March 2019 - Boost - lists.preview.boost.org

[filesystems]
by Florian Lindner 14 Mar '19

14 Mar '19

Hello, I have this innocent piece of code: namespace fs = boost::filesystem; auto path = getFilename(); // returns a string fs::create_directories(fs::path(path).parent_path()); std::ofstream ofs(path + "~"); ofs << info; ofs.close(); fs::rename(path + "~", path); which causes the exception: boost::filesystem::rename: No such file or directory: "../9f/061b4f7a5e529c964659226eedd4e5~", "../9f/061b4f7a5e529c964659226eedd4e5" However, I have no idea how that could happen. I use the rename, so that a reading process never sees an empty file, but only no file or filed with info. Is there any race involved between ofs.close() and fs:rename()? The code was executed on a distributed network filesystem (lustre). Any ideas anyone? Thanks, Florian

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Re: [boost] [Boost-users] Networking TS + Beast, NEW Tutorials, Read this to learn std::net !!!
by Vinnie Falco 14 Mar '19

14 Mar '19

On Thu, Mar 14, 2019 at 10:50 AM james <dirtydroog(a)gmail.com> wrote: > This is excellent news. Timeouts are ASIO's biggest downfall. I'll definitely check it out. > If it's low level, and performant enough, then it paves the way for ASIO-ed connectors for things like Redis and ZeroMQ. Thanks! And we are very happy to answer questions, feel free to open an issue or come to the #beast Slack channel. Regards

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Cannot serialize pointer through base without void_cast_register and register_type.
by Nicolas Guillot 14 Mar '19

14 Mar '19

Hello. *** CONTEXT *** I use your serialization library since several years on linux (gcc). Now, I'm moving to windows (_MSC_VER == 1600) (boost 1.55, but same issues on boost 1.69). For my example, I use a class A in a DLL, another class B inheriting from A in its DLL and an exe, linked to those DLLs, which serializes a B object, through its A base. _______ | A | ------- /_\ | | _______ | B | ------- I make a class serializable like that (I summurize on purpose (no #include, ...)). For A it's the same thing, but it has no base class. ----> B.h ---------------------------------------- #ifdef B_EXPORTS #define B_DLL __declspec(dllexport) #else #define B_DLL __declspec(dllimport) #endif class B_DLL B: public A { public: B(); virtual ~B(); private: friend class boost::serialization::access; template <class Archive> void serialize(Archive & ar, const unsigned int version); int i; }; BOOST_CLASS_EXPORT_KEY(B) ----> B.cpp ---------------------------------------- B::B() : i(123) {} B::~B() {} template <class Archive> void B::serialize(Archive & ar, const unsigned int) { ar & SERIALIZE_BASE(ClassA); ar & SERIALIZE(i); } #define FULL_SCOPED_SERIALIZABLE_CLASS B #include "Common/InstanciateSerializationTemplate.h" ----> InstanciateSerializationTemplate.h ---------------------------------------- This file purpose is to instanciate the template B::serialize methods for each archive type, and to register the class. Here is its contents (once again, no namesapce nor include to make it easier to read): // explicit instantiate code for all archive types expected to be use: // MUST COME BEFORE BOOST_CLASS_EXPORT_IMPLEMENT // binary: template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<binary_iarchive>(binary_iarchive & ar, const unsigned int version); template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<binary_oarchive>(binary_oarchive & ar, const unsigned int version); // XML: template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<xml_iarchive>(xml_iarchive & ar, const unsigned int version); template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<xml_oarchive>(xml_oarchive & ar, const unsigned int version); // TXT: template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<text_iarchive>(text_iarchive & ar, const unsigned int version); template __declspec(dllexport) void FULL_SCOPED_SERIALIZABLE_CLASS::serialize<text_oarchive>(text_oarchive & ar, const unsigned int version); BOOST_CLASS_EXPORT_IMPLEMENT(FULL_SCOPED_SERIALIZABLE_CLASS) *** MY ISSUE *** All that stuff works in linux, gcc, but not in Windows. If I write in my exe this serialization code: std::ofstream ofs; ofs.open("D:\\TestSerial.xml"); boost::archive::xml_oarchive ar(ofs); shared_ptr<B> b = shared_ptr<B>(new B()); shared_ptr<A> a = b; try { ar << SERIALIZE(a); } catch (boost::archive::archive_exception& ex) { std::cout << "Serialization to stream error, what: " << ex.what() << std::endl; } catch (...) { std::cout << "Catch ... Serialization to stream error" << std::endl; } ofs.close(); With this code, I have an archive_exception: "unregistered class - derived class not registered or exported". I have to write the serialization like that: ar.register_type(static_cast<B*>(0)); boost::serialization::void_cast_register(static_cast<B*>(0), static_cast<A*>(0)); ar << SERIALIZE(a); *** QUESTION *** At least, my question: I cannot do like that: what I would like to achieve: when a new class is made serializable like above, I expect the class to be registered automatically (probabley with BOOST_CLASS_EXPORT_IMPLEMENT in InstanciateSerializationTemplate.h). It's too painfull to write the register_type and void_cast_register each time I want to serialize. What am I missing? Thank you very much for any help or recommandations. Nico

