1 files changed, 108 insertions, 0 deletions
diff --git a/store/source/storcach.hxx b/store/source/storcach.hxx
new file mode 100644
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+++ b/store/source/storcach.hxx
@@ -0,0 +1,108 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#pragma once
+
+#include <sal/config.h>
+
+#include <memory>
+
+#include <sal/types.h>
+
+#include <store/types.h>
+#include "object.hxx"
+
+namespace rtl { template <class reference_type> class Reference; }
+namespace store { struct PageData; }
+
+namespace store
+{
+
+struct Entry;
+
+class PageCache :
+    public store::OStoreObject
+{
+    // Representation
+    static size_t const theTableSize = 32;
+    static_assert((theTableSize & (theTableSize-1)) == 0, "table size should be a power of 2");
+
+    Entry **     m_hash_table;
+    Entry *      m_hash_table_0[theTableSize] = {};
+    size_t       m_hash_size;
+    size_t       m_hash_shift;
+    size_t const m_page_shift;
+
+    size_t       m_hash_entries; // total number of entries in table.
+    size_t       m_nHit;
+    size_t       m_nMissed;
+
+    static int hash_Impl(sal_uInt32 a, size_t s, size_t q, size_t m)
+    {
+        return static_cast<int>(((a + (a >> s) + (a >> (s << 1))) >> q) & m);
+    }
+    int hash_index_Impl (sal_uInt32 nOffset)
+    {
+        return hash_Impl(nOffset, m_hash_shift, m_page_shift, m_hash_size - 1);
+    }
+
+    Entry * lookup_Impl (Entry * entry, sal_uInt32 nOffset);
+    void rescale_Impl (std::size_t new_size);
+
+public:
+    explicit PageCache (sal_uInt16 nPageSize);
+
+    PageCache(const PageCache&) = delete;
+    PageCache& operator=(const PageCache&) = delete;
+
+    /** load.
+     */
+    storeError lookupPageAt (
+        std::shared_ptr<PageData> & rxPage,
+        sal_uInt32   nOffset);
+
+    /** insert.
+     */
+    storeError insertPageAt (
+        std::shared_ptr<PageData> const & rxPage,
+        sal_uInt32         nOffset);
+
+    /** update, or insert.
+     */
+    storeError updatePageAt (
+        std::shared_ptr<PageData> const & rxPage,
+        sal_uInt32         nOffset);
+
+    /** remove (invalidate).
+     */
+    storeError removePageAt (
+        sal_uInt32 nOffset);
+
+protected:
+    virtual ~PageCache() override;
+};
+
+storeError PageCache_createInstance (
+    rtl::Reference< store::PageCache > & rxCache,
+    sal_uInt16                           nPageSize
+);
+
+} // namespace store
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */