September 2011 - Boost-users

Re: [Boost-users] [Threads] How to keep number of running thread constant, performing different operations
by Alessandro Candini 01 Sep '11

01 Sep '11

I've tryed implementing your suggestions with the following code: #include <iostream> #include </usr/local/include/boost/asio.hpp> #include </usr/local/include/boost/thread/thread.hpp> #include </usr/local/include/boost/bind.hpp> #include </usr/local/include/boost/date_time/posix_time/posix_time.hpp> #include </usr/local/include/boost/scoped_ptr.hpp> void handler1() { unsigned short int i; std::cout << "O--> Handler 1 <--O" << std::endl; for(i=0; i<65000; i++); std::cout << "X--> Handler 1 <--X" << std::endl; } void handler2() { unsigned short int i; std::cout << "O--> Handler 2 <--O" << std::endl; for(i=0; i<1000; i++); std::cout << "X--> Handler 2 <--X" << std::endl; } int main() { unsigned short nProc, i; boost::asio::io_service io; boost::scoped_ptr<boost::asio::io_service::work> work(new boost::asio::io_service::work(io)); boost::thread_group tg; nProc = boost::thread::hardware_concurrency(); for(i=0; i<nProc; ++i) tg.create_thread(boost::bind(&boost::asio::io_service::run, boost::ref(io))); io.post(handler2); io.post(handler1); io.post(handler2); io.post(handler2); io.post(handler2); io.post(handler2); io.post(handler2); io.post(handler2); io.post(handler2); io.post(handler1); io.post(handler2); work.reset(); tg.join_all(); return 0; } It seems to work, but it is correct, in your opinion? The only problem is that it seems to never stop if I increase the value of i in handler1 up to 70000. Have you any other suggestions? -- Alessandro Candini MEEO S.r.l. Via Saragat 9 I-44122 Ferrara, Italy Tel: +39 0532 1861501 Fax: +39 0532 1861637 http://www.meeo.it ======================================== "ATTENZIONE:le informazioni contenute in questo messaggio sono da considerarsi confidenziali ed il loro utilizzo è riservato unicamente al destinatario sopra indicato. Chi dovesse ricevere questo messaggio per errore è tenuto ad informare il mittente ed a rimuoverlo definitivamente da ogni supporto elettronico o cartaceo." "WARNING:This message contains confidential and/or proprietary information which may be subject to privilege or immunity and which is intended for use of its addressee only. Should you receive this message in error, you are kindly requested to inform the sender and to definitively remove it from any paper or electronic format."

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[test] Organizing C++ Unit Test code for maximum Unit Test efficiency?
by Martin B. 01 Sep '11

01 Sep '11

Hi! Recently asked a questing on SE http://programmers.stackexchange.com/questions/105012/how-should-c-unit-tes… that boils down to How can C++ Unit Test code be effectively organized, so that it's both efficient to edit the (test) code and to run the test code? I figured this might be of interest to Boot.Test users. cheers, Martin

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[bind] deduce arguments types
by Martin Häfner 01 Sep '11

01 Sep '11

Hi all, I have written a small grammar for command line parsing where function binders could be added as actors (callback) of a distinct option. The simple example below shows that the free function id(...) is called if the option -i is getting parsed and the bound member function is called when -j is given: bool id(int i) { return true; /* if id satisfies some preconditions, the parser will evaluate the result value */ } struct Id { void id(int i) { // the parser will not evaluate the 'void' result value } }; Id ident; bool rc = cmdline::Parser<SomePolicyA, SomePolicyB, SomePolicyC> ::parse(argc, argv, cmdline::Option<'i'>().doc("an integer identifier")) >> id <= cmdline::Option<'j'>().doc("another integer")) >> boost:bind(Id::id, &ident, _1) ); The problem now is that I want to deduce the result type of the given actor as well as the argument type. Retrieving the result type is manageable with boost binders but I have no idea how I could retrieve the argument type in order to do a proper conversion from char* to int without the usage of make_adaptable<> which breaks the elegance of the binder usage at this point. My self-written binder class exposes appropriate typedefs so the writer of the parser grammar does not have to cope with all that 'magic' template stuff, but I cannot get a working solution for boost::bind nor do I get a working solution with tr1 binders. Maybe anybody could help or at least could explain me why the boost classes do not define these simple typedefs? Regards, Martin

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[serialization] deserializing asynchronously serialized types
by Andrew Hundt 01 Sep '11

01 Sep '11

I have an unusual use case for boost.serialization, and I was wondering if it would be possible to adapt it to my needs: - I have a set of over 100 types, and instances of each are generated asynchronously then serialized to a file in that order. - The most interesting serialized data will be written just before the power is unexpectedly cut. - I need to load in and run on as much data as possible when reading the serialized data back, ignoring incomplete data at the end (due to a power cut). - The basic Boost serialization examples require you to know the type of the next piece of data to be loaded when reading. Since these types are generated asynchronously they are not known in advance. - I need to write the data out immediately when it arrives because of the power issue. - Files will be getting up to around 150GB in size for binary archives, so it can't be marshaled in memory, it needs to be written immediately even if it is redundant. Is there a way to read in that serialized file using the facilities provided in boost.serialization? I could also serialize an index or custom headers indicating the next type to appear, I would prefer to avoid doing so. One way of achieving some of these goals is writing one piece at a time using a binary archive to an fstream. But I don't know what aspects of my requirements will prove to be a problem. Thanks for your thoughts. Cheers! Andrew Hundt

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