Databases
StackOverflow2013
Postsdbo
POserialization using a memory mapped file
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POserialization using a memory mapped file
    text
    copied!<p>I want to serialize my class objects on a memory mapped file but turns out boost serialization only works with file streams. Here is an example:</p> <pre><code>class gps_position { private: friend class boost::serialization::access; // When the class Archive corresponds to an output archive, the // &amp; operator is defined similar to &lt;&lt;. Likewise, when the class Archive // is a type of input archive the &amp; operator is defined similar to &gt;&gt;. template&lt;class Archive&gt; void serialize(Archive &amp; ar, const unsigned int version) { ar &amp; degrees; ar &amp; minutes; ar &amp; seconds; } int degrees; int minutes; float seconds; public: gps_position(){}; gps_position(int d, int m, float s) : degrees(d), minutes(m), seconds(s) {} }; int main() { // create and open a character archive for output std::ofstream ofs("filename"); // create class instance const gps_position g(35, 59, 24.567f); // save data to archive { boost::archive::text_oarchive oa(ofs); // write class instance to archive oa &lt;&lt; g; // archive and stream closed when destructors are called } // ... some time later restore the class instance to its orginal state gps_position newg; { // create and open an archive for input std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); // read class state from archive ia &gt;&gt; newg; // archive and stream closed when destructors are called } return 0; } </code></pre> <p>Is there a away it can be done over memory mapped files. I am using windows API CreateFileMapping and MapViewOfFile for memory mapping.</p> <p>edit:</p> <p>This is what I tried to do using boost iostream library and memory mapped files.</p> <pre><code>namespace io = boost::iostreams; typedef io::stream_buffer &lt; io::mapped_file_source &gt; in_streambuf; typedef io::stream_buffer &lt; io::mapped_file_sink &gt; out_streambuf; int main() { // create and open a character archive for output // std::ofstream ofs("filename"); /*commented this */ boost::iostreams::mapped_file_params params; params.path = "filepath"; params.flags = io::mapped_file::mapmode::readwrite; out_streambuf obuf(params); std::ostream ofs(&amp;obuf); // create class instance const gps_position g(35, 59, 24.567f); // save data to archive { boost::archive::text_oarchive oa(ofs); // write class instance to archive oa &lt;&lt; g; // archive and stream closed when destructors are called } // ... some time later restore the class instance to its orginal state gps_position newg; { // create and open an archive for input in_streambuf ibuf(params); std::istream ifs(&amp;ibuf); //std::ifstream ifs("filename"); /* commented this */ boost::archive::text_iarchive ia(ifs); // read class state from archive ia &gt;&gt; newg; // archive and stream closed when destructors are called } return 0; } </code></pre> <p>Now I am not too familiar with boost but this code fails at run time. So, any help is really appreciated. The failure happens here itself "out_streambuf obuf(params);". Thanks guys!</p>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload