110 lines
4.2 KiB
C++
110 lines
4.2 KiB
C++
/* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#include <sys/types.h>
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#include "my_dbug.h"
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#include "my_inttypes.h"
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#include "storage/myisam/myisamdef.h"
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/*
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Read previous row with the same key as previous read
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One may have done a write, update or delete of the previous row.
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NOTE! Even if one changes the previous row, the next read is done
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based on the position of the last used key!
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*/
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int mi_rprev(MI_INFO *info, uchar *buf, int inx) {
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int error, changed;
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uint flag;
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MYISAM_SHARE *share = info->s;
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DBUG_TRACE;
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if ((inx = _mi_check_index(info, inx)) < 0) return my_errno();
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flag = SEARCH_SMALLER; /* Read previous */
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if (info->lastpos == HA_OFFSET_ERROR && info->update & HA_STATE_NEXT_FOUND)
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flag = 0; /* Read last */
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if (fast_mi_readinfo(info)) return my_errno();
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changed = _mi_test_if_changed(info);
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if (share->concurrent_insert) mysql_rwlock_rdlock(&share->key_root_lock[inx]);
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if (!flag)
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error =
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_mi_search_last(info, share->keyinfo + inx, share->state.key_root[inx]);
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else if (!changed)
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error =
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_mi_search_next(info, share->keyinfo + inx, info->lastkey,
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info->lastkey_length, flag, share->state.key_root[inx]);
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else
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error = _mi_search(info, share->keyinfo + inx, info->lastkey, USE_WHOLE_KEY,
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flag, share->state.key_root[inx]);
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if (!error) {
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int res = 0;
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while ((share->concurrent_insert &&
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info->lastpos >= info->state->data_file_length) ||
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(info->index_cond_func &&
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!(res = mi_check_index_cond(info, inx, buf)))) {
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/*
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Skip rows that are either inserted by other threads since
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we got a lock or do not match pushed index conditions
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*/
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if ((error = _mi_search_next(info, share->keyinfo + inx, info->lastkey,
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info->lastkey_length, SEARCH_SMALLER,
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share->state.key_root[inx])))
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break;
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}
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if (!error && res == 2) {
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if (share->concurrent_insert)
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mysql_rwlock_unlock(&share->key_root_lock[inx]);
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info->lastpos = HA_OFFSET_ERROR;
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set_my_errno(HA_ERR_END_OF_FILE);
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return HA_ERR_END_OF_FILE;
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}
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}
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if (share->concurrent_insert) {
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if (!error) {
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while (info->lastpos >= info->state->data_file_length) {
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/* Skip rows that are inserted by other threads since we got a lock */
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if ((error = _mi_search_next(info, share->keyinfo + inx, info->lastkey,
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info->lastkey_length, SEARCH_SMALLER,
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share->state.key_root[inx])))
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break;
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}
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}
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mysql_rwlock_unlock(&share->key_root_lock[inx]);
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}
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info->update &= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);
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info->update |= HA_STATE_PREV_FOUND;
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if (error) {
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if (my_errno() == HA_ERR_KEY_NOT_FOUND) set_my_errno(HA_ERR_END_OF_FILE);
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} else if (!buf) {
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return info->lastpos == HA_OFFSET_ERROR ? my_errno() : 0;
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} else if (!(*info->read_record)(info, info->lastpos, buf)) {
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info->update |= HA_STATE_AKTIV; /* Record is read */
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return 0;
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}
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return my_errno();
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} /* mi_rprev */
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