store/source/storcach.hxx

   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
  20 #ifndef INCLUDED_STORE_SOURCE_STORCACH_HXX
  21 #define INCLUDED_STORE_SOURCE_STORCACH_HXX
  22
  23 #include <sal/config.h>
  24
  25 #include <memory>
  26
  27 #include <sal/types.h>
  28
  29 #include <store/types.h>
  30 #include "object.hxx"
  31
  32 namespace rtl { template <class reference_type> class Reference; }
  33 namespace store { struct PageData; }
  34
  35 namespace store
  36 {
  37
  38 struct Entry;
  39
  40 class PageCache :
  41     public store::OStoreObject
  42 {
  43     // Representation
  44     static size_t const theTableSize = 32;
  45     static_assert((theTableSize & (theTableSize-1)) == 0, "table size should be a power of 2");
  46
  47     Entry **     m_hash_table;
  48     Entry *      m_hash_table_0[theTableSize] = {};
  49     size_t       m_hash_size;
  50     size_t       m_hash_shift;
  51     size_t const m_page_shift;
  52
  53     size_t       m_hash_entries; // total number of entries in table.
  54     size_t       m_nHit;
  55     size_t       m_nMissed;
  56
  57     static int hash_Impl(sal_uInt32 a, size_t s, size_t q, size_t m)
  58     {
  59         return static_cast<int>(((a + (a >> s) + (a >> (s << 1))) >> q) & m);
  60     }
  61     int hash_index_Impl (sal_uInt32 nOffset)
  62     {
  63         return hash_Impl(nOffset, m_hash_shift, m_page_shift, m_hash_size - 1);
  64     }
  65
  66     Entry * lookup_Impl (Entry * entry, sal_uInt32 nOffset);
  67     void rescale_Impl (std::size_t new_size);
  68
  69 public:
  70     explicit PageCache (sal_uInt16 nPageSize);
  71
  72     PageCache(const PageCache&) = delete;
  73     PageCache& operator=(const PageCache&) = delete;
  74
  75     /** load.
  76      */
  77     storeError lookupPageAt (
  78         std::shared_ptr<PageData> & rxPage,
  79         sal_uInt32   nOffset);
  80
  81     /** insert.
  82      */
  83     storeError insertPageAt (
  84         std::shared_ptr<PageData> const & rxPage,
  85         sal_uInt32         nOffset);
  86
  87     /** update, or insert.
  88      */
  89     storeError updatePageAt (
  90         std::shared_ptr<PageData> const & rxPage,
  91         sal_uInt32         nOffset);
  92
  93     /** remove (invalidate).
  94      */
  95     storeError removePageAt (
  96         sal_uInt32 nOffset);
  97
  98 protected:
  99     virtual ~PageCache() override;
 100 };
 101
 102 storeError PageCache_createInstance (
 103     rtl::Reference< store::PageCache > & rxCache,
 104     sal_uInt16                           nPageSize
 105 );
 106
 107 } // namespace store
 108
 109 #endif // INCLUDED_STORE_SOURCE_STORCACH_HXX
 110
 111 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */