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