/usr/include/stxxl/bits/containers/pager.h is in libstxxl-dev 1.3.1-1.
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_PAGER_HEADER
#define STXXL_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 stlcontinternals
//! \{
enum pager_type
{
random,
lru
};
//! \brief Pager with \b random replacement strategy
template <unsigned npages_>
class random_pager
{
random_number<random_uniform_fast> rnd;
public:
enum { n_pages = npages_ };
random_pager() { }
int_type kick()
{
return rnd(npages_);
}
void hit(int_type ipage)
{
assert(ipage < int_type(npages_));
assert(ipage >= 0);
}
};
//! \brief Pager with \b LRU replacement strategy
template <unsigned npages_ = 0>
class lru_pager : private noncopyable
{
typedef unsigned_type size_type;
typedef std::list<size_type> list_type;
list_type history;
simple_vector<list_type::iterator> history_entry;
public:
enum { n_pages = npages_ };
lru_pager() : history_entry(n_pages)
{
for (size_type i = 0; i < n_pages; ++i)
history_entry[i] = history.insert(history.end(), i);
}
size_type kick()
{
return history.back();
}
void hit(size_type ipage)
{
assert(ipage < n_pages);
history.splice(history.begin(), history, history_entry[ipage]);
}
void swap(lru_pager & obj)
{
history.swap(obj.history);
history_entry.swap(obj.history_entry);
}
};
// specialization, size is specified at runtime
template <>
class lru_pager<0> : private noncopyable
{
typedef unsigned_type size_type;
typedef std::list<size_type> list_type;
size_type n_pages;
list_type history;
simple_vector<list_type::iterator> history_entry;
public:
lru_pager(size_type npages_ = 0) : n_pages(npages_), history_entry(n_pages)
{
for (size_type i = 0; i < n_pages; ++i)
history_entry[i] = history.insert(history.end(), i);
}
size_type kick()
{
return history.back();
}
void hit(size_type ipage)
{
assert(ipage < n_pages);
history.splice(history.begin(), history, history_entry[ipage]);
}
void swap(lru_pager & obj)
{
std::swap(n_pages, obj.n_pages);
history.swap(obj.history);
history_entry.swap(obj.history_entry);
}
};
//! \}
__STXXL_END_NAMESPACE
namespace std
{
template <unsigned npages_>
void swap(stxxl::lru_pager<npages_> & a,
stxxl::lru_pager<npages_> & b)
{
a.swap(b);
}
}
#endif // !STXXL_PAGER_HEADER
// vim: et:ts=4:sw=4
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