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1 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 : /*
3 : * This file is part of the LibreOffice project.
4 : *
5 : * This Source Code Form is subject to the terms of the Mozilla Public
6 : * License, v. 2.0. If a copy of the MPL was not distributed with this
7 : * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 : *
9 : * This file incorporates work covered by the following license notice:
10 : *
11 : * Licensed to the Apache Software Foundation (ASF) under one or more
12 : * contributor license agreements. See the NOTICE file distributed
13 : * with this work for additional information regarding copyright
14 : * ownership. The ASF licenses this file to you under the Apache
15 : * License, Version 2.0 (the "License"); you may not use this file
16 : * except in compliance with the License. You may obtain a copy of
17 : * the License at http://www.apache.org/licenses/LICENSE-2.0 .
18 : */
19 : #ifndef _LRU_CACHE_HXX_
20 : #define _LRU_CACHE_HXX_
21 :
22 : // __CACHE_DIAGNOSE forces cache size to 4 and works only for OUString keys
23 : // #define __CACHE_DIAGNOSE 1
24 :
25 : #include <osl/mutex.hxx>
26 : #include "rtl/ustring.hxx"
27 : #include "sal/log.hxx"
28 :
29 : #include <boost/unordered_map.hpp>
30 :
31 : /** Implementation of a least recently used (lru) cache.
32 : <br>
33 : @author Daniel Boelzle
34 : */
35 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
36 : class LRU_Cache
37 : {
38 2033152 : struct CacheEntry
39 : {
40 : t_Key aKey;
41 : t_Val aVal;
42 : CacheEntry * pPred;
43 : CacheEntry * pSucc;
44 : };
45 : typedef ::boost::unordered_map< t_Key, CacheEntry *, t_KeyHash, t_KeyEqual > t_Key2Element;
46 :
47 : mutable ::osl::Mutex _aCacheMutex;
48 : sal_Int32 _nCachedElements;
49 : t_Key2Element _aKey2Element;
50 :
51 : CacheEntry * _pBlock;
52 : mutable CacheEntry * _pHead;
53 : mutable CacheEntry * _pTail;
54 : inline void toFront( CacheEntry * pEntry ) const;
55 :
56 : public:
57 : /** Constructor:
58 : <br>
59 : @param nCachedElements number of elements to be cached; default param set to 128
60 : */
61 : inline LRU_Cache( sal_Int32 nCachedElements = 128 );
62 : /** Destructor: releases all cached elements and keys.
63 : <br>
64 : */
65 : inline ~LRU_Cache();
66 :
67 : /** Retrieves a value from the cache. Returns default constructed value,
68 : if none was found.
69 : <br>
70 : @param rKey a key
71 : @return value
72 : */
73 : inline t_Val getValue( const t_Key & rKey ) const;
74 : /** Sets a value to be cached for given key.
75 : <br>
76 : @param rKey a key
77 : @param rValue a value
78 : */
79 : inline void setValue( const t_Key & rKey, const t_Val & rValue );
80 : /** Tests whether a value is cached for given key.
81 : <br>
82 : @param rKey a key
83 : @return true, if value is cached
84 : */
85 : inline sal_Bool hasValue( const t_Key & rKey ) const;
86 : /** Clears the cache, thus releasing all cached elements and keys.
87 : <br>
88 : */
89 : inline void clear();
90 : };
91 : //__________________________________________________________________________________________________
92 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
93 4025 : inline LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::LRU_Cache( sal_Int32 nCachedElements )
94 : #ifdef __CACHE_DIAGNOSE
95 : : _nCachedElements( 4 )
96 : #else
97 : : _nCachedElements( nCachedElements )
98 : #endif
99 4025 : , _pBlock( 0 )
100 : {
101 4025 : if (_nCachedElements > 0)
102 : {
103 4025 : _pBlock = new CacheEntry[_nCachedElements];
104 4025 : _pHead = _pBlock;
105 4025 : _pTail = _pBlock + _nCachedElements -1;
106 1038450 : for ( sal_Int32 nPos = _nCachedElements; nPos--; )
107 : {
108 1030400 : _pBlock[nPos].pPred = _pBlock + nPos -1;
109 1030400 : _pBlock[nPos].pSucc = _pBlock + nPos +1;
110 : }
111 : }
112 4025 : }
113 : //__________________________________________________________________________________________________
114 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
115 3917 : inline LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::~LRU_Cache()
116 : {
117 3917 : delete [] _pBlock;
118 3917 : }
119 : //__________________________________________________________________________________________________
120 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
121 199171 : inline void LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::toFront( CacheEntry * pEntry ) const
122 : {
123 199171 : if (pEntry != _pHead)
124 : {