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Re: [boost] MSVC 2019 and 1.70 beta
by Peter Dimov 14 Mar '19

14 Mar '19

> Tom Kent wrote: > > > Build support for VS 2019 RC (msvc-14.2) is on develop in boost build. > > Do we want to merge that to master for the release? > > I think we do. 1.70 and 2019 will release at about the same time. In fact looking at the calendar, 2019 will release (Apr 2) just before 1.70 is closed for release (Apr 3.)

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boost-install-ing zlib (Was: Re: [Release] Boost 1.70.0 Beta 1 Release Candidate 2)
by Peter Dimov 13 Mar '19

13 Mar '19

> I'll need to try and see what happens with <source> in user-config. > Probably nothing good, because one would expect neither <build-name> nor > <tag> to be specified in such a case. If I remove the check for ZLIB_SOURCE, and just do alias boost_zlib : /zlib//zlib ; libraries-to-install += boost_zlib ; unconditionally in libs/iostreams/build/Jamfile, this is what happens: - when `using zlib : : <source>C:/Projects/zlib-1.2.11 ;` is in user-config, the default `b2 install` fails because `address-model=32,64 variant=debug,release` conflict as all try to build `libz.lib`. When address-model=32 variant=debug is given, `libz.lib` is installed in C:\Boost\lib, and the CMake configuration for boost_zlib correctly points to it. - when using a prebuilt `using zlib : : <include>C:/Projects/include <search>C:/Projects/lib <name>zlib-8 ;`, the CMake configuration file for boost_zlib points to "${_BOOST_LIBDIR}/zlib-8", which is not correct.

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(no subject)
by Marshall Clow 13 Mar '19

13 Mar '19

Boost release 1.70.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.70.0.beta1/source/> The SHA256 checksums are as follows: dbf89645e509acb2e53eac3c633834f1dec80bd8622e6e652a9741dcf0807f17 ./boost_1_70_0_b1.7z 957b984b58656a3ec00661ecad7ef82e3a094bad36e37b9e6624843237854679 ./boost_1_70_0_b1.tar.bz2 76d149c1fb9e8a5ceb3bc1e5587edc40fa79a43e8b990d877c2210f0382b9421 ./boost_1_70_0_b1.tar.gz 71e990b2c26880521fd98459b184ee172ce1c46dcf554b6eaab7776b8b6369a6 ./boost_1_70_0_b1.zip For details of what's in the release, see < https://www.boost.org/users/history/version_1_70_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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[rational] permission to merge cmake change?
by James E. King III 13 Mar '19

13 Mar '19

Before 1.70.0 beta started, some cmake changes from Mike Dev were merged into rational. There was a typo in one of the cmake options (BOOST_RATIONA_INCLUDE_TESTS). This does not affect code nor the boost build system. Would it be okay to merge this now or should I wait? https://github.com/boostorg/rational/pull/35 Thanks. - Jim

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[release] Boost 1.70.0 Beta 1 Release Candidate 3
by Marshall Clow 12 Mar '19

