/usr/include/Poco/LRUStrategy.h is in libpoco-dev 1.3.6p1-5+deb8u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 | //
// LRUStrategy.h
//
// $Id: //poco/1.3/Foundation/include/Poco/LRUStrategy.h#3 $
//
// Library: Foundation
// Package: Cache
// Module: LRUStrategy
//
// Definition of the LRUStrategy class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
#ifndef Foundation_LRUStrategy_INCLUDED
#define Foundation_LRUStrategy_INCLUDED
#include "Poco/KeyValueArgs.h"
#include "Poco/ValidArgs.h"
#include "Poco/AbstractStrategy.h"
#include "Poco/EventArgs.h"
#include "Poco/Exception.h"
#include <list>
#include <map>
#include <cstddef>
namespace Poco {
template <class TKey, class TValue>
class LRUStrategy: public AbstractStrategy<TKey, TValue>
/// An LRUStrategy implements least recently used cache replacement.
{
public:
typedef std::list<TKey> Keys;
typedef typename Keys::iterator Iterator;
typedef typename Keys::const_iterator ConstIterator;
typedef std::map<TKey, Iterator> KeyIndex;
typedef typename KeyIndex::iterator IndexIterator;
typedef typename KeyIndex::const_iterator ConstIndexIterator;
public:
LRUStrategy(std::size_t size):
_size(size)
{
if (_size < 1) throw InvalidArgumentException("size must be > 0");
}
~LRUStrategy()
{
}
void onAdd(const void*, const KeyValueArgs <TKey, TValue>& args)
{
_keys.push_front(args.key());
std::pair<IndexIterator, bool> stat = _keyIndex.insert(std::make_pair(args.key(), _keys.begin()));
if (!stat.second)
{
stat.first->second = _keys.begin();
}
}
void onRemove(const void*, const TKey& key)
{
IndexIterator it = _keyIndex.find(key);
if (it != _keyIndex.end())
{
_keys.erase(it->second);
_keyIndex.erase(it);
}
}
void onGet(const void*, const TKey& key)
{
// LRU: in case of an hit, move to begin
IndexIterator it = _keyIndex.find(key);
if (it != _keyIndex.end())
{
_keys.splice(_keys.begin(), _keys, it->second); //_keys.erase(it->second)+_keys.push_front(key);
it->second = _keys.begin();
}
}
void onClear(const void*, const EventArgs& args)
{
_keys.clear();
_keyIndex.clear();
}
void onIsValid(const void*, ValidArgs<TKey>& args)
{
if (_keyIndex.find(args.key()) == _keyIndex.end())
{
args.invalidate();
}
}
void onReplace(const void*, std::set<TKey>& elemsToRemove)
{
// Note: replace only informs the cache which elements
// it would like to remove!
// it does not remove them on its own!
std::size_t curSize = _keyIndex.size();
if (curSize < _size)
{
return;
}
std::size_t diff = curSize - _size;
Iterator it = --_keys.end(); //--keys can never be invoked on an empty list due to the minSize==1 requirement of LRU
std::size_t i = 0;
while (i++ < diff)
{
elemsToRemove.insert(*it);
if (it != _keys.begin())
{
--it;
}
}
}
protected:
std::size_t _size; /// Number of keys the cache can store.
Keys _keys;
KeyIndex _keyIndex; /// For faster access to _keys
};
} // namespace Poco
#endif
|