October 2017 - Boost - lists.preview.boost.org

[yap] Re-announcing Yap
by Zach Laine 23 Feb '18

23 Feb '18

I posted 2-3 months ago about Yap, an expression template library I've written that I intend to propose for Boost. This is just a reminder that the library exists, and where to find it. I'm giving a talk about it at C++Now 2017, and some time after that I intend to submit it to the queue. Louis Dionne has offered to serve as review manager when the time comes. You can find the main repo on GitHub: https://github.com/tzlaine/yap And online docs are here: https://tzlaine.github.io/yap Zach

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Informal CMake meeting at CPPCon
by Robert Ramey 12 Jan '18

12 Jan '18

Thursday 28 Sept 8 AM at CPPCon a small group of us met to talk a little regarding the situation regarding support of CMake by Boost. I promoted this meeting as I've been concerned that the only discernible results of the recent Boost Steering Committee announcement on the subject was a certain level of antagonism among boost members regarding the subject. Participants ============ Robert Ramey (me) Rene Rivera Vinnie Falco Louis Dionne David Sankel Matt Calabrese This was a small but I think a representative group. After some preliminary back and forth, I think we agreed: a) Nothing was going change regarding the current build system until there was a real alternative in place. b) That we should support serious proposals to implement CMake support within boost. c) And that any such proposals should go through the Boost formal review process. Traditionally, the boost formal review process has never applied to boost tools so this would be a departure from traditional practice. d) Questions regarding the scope/implemention of such support for CMake can be handled within the formal review process. e) Other questions regarding support CMake and Boost, transition to new system, related requirements on boost libraries, etc. can be better addressed once we have some sort of consensus on the form that CMake support will take. I had contacted Paul Fultz who is the only one I know of that has proposed something specific to submit to formal review. He told me he couldn't do it at the time, but shortly there after posted such a request on the list. So I guess for now we're on our way. My motivation for posting this is to keep the boost community up to date on what's happening so that no one gets overly surprised when things start to happen. I'm not really soliciting feedback - though it wouldn't surprise me if I get some. Robert Ramey

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Re: [boost] Boost.HTTPKit, a new library from the makers of Beast!
by Vinnie Falco 01 Jan '18

01 Jan '18

On Sun, Oct 8, 2017 at 5:38 PM, Vinícius dos Santos Oliveira <vini.ipsmaker(a)gmail.com> wrote: > Now, moving on... given that you have __not__ answered how your parser's > design[1] compares to the parser I've developed I'll try to provide more clarity. `beast::basic_parser` is designed with standardization in mind, as I intent to eventually propose Beast for the standard library. Therefore, I have made the interface as simple as possible, exposing only the minimum required necessary to achieve these goals which the majority of users want: * Read the header first, if desired * Feed Asio style buffer sequences into the parser * Set independent limits on the number of header and body octets * Optional fine-grained receipt of chunked body data and metadata The design of basic_parser (the use of CRTP in particular) is meant to support the case where a user implements their own Fields container, or if they want a bit more custom handling of the fields (for example, to avoid storing them). Like all design choices, tradeoffs are made. The details of parsing are exposed only to the derived class. Complexities are hidden from the public-facing interface of `basic_parser`. Implementing a stream algorithm that operates on the parser is a straightforward process: template< class SyncReadStream, class DynamicBuffer, bool isRequest, class Derived> std::size_t read(SyncReadStream& stream, DynamicBuffer& buffer, basic_parser<isRequest, Derived>& parser, error_code& ec) { parser.eager(true); if(parser.is_done()) { ec.assign(0, ec.category()); return 0; } std::size_t bytes_transferred = 0; do { bytes_transferred += read_some( stream, buffer, parser, ec); if(ec) return bytes_transferred; } while(! parser.is_done()); return bytes_transferred; } > [1] at most it hides behind a “multiple people/stakeholders agree with me” > __shield__ There's no hiding going on here. One can only measure the relative success of designs based on the feedback from users. They opened issues, and I addressed their use-cases, sometimes with a considerable amount of iteration and back-and-forth as you have seen in the GitHub issues quoted in the previous message. Now, I don't know if the sampling of users that have participated in Beast's design are representative of the entire C++ community. However, I do know one thing - if GitHub stars are any measure of the sample size of the participants, then Beast is off to a good start. Here's a graph showing the number stars over time received by boostorg/beast, tufao, and Boost.Http (the last 2 libraries having you as the author I believe): <http://www.timqian.com/star-history/#boostorg/beast&BoostGSoC14/boost.http&…> (Note that the HTTP+WebSocket version of Beast was released in May 2016). We need to be careful interpreting results like this of course so perhaps we should look at different metrics. Here are the links to the number of closed issues for Beast, tufao, and Boost.Http: 502 Closed issues in Beast: <https://github.com/boostorg/beast/issues?q=is%3Aissue+is%3Aclosed> 38 Closed issues in tufao <https://github.com/vinipsmaker/tufao/issues?q=is%3Aissue+is%3Aclosed> 13 Closed issues in Boost.HTTP, from 6 unique users not including the author <https://github.com/BoostGSoC14/boost.http/issues?q=is%3Aissue+is%3Aclosed> Again we have to be careful interpreting results like this. But it sure looks like there is a lot of user participation in Beast. If approval from a large number of stakeholders is not a compelling design motivator then what is? > This tutorial is full of “design implications” blocks where I take the time > to dissect what it means to go with each choice. Thus far, no one has asked for more fine grained access to incoming HTTP tokens in the manner of `code::method` and `code::request_target`. If this becomes something that users consistently ask for, it can be done by changing the requirements for the derived class for `basic_parser`. This way, details about HTTP parsing which most people don't care about will not leak into the beast::http:: namespace. Such a change would not affect existing stream algorithms on parsers. Thanks