125 : // cut out element
126 152016 : if (pEntry == _pTail)
127 : {
128 12396 : _pTail = pEntry->pPred;
129 : }
130 : else
131 : {
132 139620 : pEntry->pSucc->pPred = pEntry->pPred;
133 139620 : pEntry->pPred->pSucc = pEntry->pSucc;
134 : }
135 : // push to front
136 152016 : _pHead->pPred = pEntry;
137 152016 : pEntry->pSucc = _pHead;
138 152016 : _pHead = pEntry;
139 : }
140 199171 : }
141 : //__________________________________________________________________________________________________
142 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
143 : inline sal_Bool LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::hasValue( const t_Key & rKey ) const
144 : {
145 : ::osl::MutexGuard aGuard( _aCacheMutex );
146 : const typename t_Key2Element::const_iterator iFind( _aKey2Element.find( rKey ) );
147 : return (iFind != _aKey2Element.end());
148 : }
149 : //__________________________________________________________________________________________________
150 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
151 199238 : inline t_Val LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::getValue( const t_Key & rKey ) const
152 : {
153 199238 : ::osl::MutexGuard aGuard( _aCacheMutex );
154 199238 : const typename t_Key2Element::const_iterator iFind( _aKey2Element.find( rKey ) );
155 199238 : if (iFind != _aKey2Element.end())
156 : {
157 186775 : CacheEntry * pEntry = (*iFind).second;
158 186775 : toFront( pEntry );
159 : #ifdef __CACHE_DIAGNOSE
160 : SAL_INFO("stoc.corerefl", "> retrieved element \"" );
161 : SAL_INFO("stoc.corerefl", "" << pEntry->aKey);
162 : SAL_INFO("stoc.corerefl", "\" from cache <" );
163 : #endif
164 186775 : return pEntry->aVal;
165 : }
166 12463 : return t_Val();
167 : }
168 : //__________________________________________________________________________________________________
169 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
170 12456 : inline void LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::setValue(
171 : const t_Key & rKey, const t_Val & rValue )
172 : {
173 12456 : ::osl::MutexGuard aGuard( _aCacheMutex );
174 12456 : if (_nCachedElements > 0)
175 : {
176 12396 : const typename t_Key2Element::const_iterator iFind( _aKey2Element.find( rKey ) );
177 :
178 : CacheEntry * pEntry;
179 12396 : if (iFind == _aKey2Element.end())
180 : {
181 12396 : pEntry = _pTail; // erase last element
182 : #ifdef __CACHE_DIAGNOSE
183 : if (pEntry->aKey.getLength())
184 : {
185 : SAL_INFO("stoc.corerefl", "> kicking element \"" );
186 : SAL_INFO("stoc.corerefl", "" << pEntry->aKey);
187 : SAL_INFO("stoc.corerefl", "\" from cache <" );
188 : }
189 : #endif
190 12396 : _aKey2Element.erase( pEntry->aKey );
191 12396 : _aKey2Element[ pEntry->aKey = rKey ] = pEntry;
192 : }
193 : else
194 : {
195 0 : pEntry = (*iFind).second;
196 : #ifdef __CACHE_DIAGNOSE
197 : SAL_INFO("stoc.corerefl", "> replacing element \"" );
198 : SAL_INFO("stoc.corerefl", "" << pEntry->aKey);
199 : SAL_INFO("stoc.corerefl", "\" in cache <" );
200 : #endif
201 : }
202 12396 : pEntry->aVal = rValue;
203 12396 : toFront( pEntry );
204 12456 : }
205 12456 : }
206 : //__________________________________________________________________________________________________
207 : template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
208 3959 : inline void LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::clear()
209 : {
210 3959 : ::osl::MutexGuard aGuard( _aCacheMutex );
211 3959 : _aKey2Element.clear();
212 1021422 : for ( sal_Int32 nPos = _nCachedElements; nPos--; )
213 : {
214 1013504 : _pBlock[nPos].aKey = t_Key();
215 1013504 : _pBlock[nPos].aVal = t_Val();
216 : }
217 3959 : _nCachedElements = 0;
218 : #ifdef __CACHE_DIAGNOSE
219 : SAL_INFO("stoc.corerefl", "> cleared cache <" );
220 : #endif
221 3959 : }
222 :
223 : //==================================================================================================
224 : struct FctHashOUString : public ::std::unary_function< const OUString &, size_t >
225 : {
226 232828 : size_t operator()( const OUString & rKey ) const
227 232828 : { return rKey.hashCode(); }
228 : };
229 :
230 : /** Template instance for OUString keys, Any values.<br>
231 : */
232 : typedef LRU_Cache< OUString, ::com::sun::star::uno::Any,
233 : FctHashOUString, ::std::equal_to< OUString > >
234 : LRU_CacheAnyByOUString;
235 :
236 :
237 : #endif
238 :
239 : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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