December 2012 - Boost-users - lists.preview.boost.org

[Interprocess] message queue Cannot Allocate Memory
by cons_Pavignani, Antonio 08 Dec '12

08 Dec '12

Dear all, I use the message queue. I create a queue inside a thread (called Thread A) and I use it in another thread (called Thread B). I get this error: Cannot Allocate memory. This is the code related to the Thread A: message_queue::remove(InterprocessQueueName.c_str()); message_queue mq(open_or_create,InterprocessQueueName.c_str(),MAX_INTERPROCESS_SEND_QUEUE_SIZE,CalculatingSizeStructure::maxSizeHMIExtMessage); for(;;) { try { unsigned int priority; std::size_t recvd_size; mq.receive(msgBuffer, CalculatingSizeStructure::maxSizeHMIExtMessage, recvd_size, priority); ... } catch (interprocess_exception &ex) { ... } } This is the code related to the Thread B: boost::interprocess::message_queue *mq = InterprocessQueueManager::getInstance()->openQueue("Library_Queue"); if((mq->try_send(&msgCmdSendStatusToLibraryInfoR,sizeof(LibraryInfo),0))==false) {... } I've looked for that exception, and it seems to be related to the POSIX queue. I've also tried some solutions without results. Any ideas? Thanks in advance, Best Regards Antonio

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Manually cleaning up TSS data in boost 1.49
by Andrew Harvey 08 Dec '12

08 Dec '12

Hi, I am using boost::thread for a plug-in that is loaded by a third-party Linux application. I have no control over the host's threading or when it chooses to unload my code. Unfortunately I experience a crash every time the host thread unloads the .so and terminates. I get the following backtrace: (gdb) bt #0 0x00007fffde12c460 in ?? () #1 0x00000032cf607889 in start_thread () from /lib64/libpthread.so.0 #2 0x00000032cf2e5ccd in clone () from /lib64/libc.so.6 Not much to go on... I am pretty confident the crash is happening in a pthread key destructor registered by Boost. The only parts of the boost::thread library I am currently using are the synchronization classes: shared_mutex, shared_lock, unique_lock, upgrade_lock, upgrade_to_unique_lock I'm not directly using any thread-specific storage myself. What I would like to do is force boost to call its TSS destructor in my plug-in's destroy_dso() function. Is this at all possible? Many thanks, - Andrew

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[boost][mpl] Detect a type sequence type
by Klaim - Joël Lamotte 07 Dec '12

07 Dec '12

Hi, I am writing some functions and classes that accept a sequence of type ( boost::mpl::vector/list currently) as template parameter. I'm looking for a way to enhance type checking by making sure the provided types are... type sequences. I didn't find anything relevant in standard or boost type_trait libraries. So far, I'm guessing there is no way to check that, mainly because such types would be template instances, which make checking this like checking if a type is an instance of a template which is impossible right now (as far as I know anyway). My question is: what are possible ways to enhance type checking on type sequence types? I know some boost developers around here make great efforts to make sure their meta programming libraries make early and good error reporting so maybe they have a solution? PS: I'm using Visual Studio 2012 so I can't use variadic template yet ;___; (can't rely on the CTP) Joel Lamotte

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[Graph] Labeled graph bug
by Kikohs xxx 07 Dec '12

07 Dec '12

Hello, I have created a labeled graph:

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Clients controlling server and other clients
by Gonzalo Garramuno 07 Dec '12

07 Dec '12

I am writing an application in which one of multiple clients need to control the server and the other clients. The example is the timeline of a flipbook player. If one client sets the timeline to 125, both the server and the other clients need to jump to frame 125. If the server's timeline is modified to 200, indeed the timeline needs to be set to the new value in all clients. I am puzzled on how to write this with asio. Any help is appreciated.

