mutex> safe_ipc_mx; static safe_ipc_mx __mx; int main(void) { system("pause"); try { __mx = safe_ipc_mx(new boost::interprocess::named_mutex(boost::interprocess::open_or_create_t(),"JAEGER")); std::cout << std::endl << "Mutex created !" << std::endl; } catch(boost::interprocess::interprocess_exception const& e) { std::cout << std::endl << "Mutex creation error " << e.what() << " /" << e.get_error_code() << " /" << e.get_native_error(); } system("pause"); return 0; } as far as I digged, it seems that the trouble is in the winapi::get_last_bootup_time(stamp) call in shared_dir_helpers.hpp, but up to now I had not been able to reproduce it on a machine with all the debugging tools installed does anyone have a clue on what I am doing wrong ? thanks in advance Lorenzo

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Re: [Boost-users] Project linking problem with boost
by Max 16 Apr '15

16 Apr '15

----- Original Message ----- From: <Mark.Bartosik(a)thomsonreuters.com> To: <boost-users(a)lists.boost.org> Subject: Re: [Boost-users] Project linking problem with boost Date: 2015-04-15 22:59 Try one of the /VERBOSE options on the linker’s command line will get you this information, I cannot remember which is the most painless one though. From the command line: /VERBOSE[:{CLR|ICF|INCR|LIB|REF|SAFESEH|UNUSEDLIBS}] /VERBOSE:LIB You can find this under Properties, Linker, General, Show Progress You can also set directly Properties, Linker, Command Line As I recall just /VERBOSE:LIB should generate a lot of output about which library is pulled in (and hopefully by which other library). Just the /VERBOSE output generate a huge amount of output (minimize the window and open with text editor later or it will be a long wait). - Mark - ------------------------------------------------------ Dear Mark, Thank you very much for your information - I didn't know this technique before. The problem is, though the problem seemed to be related to the linking process, the message as in my previous email was emitted by VS2008 before the linking process begins. So for the time being, I cannot benefit from adding extra switches to the link command. Best regards,Max --------------------------------------------------- From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Max Sent: Wednesday, April 15, 2015 5:49 AM To: boost-users Subject: [Boost-users] Project linking problem with boost Sent: Wednesday, April 15, 2015 5:49 AM To: boost-users Subject: [Boost-users] Project linking problem with boost Hello, The problem here relates to boost, but I'm aware it may of more general nature rather than boost specific. I had a weird problem with my project. It has a bunch of dependencies including many of the boost libraries. My platform is: Win7SP1 + VS2008SP1 + boost1.39.0. I have properly set the VC++ directories for both include and lib files pointing to the boost folder (1.39.0) and of course those for other dependencies. But I got the following message when I built the project: 1>Linking to GSL lib 1>Linking to lib file: CGAL-vc90-mt.lib 1>Linking to lib file: libboost_date_time-vc80-mt-1_34.lib 1>Linking to lib file: libboost_regex-vc80-mt-1_34.lib I don't know why VS was attempting to link to libs of boost 1.34.0 built with VC80 (I'm using VC 90 - VS2008) Could anybody please give me some hints about this problem or where the message like "Linking to lib file: ..." came from? Thanks. Best regards, Max _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] Project linking problem with boost
by Max 16 Apr '15

16 Apr '15

----- Original Message ----- From: Lorenzo Trivelli <trivelli.lorenzo(a)konvergence.it> To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Project linking problem with boost Date: 2015-04-15 22:32 Sorry, it may sound a dumb question but are you sure that there are no 1.34 includes before the 1.39 or that there is no hardcoded 1.34 include in your code ? regards Lorenzo Dear Lorenzo, Thank you for your hints and sorry for not giving more details.I don't have the 1.34.0 version of boost on my machine and I have no hardcoded dependencies on it in my code. Best regards,Max

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[Build Boost] Failed gcc.archive
by Jan Krämer 16 Apr '15

16 Apr '15

Hi all, I am trying to build boost_1_57 on Windows7 with MinGW64 (tried gcc 4.9 and 4.9.2). Compiling works fine but gcc.archive fails with: gcc.archive bin.v2\libs\atomic\build\gcc\debug\address-model-64\link-static\threading-multi\libboost_atomic-gcc-mt-d-1_57.a '"C:\mingw-w64\mingw64\bin"' is not recognized as an internal or external command, operable program or batch file. '"C:\mingw-w64\mingw64\bin"' is not recognized as an internal or external command, operable program or batch file. It does that on every gcc.archive operation. I read that this can be caused when using a path with spaces inside, which is not the case here. I did not found any other information and I am stuck right now. Full console output can be found at: http://pastebin.com/bWP0WHAA used commands were: > bootstrap.bat mingw > b2 --prefix=C:/Boost toolset=gcc address-model=64 install --debug-configuration >> boost.log Thanks in advance, any help would be appreciated. Cheers, Jan

