io/test_cancel.cpp

This tests the request cancelation mechanisms.

/***************************************************************************
 * io/test_cancel.cpp
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2009-2011 Johannes Singler <[email protected]>
 * Copyright (C) 2009 Andreas Beckmann <[email protected]>
 *
 * 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/aligned_alloc>


using stxxl::file;

struct print_completion
{
 void operator () (stxxl::request * ptr)
 {
 std::cout << "Request completed: " << ptr << std::endl;
 }
};

int main(int argc, char ** argv)
{
 if (argc < 3)
 {
 std::cout << "Usage: " << argv[0] << " filetype tempfile" << std::endl;
 return -1;
 }

 const stxxl::uint64 size = 64 * 1024 * 1024, num_blocks = 16;
 char * buffer = (char *)stxxl::aligned_alloc<4096>(size);
 memset(buffer, 0, size);

 stxxl::compat_unique_ptr<stxxl::file>::result file(
 stxxl::create_file(argv[1], argv[2], stxxl::file::CREAT | stxxl::file::RDWR | stxxl::file::DIRECT));

 file->set_size(num_blocks * size);
 stxxl::request_ptr req[num_blocks];

 //without cancelation
 std::cout << "Posting " << num_blocks << " requests." << std::endl;
 stxxl::stats_data stats1(*stxxl::stats::get_instance());
 unsigned i = 0;
 for ( ; i < num_blocks; i++)
 req[i] = file->awrite(buffer, i * size, size, print_completion());
 wait_all(req, num_blocks);
 std::cout << stxxl::stats_data(*stxxl::stats::get_instance()) - stats1;

 //with cancelation
 std::cout << "Posting " << num_blocks << " requests." << std::endl;
 stxxl::stats_data stats2(*stxxl::stats::get_instance());
 for (unsigned i = 0; i < num_blocks; i++)
 req[i] = file->awrite(buffer, i * size, size, print_completion());
 //cancel first half
 std::cout << "Canceling first " << num_blocks / 2 << " requests." << std::endl;
 unsigned num_canceled = cancel_all(req, req + num_blocks / 2);
 std::cout << "Successfully canceled " << num_canceled << " requests." << std::endl;
 //cancel every second in second half
 for (unsigned i = num_blocks / 2; i < num_blocks; i += 2)
 {
 std::cout << "Canceling request " << &(*(req[i])) << std::endl;
 if (req[i]->cancel())
 std::cout << "Request canceled: " << &(*(req[i])) << std::endl;
 else
 std::cout << "Request not canceled: " << &(*(req[i])) << std::endl;
 }
 wait_all(req, num_blocks);
 std::cout << stxxl::stats_data(*stxxl::stats::get_instance()) - stats2;

 stxxl::aligned_dealloc<4096>(buffer);

 return 0;
}