12 Mar '19

A new release candidates for the first 1.70.0 beta release are now available at: https://dl.bintray.com/boostorg/beta/1.70.0.beta1.rc3/source/ Changes since RC2: * Relative paths for --prefix, --libdir, etc. are now bound relative to the current working directory, instead of being relative to the Jamfile. Thanks to Tom Kent for the report, and Steven and Peter for the fixes. Changes since RC1: * The Jamfile for Boost.Predef has been updated to allow running the tests from /status. Thanks to mike.dev(a)gmx.de for the report, and to Rene for the fix. The release notes are not yet available. The SHA256 checksums are as follows: dbf89645e509acb2e53eac3c633834f1dec80bd8622e6e652a9741dcf0807f17 ./boost_1_70_0_b1_rc3.7z 957b984b58656a3ec00661ecad7ef82e3a094bad36e37b9e6624843237854679 ./boost_1_70_0_b1_rc3.tar.bz2 76d149c1fb9e8a5ceb3bc1e5587edc40fa79a43e8b990d877c2210f0382b9421 ./boost_1_70_0_b1_rc3.tar.gz 71e990b2c26880521fd98459b184ee172ce1c46dcf554b6eaab7776b8b6369a6 ./boost_1_70_0_b1_rc3.zip 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. -- The Boost Release Managers

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[Release] Boost 1.70.0 Beta 1 Release Candidate 2
by Marshall Clow 12 Mar '19

12 Mar '19

A new release candidates for the first 1.70.0 beta release are now available at: https://dl.bintray.com/boostorg/beta/1.70.0.beta1.rc2/source/ Changes since the last RC: * The Jamfile for Boost.Predef has been updated to allow running the tests from /status. Thanks to mike.dev(a)gmx.de for the report, and to Rene for the fix. The release notes are not yet available. The SHA256 checksums are as follows: 26dba8156ad08041c6da52c84a2654aefda292180afe3546a9a74dda0dfb3781 ./boost_1_70_0_b1_rc2.7z ee794d98429bc2bfae054f2fab6fde53ea95f7c5967d8b267e57c894a4d46e57 ./boost_1_70_0_b1_rc2.tar.bz2 bca5f189d87b26ab903838dee2fd4c54e9043bd35d27b8923cdef42651ae7261 ./boost_1_70_0_b1_rc2.tar.gz 6c8f3af4e64d3a04a3d3a5e98499d2f6bb460ad82c1f33ff7da800b5ab182b0b ./boost_1_70_0_b1_rc2.zip 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. -- The Boost Release Managers

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Re: [boost] [Boost-users] [release] Boost 1.70.0 Beta 1 Release Candidate 1
by Tom Kent 11 Mar '19

