September 2015 - Boost - lists.preview.boost.org

Re: [boost] Error while building boost
by Roshan 22 Sep '15

22 Sep '15

Hi, This list is specific to the Boost.Compute library. This mail is probably meant for the main Boost mailing list. Forwarding you there. P.S. I'm not sure if the attachment is being forwarded properly, please check. On Tue, Sep 22, 2015 at 12:24 PM, <valnci89(a)gmail.com> wrote: > Hi, > > > I'm trying to install boost on my machine but its not building properly. > Attached is the output generated on running ./b2 install. > > > Commands used: > > ./bootstrap.sh --prefix=/usr/include/boost > > ./b2 install > > > Machine Info: > > OS: RHEL ppc64le > > Boost version: boost_1_59_0 > > > Let me know if any other info is required. > > > Please advice me on this issue. > > > Thanks, > > Valnci > -- Warm regards Roshan

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[Container] interest in a flat_unordered_map
by Treb Connell 21 Sep '15

21 Sep '15

I'm hoping to port a flat hash map that I've written to boost. Since boost has a flat_map I think it'd be good to have a flat_unordered_map as well, especially since there's an opportunity to be much more efficient. The one I would like to use is based on the hash map used in Lua, which is a mix of Coalesced and Robin Hood hashes. I don't think there's a name that describes it yet unfortunately, but I describe it near the end of this post. *Performance (primary reason for use):* It uses memory and cache very effectively and ends up being *very fast*. It's hard to benchmark real world situations, but in inserting, finding, erasing, and iterating over a dictionary it was up to six orders of magnitude faster than VS2013's unordered_map. This isn't a totally fair test because the cache efficiency really shines. *Standards compliance:* Differences from std::unordered_map are widely the same differences as flat_map listed here <http://www.boost.org/doc/libs/1_59_0/doc/html/container/non_standard_contai…>. Also bucket related methods no longer apply, so will be removed. *That said there's one major standards compliance issue that I'm struggling with:* The most optimal implementation of iterators for this container *does not have constant time traversal*. The implementation is a vector with elements scattered across it. To increment an iterator I continue to increment the internal vector iterator until I hit a new element. In practice elements should be scattered evenly, and will be close to one another, but in the worst case this is N-1. Additional memory or logic could be added to make this O(1), but I don't think that trade is worth it. In my applications of unordered_map I rarely iterate, and would not want to penalize insert, find, or erase to make iteration faster. I could make a new concept for this, pay the cost for making it truly O(1), or *since the common case is not O(N) would it be okay to consider these bidirectional iterators*? *Implementation details:* You can see Lua's implementation here <http://www.lua.org/source/5.3/ltable.c.html>. The applicable logic is in and below *luaH_newkey, *comments are useful. It's primarily a Coalesced hash table, but differs in collision behavior. When a new key collides with an old key, we check to see if the old key is in it's "*main position"*. The main position is the index that the key hashes to. If it's not in it's main position that means that it previously collided and was displaced. Since this is the new keys main position, we displace again the current key, and place ourselves there. This drastically decreases chain length, and improves the load factor that the hash map can optimally reach. Sorry about long post, can go into additional details upon request. Thanks, Treb

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A compile-time-counter code snippet for boost
by Igor V. Chesnokov 21 Sep '15

21 Sep '15

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[serialization] bug in static_warning.hpp
by Alain Miniussi 21 Sep '15

21 Sep '15

Hi, In static_warning.hpp we have the following code (which, if I trust its name, should trigger a *warning*): #define BOOST_SERIALIZATION_BSW(B, L) \ typedef boost::serialization::BOOST_SERIALIZATION_SS< \ sizeof( boost::serialization::static_warning_test< B, L > ) \ > BOOST_JOIN(STATIC_WARNING_LINE, L) BOOST_STATIC_ASSERT_UNUSED_ATTRIBUTE; #define BOOST_STATIC_WARNING(B) BOOST_SERIALIZATION_BSW(B, __LINE__) Now, since, since there is no BOOST_STATIC_ASSERT_UNUSED_ATTRIBUTE defined in boost (there used to be one in static_assert.hpp) this thing will generate a typedef of the form: typedef boost::serialization::BOOST_SERIALIZATION_SS< \ sizeof( boost::serialization::static_warning_test< B, L > ) \ > $STATIC_WARNING_LINE$L BOOST_STATIC_ASSERT_UNUSED_ATTRIBUTE; which is wrong. The MPI test are failing on that. Maybe BOOST_STATIC_ASSERT_UNUSED_ATTRIBUTE should be replaced with BOOST_ATTRIBUTE_UNUSED, but I am not sure what that macro is trying to achieve. Thks Alain

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[locale] char conversion issue
by Alain Miniussi 21 Sep '15

21 Sep '15

Hi, My build is failing on message.cpp with: ../../../libs/locale/src/shared/message.cpp(439): error: invalid type conversion: "const wchar_t *" to "const char *" static_cast<char const *>(p), ^ detected during: [...] caused by code like: ================= template<typename CharType> struct hash_function { size_t operator()(message_key<CharType> const &msg) const { pj_winberger_hash::state_type state = pj_winberger_hash::initial_state; CharType const *p = msg.context(); if(*p != 0) { CharType const *e = p; while(*e) e++; state = pj_winberger_hash::update_state(state, static_cast<char const *>(p), static_cast<char const *>(e)); state = pj_winberger_hash::update_state(state,'\4'); } =================== Which looks like a legitimate error since that conversion does not seems t be covered by static_cast. This is on bot master and develop branch. The compiler is intel 16: [alainm@gurney build]$ icpc --version icpc (ICC) 16.0.0 20150815 Copyright (C) 1985-2015 Intel Corporation. All rights reserved. [alainm@gurney build]$ Regards Alain

