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/* Copyright (C) 2003 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
#ifndef WOPOOL_HPP
#define WOPOOL_HPP
#include "Pool.hpp"
struct WOPage
{
STATIC_CONST( WOPAGE_WORDS = GLOBAL_PAGE_SIZE_WORDS - 2 );
Uint32 m_type_id;
Uint32 m_ref_count;
Uint32 m_data[WOPAGE_WORDS];
};
/**
* Write Once Pool
*/
struct WOPool
{
Record_info m_record_info;
WOPage* m_memroot;
WOPage* m_current_page;
Pool_context m_ctx;
Uint32 m_current_page_no;
Uint16 m_current_pos;
Uint16 m_current_ref_count;
public:
WOPool();
void init(const Record_info& ri, const Pool_context& pc);
bool seize(Ptr<void>&);
void release(Ptr<void>);
void * getPtr(Uint32 i);
private:
bool seize_new_page(Ptr<void>&);
void release_not_current(Ptr<void>);
void handle_invalid_release(Ptr<void>);
void handle_invalid_get_ptr(Uint32 i);
void handle_inconsistent_release(Ptr<void>);
};
inline
bool
WOPool::seize(Ptr<void>& ptr)
{
Uint32 pos = m_current_pos;
Uint32 size = m_record_info.m_size;
WOPage *pageP = m_current_page;
if (likely(pos + size < WOPage::WOPAGE_WORDS))
{
ptr.i = (m_current_page_no << POOL_RECORD_BITS) + pos;
ptr.p = (pageP->m_data + pos);
pageP->m_data[pos+m_record_info.m_offset_magic] = ~(Uint32)m_record_info.m_type_id;
m_current_pos = pos + size;
m_current_ref_count++;
return true;
}
return seize_new_page(ptr);
}
inline
void
WOPool::release(Ptr<void> ptr)
{
Uint32 cur_page = m_current_page_no;
Uint32 ptr_page = ptr.i >> POOL_RECORD_BITS;
Uint32 *magic_ptr = (((Uint32*)ptr.p)+m_record_info.m_offset_magic);
Uint32 magic_val = *magic_ptr;
if (likely(magic_val == ~(Uint32)m_record_info.m_type_id))
{
* magic_ptr = 0;
if (cur_page == ptr_page)
{
if (m_current_ref_count == 1)
{
m_current_pos = 0;
}
m_current_ref_count--;
return;
}
return release_not_current(ptr);
}
handle_invalid_release(ptr);
}
inline
void*
WOPool::getPtr(Uint32 i)
{
Uint32 page_no = i >> POOL_RECORD_BITS;
Uint32 page_idx = i & POOL_RECORD_MASK;
WOPage * page = m_memroot + page_no;
Uint32 * record = page->m_data + page_idx;
Uint32 magic_val = * (record + m_record_info.m_offset_magic);
if (likely(magic_val == ~(Uint32)m_record_info.m_type_id))
{
return record;
}
handle_invalid_get_ptr(i);
return 0; /* purify: deadcode */
}
#endif
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