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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include "Undo_buffer.hpp"
#define DBTUP_C
#include "Dbtup.hpp"
#if ZPAGE_STATE_POS != 0
#error "PROBLEM!"
#endif
struct UndoPage
{
File_formats::Page_header m_page_header;
Uint32 _tupdata1;
Uint32 m_state; // Used by buddy alg
Uint32 m_words_used;
Uint32 m_ref_count;
Uint32 m_data[GLOBAL_PAGE_SIZE_WORDS-4-(sizeof(File_formats::Page_header)>>2)];
STATIC_CONST( DATA_WORDS = GLOBAL_PAGE_SIZE_WORDS-4-(sizeof(File_formats::Page_header)>>2) );
};
Undo_buffer::Undo_buffer(Dbtup* tup)
{
m_tup= tup;
m_first_free= RNIL;
}
Uint32 *
Undo_buffer::alloc_copy_tuple(Local_key* dst, Uint32 words)
{
UndoPage* page;
assert(words);
if(m_first_free == RNIL)
{
Uint32 count;
m_tup->allocConsPages(1, count, m_first_free);
if(count == 0)
return 0;
page= (UndoPage*)m_tup->c_page_pool.getPtr(m_first_free);
page->m_state= ~ZFREE_COMMON;
page->m_words_used= 0;
page->m_ref_count= 0;
}
page= (UndoPage*)m_tup->c_page_pool.getPtr(m_first_free);
Uint32 pos= page->m_words_used;
if(words + pos > UndoPage::DATA_WORDS)
{
m_first_free= RNIL;
return alloc_copy_tuple(dst, words);
}
dst->m_page_no = m_first_free;
dst->m_page_idx = pos;
page->m_ref_count++;
page->m_words_used = pos + words;
return page->m_data + pos;
}
void
Undo_buffer::shrink_copy_tuple(Local_key* key, Uint32 words)
{
assert(key->m_page_no == m_first_free);
UndoPage* page= (UndoPage*)m_tup->c_page_pool.getPtr(key->m_page_no);
assert(page->m_words_used >= words);
page->m_words_used -= words;
}
void
Undo_buffer::free_copy_tuple(Local_key* key)
{
UndoPage* page= (UndoPage*)m_tup->c_page_pool.getPtr(key->m_page_no);
Uint32 cnt= page->m_ref_count;
assert(cnt);
page->m_ref_count= cnt - 1;
if(cnt - 1 == 0)
{
page->m_words_used= 0;
if(m_first_free == key->m_page_no)
{
//ndbout_c("resetting page");
}
else
{
//ndbout_c("returning page");
m_tup->returnCommonArea(key->m_page_no, 1);
}
}
key->setNull();
}
Uint32 *
Undo_buffer::get_ptr(Local_key* key)
{
return ((UndoPage*)(m_tup->c_page_pool.getPtr(key->m_page_no)))->m_data+key->m_page_idx;
}
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