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[Boost.Lockfree] Interest in a ringbuffer class
by Raphaël Londeix 27 Jan '17

27 Jan '17

Hi everyone, Is there any interest in having a lower level ringbuffer type in Boost.Lockfree ? The containers provided today in the library can only store homogeneous types of fixed size. At work, we have refined many implementations of ringbuffer classes that allow one to push/pop raw buffers. Before investing some time into a pull request, I wanted to know if there's some interest in such a type. The interface looks like this: template<typename Self, typename... Policies> class basic_ringbuffer { public: typedef ... buffer; public: buffer* start_write(size_t); void commit_write(size_t); void commit_write(buffer const*); buffer const* start_read(); void commit_read(size_t); void commit_read(buffer const*); public: void reader_reset(); void writer_reset(); private: buffer* _ring() { return static_cast<Self>(*this).ring(); } }; Of course, these are only the lowest level methods, one could implement push()/pop() or other higher level methods. Beyond the fact that this API provides by default zero-copy semantics, this interface is also agnostic to the actual owner of the memory, which allow users to implement custom ringbuffers easily (shared memory, mmap trick to map the beginning at the end, etc.), for example: class custom_ringbuffer : basic_ringbuffer<custom_ringbuffer, SomePolicies...> { buffer* ring() { return some_memory; } }; The usage would look like: custom_ringbuffer rb; // the write side if (auto buf = rb.start_write(100)) { memcpy(buf.data, "some data", 9); rb.commit_write(9); } // the read side if (auto buf = rb.start_read()) { std::cout << std::string_view(buf.data, buf.size) << std::endl; rb.commit_read(buf); } What do you think ? Did I miss something in boost itself ? Should I give a more complete overview of the API ? Cheers, -- Raphaël Londeix http://hotgloupi.fr

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[outcome] Requesting second pre-review of Boost.Outcome tutorial
by Niall Douglas 27 Jan '17

27 Jan '17

Dear Boost, Last November you gave me some valuable feedback on rewriting the tutorial for Boost.Outcome, a C++ 14 library providing a factory and family of policy driven lightweight monadic value-or-error transports. I recently came out of employment contract and so have had the time to rewrite Outcome's Tutorial (anyone interested in employing a remote working C++ consultant please do get in contact). I'd appreciate feedback on https://ned14.github.io/boost.outcome/: 1. Is this rewritten tutorial too simple, too detailed or about right? 2. Do you feel you could use Outcome in your own code without difficulty after reading it? If not, what information is missing? 3. Are you persuaded of the merits of using Outcome after reading it? If not, what else do I need to say? The first FOUR sections at https://ned14.github.io/boost.outcome/ have been rewritten by me to hopefully reflect the feedback you gave me last November, so these have been refactored so far: * Description, Prerequisites and Support * Installing, building and testing Outcome * Quick start for the expert * Tutorial The package repo install methods haven't been implemented yet, these are marked in the docs as todo. These sections have yet to be refactored: * Frequently Asked Questions * Advanced usage: Outcome as a Monad * Outcome and the upcoming std::expected<T, E> Many thanks in advance for any feedback received. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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Why is this message in Spam?
by Olaf van der Spek 26 Jan '17

26 Jan '17

Hi, > Why is this message in Spam? It has a from address in microsoft.com but has failed microsoft.com's required tests for authentication. Learn more I think this list isn't configured properly.. and this causes some messages to end up in Spam consistently.. Who's responsible for the mailing list infrastructure? Gr, -- Olaf

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[sort] pdqsort
by Steven Ross 26 Jan '17

26 Jan '17

I've been reviewing a proposed addition to Boost.Sort called pdqsort. When using a general-case partitioning algorithm, it performs comparably to std::sort in my testing (Windows and Linux). When used as a replacement for the std::sort fallback in spreadsort, using a branch-reducing optimization it is ~20% faster on ints and floats, and ~40% slower on strings. The concerning part is that any comparison operator that involves a branch may have a comparable slowdown to the string case. pdqsort is also significantly faster than std::sort on mostly-sorted data and some other (relatively common) special cases. This makes little difference when used as a fallback by spreadsort, but does make a difference when used on its own. I see these possible things to do with pdqsort: 1) Reject it completely as too similar to std::sort, which is already highly optimized. 2) Add it as another optional library in the Boost.Sort library. 3) Add it to Boost.Sort, and only use it as a fallback for ints and floats. 4) Add it to Boost.Sort, use it as a fallback for all of spreadsort, and have pdqsort itself only use its branch-reduction optimization on ints and floats. 5) #4, except eliminate the branch-reduction optimization completely from pdqsort for simplicity. Does anyone have a strong preference, advice, or comments on how they use Boost.Sort? Should I run a mini-review for pdqsort?

