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
|
/*
Copyright (C) 2003 Nikolas Zimmermann <wildfox@kde.org>
This file is part of the KDE project
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
aint with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef T2P_CACHE_H
#define T2P_CACHE_H
#include <map>
#include <string>
#include <vector>
#include <iostream>
#include <memory>
namespace T2P
{
class CacheElement
{
public:
CacheElement(std::string key) : m_key(key), m_usage(0) { }
~CacheElement() { }
std::string key() const { return m_key; }
int usage() const { return m_usage; }
void incUsage() { m_usage++; }
private:
std::string m_key;
int m_usage;
};
template<typename T>
class Cache
{
public:
typedef std::shared_ptr<T> SharedT;
Cache(int maxSize = 10) : m_size(0), m_maxSize(maxSize) { }
~Cache() { clear(); }
// Number of elements in cache
int size() const { return m_size; }
// Maximum number of elements in cache
int maxSize() const { return m_maxSize; }
// Add new entry
void insert(const std::string &key, SharedT &value)
{
// TODO: Add real LRU logic, now i will just delete the less
// used item when inserting a new item would exceed maxSize
if(m_size == m_maxSize)
{
// Find less used item
typename std::map<SharedT, CacheElement *>::const_iterator it = m_cacheMap.begin();
int usage = (*it).second->usage(); std::string keyUsage = (*it).second->key();
for(it++; it != m_cacheMap.end(); ++it)
{
int curUsage = (*it).second->usage();
if(curUsage < usage)
{
usage = curUsage;
keyUsage = (*it).second->key();
}
}
// std::cout << "[CACHE] Removing less used element with key: " << keyUsage << " (Used " << usage << " times!)" << std::endl;
remove(keyUsage);
}
m_size++;
m_entries.push_back(value);
m_cacheMap[value] = new CacheElement(key);
}
// Remove single entry
void remove(const std::string &key)
{
for(typename std::vector<SharedT>::iterator it = m_entries.begin(); it != m_entries.end(); ++it)
{
SharedT cur = *it;
if(m_cacheMap[cur]->key() == key)
{
m_size--;
typename std::map<SharedT, CacheElement *>::iterator cacheElement = m_cacheMap.find(cur);
m_cacheMap.erase(cacheElement);
delete cacheElement->second;
m_entries.erase(it); // Only valid to write because we don't go on here!
break; // Otherwhise the iterators _may_ be invalid!
}
}
}
// Remove all entries
void clear()
{
m_size = 0;
m_entries.clear();
m_cacheMap.clear();
}
// Lookup entry
SharedT find(const std::string &key)
{
for(typename std::vector<SharedT>::const_iterator it = m_entries.begin(); it != m_entries.end(); ++it)
{
SharedT cur = *it;
if(m_cacheMap[cur]->key() == key)
{
m_cacheMap[cur]->incUsage();
return cur;
}
}
return SharedT();
}
void dump()
{
std::cout << "[CACHE] " << size() << " of " << maxSize() << " Objects in the cache." << std::endl;
for(typename std::vector<SharedT>::iterator it = m_entries.begin(); it != m_entries.end(); ++it)
{
SharedT cur = *it;
std::cout << "[CACHE] - " << m_cacheMap[cur]->key() << " -> " << cur << " (Usage: " << m_cacheMap[cur]->usage() << ")" << std::endl;
}
}
private:
std::vector<SharedT> m_entries;
std::map<SharedT, CacheElement *> m_cacheMap;
int m_size, m_maxSize;
};
}
#endif
|
