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