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bad include guards
by Steven Watanabe 26 Jan '17

26 Jan '17

AMDG The following pairs of files have identical include guards ./boost/concept_check/general.hpp ./boost/concept/detail/msvc.hpp ./boost/concept_check/msvc.hpp ./boost/concept/detail/msvc.hpp ./boost/filesystem/cerrno.hpp ./boost/cerrno.hpp ./boost/interprocess/containers/tree.hpp ./boost/interprocess/containers/detail/tree.hpp ./boost/mpl/min_max.hpp ./boost/mpl/max.hpp ./boost/mpl/vector/aux_/front.hpp ./boost/mpl/list/aux_/front.hpp ./boost/multi_index/identity_fwd.hpp ./boost/multi_index/identity.hpp ./boost/python/pointee.hpp ./boost/python/detail/pointee.hpp ./boost/spirit/phoenix/closures.hpp ./boost/lambda/closures.hpp ./boost/xpressive/proto/v1_/proto_typeof.hpp ./boost/xpressive/proto/proto_typeof.hpp ./libs/config/test/boost_no_dep_nested_class.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_mem_templates.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_std_allocator.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/conversion/test.hpp ./libs/any/test.hpp ./libs/interprocess/example/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/expand_bwd_test_template.hpp ./libs/interprocess/test/allocation_test_template.hpp ./libs/interprocess/test/printcontainer.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/iostreams/test/detail/utf8_codecvt_facet.hpp ./boost/detail/utf8_codecvt_facet.hpp ./libs/regex/test/regress/test_regex_search.hpp ./libs/regex/test/regress/test_partial_match.hpp ./libs/serialization/test/C.hpp ./libs/serialization/test/A.hpp ./libs/xpressive/perf/regex_comparison.hpp ./libs/regex/performance/regex_comparison.hpp ./tools/inspect/time_string.hpp ./tools/common/time_string.hpp In Christ, Steven Watanabe

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Boost XML Serialization Stability across library versions
by Adlai Shawareb 26 Jan '17

26 Jan '17

Hi, We want to generate an Serialized XML archive now, and be able to deserialize it and get the same data it in the future. Is Boost XML Serialization guaranteed to be compatible across versions of the library? The XML serialized archive would be stored in a memory chip and, in the future, read back and deserialized. I don't believe that would impact the answer, but want to offer that. Adlai

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Moving away from SourceForge
by Louis Dionne 26 Jan '17

26 Jan '17

Hi, I know this has been discussed in the past, but I would like to revive the discussion about moving away from SourceForge as Boosts' release hosting provider. SourceForge has at least the following issues: - There is no way of controlling the format when downloading an archive of the latest release. This can break people that rely on this in their CI scripts. For example, Metabench's[1] CI was broken for a while when the archive changed from .bz2 to .zip. - SourceForge has been in the middle of some controversies[2]. - Their reliability has not been so great. In the past year, I've had quite a few of my Travis jobs fail due to SourceForge being unresponsive. There are most likely other concerns, but these are the ones that really bite me as a user right now. Am I the only one? If there's some push to do the move, the two main candidates I see would be - GitHub's native hosting - Bintray Thoughts? Louis [1]: https://github.com/ldionne/metabench [2]: https://en.wikipedia.org/wiki/SourceForge#Controversies -- View this message in context: http://boost.2283326.n4.nabble.com/Moving-away-from-SourceForge-tp4691184.h… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Boost.Endian - endian_buffer requirements
by Vicente J. Botet Escriba 26 Jan '17

26 Jan '17

Hi, I wanted to put an Int wrapper inside a endian_buffer and I have some compiler errors depending on whether it is aligned ort not. http://melpon.org/wandbox/permlink/k52wH2A7yagL2vMP I was expecting that the endian_buffer would make abstraction of the wrapped type and consider it just as a sequence of bytes, but it seems that it instead works only for some builtin integral. Am I missing something? Was this restriction intended? Could this restriction be removed and if yes, how? Best, Vicente

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[program_options] implicit value and non-adjacent tokens
by Vladimir Prus 25 Jan '17

25 Jan '17

Hi, some time ago, program_options was modified so that options with implicit value would only take value from the same token. Previously, one could have: ./program -a foo -b # uses 'foo' as value for 'a' ./program -a -b # uses some default value for 'a' ./program -b # has no value for 'a' Now, the first syntax interprets 'foo' as positional option, and one has two write ./program -a=foo Ever since, I hear concerns from users about this behavior. Maybe not very loud, but quite consistent. Maybe, the new behavior is not very good, indeed, because it now mixes syntax matter (whether value is in the same token) with semantic matter (whether an option has implied value). I am considering reverting this change for next version of Boost. Does anybody have opinions either way? Thanks, Volodya

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C++Now / BoostCon 2017 -- Call For Submissions
by Michael Caisse 23 Jan '17

23 Jan '17

This is a quick reminder that the C++Now 2017 Call For Submissions is *open*. All submissions must be made by February 3rd. For more information, see http://cppnow.org/

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