- Boost-users - lists.boost.org

Re: [Boost-users] How to design proper release of a boost::asio socket or wrapper thereof
by Bjorn Reese 06 Apr '17

06 Apr '17

On 04/05/2017 10:32 PM, Christopher Pisz via Boost-users wrote: > The problem I have with this example listing is that it cheats and it cheats > big, by making the tcp_connection a shared_ptr, such that it doesn't worry > about the lifetime management of each connection. That is not cheating. > Consider we'd have a callstack that looked something like this: > tcp_connection::~tcp_connection > tcp_server::OnDisconnect > tcp_connection::OnDisconnect > tcp_connection::Disconnect If Disconnect is an asynchronous operation, then it should not call OnDisconnect directly. You can post it on the io_service instead. > I imagine everyone doing server programming comes across this scenario in > some fashion. What is a strategy for handling it? Preferably shared_ptr, or io_service::post() if for some reason you cannot use shared_ptr, e.g. if the object has to be destroyed by a a specific thread.

3 3

[gsoc17] Help review Google Summer of Code proposals
by Niall Douglas 06 Apr '17

06 Apr '17

Dear Boost, Student proposals for Google Summer of Code are submitted, please help us decide which have the most merit. I have reduced the fifty something proposals submitted down to twenty seven which have some chance. To be able to view and rank the student proposals, please do the following: 1. Send to gsoc-admin(a)boost.org your Google login. We will invite you to view the student proposals on the Boost Google Drive. Until you receive the invitation email, you won't be able to view the proposals. 2. Go to https://goo.gl/forms/EVppdHsHMnjkcUoD3 which is a Google form where you can score the proposals. We have linked each proposal there to the Google Drive item and there you can rank a proposal between 1 and 5. Make sure you use the same email as your Google login in the form, otherwise we will ignore any forms submitted to prevent gaming the results. 3. Even if you can't rank all twenty seven proposals, try to do as many as you can and then PRESS SUBMIT at the end of the form (forgetting to press SUBMIT means we never get your rankings). The proposals are presented in random order per person so any work you do will be useful. 4. Please try to have your rankings done by Monday 10th. You may find reviewing the page at https://svn.boost.org/trac/boost/wiki/SoC2017 useful. 5. Finally, if you'd like to mentor any of the proposals, send to gsoc-admin(a)boost.org your Google login so we may invite you onto the Google website as a mentor. Many thanks in advance. Niall & Bryce

1 0

[Fusion] wide-char output
by Leo Cacciari 05 Apr '17

05 Apr '17

Hi, the documentation of the Boost.Fusion library (1.63.0) at http://www.boost.org/doc/libs/1_63_0/libs/fusion/doc/html/fusion/sequence/o… affirms that operator<< is defined in the boost::fusion namespace with the following synopsis: template <typename OStream, typename Sequence> OStream& operator<<(OStream& os, Sequence& seq); where the template parameter OStream is defined as "An output stream". Accordingly, I thought that the following would work: using boost::fusion::operator<<; fusion::vector<int, double, const char *> v = fusion::make_vector(42, 3.1415, "foobar"); std::wcout << "v = " << v << std::endl; However, the compiler (MSVC 9) complains that it has: "found no defined operator << taking a right-hand argument of type boost::fusion::vector<T0,T1,T2> with T0 = int, T1 = double, T2 = char *" If I replace std::wcout with its narrow-char sibling std::cout, everything works as expected; i.e. the code compiles and when run prints (42,3.1415, foobar). Looking into the source (file boost/fusion/sequence/io/out.hpp) it seems that the operator<< is only defined for left-hand argument of type std::ostream. Thus the questions: 1. Is this a bug and should I post a ticket about it? (I looked in the bugs database but I couldn't find it) 2. If it's a bug, are there any plan to patch it soon? 3. If not, does exist any reason why it shouldn't be patched nevertheless? If needed, I could volunteer for writing a patch. Thank for your attention -- Leo Cacciari Aliae nationes servitutem pati possunt. Populi Romani est propria libertas.

