July 2011 - Boost-users - lists.preview.boost.org

[Review] Lockfree review: today (July 28th) is the last day
by Hartmut Kaiser 28 Jul '11

28 Jul '11

All, Today is the last day of the review of Tim Blechmann's Lockfree library. If you're interested in this library, please consider contributing a review! If you need more time, please contact me privately. Please see the original (slightly corrected) announcement below: ----------------------------------------------------- About the library: Boost.Lockfree provides implementations of lock-free data structures. Lock-free data structures can be accessed by multiple threads without the necessity of blocking synchronization primitives such as guards. Lock-free data structures can be used in real-time systems, where blocking algorithms may lead to high worst-case execution times, to avoid priority inversion, or to increase the scalability for multi-processor machines. The following data structures are provided: - boost::lockfree::fifo, a lock-free fifo queue - boost::lockfree::stack, a lock-free stack - boost::lockfree::ringbuffer, a wait-free single-producer/single-consumer ringbuffer. The library is accessible from here: http://tim.klingt.org/boost_lockfree.tar.gz. Boost.Lockfree depends on C++0x atomics. They are not well supported with current compilers yet. For this reason Boost.Lockfree depends on the *unreviewed* Boost.Atomic library, that emulates C++0x atomics for C++98. This review is about Boost.Lockfree and not about Boost.Atomic, although it is included in the tarball and the git repository. If Boost.Lockfree will be accepted, it won't be merged into trunk before Boost.Atomic is accepted. --------------------------------------------------- Please always state in your review, whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Regards Hartmut Review Manager

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Odd Warning in transform_iterator.hpp ?
by John M. Dlugosz 28 Jul '11

28 Jul '11

I'm using the current Boost library on Microsoft Visual Studio 2005. I'm getting a warning on line 121 of transform_iterator.hpp, complaining "returning address of local variable or temporary". The line in question is the body of this function: typename super_t::reference dereference() const { return m_f(*this->base()); } My m_f supplied to the template is ordinary enough; it returns a value. The exact same situation in a unit test gives no complaint! Any idea what this is all about?

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Linker options
by Sergiy Nazarenko 28 Jul '11

28 Jul '11

Hi everyone! I'm begginers to use bjam and boost. I've built python-extension. I successfully compiled it by bjam. My Jamroot file like this: use-project boost : ../../.. ; project : requirements <library>/boost/python//boost_python ; python-extension myext : myext.cpp ; And I have custom shared library with extra functions . Now I'm trying to use extra functions in python library. My questions is how put linker options in bjam project? Something like this: -L/path/to/my/library/lib64/ -lmylib.0.1 If I append include options for a file, my MyLib.h is found but linker does not find library itself. I append like this: python-extension myext : myext.cpp <include>/path/to/my/library/include; I've tried to use following # <library-path>/path/to/my/library/lib64/ # <library-file>mylib.0.1.so but with these options my extension is not compiled. Cheers,

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Boost Shared Memory Compilation Issue
by Nathan Lewis 27 Jul '11

27 Jul '11

What an great library! I am trying to extend one of the shared memory examples but I am getting a compilation error. Basically I have added a vector of char_strings to the complex object and added a method to add a string to the vector. If anyone would take a moment to give me suggestion for how to fix this issue or a suggestion for how I should better add strings to this vector I would appreciate your input. The error is: error C2664: 'void boost::container::vector<T,A>::push_back(const boost::interprocess::rv<T> &)' : cannot convert parameter 1 from 'char_string *' to 'const boost::interprocess::rv<T> &' with [T=char_string, A=char_allocator] and[T=boost::container::basic_string<char,std::char_traits<char>,char_allocator>] Reason: cannot convert from 'char_string *' to 'const boost::interprocess::rv<T>' with [T=boost::container::basic_string<char,std::char_traits<char>,char_allocator>] No constructor could take the source type, or constructor overload resolution was ambiguous The code is: #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/map.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> using namespace boost::interprocess; //Typedefs of allocators and containers typedef managed_shared_memory::segment_manager segment_manager_t; typedef allocator<void, segment_manager_t> void_allocator; typedef allocator<int, segment_manager_t> int_allocator; typedef vector<int, int_allocator> int_vector; typedef allocator<int_vector, segment_manager_t> int_vector_allocator; typedef vector<int_vector, int_vector_allocator> int_vector_vector; typedef allocator<char, segment_manager_t> char_allocator; typedef basic_string<char, std::char_traits<char>, char_allocator> char_string; typedef vector<char_string, char_allocator> char_string_vector_vector; class complex_data { public: //Obviously making the variables of complex_data public isn't a good idea I am just playing here for the moment int id_; char_string char_string_; char_string_vector_vector char_string_vector_vector_; double price_; //Since void_allocator is convertible to any other allocator<T>, we simplify //the initialization taking just one allocator for all inner containers. complex_data(int id, const char *name, double prce, const void_allocator &void_alloc) : id_(id), char_string_(name, void_alloc), char_string_vector_vector_(void_alloc), price_(prce) {} // add a string --> Error is on the next line void addStringItem(char_string* s){char_string_vector_vector_.push_back(s);} }; int main () { //Remove shared memory on construction and destruction struct shm_remove { shm_remove() { shared_memory_object::remove("MySharedMemory"); } ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); } } remover; //Create shared memory managed_shared_memory segment(create_only,"MySharedMemory", 65536); //An allocator convertible to any allocator<T, segment_manager_t> type void_allocator alloc_inst (segment.get_segment_manager()); //Construct the shared memory map and fill it complex_data *mymap = segment.construct<complex_data>("Complex_Data")(7, "hi", 7.0, alloc_inst); // return 0; }

