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/***************************************************************************
* examples/containers/copy_file.cpp
*
* This example shows three methods to copy a file to another file using
* stxxl:vectors.
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2004-2006 Roman Dementiev <dementiev@mpi-sb.mpg.de>
* Copyright (C) 2013 Timo Bingmann <tb@panthema.net>
*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
**************************************************************************/
#include <stxxl/io>
#include <stxxl/vector>
#include <stxxl/stream>
void copy_file(const char* input_path, const char* output_path, unsigned int method)
{
using stxxl::file;
file::unlink(output_path); // delete output file
stxxl::timer tm(true); // start a timer
// input file object
stxxl::syscall_file InputFile(input_path, file::RDONLY | file::DIRECT);
// output file object
stxxl::syscall_file OutputFile(output_path, file::RDWR | file::CREAT | file::DIRECT);
typedef stxxl::vector<unsigned char> vector_type;
std::cout << "Copying file " << input_path << " to " << output_path << std::endl;
// InputVector is mapped to InputFile
vector_type InputVector(&InputFile);
vector_type OutputVector(&OutputFile); // OutputVector is mapped to OutputFile
std::cout << "File " << input_path << " has size " << InputVector.size() << " bytes." << std::endl;
if (method == 1)
{
// First method: copy vector elements. This is rather slow, because no
// prefetching is used and the vector's pager does lots of internal
// work!
std::cout << "Using first method: copying vector elements." << std::endl;
for (vector_type::const_iterator it = InputVector.begin(); // iterate through InputVector
it != InputVector.end(); ++it)
{
OutputVector.push_back(*it); // add the value pointed by 'it' to OutputVector
}
}
else if (method == 2)
{
// Second method: use a vector_iterator2stream to prefetch blocks in
// the input vector and a vector_bufwriter for buffered writing to the
// output.
std::cout << "Using second method: vector_iterator2stream and vector_bufwriter." << std::endl;
// prepare output vector's size
OutputVector.resize(InputVector.size());
// construct prefetching input stream
stxxl::stream::vector_iterator2stream<vector_type::const_iterator>
input(InputVector.begin(), InputVector.end());
// construct buffered output writer
vector_type::bufwriter_type writer(OutputVector.begin());
while (!input.empty()) // iterate through InputVector
{
writer << *input;
++input;
}
writer.finish(); // flush buffers
}
else if (method == 3)
{
// Third method: use a vector_iterator2stream to prefetch blocks in the
// input vector and materialize to write the stream to the output.
std::cout << "Using third method: vector_iterator2stream and materialize." << std::endl;
// prepare output vector's size
OutputVector.resize(InputVector.size());
// construct prefetching input stream
stxxl::stream::vector_iterator2stream<vector_type::const_iterator>
input(InputVector.begin(), InputVector.end());
// materilize intput directly into output vector
stxxl::stream::materialize(input, OutputVector.begin(), OutputVector.end());
}
std::cout << "Copied in " << tm.seconds() << " at "
<< (double)InputVector.size() / tm.seconds() / 1024 / 1024 << " MiB/s" << std::endl;
}
int main(int argc, char* argv[])
{
if (argc < 3)
{
std::cout << "Usage: " << argv[0] << " input_file output_file [method 1-3]" << std::endl;
return -1;
}
int method = (argc >= 4) ? atoi(argv[3]) : 3;
copy_file(argv[1], argv[2], method);
return 0;
}
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