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[Compute] array support
by Fabian Bösch 19 Sep '15

19 Sep '15

Hi, I've been using Boost.Compute for some tests in the last couple of days. So far, it has proven very useful and I came to like it quite a bit. One thing I would add to it, though, is support for arrays when adapting your own classes for OpenCl through the Macro BOOST_COMPUTE_ADAPT_STRUCT. A simple overload would do the trick in my opinion: namespace boost { namespace compute { namespace detail { template<class Struct, class T> inline std::string adapt_struct_insert_member(T Struct::*, const char *name) { std::stringstream s; s << " " << type_name<T>() << " " << name << ";\n"; return s.str(); } template<class Struct, class T, int N> inline std::string adapt_struct_insert_member(T (Struct::*)[N], const char *name) { std::stringstream s; s << " " << type_name<T>() << " " << name << "[" << N << "]" << ";\n"; return s.str(); } } // end detail namespace } // end compute namespace } // end boost namespace Hope something along this lines can be added, thanks, Fabian

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[Coroutine] Back to the caller
by Mikhail Strelnikov 18 Sep '15

18 Sep '15

Hi, I have an issue after switching from Boost.Coroutine to Boost.Coroutine2 - nested coroutine switches to its creator - not to the caller. Here is the code - http://codepad.org/WGNs0N7F There are two coroutines (1st coroutine starts, makes some progress, then spawns 2nd coroutine. But 1st coroutine knows nothing about 2nd and does not communicate with it - main thread does). With Boost.Coroutine it works as expected and outputs: g1g1g1g1g2g1g2g1g2g1g2g1g2g1g2g1 leaving coroutine 1 g2g2g2g2 leaving coroutine 2 Here you can see that 1st coroutine exits but 2nd keeps working normally. And control from coroutines is returned back to the caller (g - caller, 1 and 2 - coroutines). But with Boost.Coroutine2 it outputs: g1g1g1g1g21g1g21g1g1g21 leaving coroutine 1 assertion failed : (false) && ("pull_coroutine is complete") Here you can see that when caller (g) calls 2nd coroutine, it does not yield back to caller, but instead switches to 1st coroutine ("g21" in output).Then it terminates on assert "pull_coroutine is complete". Is it a bug of Boost.Coroutine2? If not, how can I change this code to work equally for Boost.Coroutine and Boost.Coroutine2? Thanks! P.S. What is the reason of boost::coroutines2::coroutine<void>::pull_type not having default constructor? It is still possible to have an "empty" pull_type, but it is painful process.

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Interest in algorithm for arithmetic mean of integers
by Matt Calabrese 17 Sep '15

17 Sep '15

AFAICT the only function for calculating arithmetic mean in boost is in the accumulators library and it's not really appropriate for integral types. In practice, properly calculating the mean for a range (especially a range that's only an input range but not a forward range) is surprisingly tricky to do in a way that avoids overflow and provides an exact result. I have a couple of solutions, including one that works for input ranges. Is this something that people would find useful? Is there a similar algorithm already implemented in boost that I'm not aware of? The approach I've taken yields an exact result as a mixed number and should work without overflow (assuming only that the range's size is able to be represented by its difference type). I believe the implementation that works for input ranges could theoretically be adapted to work with Boost.Accumulators, though I'm admittedly not too familiar with the library. -- -Matt Calabrese

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integrating NaCl support into boost
by Konstantin Ivlev 17 Sep '15

17 Sep '15

Hi boost community, some introdution: NaCl (Google NativeClient, https://developer.chrome.com/native-client) - open-source technology authored by Google Inc. providing way to run native code inside web-browser in portable and secure manner. NaCl provides posix-like environment, and supports newlib and glibc standard libraries. currently NaCl is supported by Google Chrome web-browser, and range of applications and software libraries are ported to NaCl (include zlib, quake, etc.). how about integrating NaCl support patches into the boost main-line (trunk/master), I am talking about these NaCl ports patches from Google: https://chromium.googlesource.com/external/naclports/+/master/ports/boost (I actually have a bit more correct patches that allow to compile boost 1.59 for NaCl platforms, while Google patches are still for old version 1.55). some details about patches and which boost areas are covered by patches: - boost/config - common setup for NaCl - boost/cstdint - small change to expose boost::uintptr_t/boost::intptr_t for NaCl, similarly to how it was done to other compilers - buitin.jam and gcc.jam - introduced new os-name for NaCl, in order to properly setup threading libraries (NaCl has pthread but no rt, just like BSD) - boost/system/errorcode - oddball version of strerror_r (just like cygwin), also ENOTRECOVERABLE & EOWNERDEAD errno codes are not supported by PNaCl - boost/log/light_rw_mutex - not supported on NaCl note that boost build is incomplete - certain libraries are not (yet) ported to NaCl, because of platform-specific stuff like file/network I/O : - context - coroutine - coruutine2 - log - filesystem - test - timer - wave not sure if it's OK for start, or all boost libraries should be ported together in order to process further. I would be grateful to hear suggestion about how to process with it, e.g. which actions should I take to make it really happen. I personally suppose making boost to officially support more platforms will make boost even more popular and allow more developers to use it and port their applications to other platforms. I look forward to hearing from you soon. yours sincerely, Konstantin

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Windows Phone and Visual Studio 2015
by Vladimir Prus 17 Sep '15

17 Sep '15

Folks, did anybody had success building Boost for Windows Phone using Visual Studio 2015 (aka 14.0)? We have Boost.Build code to do so, but it tries to find vcvarsphoneall.bat script, and some other similarly named scripts, that I don't seem to have anywhere, despite been able to build WP app from the IDE. Has anybody solved this? Thanks, Volodya

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