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14798e73 CT |
1 | |
2 | /* | |
3 | */ | |
4 | ||
5 | #ifndef SQUID_LRUMAP_H | |
6 | #define SQUID_LRUMAP_H | |
7 | ||
8 | #include "SquidTime.h" | |
9 | #if HAVE_LIST | |
10 | #include <list> | |
11 | #endif | |
12 | #if HAVE_MAP | |
13 | #include <map> | |
14 | #endif | |
15 | ||
16 | template <class EntryValue, size_t EntryCost = sizeof(EntryValue)> class LruMap | |
17 | { | |
18 | public: | |
19 | class Entry | |
20 | { | |
21 | public: | |
22 | Entry(const char *aKey, EntryValue *t): key(aKey), value(t), date(squid_curtime) {} | |
23 | ~Entry() {delete value;} | |
24 | private: | |
a70d5f19 CT |
25 | Entry(Entry &); |
26 | Entry & operator = (Entry &); | |
14798e73 CT |
27 | public: |
28 | std::string key; ///< the key of entry | |
29 | EntryValue *value; ///< A pointer to the stored value | |
30 | time_t date; ///< The date the entry created | |
31 | }; | |
32 | typedef std::list<Entry *> Queue; | |
33 | typedef typename std::list<Entry *>::iterator QueueIterator; | |
4c304fb9 | 34 | |
14798e73 CT |
35 | /// key:queue_item mapping for fast lookups by key |
36 | typedef std::map<std::string, QueueIterator> Map; | |
37 | typedef typename Map::iterator MapIterator; | |
38 | typedef std::pair<std::string, QueueIterator> MapPair; | |
39 | ||
14798e73 CT |
40 | LruMap(int ttl, size_t size); |
41 | ~LruMap(); | |
42 | /// Search for an entry, and return a pointer | |
43 | EntryValue *get(const char *key); | |
44 | /// Add an entry to the map | |
45 | bool add(const char *key, EntryValue *t); | |
46 | /// Delete an entry from the map | |
47 | bool del(const char *key); | |
48 | /// (Re-)set the maximum size for this map | |
49 | void setMemLimit(size_t aSize); | |
50 | /// The available size for the map | |
51 | size_t memLimit() const {return memLimit_;} | |
52 | /// The free space of the map | |
53 | size_t freeMem() const { return (memLimit() - size());} | |
54 | /// The current size of the map | |
55 | size_t size() const {return (entries_ * EntryCost);} | |
56 | /// The number of stored entries | |
57 | int entries() const {return entries_;} | |
58 | private: | |
a70d5f19 CT |
59 | LruMap(LruMap const &); |
60 | LruMap & operator = (LruMap const &); | |
4c304fb9 | 61 | |
14798e73 CT |
62 | bool expired(Entry &e); |
63 | void trim(); | |
64 | void touch(const MapIterator &i); | |
65 | bool del(const MapIterator &i); | |
66 | void findEntry(const char *key, LruMap::MapIterator &i); | |
67 | ||
68 | Map storage; ///< The Key/value * pairs | |
69 | Queue index; ///< LRU cache index | |
70 | int ttl;///< >0 ttl for caching, == 0 cache is disabled, < 0 store for ever | |
71 | size_t memLimit_; ///< The maximum memory to use | |
72 | int entries_; ///< The stored entries | |
73 | }; | |
74 | ||
75 | template <class EntryValue, size_t EntryCost> | |
76 | LruMap<EntryValue, EntryCost>::LruMap(int aTtl, size_t aSize): entries_(0) | |
77 | { | |
78 | ttl = aTtl; | |
79 | ||
80 | setMemLimit(aSize); | |
81 | } | |
82 | ||
83 | template <class EntryValue, size_t EntryCost> | |
84 | LruMap<EntryValue, EntryCost>::~LruMap() | |
85 | { | |
86 | for (QueueIterator i = index.begin(); i != index.end(); ++i) { | |
87 | delete *i; | |
88 | } | |
89 | } | |
90 | ||
91 | template <class EntryValue, size_t EntryCost> | |
92 | void | |