3 4

Query regarding Boost.Log
by Leo Carreon 02 Apr '17

02 Apr '17

Hi, Does Boost.Log require synchronization when multiple processes log to the same log file? Kind regards, Leo

1 0

[Stacktrace] Review 2 Manager report
by Niall Douglas 31 Mar '17

31 Mar '17

Many thanks to all those who participated in the second review of proposed Boost.Stacktrace. I received the following formal reviews: 1. Peter Dimov (ACCEPT) 2. Vladimir Batov (ACCEPT) 3. Artyom Bellis (CONDITIONAL ACCEPT) 4. Bjorn Reese (ACCEPT) 5. Edward Diener (ACCEPT) Extensive comments without a formal recommendation were also made by: 1. Mark Bartosik 2. Florian Weimer Some of the more important conditions for acceptance as judged by the review manager are: * Problems on FreeBSD (and by inference OS X?). * Per frame execution of addr2line rather than calling it once. * Throw-with-trace was asked for by a lot of people. * One reviewer suggested that the addr2line backend was async signal unsafe. My reading of the code is that it is async signal unsafe to parse a stacktrace (and unavoidably so on any platform), but the capture of backtraces is now fully async signal safe. * Some disliked the bringing in of windows.h and the COM headers on Windows. For a header only library I consider this acceptable, Stacktrace when configured in non-header only mode does not inject windows.h into everything including stacktrace. Congratulations to Antony on getting yet another library of his into Boost! Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

2 1

Problem statically linking Boost 1.63
by Balázs Bámer 31 Mar '17

31 Mar '17

Hi All, I have asked it on Stackoverflow, but know one seems to know the answer who saw it. I post it here, too, because 1.55 (which works for me) is quite old and has problems in logging: writing logfiles stops whithin a day every time. So 1.63 would be important for me to try. Link to the Stackoverflow post: http://stackoverflow.com/questions/42978843/boost-inner-function-argument-m… Thank you in advance. Best regards: Balazs PS: I copy the post here, but its formatting will break in plain text. I have a strange problem during linking Boost 1.63.0. I use the following cmake lines to configure Boost: add_compile_options(-std=c++14 -DBOOST_LOG_DYN_LINK)set(BOOST_ROOT "/usr/local/alk/boost_1_63_0/") SET(Boost_USE_STATIC_LIBS OFF) find_package(Boost 1.63 REQUIRED COMPONENTS log_setup log regex thread date_time filesystem system) Then the sources compile, and the linker tells me similar messages: CMakeFiles/dsmip.dir/main.cpp.o: In function `boost::log::v2_mt_posix::sources::aux::logger_singleton<dataLogger>::init_instance()': /home/balazs/munka/neovoltaic/aufgaben/dsmip/main.cpp:(.text._ZN5boost3log11v2_mt_posix7sources3aux16logger_singletonI10dataLoggerE13init_instanceEv[_ZN5boost3log11v2_mt_posix7sources3aux16logger_singletonI10dataLoggerE13init_instanceEv]+0x2d): undefined reference to `boost::log::v2_mt_posix::sources::aux::global_storage::get_or_init(std::type_info const&, boost::shared_ptr<boost::log::v2_mt_posix::sources::aux::logger_holder_base> (*)())' Here the following function is missing: *boost::log::v2_mt_posix::sources::aux::global_storage::get_or_init(std::type_info const&, boost::shared_ptr (*)())* Going into the freshly compiled Boost stage directory: balazs@balazs:/usr/local/alk/boost_1_63_0/stage/lib$ grep get_or_init *Binary file libboost_log.so matchesBinary file libboost_log.so.1.63.0 matches balazs@balazs:/usr/local/alk/boost_1_63_0/stage/lib$ strings libboost_log.so |grep get_or_init _ZN5boost3log11v2_mt_posix7sources3aux14global_storage11get_or_initENS_9typeindex14stl_type_indexEPFNS_10shared_ptrINS3_18logger_holder_baseEEEvE Demangling it yields: *boost::log::v2_mt_posix::sources::aux::global_storage::get_or_init(boost::typeindex::stl_type_index, boost::shared_ptr (*)())* which are not identical, the first function argument type differs. I used these commands to compile Boost: ./bootstrap.sh --with-toolset=clang./b2 --build-type=minimal --layout=system toolset=clang variant=release link=shared threading=multi runtime-link=shared stage How can this happen? Actually, this dynamically linked Boost is my second experiment. Originally I wanted to link it statically. Thank you in advance. Best regards: Balázs Bámer EDIT Now I have tried the Boost libraries I get with apt-get, and the situation is the same. However, I have found my old settings. They do work: add_compile_options(-std=c++14) SET(Boost_USE_STATIC_LIBS ON) find_package(Boost 1.55 REQUIRED COMPONENTS log_setup log thread date_time filesystem system) find_package(Threads REQUIRED)

