July 2009 - Boost-users - lists.preview.boost.org

[asio] async_read and 100% CPU
by Etienne Philip Pretorius 01 Jul '09

01 Jul '09

Hello list, Could someone please shed some light on this subject. It seems that me read handler keeps on being called even when there has been no data transferred... Here is the accept handler that starts off the read handler (All methods are part of the same class, namely 'client'): /* Accept Handler */ void handle_accept( const boost::system::error_code& error ) { client* c; switch(error.value()) { case boost::system::posix_error::success: { c = new client(); socket.async_receive( boost::asio::buffer( buffer ),boost::bind( &client::handle_read, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred ) ); break; } case boost::system::posix_error::interrupted: case boost::system::posix_error::connection_aborted: { c = this; break; } default: { throw error; } } acceptor.async_accept( c->socket, boost::bind( &client::handle_accept, c, boost::asio::placeholders::error ) ); }; And here is the read handler.... /* Read Handler */ void handle_read( const boost::system::error_code& error, std::size_t bytes_transferred ) { switch(error.value()) { case boost::system::posix_error::success: { if(bytes_transferred > 0) { std::copy( buffer.begin(), buffer.end(), std::back_insert_iterator<std::string>(data) ); break; } } case boost::system::posix_error::interrupted: { socket.async_receive( boost::asio::buffer( buffer ),boost::bind( &client::handle_read, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred ) ); return; } default: { throw error; } } //TODO: parse contents.. }; Using epoll interface, as I am running Ubuntu Jaunty. Calling io_service.run() from the main thread. Thank you, Etienne Pretorius.

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Default table size of unordered map
by MeMooMeM 01 Jul '09

01 Jul '09

Hi, What is the default table size of unordered maps in boost? I am trying to figure out how scalable this function is. My guess is that boost assumes a default initial table length. If it is exceeded, it needs to re-create hashes for all entries to grow it, which is costly. I would like to find that threshold... Thanks so much! -- View this message in context: http://www.nabble.com/Default-table-size-of-unordered-map-tp24283133p242831… Sent from the Boost - Users mailing list archive at Nabble.com.

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Python embedding - vector problem
by Tyomich on the AIR 01 Jul '09

01 Jul '09

Hello! I'm currently embedding Python in C++ and now having some problems with std::vector. I used indexing suite to wrap it and work with it in Python like a Python list. But there is a problem: when I copy it in Python style (e.g. a[:] = b) it seems like it copies elements recursively, here is a log of copying: Copy constructor Copy constructor Destructor Copy constructor Copy constructor Copy constructor Destructor Destructor Copy constructor Copy constructor Copy constructor Copy constructor Destructor Destructor Destructor .. This is a real problem when the number of elements is more than 100000, because it takes a long time to finish. Is there anything to do with it? Regards, Chirkov Artyom

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[serialization] Multiple archives in same stream
by Chard 01 Jul '09

01 Jul '09

Pardon me if this issue has been discussed earlier, but is there a particular technical issue why multiple archives cannot be serialized to (or, specifically, de-serialized from) the same stream? (I'm still on 1.38, so slap me if this works with 1.39+). Given the following example: #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/serialization.hpp> void test_ser_app() { { { std::ofstream file("ser.txt"); archive::text_oarchive arch(file); std::string s("Hello World"); arch & s; size_t pos = file.tellp(); // [1] } { std::ofstream file("ser.txt", std::ios::app | std::ios::ate); archive::text_oarchive arch(file); std::string s("Goodbye World"); arch & s; } } // [2] { std::string s1, s2; std::ifstream file("ser.txt"); { archive::text_iarchive arch(file); arch & s1; } size_t pos = file.tellg(); // [3] try { archive::text_iarchive arch(file); arch & s2; } catch (archive::archive_exception &e) { std::cout << e.what() << std::endl; } } } The stream position reported at [1] is (correctly) 42, and examination of the text file (at [2]) shows the two archives serialized okay. However, the stream position at [3] appears to be at the end of the stream. Does the serialization read in a big chunk, regardless of whether it will be processing it all? If I hack in a set stream position at [3], then the library quite happily reads the second archive. Is it possible to have the library leave the stream pointer at the correct end position?

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STLPort Install Before Building Boost 1.39.0
by biolaser 01 Jul '09

01 Jul '09

I'm on Windows XP SP3, msvc71 SP1, and I want to install STLport 5.2.1 before I install/build Boost 1.39.0. The STLport distribution install file (configure.bat) has two options I need help with: "--with-static-rtl" "-with-dynamic-rtl" Does Boost care whether I enable the static (libc.lib family) or whether I enable the dynamic (msvcrt.lib family) C/C++ library when linking with STLport? Then, there is the "-use-boost <boost install path>" option - I assume I should use this STLport option for Boost 1.39.0 - correct? Finally, is there anything I need to do in my building/installing of Boost itself to make sure it knows I have STLport installed? Thanks much! William Stroupe

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[asio] Thread safety
by Laurent Fert 01 Jul '09

01 Jul '09

Hi, I have a thread that runs io_service::run(). I have another thread that creates a timer and schedules it to fire later. Once the timer has been scheduled, the second thread forgets about it and everything is handled by the thread that runs the service. Is it safe to create/schedule a timer with an io_service from a thread while this services is being run in another thread? Thank you for your replies, Laurent

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[asio] ICMP protocol support
by Chris Miceli 01 Jul '09

01 Jul '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 I am attempting to use the ICMP protocol that is "off-the-shelf" in Boost.Asio, but am unable to get any use of it working. Following the code listed here: http://www.boost.org/doc/libs/1_36_0/doc/html/boost_asio/overview/networkin… I immediately run into problems. The DAYTIME protocol is defined to operate on TCP or UDP port 13. ICMP should be used for control messages, not data transmission. Trying to connect to a server supported DAYTIME with ICMP does not work using the code at the previously mentioned site, this error is returned: Service not found Which makes sense because this service is not defined for this protocol. My question is, what is the intended purpose of the current implementation of this protocol? If to use ICMP to tranfer data by using the payload, why? If to construct messages useful for writing a traceroute or ping utility, how would I do this? Has anyone used this library? Online there is a desire to use boost.Asio and ICMP to write ping using boost, but they all reach these same questions. I am appreciative of any help on this topic. - -Chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEAREKAAYFAkpK05UACgkQS3i4IU3+Scsw2QCbBAQpHwqzTqIvn3hVunI6bnK9 Z6AAn0EfsRAwPbon8jJYVotEe6awn7Xy =/gWa -----END PGP SIGNATURE-----

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boost::bind with references
by Zachary Turner 01 Jul '09

01 Jul '09

I have a function defined as template<typename T> void foo(const T& x); and then I use boost::bind(foo, x); However, once the code is inside the body of foo, the addresses of x inside foo and the addresses of x when I called bind are different. So somehow a copy is being made. I can get around it by using boost::ref(), but is there a technical reason why it doesn't "just work" and pass it by reference?

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