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[gsoc15] Attn: We need 2015 mentors and project ideas for Boost!
by Niall Douglas 11 Feb '15

11 Feb '15

Dear Boost community, We are now within one month of the beginning of Google Summer of Code 2015! Last year's GSoC furthered the continuing success of the Boost GSoC programme with the first ever Boost funded extension to a GSoC project (that being Boost.Hana by Louis Dionne mentored by Joel Falcou, congrats to both of them on passing an exceptionally tough selection process), and over $50,000 of Google funding brought to Boost in 2014. We also sent three representatives to last year's mentor summit, including one student whose entire expenses the Boost Steering Committee very generously covered. As part of filling in our application for 2015, we must supply to Google a list of potential GSoC mentors and potential GSoC projects for summer 2015. There are a number of changes to how we design project ideas for students this year intended to improve the GSoC experience for both students and mentors, so please examine the ideas page which outlines those changes at https://svn.boost.org/trac/boost/wiki/SoC2015 and if you have any questions or concerns about those changes, please ask now rather than just before the GSoC deadline. If you think yourself able to mentor a student doing some work on Boost this summer, *please* consider adding a description of the proposed work item and your name to the list. Last year we acquired eight slots from Google and had to disappoint two mentors and students, we hope with the improved selection process we can get back to the ten annual slots we once had. If you want to know more about mentoring a Google Summer of Code funded student work before you nominate yourself, please feel free to ask on the main Boost developers mailing list boost(a)lists.boost.org. Thank you in advance for your time. Niall Douglas (Boost Google Summer of Code admin) Boris Schäling (Boost Google Summer of Code admin) --- Boost C++ Libraries Google Summer of Code 2014 admin https://svn.boost.org/trac/boost/wiki/SoC2014

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[iostreams] How to utilize zlib setDictionary method
by Ringel, Rick 10 Feb '15

10 Feb '15

I have a use-case that requires highly efficient bandwidth utilization over a narrow WAN connection, where communication is message-oriented. I have successfully used boost to gzip, zlib, and bzip2 my messages, and ran some numbers (bzip2 is best so far). However, in researching and profiling zlib's native API, I found I could improve efficiently by an additional 15% over bzip2 by using zlib's SetDictionary methods for deflate and inflate. How would I go about extending boost:iostream's zlib_compressor and zlib_decompressor classes to utilized a predefined/static dictionary? Or, is it best just to use zlib's API directly, and bypass boost for this specialized zlib compression case? -Rick

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Re: [Boost-users] Boost-users Digest, Vol 4049, Issue 1
by David Frank 10 Feb '15

10 Feb '15

Thanks Howard ! On Monday, February 9, 2015 12:00 PM, "boost-users-request(a)lists.boost.org" <boost-users-request(a)lists.boost.org> wrote: Send Boost-users mailing list submissions to boost-users(a)lists.boost.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.boost.org/mailman/listinfo.cgi/boost-users or, via email, send a message with subject or body 'help' to boost-users-request(a)lists.boost.org You can reach the person managing the list at boost-users-owner(a)lists.boost.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Boost-users digest..." Today's Topics: 1. Re: Signals2 benchmark (Klaim - Jo?l Lamotte) 2. Re: Signals2 benchmark (Michael Powell) 3. write starvation of upgradable lock (David Frank) 4. Re: write starvation of upgradable lock (Howard Hinnant) 5. Re: Signals2 benchmark (Nevin Liber) 6. Re: [Serialization] XML: float format is scientific instead of human-readable since Boost 1.57 (Frank St?hr) 7. Re: Signals2 benchmark (Dominique Devienne) ---------------------------------------------------------------------- Message: 1 Date: Sun, 8 Feb 2015 18:49:06 +0100 From: Klaim - Jo?l Lamotte <mjklaim(a)gmail.com> To: Boost users list <boost-users(a)lists.boost.org> Subject: Re: [Boost-users] Signals2 benchmark Message-ID: <CAOU91ON-+ywWjniue3n56sYSy2ZALtYykDN9ehLp4Qcm6BYoxg(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" On Sun, Feb 8, 2015 at 4:42 PM, Michael Powell <mwpowellhtx(a)gmail.com> wrote: > On Sun, Feb 8, 2015 at 8:02 AM, Klaim - Jo?l Lamotte <mjklaim(a)gmail.com> > wrote: > > > > > > An executor takes arbitrary tasks as input and only > > guarantee that these tasks will be executed, under some constraints > > defined by the specific executor type. > > A signal dispatch it's call and parametters to a set of observers. > > Using the Boost.Signals2 for example, it is easy AFAIK to type-define > a signal, and re-use that type anywhere that signal is required. So a > listener could receive a signal, and subsequently do whatever it > wanted to with that message; dispatch it again, process it, > whatever... > > Yes but the executor would specify how the observers are notified, not how the observer's work is executed (which depends on the observer implementation indeed). There is an important nuance here.

