November 2014 - Boost-users

ASIO: Windows/Linux/Mac socket inter-operability
by Joost Kraaijeveld 03 Nov '14

03 Nov '14

Hi, I have a C/S-application that uses ASIO-sockets. The application runs fine if I try to connect between 2 Windows or 2 Linus or 2 Mac machineas. However, it fails to work with a "reset by peer" error if I try to connect between Windows and Linux, Windows and Mac or Linux and Mac. Is there anything known about problems wrt inter-os connections, and if so, is there a solution for this? TIA -- Groeten, Joost Kraaijeveld Molukkenstraat 14 6524NB Nijmegen tel: 024-3607445 / 06-51855277

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Boost IOStream - Buffer as an input stream
by Lloyd 03 Nov '14

03 Nov '14

Hi, We am trying to use a buffer as an input stream. For that we have used "basic_array_source" like this boost::iostreams::basic_array_source<BYTE> source(mem_ptr,size); boost::iostreams::stream<boost::iostreams::basic_array_source <BYTE>> streamReader; streamReader.open(source, std::ios::binary); But this method does not give input-stream related methods (functions like seekg), instead it give methods related to output stream (seekp). Can you please tell what is wrong with this approach? Thanks, Lloyd

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[1.57.0] Release candidates available
by Marshall Clow 03 Nov '14

03 Nov '14

[ Please disregard previous message; apparently I am brain-dead this morning. The uploaded files are correct, though. ] Release candidate files for 1.57.0 are available at http://boost.cowic.de/rc/ As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: MD5 (./boost_1_57_0_rc1.7z) = 17c98dd78d6180f553fbefe5a0f57d12 MD5 (./boost_1_57_0_rc1.tar.bz2) = 1be49befbdd9a5ce9def2983ba3e7b76 MD5 (./boost_1_57_0_rc1.tar.gz) = 25f9a8ac28beeb5ab84aa98510305299 MD5 (./boost_1_57_0_rc1.zip) = 5e040e578e3f0ba879da04a1e0cd55ff Thanks! -- The release managers P.S. Release notes are here: http://www.boost.org/users/history/version_1_57_0.html

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[Asio] null_buffer behaviors
by lin li 03 Nov '14

03 Nov '14

Hi, guys. In the doc of asio, it says 'A null_buffers operation doesn't return until the I/O object is "ready" to perform the operation'. But when I use it on a server side socket, i.e. a socket created by "accept" call when a new connection has arrived. It seems to return immediately even the other end has not started to send the data yet. Is this normal?

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How to know whether a boost heade has been included?
by Vincenzo Romano 03 Nov '14

03 Nov '14

I thought I could check for the symbol BOOST_VERSION to be defined. But, as of v1.55, it's not the case at least for the <boost/any.hpp> header. Any hint? Thanks in advance.

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[boost.variant] accessing variant with pattern-matching instead of visitors
by Roger 02 Nov '14

02 Nov '14

Hi! The CppCon 2014, Yuriy Solodkyy had an interesting talk "Accept no visitors"(*). It presents an alternative accessing technique for variant data-type. It basically use pattern matching syntax, similar to that in functional languages, instead of visitors. I think this would be a great benefit for boost::variant data-type... being able to access variables from the same scope, group states similar in behavior, and take care of the loop unrolling for dispatching oneself. Especially when using variant as polymorphism, like the other interesting CppCon 2014 talking, Jason Lucas "Polymorphism with Unions" (**) covered. Would it be worth to implement a tiny pattern-matching library for boost::variant itself? Has anyone elaborated with this? Thanks for any hints! /perrog * Yuriy Solodkyy "Accept no visitors, http://youtu.be/QhJguzpZOrk ** Jason Lucas "Polymorphism with Unions", http://youtu.be/uii2AfiMA0o

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(no subject)
by Johnny McCullough 01 Nov '14

01 Nov '14

I'm new to boost, and I'm wondering about the best / most efficient way to transfer a large dataset via boost::asio. I've retrieved a datasetfrom a database (Cassandra) and I'm using boost asio to provide a network service that responds to queries. So I have a client socket and a dataset. I have to iterate the dataset, perform some simple formatting (e.g. csv, json, xml), then write it out to the client socket. But there's a lot of data. Perhaps gigabytes. So my initial thoughts were the producer / consumer pattern - the producer writing to a streambuf and the consumer async_write-ing it out to the client's socket. But I'm not sure this is a good approach - I know that streambuf isn't threadsafe and so managing the streambuf with locks may well become a performance bottleneck. Obviously, I don't want to replicate what may be gigabyte(s) of data from a resultset into a buffer just so it can be written out to a socket, So should I write this data synchronously straight to the socket instead? What's the best approach to solving this kind of problem? thanks for your consideration

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