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+/*************************************************************************
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Copyright 2000, 2010 Oracle and/or its affiliates.
+ *
+ * OpenOffice.org - a multi-platform office productivity suite
+ *
+ * This file is part of OpenOffice.org.
+ *
+ * OpenOffice.org is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3
+ * only, as published by the Free Software Foundation.
+ *
+ * OpenOffice.org 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 Lesser General Public License version 3 for more details
+ * (a copy is included in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * version 3 along with OpenOffice.org. If not, see
+ * <http://www.openoffice.org/license.html>
+ * for a copy of the LGPLv3 License.
+ *
+ ************************************************************************/
+#ifndef _LRU_CACHE_HXX_
+#define _LRU_CACHE_HXX_
+
+// __CACHE_DIAGNOSE forces cache size to 4 and works only for OUString keys
+// #define __CACHE_DIAGNOSE 1
+
+#include <osl/mutex.hxx>
+#include "rtl/ustring.hxx"
+
+#include <hash_map>
+
+
+/** Implementation of a least recently used (lru) cache.
+ <br>
+ @author Daniel Boelzle
+*/
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+class LRU_Cache
+{
+ struct CacheEntry
+ {
+ t_Key aKey;
+ t_Val aVal;
+ CacheEntry * pPred;
+ CacheEntry * pSucc;
+ };
+ typedef ::std::hash_map< t_Key, CacheEntry *, t_KeyHash, t_KeyEqual > t_Key2Element;
+
+ mutable ::osl::Mutex _aCacheMutex;
+ sal_Int32 _nCachedElements;
+ t_Key2Element _aKey2Element;
+
+ CacheEntry * _pBlock;
+ mutable CacheEntry * _pHead;
+ mutable CacheEntry * _pTail;
+ inline void toFront( CacheEntry * pEntry ) const;
+
+public:
+ /** Constructor:
+ <br>
+ @param nCachedElements number of elements to be cached; default param set to 128
+ */
+ inline LRU_Cache( sal_Int32 nCachedElements = 128 );
+ /** Destructor: releases all cached elements and keys.
+ <br>
+ */
+ inline ~LRU_Cache();
+
+ /** Retrieves a value from the cache. Returns default constructed value,
+ if none was found.
+ <br>
+ @param rKey a key
+ @return value
+ */
+ inline t_Val getValue( t_Key const & rKey ) const;
+ /** Sets a value to be cached for given key.
+ <br>
+ @param rKey a key
+ @param rValue a value
+ */
+ inline void setValue( t_Key const & rKey, t_Val const & rValue );
+ /** Tests whether a value is cached for given key.
+ <br>
+ @param rKey a key
+ @return true, if value is cached
+ */
+ inline sal_Bool hasValue( t_Key const & rKey ) const;
+ /** Clears the cache, thus releasing all cached elements and keys.
+ <br>
+ */
+ inline void clear();
+};
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::LRU_Cache( sal_Int32 nCachedElements )
+#ifdef __CACHE_DIAGNOSE
+ : _nCachedElements( 4 )
+#else
+ : _nCachedElements( nCachedElements )
+#endif
+ , _pBlock( 0 )
+{
+ if (_nCachedElements > 0)
+ {
+ _pBlock = new CacheEntry[_nCachedElements];
+ _pHead = _pBlock;
+ _pTail = _pBlock + _nCachedElements -1;
+ for ( sal_Int32 nPos = _nCachedElements; nPos--; )
+ {
+ _pBlock[nPos].pPred = _pBlock + nPos -1;
+ _pBlock[nPos].pSucc = _pBlock + nPos +1;
+ }
+ }
+}
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::~LRU_Cache()
+{
+ delete [] _pBlock;
+}
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline void LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::toFront(
+ CacheEntry * pEntry ) const
+{