93 | LruMap<EntryValue, EntryCost>::setMemLimit(size_t aSize) | |
94 | { | |
95 | if (aSize > 0) | |
96 | memLimit_ = aSize; | |
97 | else | |
98 | memLimit_ = 0; | |
99 | } | |
100 | ||
101 | template <class EntryValue, size_t EntryCost> | |
102 | void | |
103 | LruMap<EntryValue, EntryCost>::findEntry(const char *key, LruMap::MapIterator &i) | |
104 | { | |
105 | i = storage.find(key); | |
106 | if (i == storage.end()) { | |
107 | return; | |
108 | } | |
109 | index.push_front(*(i->second)); | |
110 | index.erase(i->second); | |
111 | i->second = index.begin(); | |
4c304fb9 | 112 | |
9aea094e | 113 | Entry *e = *i->second; |
14798e73 CT |
114 | |
115 | if (e && expired(*e)) { | |
116 | del(i); | |
117 | e = NULL; | |
118 | } | |
119 | } | |
120 | ||
121 | template <class EntryValue, size_t EntryCost> | |
122 | EntryValue * | |
123 | LruMap<EntryValue, EntryCost>::get(const char *key) | |
124 | { | |
9aea094e | 125 | MapIterator i; |
14798e73 | 126 | findEntry(key, i); |
9aea094e | 127 | Entry *e = *i->second; |
14798e73 CT |
128 | if (i != storage.end()) { |
129 | touch(i); | |
130 | return e->value; | |
131 | } | |
132 | return NULL; | |
133 | } | |
134 | ||
135 | template <class EntryValue, size_t EntryCost> | |
136 | bool | |
137 | LruMap<EntryValue, EntryCost>::add(const char *key, EntryValue *t) | |
138 | { | |
139 | if (ttl == 0) | |
140 | return false; | |
141 | ||
142 | del(key); | |
143 | trim(); | |
144 | index.push_front(new Entry(key, t)); | |
145 | storage.insert(MapPair(key, index.begin())); | |
146 | ||
147 | ++entries_; | |
148 | return true; | |
149 | } | |
150 | ||
151 | template <class EntryValue, size_t EntryCost> | |
152 | bool | |
153 | LruMap<EntryValue, EntryCost>::expired(LruMap::Entry &entry) | |
154 | { | |
155 | if (ttl < 0) | |
156 | return false; | |
157 | ||
158 | return (entry.date + ttl < squid_curtime); | |
159 | } | |
160 | ||
161 | template <class EntryValue, size_t EntryCost> | |
162 | bool | |
163 | LruMap<EntryValue, EntryCost>::del(LruMap::MapIterator const &i) | |
164 | { | |
4c304fb9 | 165 | if (i != storage.end()) { |
14798e73 CT |
166 | delete *(i->second); |
167 | index.erase(i->second); | |
168 | storage.erase(i); | |
169 | --entries_; | |
170 | return true; | |
171 | } | |
172 | return false; | |
173 | } | |
174 | ||
175 | template <class EntryValue, size_t EntryCost> | |
176 | bool | |
177 | LruMap<EntryValue, EntryCost>::del(const char *key) | |
178 | { | |
9aea094e | 179 | MapIterator i; |
14798e73 CT |
180 | findEntry(key, i); |
181 | return del(i); | |
182 | } | |
183 | ||
184 | template <class EntryValue, size_t EntryCost> | |
185 | void | |
186 | LruMap<EntryValue, EntryCost>::trim() | |
187 | { | |
4c304fb9 | 188 | while (memLimit() > 0 && size() >= memLimit()) { |
9aea094e | 189 | QueueIterator i = index.end(); |
14798e73 CT |
190 | --i; |
191 | if (i != index.end()) { | |
192 | del((*i)->key.c_str()); | |
193 | } | |
194 | } | |
195 | } | |
196 | ||
197 | template <class EntryValue, size_t EntryCost> | |
198 | void | |
199 | LruMap<EntryValue, EntryCost>::touch(LruMap::MapIterator const &i) | |
200 | { | |
201 | // this must not be done when nothing is being cached. | |
202 | if (ttl == 0) | |
203 | return; | |
204 | ||
205 | index.push_front(*(i->second)); | |
206 | index.erase(i->second); | |
207 | i->second = index.begin(); | |
208 | } | |
209 | ||
210 | #endif |