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Re: [Boost-users] boost vs std atomic sequential consistency semantics
by Isaac To 16 Apr '15

16 Apr '15

On Wed, Apr 15, 2015 at 4:34 PM, Olivier Tristan <o.tristan(a)uvi.net> wrote: Have you tried Boost LockFree ? > http://www.boost.org/doc/libs/1_55_0/doc/html/lockfree.html > which handle multiple producer/Multiple-consumer queue > I know about the lockfree library, I've read the book underlying it (the Art of Multiprocessor Programming), and think I've understood at least 80% of it. My problem is not multiple producer multiple consumer queue, so it doesn't work for me. In particular, although there are multiple log producers, there is no consumer. They log into a ring buffer, and normally nobody would care and the log entries get overwritten by new entries (I want to avoid having to wait when logging). When the reader wants to read, it simply dumps everything in the ring buffer, and won't change the status of the buffer (i.e., it doesn't "consume"). And I don't care if the reader found a few entries are busy being overwritten, it just has to know about that so as to avoid using the data (which leads to wrong output and could lead to crash). The problem is in fact a lot easier than any of the queues / stacks that is implemented by lockfree. I've also inspected the assembly generated by g++ over my code in x86-64, and I think it is okay (i.e., no reordering with non-atomic statement is done by the compiler -- together with the strong consistency guarantee under x86-64 the code should be okay I think). Of course, "okay for one version of a brand of compiler and library under one platform" does not mean my program is correct: a new version of the compiler / library could break it, which is my main worry. But I've got something more fundamental to ask: what the memory model really means, and what to do once we (inevitably) move away from Boost and join the C++1x/y/z family. It seems to me that the C++ standard provides something quite a bit weaker than what Boost promises, and I don't know how to get the Boost promise from the C++ standard. That's the other reason why I ask. > Le 15/04/2015 08:42, Isaac To a ?crit : > > > I'd like to write a C++ object where there are many logger threads > > logging to a large global (non-atomic) ring buffer, with an occasional > > reader thread which wants to read as much data in the buffer as > > possible. I ended up having a global atomic counter where loggers get > > locations to write to, and each logger increments the counter > > atomically before writing. The reader tries to read the buffer and > > per-logger local (atomic) variable to know whether particular buffer > > entries are busy being written by some logger, so as to avoid using them. > Regards, Isaac

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Re: [Boost-users] Possible to use with JNI?
by Lorenzo Trivelli 15 Apr '15

15 Apr '15

At 06:30 13/04/2015, you wrote: >Hi, I really need to use Java with this library. Is it possible to use JNI on this library or do I need to convert this library to Java? I find the latter task is going to be really difficult so I hope that I can use JNI. > >Thank you for your help. Hi, AFAIK it is not easy to do that due to C++ name mangling and the absence of any ABI in C++ itself like C A possible but limited workaround should be to create a DLL with a C interface which uses the boost objects you need. Next, you can call it through JNI, but obviously you can pass only basic data types regardds Lorenzo

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[asio][bind] Access violation with placeholders used by static objects
by Olivier Sauvageau 15 Apr '15

15 Apr '15

Hello, I had an access violation issue using boost::asio::placeholders::error as parameter to boost::bind in a class that was used as type for a static class member object. I realized that the placeholders, both those in Asio and those in Bind (e.g., _1) are themselves static objects, and thus found out that my problem was due to the famous undefined order of initialization of static objects. I was able to fix my problem simply by encapsulating my static object in a function and making sure it's called only after main() has started. However, I'm still wondering, has this issue ever been discussed and any correction or alternative proposed? I couldn't find anything on the topic. On the other hand, I noticed that Asio's placeholders are initialized from functions, e.g. from <boost/asio/placeholders.hpp>: boost::arg<1>& error = boost::asio::placeholders::detail::placeholder<1>::get(); Using that function instead could be an alternative, but since it is not in the "public" namespace and is not in the library documentation, using it would not be a good idea for maintainability. Finally, is there any documentation stating the fact that placeholders such as boost::asio::placeholders::error and _1 are static? I can't find any in the Asio or Bind documentation, and I feel this is a limitation that should at least be documented. Thank you, -- Olivier Sauvageau

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