11 Mar '19

On Fri, Mar 8, 2019 at 9:44 PM Tom Kent <lists(a)teeks99.com> wrote: > > > On Fri, Mar 8, 2019 at 8:57 PM Tom Kent <lists(a)teeks99.com> wrote: > >> >> >> On Fri, Mar 8, 2019 at 6:42 PM Marshall Clow via Boost-users < >> boost-users(a)lists.boost.org> wrote: >> >>> On Fri, Mar 8, 2019 at 10:21 AM Marshall Clow <mclow.lists(a)gmail.com> >>> wrote: >>> >>>> The release candidates for the first 1.70.0 beta release are now >>>> available at: >>>> >>>> https://dl.bintray.com/boostorg/beta/1.70.0.beta.1.rc1/source/ >>>> >>>> The release notes are not yet available. >>>> >>>> The SHA256 checksums are as follows: >>>> >>>> a7c570d6307d05dc8d45a3b4c69a0afdcba2b22eac0c4da4d496559f53db7b89 >>>> ./boost_1_70_0_b1_rc1.7z >>>> 4b91b9a203cf12f6001cf39de83c7cc005fbc5390e2b4b2fc29ce7b19c0537a7 >>>> ./boost_1_70_0_b1_rc1.tar.bz2 >>>> 460dd6499bba9df04c6bfa219b26097bad803b8758304ba45f2fc291aa42c96e >>>> ./boost_1_70_0_b1_rc1.tar.gz >>>> f209c9a086ed2c7882a0bc8755792f436eb141eaeb8c823ed57295ca9ce25b93 >>>> ./boost_1_70_0_b1_rc1.zip >>>> >>>> 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. >>>> >>> >>> >> I'm having a problem with B2 in this release. >> >> For many releases now, I have run a command such as: >> b2 -j16 --build-type=complete toolset=msvc-10.0 address-model=64 >> architecture=x86 --prefix="./" --libdir=lib32-msvc-10.0 >> --includedir=temp_inc install >> >> to get the windows builds of each toolset. For the install, I set the >> prefix as the current directory, so that I'll get a lib{arch}-msvc-{ver} >> directory for each toolset in there. However, with this 1.70 release, it >> seems to ignore my prefix and put the headers in >> libs/headers/build/temp_inc/boost-1_70/boost, instead of >> temp_inc/boost-1_70/boost. For the libraries, it scattered them throughout >> the build in directories such as libs/coroutine/build/lib32-msvc-10.0/. >> >> Any thoughts on what might be causing this? Am I using the --prefix >> --libdir and --inlcudedir correctly? Or at least not badly enough to >> warrant this? >> > > Also, even though I have BZIP2_SOURCE and ZLIB_SOURCE set, I'm not seeing > the appropriate bzip2 and zlib libraries being generated. > > After updating my scripts to us "staging" instead of "install" to avoid the above issue, I was able to get everything else to build successfully for Visual Studio (msvc-10.0 through msvc-14.1, note this is the first release I haven't built against msvc-8.0 and 9.0). The only exception being the lack of bzip2 and zlib support mentioned above. toolset arch compile Link Execute msvc-10.0 32 X X X msvc-10.0 64 X X X msvc-11.0 32 X X X msvc-11.0 64 X X X msvc-12.0 32 X X X msvc-12.0 64 X X X msvc-14.0 32 X X X msvc-14.0 64 X X X msvc-14.1 32 X X X msvc-14.1 64 X X X Compile means that the b2 command completed without errors Link means that visual studio was able to link a sample executable to a library (libboost_thread-vcXXX-mt[-gd]-1_XX.lib) generated Execute means that the linked program executed without errors. Full build logs can be found at https://gist.github.com/teeks99/0aeed77c9251ba02090d9ab7372e2c73 Tom

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Regarding GSoc 2019
by karmanya grover 11 Mar '19

11 Mar '19

Sir/Madam, I am a Google Summer of Code 2019 aspirant. This email is regarding inquiry of possible projects that I am interested in. Please provide the specifics for following questions. In Boost.uBLAS library, I want to know if there's some work done for python integration previously or not. I also want to inquire about Boost Astronomy library. Looking into git repository, I found that this library is fairly new. What are the aspects hoped to be achieved for this library as a full efficient and mathematical friendly. I have always been interested in Astrophysics and applying those concepts in problem solving. Apart from that, What were the previous works done in Boost.Real library by past GSoc'ers. with regards, Yours sincerely, Karmanya Grover (B.E). NSUT

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[release] 1.70 Windows binaries
by Sean Farrow 10 Mar '19

10 Mar '19

Hi, I know there is a discussion regarding building 1.70 with zlib in another thread, but wondered whether there are any binaries available for msvc without zlib for the 1.70 beta rc1/2? Kind regards Sean.

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[variant2] documentation request
by Andrzej Krzemienski 10 Mar '19

10 Mar '19

Hi Peter, Given that the never-empty guarantee appears to be at the heart of the motivation for boost::variant2, I would suggest to: 1. put in the documentation some motivation behind pursuing the never-empty guarantee. 2. Make it clear that never-empty guarantee is not a strong exception-safety guarantee. 3. Describe the algorithm for achieving the guarantee. The current description does not seem to cover all interesting cases, and I found the behavior quite surprising. For instance, the variant's move assignment will sometimes use T's move assignment rather than move constructor when changing the variant's type, as in the following example: https://wandbox.org/permlink/GDRyS54bpdLP7GVa Regards, Andrzej