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boost variant + boost serialization unused type
by Merrill Cornish 10 Feb '15

10 Feb '15

Using boost::variant with boost::serialization gives me a warning about unused type in the boost::serialization namespace: D:/Boost/boost/serialization/variant.hpp:69:75: warning: typedef 'types' locally defined but not used [-Wunused-local-typedefs] typedef typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::types types; I looked up boost::ignore_unused, which says it's for unused types also, but everything I've tried for using in my code (following the definition of my variant) results in a syntax error or other bug claim. How should I use ignore_unused in this case?

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[Serialization] XML: float format is scientific instead of human-readable since Boost 1.57
by Frank Stähr 09 Feb '15

09 Feb '15

Hello Boost guys, when I switched from Boost 1.55 to 1.57 there was a change in the formation of floats and doubles for xml archives. Look at this example: #include <fstream> #include <boost/archive/xml_oarchive.hpp> class MyClass { friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & boost::serialization::make_nvp("accuracy", accuracy); } double accuracy = 0.03; }; int main() { MyClass obj; std::ofstream ofs("sample.xml"); boost::archive::xml_oarchive oa(ofs); oa & boost::serialization::make_nvp("myclass", obj); } I compiled it with VS 2013 for 32 bit. The output file has the line: <m_accuracy>2.99999999999999990e-002</m_accuracy> In Boost 1.55 it was much better human-readable: 0.03. Is this behaviour (this change) intended? In any case, what is the best way to format floats and doubles? (i. e. a manipulator for the ofstream?) Thanks, Frank -- Frank Stähr Technische Universität Berlin Communication Systems Group Sekr. EN1 Einsteinufer 17 10587 Berlin, Germany

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write starvation of upgradable lock
by David Frank 09 Feb '15

09 Feb '15

From this discussion, http://stackoverflow.com/questions/21773618/starvation-with-upgrade-lock?no… There seems to be a starvation of writer with upgradable lock, I'm wondering if there is any fix/improvement with later release, e.g, 1.56, or 1.57 Thanks,David

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[website] File appears truncated
by Joaquin M Lopez Munoz 08 Feb '15

08 Feb '15

The following file (which is linked from Boost.MultiIndex docs): http://www.boost.org/doc/libs/1_57_0/libs/multi_index/example/hashed.cpp appears truncated at line 8, yet it is perfectly OK in github: https://github.com/boostorg/multi_index/blob/master/example/hashed.cpp Any clue what's going on? Thank you, Joaquín M López Muñoz Telefónica

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[System] Link issues using BOOST_ERROR_CODE_HEADER_ONLY
by Jonathan Jones 07 Feb '15

07 Feb '15

Hello, We're in the process of upgrading from Boost 1.49 to Boost 1.56. As part of this upgrade, we've noticed the linkage requirements for using the "system" library are much more strict in 1.56. We are getting linker errors like the following across dozens of our libraries: boost/system/error_code.hpp: undefined reference to `boost::system::generic_category()' boost/system/error_code.hpp: undefined reference to `boost::system::system_category()' We decided to fix these by defining the macro BOOST_ERROR_CODE_HEADER_ONLY according to this link: http://www.boost.org/doc/libs/1_56_0/libs/system/doc/reference.html#Header- error_code However, when building Boost itself with this macro defined, we're encountering several problems: 1) Some Boost libraries (chrono, filesystem, random) that use the "system" library no longer link, as if they are still expecting the library to be present. Note that some libraries, like thread, that use "system", link fine without the shared library being present. 2) We get multiple definitions of "boost::system::throws" Any thoughts on how to resolve these? Google search has not turned up any bugs that I can find. Sincerely, Jonathan Jones

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[msm] multi thread access
by Sam Fisher 05 Feb '15

05 Feb '15

Hi Christophe, Did you consider adding build-in multi-thread support? (via policies maybe?) For example, I can guaranteed that all access to sub-fsm within its handlers (process_event()) will be synchronized. The problem is, sub-fsm "knows" about its parent and internally communicates with it (forwarding events etc). I can't control it from my side. typical scenario: an action from sub-fsm struct A_Init { template <typename Evt, typename FSM, typename SourceState, typename TargetState> void operator()(Evt&, FSM& fsm, SourceState&, TargetState&) const { std::thread([=]() mutable { std::lock_guard<std::mutex> l(access); fsm.process_event(some_event()); }).detach(); } }; locking proccess_event() in sub-fsm doesn't help if it alters the root.

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Using io_service for synchronous tcp accept + custom tasks
by Aaron Levy 05 Feb '15

05 Feb '15

I've written code of the form: Code: io_service svc; io_service::work work(svc); thread t1( [&svc]() { svc.run(); } ); thread t2( [&svc]() { svc.run(); } ); thread t3( [&svc]() { svc.run(); } ); endpoint ep(ip::tcp::v4(), port); acceptor acceptor(svc, ep); while (true) { shared_ptr<socket> sock(new socket(svc)); acceptor.accept(*sock); svc.post( [sock]() { /* do stuff on sock here */ }); } Is this way of using io_service for accepting tcp connections and also as a thread pool for serving connected clients valid or could I hit some undefined behavior. -- Aaron Levy aaron.levy(a)yandex.com

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