+ if (pEntry != _pHead)
+ {
+ // cut out element
+ if (pEntry == _pTail)
+ {
+ _pTail = pEntry->pPred;
+ }
+ else
+ {
+ pEntry->pSucc->pPred = pEntry->pPred;
+ pEntry->pPred->pSucc = pEntry->pSucc;
+ }
+ // push to front
+ _pHead->pPred = pEntry;
+ pEntry->pSucc = _pHead;
+ _pHead = pEntry;
+ }
+}
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline sal_Bool LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::hasValue(
+ t_Key const & rKey ) const
+{
+ ::osl::MutexGuard aGuard( _aCacheMutex );
+ typename t_Key2Element::const_iterator const iFind( _aKey2Element.find( rKey ) );
+ return (iFind != _aKey2Element.end());
+}
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline t_Val LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::getValue(
+ t_Key const & rKey ) const
+{
+ ::osl::MutexGuard aGuard( _aCacheMutex );
+ const typename t_Key2Element::const_iterator iFind( _aKey2Element.find( rKey ) );
+ if (iFind != _aKey2Element.end())
+ {
+ CacheEntry * pEntry = (*iFind).second;
+ toFront( pEntry );
+#ifdef __CACHE_DIAGNOSE
+ OSL_TRACE( "> retrieved element \"" );
+ OSL_TRACE( ::rtl::OUStringToOString( pEntry->aKey, RTL_TEXTENCODING_ASCII_US ).getStr() );
+ OSL_TRACE( "\" from cache <\n" );
+#endif
+ return pEntry->aVal;
+ }
+ return t_Val();
+}
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline void LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::setValue(
+ t_Key const & rKey, t_Val const & rValue )
+{
+ if (_nCachedElements > 0)
+ {
+ ::osl::MutexGuard aGuard( _aCacheMutex );
+ typename t_Key2Element::const_iterator const iFind( _aKey2Element.find( rKey ) );
+
+ CacheEntry * pEntry;
+ if (iFind == _aKey2Element.end())
+ {
+ pEntry = _pTail; // erase last element
+#ifdef __CACHE_DIAGNOSE
+ if (pEntry->aKey.getLength())
+ {
+ OSL_TRACE( "> kicking element \"" );
+ OSL_TRACE( ::rtl::OUStringToOString( pEntry->aKey, RTL_TEXTENCODING_ASCII_US ).getStr() );
+ OSL_TRACE( "\" from cache <\n" );
+ }
+#endif
+ _aKey2Element.erase( pEntry->aKey );
+ _aKey2Element[ pEntry->aKey = rKey ] = pEntry;
+ }
+ else
+ {
+ pEntry = (*iFind).second;
+#ifdef __CACHE_DIAGNOSE
+ OSL_TRACE( "> replacing element \"" );
+ OSL_TRACE( ::rtl::OUStringToOString( pEntry->aKey, RTL_TEXTENCODING_ASCII_US ).getStr() );
+ OSL_TRACE( "\" in cache <\n" );
+#endif
+ }
+ pEntry->aVal = rValue;
+ toFront( pEntry );
+ }
+}
+//__________________________________________________________________________________________________
+template< class t_Key, class t_Val, class t_KeyHash, class t_KeyEqual >
+inline void LRU_Cache< t_Key, t_Val, t_KeyHash, t_KeyEqual >::clear()
+{
+ ::osl::MutexGuard aGuard( _aCacheMutex );
+ _aKey2Element.clear();
+ for ( sal_Int32 nPos = _nCachedElements; nPos--; )
+ {
+ _pBlock[nPos].aKey = t_Key();
+ _pBlock[nPos].aVal = t_Val();
+ }
+#ifdef __CACHE_DIAGNOSE
+ OSL_TRACE( "> cleared cache <\n" );
+#endif
+}
+
+//==================================================================================================
+struct FctHashOUString : public ::std::unary_function< ::rtl::OUString const &, size_t >
+{
+ size_t operator()( ::rtl::OUString const & rKey ) const
+ { return (size_t)rKey.hashCode(); }
+};
+
+/** Template instance for OUString keys, Any values.<br>
+*/
+typedef LRU_Cache< ::rtl::OUString, ::com::sun::star::uno::Any,
+ FctHashOUString, ::std::equal_to< ::rtl::OUString > >
+ LRU_CacheAnyByOUString;
+
+
+#endif
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