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[gsoc19] Seeking Guidance along with mentor for Boost.GIL Project
by Keshav Gupta 10 Mar '19

10 Mar '19

Respected Sir, I am Keshav Gupta currently doing my B.E. in Computer Engineering from Thapar University, Patiala, Punjab, India. Actually I want to participate in GSOC19 and want to work with you during that period. Actually I am interested in implementing various Image Processing algorithms using BOOST.GIL. and I think that I can perfectly work upon this as I am also currently doing my research in the area of Fingerprint Matching and you absolutely know that this definitely includes the usage of image processing algorithms and that why I am interested for this as I know I have the proper knowledge of C++ along with image processing algorithms. Kindly guide me how to proceed further so as to increase my chances of getting being selected in GSOC19. Also please tell me any other way how to contact the mentor of this project as I have mailed him certain number of times but didn't get any response. Waiting for your reply Regards Keshav Gupta

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Re: [boost] [Release] Boost 1.70.0 Beta 1 Release Candidate 2
by Peter Dimov 09 Mar '19

09 Mar '19

> Tom Kent wrote: > > > * Can't create libraries for bzip2 and zlib (showstopper? anyone else > > seeing this?) > > I haven't seen your initial report of this issue (on the users list?) but > it's probably caused by this change: > > https://github.com/boostorg/build/commit/5ad92cd76ff393792f30aa50688c95eff2… Or maybe not. This is in 1.69.0, so it can't be the cause.

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[release] Boost 1.70.0 Beta 1 Release Candidate 1
by Marshall Clow 09 Mar '19

09 Mar '19

The release candidates for the first 1.70.0 beta release are now available at: https://dl.bintray.com/boostorg/beta/1.70.0.beta.1.rc1/source/ The release notes are not yet available. The SHA256 checksums are as follows: a7c570d6307d05dc8d45a3b4c69a0afdcba2b22eac0c4da4d496559f53db7b89 ./boost_1_70_0_b1_rc1.7z 4b91b9a203cf12f6001cf39de83c7cc005fbc5390e2b4b2fc29ce7b19c0537a7 ./boost_1_70_0_b1_rc1.tar.bz2 460dd6499bba9df04c6bfa219b26097bad803b8758304ba45f2fc291aa42c96e ./boost_1_70_0_b1_rc1.tar.gz f209c9a086ed2c7882a0bc8755792f436eb141eaeb8c823ed57295ca9ce25b93 ./boost_1_70_0_b1_rc1.zip 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. -- The Boost Release Managers

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Interest in GSoC Project
by Kanav Gupta 09 Mar '19

09 Mar '19

Hello, I am third-year undergrad research student at International Institute of Information Technology, Hyderabad. I would like to contribute to Boost.GIL as a part of GSoC '19. I am currently working on a research project involving image processing and have also worked on various projects involving C++ so I guess I am competent for the project. Can you please guide me on how should I proceed? Thanks and Regards, Kanav Gupta

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[release] 1.70.0 closed for major changes
by Marshall Clow 07 Mar '19

07 Mar '19

The master branch is now closed for new libraries and breaking changes, and will be closing for the beta in one week. Also, if you're ready, you can also add your libraries' changes to the release notes at: < https://github.com/boostorg/website/blob/master/feed/history/boost_1_69_0.q… > After editing the release notes, you should get a form to create a pull request, remember to submit it, otherwise I won't see your change. As always, the calendar for the release cycle is available at: https://www.boost.org/development/ Thanks, -- The Boost Release Team

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[Release 1.70] Master branch is now closed for the beta
by Marshall Clow 07 Mar '19

07 Mar '19

Except with explicit permission by a release manager. Do whatever you want on develop, just don't change master. We'll re-open master after the beta. As always, check the calendar at https://www.boost.org/development 6-Mar: Boost 1.70.0 closed for all changes 13-Mar: Boost 1.70.0 beta; master branch re-opened 2-Aug: Release closed for all changes, except by permission of a release manager. 3-Apr: Boost 1.70.0 closed for all changes 10-Apr: Boost 1.70.0 release -- The release managers

