/usr/include/stxxl/bits/containers/pager.h is in libstxxl-dev 1.4.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* include/stxxl/bits/containers/pager.h
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2002, 2003, 2006 Roman Dementiev <dementiev@ira.uka.de>
* Copyright (C) 2011 Andreas Beckmann <beckmann@cs.uni-frankfurt.de>
*
* 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)
**************************************************************************/
#ifndef STXXL_CONTAINERS_PAGER_HEADER
#define STXXL_CONTAINERS_PAGER_HEADER
#include <list>
#include <cassert>
#include <stxxl/bits/noncopyable.h>
#include <stxxl/bits/common/rand.h>
#include <stxxl/bits/common/simple_vector.h>
STXXL_BEGIN_NAMESPACE
//! \addtogroup stlcont_vector
//! \{
enum pager_type
{
random,
lru
};
//! Pager with \b random replacement strategy
template <unsigned npages_>
class random_pager
{
enum { n_pages = npages_ };
typedef unsigned_type size_type;
size_type num_pages;
random_number<random_uniform_fast> rnd;
public:
random_pager(size_type num_pages = n_pages) : num_pages(num_pages) { }
size_type kick()
{
return rnd(size());
}
void hit(size_type ipage)
{
STXXL_ASSERT(ipage < size());
}
size_type size() const
{
return num_pages;
}
};
//! Pager with \b LRU replacement strategy
template <unsigned npages_ = 0>
class lru_pager : private noncopyable
{
enum { n_pages = npages_ };
typedef unsigned_type size_type;
typedef std::list<size_type> list_type;
list_type history;
simple_vector<list_type::iterator> history_entry;
public:
lru_pager(size_type num_pages = n_pages) : history_entry(num_pages)
{
for (size_type i = 0; i < size(); ++i)
history_entry[i] = history.insert(history.end(), i);
}
size_type kick()
{
return history.back();
}
void hit(size_type ipage)
{
assert(ipage < size());
history.splice(history.begin(), history, history_entry[ipage]);
}
void swap(lru_pager& obj)
{
history.swap(obj.history);
history_entry.swap(obj.history_entry);
}
size_type size() const
{
return history_entry.size();
}
};
//! \}
STXXL_END_NAMESPACE
namespace std {
template <unsigned npages_>
void swap(stxxl::lru_pager<npages_>& a,
stxxl::lru_pager<npages_>& b)
{
a.swap(b);
}
} // namespace std
#endif // !STXXL_CONTAINERS_PAGER_HEADER
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