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[beast] Security
by Phil Endecott 13 Dec '17

13 Dec '17

Dear All, To what extent do we think that Beast should be "secure"? I am thinking mostly about handling malicious input. Has it been reviewed by anyone with specific experience of how HTTP can be attacked? Has it been "fuzzed"? Regards, Phil.

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MSVC 15.5 support
by Olaf van der Spek 05 Dec '17

05 Dec '17

Hi, 15.5 Preview has been released: https://blogs.msdn.microsoft.com/vcblog/2017/10/11/productivity-structure-v… > Unknown compiler version - please run the configure tests and report the results How do I do this? Could this message be updated to indicate it comes from Boost? Gr, -- Olaf

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icl mainainership?
by Avi Kivity 21 Nov '17

21 Nov '17

Hello, I see there are 7 pull requests outstanding against icl (including one of mine), but not activity. Joachim, are you still maintaining the library? If not, perhaps someone can step up.

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[devector] optimum growing/insertion policy
by Joaquin M López Muñoz 08 Nov '17

08 Nov '17

Hi, Much an worthy discussion has taken place with respect to growing and insertion policies of boost::double_ended::devector. I think I can justify what the optimum policy is when the overall goal is to minimize number of element movements. What follows is *not* a formal optimality proof, though it's my hunch one could be provided relatively easily. Assumptions * The cost of allocating new memory is negligible when compared to the cost of moving elements around (either intra-buffer or when migrating to a new buffer); so, the growing/insertion policy should focus on minimizing number of elements moved. This implies fully occupying free space before reallocation is *not* the primary goal of the growing/insertion policy. * For the purposes of our discussion, we consider an ever-growing devector without intervening erasures --erasures can be accomodated later as we will see. * Element insertion is modelled as a process where each new insertion happens at a random position within the current devector. The minimal characterization (i.e. its 1st moment in stochastic process theory terminology) is just the percentage R of insertions that happen within the right half of the devector --we call these *right insertions*; left insertions happen then with a frequency L=1-R. push_back is a right insertion, push_front a left insertion. Facts * When a right insertion arrives, if there's free back capacity the optimum insertion policy is to shift elements to the right, as this involves fewer movements than the other way around. The symmetrical applies for left insertions. * If a right insertion at position N arrives and there's no free back capacity (but there is free front capacity), we have only two options: A. Reallocate to get back free capacity. B. Shift elements to the left. The key observation here is that A is cheaper in the long run: as the scenario is one of an ever-growing sequence, reallocation will happen eventually and we can just amortize it in our analysis, so reallocating early saves us the extra movements incurred when left shifting on a right insertion, namely N - (size()-N) = 2*N - size() movements. In fact, we save more than that as insertion is done simultaneously with reallocation, hence no shifting occurs additionally to the (amortized) reallocation cost. All this analysis applies symmetrically to left insertions, of course. * The optimum growing policy is that which maximizes the probability that *both* front and back free capacities get exhausted at the same time. With our 1st moment characterization of the insertion random process, this implies that when reallocating a percentage R of the new space should be devoted to the right side, and a percentage L to the left side. Description of resulting policy * Fix the growing factor to G (this can be 1.5 or 2 or anything greater than one, the actual figure is orthogonal to the discussion). * Maintain a counter right_ of right insertions that gets incremented when a right insertion occurs and *decremented* when an erasure is issued past the middle of the devector. * Right insertions trigger right shifting except when there's no back free capacity, in which case a reallocation is performed. * Left insertions trigger left shifting except when there's no front free capacity, in which case a reallocation is performed. * Reallocation reserves space for G*size() elements: of the resulting G*size()-size() free space, a fraction right_/size() is devoted to back free capacity, the rest to front free capacity. In practice, we may want to keep some minimum space at each end as determined by some empirical threshold. And that's it. Comments welcome. Joaquín M López Muñoz