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[build] Boost.Build/develop broken with msvc?
by John Maddock 07 Mar '19

07 Mar '19

Currently I see: D:/data/boost/boost/tools/build/src/tools\msvc.jam:1388: in configure-really *** argument error * rule generate-setup-cmd ( version : command : parent : options * : cpu : global-setup ? : default-global-setup-options : default-setup ) * called with: ( 14.16.27023 14.11.25503 : D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64 : D:\compilers\visual studio\2017\VC\Tools\MSVC\14.11.25503\bin\HostX64 : <command>D:\compilers\visual studio\2017\VC\Tools\MSVC\14.16.27023\bin\Hostx64\arm\cl.exe <command>D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64/cl.exe : i386 : : x86 : vcvars32.bat ) * extra argument 14.11.25503 D:/data/boost/boost/tools/build/src/tools\msvc.jam:1003:see definition of rule 'generate-setup-cmd' being called D:/data/boost/boost/tools/build/src/tools\msvc.jam:393: in configure D:/data/boost/boost/tools/build/src/tools\msvc.jam:345: in msvc.init D:/data/boost/boost/tools/build/src/build\toolset.jam:44: in toolset.using D:/data/boost/boost/tools/build/src/build\project.jam:1104: in using C:\cygwin64\home\John Maddock\user-config.jam:46: in modules.load D:/data/boost/boost/tools/build/src\build-system.jam:255: in load-config D:/data/boost/boost/tools/build/src\build-system.jam:453: in load-configuration-files D:/data/boost/boost/tools/build/src\build-system.jam:607: in load D:\data\boost\boost\tools\build\src/kernel\modules.jam:295: in import D:\data\boost\boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build D:\data\boost\boost\boost-build.jam:17: in module scope Master is fine BTW. Best, John. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[interprocess] support for a new synchronisation mechanism
by Dudi Likvornik 06 Mar '19

06 Mar '19

Hi, My name is David, I would like to suggest a new synchronisation mechanism based on linux futex. as far as I saw, its not being supported as of now with in the interprocess communication library. One suggestion is to support a mutex, here is an example, possible partial implementation, based upon the following paper: http://dept-info.labri.fr/~denis/Enseignement/2008-IR/Articles/01-futex.pdf Mutex::Mutex(): m_word(UNLOCK) {} void Mutex::lock() { int lockState = UNLOCK; if(std::atomic_compare_exchange_strong(&m_word, &lockState, static_cast<int>(LOCK_SINGLE)) == false) { if(lockState != LOCK_MANY) lockState = std::atomic_exchange(&m_word, static_cast<int>(LOCK_MANY)); while(lockState != UNLOCK) { #if defined(__linux) syscall(SYS_futex, &m_word, FUTEX_WAIT, LOCK_MANY, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wait is not being supported by current platform"); #endif lockState = std::atomic_exchange(&m_word, static_cast<int>(LOCK_MANY)); } } } void Mutex::unlock() { if(std::atomic_fetch_sub(&m_word, 1) == LOCK_SINGLE) return; m_word = UNLOCK; #if defined(__linux) syscall(SYS_futex, &m_word, FUTEX_WAKE, 1, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wake is not being supported by current platform"); #endif } bool Mutex::try_lock() { int lockState = UNLOCK; return std::atomic_compare_exchange_strong(&m_word, &lockState, static_cast<int>(LOCK_SINGLE)); } ————————————————————————————————————————————————————————— And a conditional variable: Condition::Condition(): m_command(SLEEP), m_waitersCount(0){} void Condition::signal(Command command) { m_wakeLock.lock(); if(m_waitersCount == 0) { m_wakeLock.unlock(); return; } m_command.store(command, std::memory_order_relaxed); #if defined(__linux) syscall(SYS_futex, &m_command, FUTEX_WAKE, command == NOTIFY_ONE ? 1 : std::numeric_limits<int>::max(), nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wake is not being supported by current platform"); #endif while(m_command.load(std::memory_order_relaxed) != SLEEP && m_waitersCount.load(std::memory_order_relaxed) != 0){} m_wakeLock.unlock(); } void Condition::wait(std::unique_lock<core::Mutex> &lock) { m_waitersCount++; lock.unlock(); while(true) { while(m_command.load(std::memory_order_relaxed) == SLEEP) #if defined(__linux) syscall(SYS_futex, &m_command, FUTEX_WAIT, SLEEP, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wait is not being supported by current platform"); #endif int fromCommand_one = NOTIFY_ONE; if(m_command.compare_exchange_strong(fromCommand_one, static_cast<int>(SLEEP), std::memory_order_relaxed)) { m_waitersCount--; lock.lock(); return; } else if(m_command.load(std::memory_order_relaxed) == NOTIFY_ALL) { if(m_waitersCount.fetch_sub(1, std::memory_order_relaxed) == 1) m_command.store(SLEEP, std::memory_order_relaxed); lock.lock(); return; } } } ConditionVariable::ConditionVariable() {} void ConditionVariable::wait(std::unique_lock<core::Mutex> &lock) { m_condition.wait(lock); } void ConditionVariable::notify_one() { m_condition.signal(Condition::NOTIFY_ONE); } void ConditionVariable::notify_all() { m_condition.signal(Condition::NOTIFY_ALL); } class ConditionVariable { public: ConditionVariable(); ConditionVariable(const ConditionVariable&) = delete; ConditionVariable& operator=(const ConditionVariable&) = delete; void wait(std::unique_lock<Mutex>& lock); template<typename Predict> void wait(std::unique_lock<Mutex>& lock, const Predict& predict) { while(predict() == false) m_condition.wait(lock); } void notify_one(); void notify_all(); private: Condition m_condition; }; Your thoughts of the idea, if any. p.s. Please be soft, its my first post ever :).