2 1

Aliased parameters in boost::bind
by Evgeny Fraimovitch 31 Mar '17

31 Mar '17

Hello, The tutorial for Boost.Bind library contains the following sample code: bind can handle functions with more than two arguments, and its argument substitution mechanism is more general: bind(f, _2, _1)(x, y); // f(y, x) bind(g, _1, 9, _1)(x); // g(x, 9, x) bind(g, _3, _3, _3)(x, y, z); // g(z, z, z) bind(g, _1, _1, _1)(x, y, z); // g(x, x, x) As can be seen, all but the first of those samples alias the placeholder parameters, substituting a single passed argument several times. What is not mentioned in the tutorial (http://www.boost.org/doc/libs/1_63_0/libs/bind/doc/html/bind.html#bind.purp ose.using_bind_with_functions_and_fu) is the fact that such aliasing for any parameter with nontrivial move behavior is unexpected and possibly dangerous. For instance, given the function: void f(std::string x, std::string y, std::string z) { std::cout << x << y << z; } One could following the tutorial naively write: auto triple = boost::bind(f, _1, _1, _1); and this would even work for: std::string x = "a pretty long string"; triple(x); printing the string thrice, as expected. However the result of triple(std::string("a pretty long string")) would be the string only printed once, which is hardly what the user would expect. In fact, any bind expression produced with aliasing would be sensitive to the type of the reference passed, violating the functor abstraction badly. So, the question is: 1. This behavior seems to match the std::bind behavior documented in the standard. However, would it not be wise to warn against parameter aliasing in the tutorial then? (instead of demonstrating it as one of the first samples) 2. Maybe we can actually check if a parameter is aliased in boost::bind and copy it if it is - I have not tried it, but I think it can be done. Would it be a more sensible thing to do? The sample above might seem contrived, but I've actually encountered this bug in production code when porting it to boost 1.63 (the boost.signals code implicitly does boost::forward, so it was not outwardly apparent what was happening) Sincerely yours, Evgeny

3 6

[asio] sslv3 handshake
by Jim Gallogly 30 Mar '17

30 Mar '17

I want to do a simple C++ web get similar to what is done by this curl command. I must use boost 1.49 > curl https://mysite.dev/api/v1/search?q=test -k --cert > C:\work\testCert.pem The server is requiring the client certificate. I started by using this as an example http://www.boost.org/doc/libs/1_49_0/doc/html/boost_asio/example/ssl/client… and I added modifications by adding calls to the context like ctx.set_options(boost::asio::ssl::context::default_workarounds); ctx.use_certificate_file("C:\\work\\testCert.pem", boost::asio::ssl::context_base::pem); My Request Looks like this: > GET /api/v1/search?q=test HTTP/1.0<br> > Host: mysite.dev <br> > Accept: \*/* but I keep getting messages like this > Error: sslv3 alert handshake failure Does any one know what other steps I need to do? Is this possible in boost 1.49? Thanks, Jim

3 3

[release] Boost 1.64.0 Beta 2
by Rene Rivera 30 Mar '17

30 Mar '17

Boost release 1.64.0 beta 2 is now available at: <https://dl.bintray.com/boostorg/beta/1.64.0.beta.2/source/> The SHA256 checksums are as follows: 49c9339b9d8e7b2610ef84c80cd10b2252c119ebcc3222450beb0e94c1da1522 boost_1_64_0_b2.7z 92ec7cbf1e77c5979e381dd8104f9e96c0471c276e566272751a981d806db94b boost_1_64_0_b2.tar.bz2 da5670892b7b572808491b13a7b9421c3c18e6f395d6a5ec822466db466eda01 boost_1_64_0_b2.tar.gz 61d6e29e8a1d7503fe13a9d916842f0ec2e625f733b98b29ce563f8cbdb482bf boost_1_64_0_b2.zip The notable difference from Beta 1 is the inclusion of the missing Boost Process library. For details of what's in the release, see < http://www.boost.org/users/history/version_1_64_0.html>. Note that the links to files on this web page are for the final release - use the link above to get the beta files. There are also pre-built libraries provided by Tom Kent here: <https://dl.bintray.com/boostorg/beta/1.64.0.beta.2/binaries/> Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

2 1

[statechart] process_event vs post_event confusion
by Robert Dailey 30 Mar '17

30 Mar '17

I'm seeing a usability issue between post_event and process_event. Basically, depending on where in the state itself I'm executing an event, I need to know which to invoke. My understanding is that if I'm calling within the context of the constructor of the state, I need to use post_event. Anywhere else (outside of construction, but still within a member function of the state subclass itself), you invoke "context<MyMachine>().process_event()". Why can't post_event() automatically query the state machine to see if it is "busy" constructing a state, and if it isn't, forward the event to process_event() for me instead? Is there really a reason to have to make a logical decision between the two in code? I'm using boost::statechart in my code at $DAYJOB and this is a reasonable complaint I get in my code reviews, especially from those not very familiar with boost itself. They have an expectation for the implementation of the state machine to be intuitive and easy to understand.

2 2