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[optional] Regression in develop
by Andrzej Krzemienski 06 Nov '17

06 Nov '17

Hi Everyone, Over the weekend I added changes to Boost.Optional in develop which caused regression in Boost.Beast and maybe more libraries. I would like to ask for your input as to how to best approach this. The change was: for trivial `T` use a different specialization of `optional<T>` which is trivially-copyable. For this, I need the ability to declare defaulted functions, and to detect that a given type is trivial. Boost.TypeTraits do not have `is_trivial` trait, so I compose it form `has_trivial_move` and the like. But it seems there are compilers for which Boost.config and Boost.TypeTraits report support for deleted functions/triviality detection, but where this support is buggy. The following is a test case in type_traits by Vinnie Falco: https://github.com/boostorg/type_traits/pull/52/commits/9779157a787620d1633… In addition, the deadline for changes in release 1.66 is getting nigh. I can see a couple of ways to fix this: 1. Fix Boost.Config and/or Boost.TypeTraits so that they only report support for the features in question when it is supported without bugs. But I do not know if there is enough time for this given the deadline. 2. Disable my feature on the compilers with buggy support. But I would need a help from someone who knows all the compilers and their bugs in implementation of trivial type traits so that I can put the wight `#ifdef`s. 3. Just revert my changes to Optional, which is also an option, but would also be a loss. Any input from Boost experts would be appreciated. Regards, &rzej;

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Building Quickbook docs from source code in HTML format
by Kolya Kosenko 31 Oct '17

31 Oct '17

Hello, I'm trying to build QuickBook HTML Boost library documentation from source code. I got *.docbook file, but there is no HTML files at all. For example I built stacktrace library docs: ./b2 -a libs/stacktrace/doc/ And I didn't get any HTML, only stacktrace.docbook: $ find . ./doc ./doc/gcc-5.4.0 ./doc/gcc-5.4.0/debug ./doc/gcc-5.4.0/debug/stacktrace.xml ./doc/gcc-5.4.0/debug/stacktrace.docbook ./doc/none ./doc/none/gcc-5.4.0 ./doc/none/gcc-5.4.0/debug ./doc/none/gcc-5.4.0/debug/autodoc-xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/classboost_1_1stacktrace_1_1basic__stacktrace.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/dir_3516969ce87a02a0560c741857e33749.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/dir_c8984f1860c11f62f47abb6761e46c1e.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/combine.xslt ./doc/none/gcc-5.4.0/debug/autodoc-xml/stacktrace_2stacktrace_8hpp.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/classboost_1_1stacktrace_1_1frame.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/compound.xsd ./doc/none/gcc-5.4.0/debug/autodoc-xml/index.xsd ./doc/none/gcc-5.4.0/debug/autodoc-xml/stacktrace__fwd_8hpp.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/index.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/stacktrace_8hpp.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/namespaceboost_1_1stacktrace.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/namespaceboost_1_1stacktrace_1_1detail.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/namespaceboost.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/dir_72bdf9838375a891eaf35cbacea5f7be.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/frame__decl_8hpp.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/frame_8hpp.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml/safe__dump__to_8hpp.xml ./doc/none/gcc-5.4.0/debug/autodoc-xml.doxyfile ./doc/none/gcc-5.4.0/debug/autodoc-xml.xml-dir ./doc/none/gcc-5.4.0/debug/autodoc-xml.boostbook ./doc/none/gcc-5.4.0/debug/autodoc-xml.doxygen But I need something like this: http://www.boost.org/doc/libs/1_65_1/doc/html/stacktrace.html I have used quickbook install instructions for Ubuntu: http://www.boost.org/doc/libs/1_65_1/doc/html/quickbook/install.html#quickb… It looks like docbook to html conversion is required using some xsl file but I don't know how to do it and what files are used. There is some XSL files in boost/tools/boostbook/xsl folder but I don't know how to use it with b2 build. PS. I have installed xsltproc, docbook-xsl, docbook-xml packages. $ cat ~/user-config.jam using boostbook ; using xsltproc ; using boostbook : /usr/share/xml/docbook/stylesheet/nwalsh : /usr/share/xml/docbook/schema/dtd/4.2 ; using doxygen ; ----- Regards, Kolya.

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[GitHelp] Getting boost stable release from GitHub after git clone
by Kostiantyn Ponomarenko 31 Oct '17

31 Oct '17

Hi, guys. I would appreciate little help in understanding what is the right way of switching to the latest stable boost release after git repository is cloned. My intention is to clone boost, because then, with new releases, I can easily update it with git and switch (checkout) to the next "current" release. PS: I like that boost uses git =). --- Kostia Kyiv, Ukraine

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