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[Boost][Serialization] ASSERT triggered during reading 1.40 binary archive w/ Boost 1.47
by Marc Perso 27 Jul '11

27 Jul '11

Hello Booster, We are trying to jump from Boost 1.40 to Boost 1.47 but we are facing an issue: an ASSERT is raised in debug mode when reading back binary archive generated by Boost.Serialization 1.40 with the Boost.Serialization 1.47. This ASSERT is at line 116 in basic_archive.hpp: BOOST_ASSERT(t_ <= boost::integer_traits<base_type>::const_max) And it occurs with the following platform: MSVC 8.0 and Windows XP/32bits or Win7/64bits. Looking at the load_override and save_override implementations for class_id_type in #1.40, they seem loading and saving an 'int_least16_t' (equiv. to a short for our platform) while load_override(class_id_type) for #1.47 attempts to read an 'int' (file: basic_binary_iarchive.hpp @ line 98). My questions are: - This assert suggests that we can't read back previous binary archives (#1.40 at least) with Boost.Serialization 1.47, is this a known pending issue for Boost.Serialization? - If yes, how we can manage that and how we can complete the migration to 1.47 in our case (it should be noted that we must be able to read back our 1.40 binary archives)? Is there any known patch for this problem? Any assistance will be greatly appreciated. Best regards, Marc Viala PS: I'm not sure but ticket #5567 seems already opened on this issue but has not been yet fixed (https://svn.boost.org/trac/boost/ticket/5567).

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TR1 on Mac OS X
by John M. Dlugosz 27 Jul '11

27 Jul '11

It seems that the CLANG compiler that is used for Mac development, Apple LLVM 2.1, is missing _some_ of the TR1 headers. For example, it has <array>, but does not find <type_traits>. If the |boost-install-path/boost/tr1/tr1 is put first in the include path, is it set up to use the native stuff that does exist, and Boost for the rest? What about the per-feature usage that is used within the library, <boost/tr1/xxxxx.hpp> ? Will that bring in the native <array>, but the Boost type_traits.hpp? Any general suggestions on writing portable code on the Mac that will use TR1 and whatever newer features are available? Thanks, —John |

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[Boost.Serialization] Dealing with offsets
by Júlio Hoffimann 27 Jul '11

27 Jul '11

Dear Boost users/devs, Suppose i have a simulator S: R^n ---> R such that each run is during about 1 hour. Even using Boost.MPI, is expensive to run thousands of simulations all the time. To solve this problem, i'm wondering in use Boost.Serialization to store the pairs inputs/output in a boost::serialization::binary_archive and check before run if those inputs had an associated output already. By reading the Boost.Serialization docs, i can't found a way to deal with offsets in the archive, in really i don't know if it's possible. My intention is to get an archive like: 1.3, 2.5, ..., 4.6 0.1, 4.3, ..., 5.0 ... ... 123445 1234542 9893 1234 ... and skip the first rows, which are the inputs, to get the associated outputs. If you have any advice to solve this or know another more appropriate approach for this restart feature, please let me know. The second option i have in mind is work with C++ file streams and save the floating points by using the low-level std::fstream::read std::fstream::write functions. Best regards, Júlio.

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ASIO async_accept() and c++2011 lambas
by Claude 27 Jul '11

27 Jul '11

Hi, I found this example for use the async_accept() method: void accept_handler(const boost::system::error_code& error) { if (!error) { // Accept succeeded. } } ... boost::asio::ip::tcp::acceptor acceptor(io_service); ... boost::asio::ip::tcp::socket socket(io_service); acceptor.async_accept(socket, accept_handler); It is possible use the async_accept with a (c++0x) lambda function instead of the function accept_handler()? -- View this message in context: http://boost.2283326.n4.nabble.com/ASIO-async-accept-and-c-2011-lambas-tp36… Sent from the Boost - Users mailing list archive at Nabble.com.

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Chrono.hpp
by Sarkar, Arup 27 Jul '11

27 Jul '11

Hi: I am just getting to know boost library, I was able to execute the lambda program mentioned in the documentation without any problem. Now I am trying out with chrono, so I am doing the following, I am getting an error. #include <boost/chrono/chrono.hpp> Same is true for posix_time.hpp as well, the error says Cannot open include library file: 'boost/chrono/chrono.hpp' No such file or directory, but it is not complaining when I am using lambda. Can anyone please help. Regards, Arup

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Is now a good time to use Boost.Log?
by bear330 27 Jul '11

27 Jul '11

Hi, I am looking for a good logging library, I very like boost libraries and almost all my C++ projects use it. So the Boost.Log is the first choice I am considering. But Boost.Log is accepted for a long time and still not ship with latest Boost library. I heard about it is developing v2. I am not sure about its API will change a lot or not. If I use Boost.Log v1 now, would that be painful to upgrade to final Boost.Log that ships with Boost library? And is Boost.Log v1 efficient enough or stable enough just like other boost libraries? (I concern about that because it is not ship with boost release for a long time). Thanks a lot. -- View this message in context: http://boost.2283326.n4.nabble.com/Is-now-a-good-time-to-use-Boost-Log-tp36… Sent from the Boost - Users mailing list archive at Nabble.com.

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