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Boost.uBLAS [gsoc19]
by Sarthakag 06 Mar '19

06 Mar '19

Hello, I am Sarthak Agarwal, 3rd-year undergraduate student from Birla Institute of Technology and Science, Pilani - Goa, India currently pursuing a double major MSc. Mathematics and B.E. Computer Science and Engineering. I am an active Competitive Programmer on various online judges for the last 4 years. I am comfortable in C/C++(STL) and Python(Django). I wish to contribute to Boost.uBLAS, specifically to Project 4 on implementing non-negative matrix factorization(NMF). I would also like to know if there are any upcoming ideas to implement in Boost.intrusive. I have completed the Boost Competency test and learned a lot while doing it. How can I share it for valuable feedback? I look forward to your guidance. Sarthak Agarwal -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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Regarding GSOC'19
by Keshav Gupta 05 Mar '19

05 Mar '19

Hi I am Keshav Gupta from India and wanted to work with Boost during GSOC 2019 on the major topic of Boost GIL. So can you tell me how to proceed with? Regards Keshav Gupta

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[variant2] Need rationale for never-empty guarantee
by Andrzej Krzemienski 04 Mar '19

04 Mar '19

Hi Peter, Thank you for writing and sharing this implementation of variant. I am sorry if I am bringing back an issue that has been already discussed and solved before, but I do not understand the rationale behind doing compromises in order to provide the never-empty guarantee. The short rationale provided in Boost.Variant library: https://www.boost.org/doc/libs/1_69_0/doc/html/variant/design.html#variant.… was provided before we got C++11 the moved-from state in the language. Today, it should come as no surprise to programmers that a type might be in a "moved from" state where only a limited interface of an object can be used. The guarantee provided by variant's assignment is not a strong exception safety guarantee: it is possible that my variant has value A, I want to assign value B, and (due to an exception) I end up with value C. If this happens, the only thing I can reasonably do is to either abandon whatever I was doing or reset the variant to the state that I need. So the guarantee that it is not left empty does not seem to be of much use. But the cost to be paid is noticeable. I think that this question should be addressed in the documentation. Regards, Andrzej

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[gsoc19][astronomy] Code for review
by Avinal Kumar 04 Mar '19

04 Mar '19

where should I submit my code for programming competency test ??

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