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Re: [Boost-users] [Graph] How to do multi source shortest path
by ratnesh kumar 07 Dec '12

07 Dec '12

Hi All, I need to use the parallel dijkstra for multiple source shortest path as mentioned before in this thread. I copied the part of last email below. Is this feature now implemented in BGL ? Thanks Ratnesh

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text_file_backend with append and rotate
by Victor Yankee 06 Dec '12

06 Dec '12

Hello everyone! How to create a text_file_backend that appends to existing log file and also has rotation. The init function below always creates a new file every time I run my program no matter the rotation settings. I am using svn version 774 (latest as of Dec 5, 2012. I tried many ways but no joy. There is not an example like this, and there does not seem to be a test for appending either, so maybe it is not supported, but that would be bad. So I must be doing something wrong. Here is my function to set up the logger (using my custom severity levels): void init() { typedef boost::log::sinks::synchronous_sink< boost::log::sinks::text_file_backend > FileSink_t; boost::shared_ptr< FileSink_t> mySink( new FileSink_t( boost::log::keywords::file_name = "%Y%m%d_%H%M%S_%5N.log" , boost::log::keywords::rotation_size = 16 * 1024 * 1024 /3 , boost::log::keywords::time_based_rotation = boost::log::sinks::file::rotation_at_time_point(0,0,0) , boost::log::keywords::auto_flush = true , boost::log::keywords::open_mode=(std::ios::out | std::ios::app) // seems to have no effect )); // this method of setting append does not seem to work either, so I must be doing something wrong mySink->locked_backend()->set_open_mode(std::ios::out|std::ios::app); mySink->locked_backend()->set_file_collector(boost::log::sinks::file::make_collector( boost::log::keywords::target = "logs" , boost::log::keywords::max_size = 16 * 1024 * 1024 , boost::log::keywords::min_free_space = 2 * 16 * 1024 * 1024 )); mySink->set_filter(boost::log::filters::attr< LOGGING::LOG_LEVEL >("Severity", std::nothrow) >= LOGGING::warning); mySink->locked_backend()->scan_for_files(); mySink->set_formatter( boost::log::formatters::format("[%1% | %2%] %3%") % boost::log::formatters::date_time< boost::posix_time::ptime >("TimeStamp") % boost::log::formatters::attr< LOGGING::LOG_LEVEL >("Severity", std::nothrow) % boost::log::formatters::message() ); boost::log::core::get()->add_sink(mySink); boost::log::core::get()->add_global_attribute("TimeStamp", boost::log::attributes::local_clock()); }

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Why does gcc require explicit template arguments with my boost::bind
by Chris Stankevitz 06 Dec '12

06 Dec '12

Hello, Below I implement a function "Chain" that takes two functions and executes them both. The first approach succeeds: direct function call. The second approach succeeds: call via bind with explicit template arguments The third and fourth approaches fail: call via bind without explicit template arguments (with/without boost::protect) Question: Why do I have to use explicit template arguments when using bind with Chain? Thank you, Chris === #include <boost/bind.hpp> #include <boost/function.hpp> template <typename TAFunc1, typename TAFunc2> void Chain(const TAFunc1& Func1, TAFunc2& Func2) { Func1(); Func2(); } void f() { } void foo() { boost::function<void()> x = boost::bind(f); boost::function<void()> y = boost::bind(f); Chain(x, y); boost::bind(Chain<boost::function<void()>, boost::function<void()> >, x, y)(); boost::bind(Chain, x, y)(); boost::bind(Chain, boost::protect(x), boost::protect(y))(); }

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Experience with dealing with warnings from the Clang toolset?
by Paul A. Bristow 06 Dec '12

06 Dec '12

I have added a little information on dealing with warnings when using the Clang toolset at https://svn.boost.org/trac/boost/wiki/Guidelines/WarningsGuidelines but I am sure there are people using Clang who can provide more detailed information and suggestions from their experiences. Please tell me if you have anything to add. Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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Boost::Asio read_until and streambuf usage
by Gonzalo Garramuno 06 Dec '12

06 Dec '12

I have a server that sends three lines, each of which have to be parsed independently. I am using read_until but have a problem with its usage. When read_until reads once, the streambuf seems to contain the three lines but not in the istream and only when I call read_until several times, I get the lines. I am wondering how can I safely read_until the buffer is empty (the 3 or more lines are read) and then exit the loop. boost::asio::streambuf buf; while( 1 ) { size_t reply_length = boost::asio::read_until( socket_, buf, '\n' ); std::istream is(&buf); std::string reply; std::getline(is, reply); // only 1 line obtained }

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